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    • 专利摘要:
    The invention relates to a screen basket to be used for treating pulp, comprising on the feed stream side of the stock a screen surface and screen openings on the feed side, the screen openings being arranged to direct a portion of the fiber mass fed on the feed side of the screen basket to an accept side on the screen basket. In one example, at least a portion of the screen surface and the wall length of the screen openings on the feed side are coated with a first coating layer containing chemical nickel. Additionally, at least a portion of the feed side screen surface coated with the first coating layer is coated with a second coating layer that is a hard chrome or hard metal coating. The invention also relates to a method for coating the screen basket.
    公开号:AT13675U1
    申请号:TGM167/2013U
    申请日:2013-05-07
    公开日:2014-06-15
    发明作者:Tarja Laitinen；Joni Miettinen
    申请人:Metso Paper Inc；
    IPC主号:
    专利说明:

    Austrian Patent Office AT 13 675 Ul 2014-06-15
    description
    SCOPE OF THE INVENTION
    The present invention is a coating for a used in the treatment of fiber mass metal wear part and a method for producing the coating. In particular, the invention relates to a wear-resistant double coating for a screen basket and its manufacture.
    BACKGROUND OF THE INVENTION
    Sieve baskets are used in the paper and cellulose industry in the fiber pulp manufacturing process to separate impurities from the pulp and fibers of different lengths from each other. The pulp may be from its origin new wood material from the forest or used paper or cardboard.
    A sieve surface on the sieve basket comprises sieve nips via which a liquid to be treated in a sieve sorter which is in a pulp mixture and a fraction of the fibers determined by the size of the sieve nips from the feed side of a sieve drum to the outside of the sieve drum, i. to the acceptance side and from there on in the mass production process. The portion of the pulp mixture that has not flowed from the feed side on the screen drum to the accept side on the screen drum is removed to be further processed. For the strainer, the term sieve drum can also be used, i. it is a wear component that is attached to a screen body. The entire system is referred to as Siebsortierer.
    During the deposition process of the pulp mixture, in particular, the hard impurities present in the pulp, such as sand, glass and metal, wear the profile and the sieve gaps on the sieve surface on the sieve basket. Metal wear parts, such as screen baskets, can be electroplated by hard chrome plating, i. by precipitating pure chromium from an electrolyte solution onto the surface of the part. The purpose of hard chrome plating is to increase the hardness of the surface and thus to improve the wear resistance of the part. In hard chrome plating, either sulfate or an organic catalyst can be used as the catalyst in the electrolyte solution to be used (chromic acid bath). Hard chromium plating forms hexavalent chromium (Cr6 +), which is a highly carcinogenic hazardous waste and is removed from the process with, among other things, waste water. Also, the entire chromic acid bath must be renewed at certain time intervals. A problem in the chrome plating are also cracks and embrittlement at larger coating thicknesses.
    In the publication US2004 / 0195158 a multilayer coating for a screen basket is shown. The coating comprises both a hard chrome plating cover and an iron-free coating layer which serves as an indicator layer for detecting the wear of the hard chrome plating.
    BRIEF SUMMARY OF THE INVENTION
    The present invention is a Siebkorb to be used for sorting and cleaning fiber mass, which comprises on the Zuführstromseite the fiber mass a screen surface and screen openings, wherein the screen openings are arranged, a portion of the supplied on the feed side of the strainer fiber mass on an accept side to guide on the screen basket. It is characteristic of the screen basket that at least part of the screen surface and the wall lengths of the screen openings on the feed side of the screen basket are coated with a first coating layer containing chemical nickel. In addition, it is characteristic of the screen basket that at least part of the screen surface coated with the first coating layer is coated on the feed side with a second coating layer. The second coating layer may be a hard chrome coating or a carbide-hard cemented carbide coating.
    The invention also relates to a method for coating a screen basket for producing a double coating. The coating process comprises at least the following steps: the coating of at least a portion of the screen surface and the wall length of the screen openings on the feed side of the screen basket with chemical nickel to form a first coating layer and the coating of at least a portion of the screen surface on the feed side with hard chrome or a carbide-containing cemented carbide Forming a second coating layer.
    In the dependent claims, some preferred embodiments of the invention are shown.
    According to one embodiment of the invention, the thickness of the first coating layer is 5 to 80 pm, preferably 10 to 60 pm, most preferably 10 to 40 pm.
    According to one embodiment of the invention, the thickness of the second coating layer is 50 to 500 μm. According to one embodiment of the invention, the first and second coating layers form a double coating in which the relative proportion of the first coating layer to the thickness of the double coating becomes smaller as the thickness of the second coating layer.
    According to one embodiment of the invention, a screen opening on the screen basket has a diameter which is at least partially formed by the thickness of the first coating layer at least from the direction of the feed side.
    According to one embodiment of the invention, the diameter of the sieve opening on the sieve basket is 0.1 to 15 mm, preferably 0.1 to 0.8 mm.
    According to one embodiment of the invention, the first coating layer of the screen basket made of chemical nickel containing 1 to 14% phosphorus or 1 to 6% boron.
    According to one embodiment of the invention, the second coating layer consists of carbide-containing cemented carbide which has been produced by thermal spraying onto the first coating layer on the sieve surface.
    According to one embodiment of the invention, the carbide-containing cemented carbide coating contains tungsten carbide particles and / or chromium carbide particles. The carbide-containing hard metal coating may be, for example, a metal alloy WC-10Co-4Cr, CrC3C2-25NiCr, WC-20Cr3C2-7Ni, and Cr3C2-37WC-18, respectively, in composition. The metal alloy may, for example, consist of a predominantly nickel and cobalt-containing metal alloy.
    According to one embodiment of the invention, at least a portion of the wall length of the screen opening from the direction of the feed side to form the Sieböffnungsdurchmessers coated with chemical nickel, for example a sieve gap on the wire mesh basket. With chemical nickel at least 5%, preferably at least 10% of the sieve opening diameter can be formed.
    According to one embodiment of the invention, the nickel chemical coating is formed with a dip coating in a nickel plating bath, wherein the phosphorus content in the bath is 1 to 14% or the boron content is 1 to 6%. The nickel chemical coating may be cured by thermally treating the coated part at 200 to 500 ° C before forming the second coating layer.
    According to one embodiment of the invention, the second coating layer is formed by thermal spraying with carbide-containing cemented carbide. The thermal spraying can be carried out in the vertical direction with respect to the surface profile of the first surface on the screen surface.
    According to one embodiment of the invention, the wear resistance of the thermally sprayed hard metal coating can be improved by brushing or grinding the surface, for example with a diamond brush or a sanding belt. A smoothed surface also prevents adhesion of fibers and contaminants to the surface. Such a surface may also reduce flow resistance, most preferably resulting in energy savings in such sorters in which the screen basket rotates and a vane rotor is a fixed stator in place.
    According to one embodiment of the invention, the coating method further comprises a part for removing an existing double coating from the surface before the formation of the first coating layer. An existing double coating can be removed by chemical treatment in such a way that both layers of the double coating dissolve at the same time. DESCRIPTION OF THE DRAWINGS Some embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 Figure 2 Figure 3 [0026] Figure 4 Fig. 6 Fig. 7 Fig. 9 Fig. 9 Fig. 10 Fig. 12 in cross section a construction of a screen basket from the end of the strainer basket, as a cross-section illustrating the construction of a perforated screen plate on a perforated screen, represented as a cross-section of an example of a perforated screen profile for a strainer, represented as a cross section by an example of a strainer screen, as a cross section a construction of a wire strainer basket from the end of the screen wires when viewed in cross-section, a construction of a coated wire mesh basket viewed from the end of the screen wires is shown in cross-section as a construction of a coated wire mesh basket viewed from the end of the screen wires in cross-section illustrating a construction of a coated wire mesh basket as viewed from the end of the screen wires, as a cross-section illustrating a construction of a coated wire mesh basket as seen from the end of the screen wires, seen in cross section a construction of a coated wire mesh basket from the end of the screen wires and an example of a thermal spray angle Spraying, when viewed in cross-section as a construction of a coated wire mesh basket from the end of the screen wires and an example of a spray angle for thermal spraying, is a schematic of a thermally sprayed coating.
    DETAILED DESCRIPTION OF THE INVENTION
    By the term " screen basket " In this application, a wear part of a sieve sorter is meant, which is used in the cleaning and sorting of pulp mixture. The screen basket may be a perforated perforated screen basket or a wire screen basket formed of wires and including gaps between the wires. The strainer basket may also be a column screen basket formed by plates by machine. For perforated sieve basket, column sieve basket and wire sieve basket, the general designation sieve basket is used in this application. The sieve basket can also be called a sieve drum. 3/22 Austrian Patent Office AT13 675U1 2014-06-15 [0036] For the holes and gaps in the sieve basket, the general designation opening or sieve opening is used in the application. The screen opening of the screen basket forms between the feed side and the accept side of the screen surface on the screen basket from a channel which is usually in the form of a circle or an elongated gap, with a screen gap at the narrowest point of the channel. the sieve opening is located. The sieve opening is for a sorting capacity of the screen basket and on the other hand for a permeability, i. for production, central. The channel between the feed side and the accept side may also have a different shape. The opening in the strainer basket or channel is made in such a way that the narrowest point of the opening or channel is typically located closer to the edge of the feed side of the channel than to the edge of the accept side. The feed opening or the channel narrows or narrows from the edge of the feed side to the screen surface to the point of the sieve hole or the sieve gap, from where the opening or the channel widens towards the edge of the accept side. The narrowest point can also be arranged on the edge of the feed side and in some cases also on the edge of the accept side. The liquid present in the pulp mixture and the proportion of the fibers determined by the size of the sieve openings can be flowed from the side of the feed flow of the sieve basket to the outside of the sieve basket or to the accept side via the sieve openings in the sieve basket. The term " diameter " is used in the application as a general name for the diameter of a hole in Lochsiebkorb and for the width of a sieve column in Drahtsiebkorb or Spaltsiebkorb.
    By the term " wearing part " is meant a part which is at least covered by one face with a different mechanism wear, i. is exposed to a release of material, for example, which causes pressure drops, dimensional changes and deformations or a weakening of the surface quality at the part. Among other things, wear can be caused by adhesive wear, abrasive wear and erosion wear. By the term " double coating " is meant a coating composed of a first and a second coating layer. For the double coating, the term double layer coating or combination coating can also be used.
    Unless otherwise stated, the percentages in this application are weight percentages. With the character > before a numeric value is " more, greater than " and with the character < " less, less than " meant.
    In Fig. 1, a schematic diagram of a cross section of a strainer basket 1 in a sieve sorter in the axial direction of the strainer basket, i. seen from the end of the strainer. The inner circumference of the sieve basket forms a sieve surface 2 on the sieve basket. The sieve surface 2 on the sieve basket 1 can consist of a curved perforated sieve plate.
    Alternatively, the screen surface on the screen basket consist of juxtaposed screen wires, which are typically mounted on a support rod 4, wherein the support rod is bent in a circle to reach a certain diameter H of the screen basket. The screen wires can also be mounted on a cut from a plate mounting ring, which eliminates a separate bending work. The feed side (feed flow side) S for the pulp mass may be positioned on the inside 10 of the screen basket, whereby the pulp flows from the inside of the screen basket to the outside. Alternatively, the feed side of the screen basket may be positioned on the outside of the screen basket, i. the pulp flows from the outside to the inside 10.
    In Fig. 2, a cross section of a construction of the screen surface 2 is shown schematically on the screen basket 1, which is formed by a plate 6 and present in the plate holes / columns 8, which from the side of the feed flow S in the strainer to accept side AK openings form. The openings have both a first wall 5 and a second wall 7. The walls have a total length which corresponds to the dimension of the screen surface from the feed side to the accept side. The opening may be uniform in diameter and the walls thereof may be parallel, as shown in Figs. 2 and 3 of the Austrian Patent Office AT13 675U1 2014-06-15. Alternatively, the diameter of the opening on the accept side AK on the screen surface may be larger than on the feed side S of the screen basket, as shown in FIG. 4. A surface 18 provided in the direction of the feed side S of the plate 6 forms the screen surface 2 on the feed side S of the screen basket, i. a surface which is on the side of the supply flow S of the pulp.
    In Figs. 3 and 4 alternative constructions of a screen surface are shown, wherein the existing in the direction of the feed side S of the plate 6 surface 18 is profiled. The profiled surface of the plate thus forms the screen surface 2 on the feed side S. The profiled surface may be, for example, such that the first wall of the opening 8 is higher than the second wall. The profiled perforated screen basket can be made, for example, by machining a profile in the drum and drilling holes.
    The wire mesh basket, in turn, can be made, for example, from a sieve panel which is made by attaching cold drawn sieve wires to the support rod 4 either mechanically by adding, gluing or welding. The screen panel is further bent into a drum and the ends are joined by welding. The screen wire basket can also be made by attaching the screen wires to a cut-out mounting ring, eliminating a separate bending work. Support rings can be added to the wires and at their ends to increase stiffness and allow attachment to the housing. The slotted screen basket can be made, for example, by machining such deep grooves on the feeding and / or accepting side of the screen basket that continuous gaps are formed on the screen surface from the feeding side to the accepting side.
    In Fig. 5, an example of a screen surface 2 is shown on a wire mesh basket as a cross section seen from the end of a wire rod 22. In the figure, three adjacent screen wires 22 are shown, which are arranged side by side at a certain distance from each other in such a way that a sieve gap 3 remains between them. A first surface 12 of the wire is in the screen basket construction on the side of the supply flow S (feed side) of the fiber mass and forms part of the area on the feed side of the screen surface 2. The wire also has a first side 14 and a second side 16. The total length of the page corresponds to the length of the page from the feed side to the accept side. The screen gap 3 remains between the sides 14 and 16 of the adjacent wires on the feed side. In connection with the sieve gap, the term wall can also be used for side. The first surfaces 12 of the adjacent screen wires located in the direction of the feed side S of the screen basket form the screen surface on the feed side of the screen basket, i. the area that lies on the side of the supply flow S of the fiber mass. The screen surface on the feed side also includes a tip 20 of the wire screen.
    The strainer basket is typically made of a metallic material. For example, metallic material may be acid-resistant stainless steel (FeCrNiMo), such as austenitic stainless steel 1.4404, 1.4307 or 1.4547 or duplex steel 1.4462 according to EN standard. In practice, the strainer basket is subject in particular to erosion wear which is caused by the impact of solid and hard particles moving in the material flow against the wear surface. In the screen basket, in particular, the screen surface 2 on the feed side S and the screen openings 3, 8 opening to the feed side are subject to wear, i. in other words, the surfaces 12 of the screen wires 22 on the screen surface 2 located in the wire screen basket on the side of the feed flow S of the fiber mass and the sides 14, 16 delimiting the gap spacing of the adjacent screen wires, in particular from the side of the feed flow. Correspondingly, the surface 18 on the side of the supply flow at the perforated wire plate 6 of the perforated screen basket and the edge surfaces (walls) of the holes / openings 8 are subject to wear, in particular from the side of the feed flow S. For example, the profile of the screen wires of the screen basket may wear in such a way as to cause enlargement / reduction of the screen gap 3 between the wires or a rounding of the tip 20 on the wire on the side of the feed flow. The size, mass, amount of movement and hardness of the particles impacting the wear, as well as the thickness and hardness of the coating, affect the wear. The screen openings 3, 8 on the screen surface on the feed side are subject in particular to wear due to fine particles. The enlargement of the sieve gaps weakens, for example, the cleaning / sorting capacity of the sieve basket. For example, wear on the profile of the wires on the wire mesh basket can cause a reduction in turbulence at the feed surface, which in turn results in a reduction in screen basket capacity.
    The wear resistance of the strainer basket can be improved with a two-phase coating process with which a double coating consisting of a first and a second coating layer is produced on the surface of the strainer basket. The surface underlying the first coating layer may be referred to as a base material surface. At least the screen surface 2 on the screen basket has a coating. According to one embodiment, at least the surface on the side of the feed flow S of the fiber mass substantially at the screen surface 2 on the screen basket, i. the screen surface 18, 12 on the feed side, a double coating on. Preferably, at least one coating layer is also present in the screen openings 3, 8 located on the screen surface 2. In particular, the walls of the screen openings have a coating which is present essentially on the side of the feed flow S on the screen surface. The coating does not necessarily extend the entire length of the sieve opening, i. over the entire wall length of the opening from the side of the feed flow S to the accept side AK. For example, the coating in the gap spacings 3 on the wire screen basket may only be present over a certain length on the side 14, 16 of the wire screen. For example, the coating on the sides of the wire may extend only to the joint L between the wire and the support rod, as illustrated, inter alia, in FIG. According to a preferred embodiment, in particular the first coating layer is formed on the entire screen surface 2 on the feed side of the screen basket. In addition, the first coating layer is formed in the sieve opening or in the channel at the narrowest point of the sieve opening or the channel. The coating layer can also extend slightly beyond the narrowest point of the sieve opening or the channel out of the direction of the feed side S in the direction of the acceptance side AK. By controlling the thickness of the first coating layer, it is preferable that the diameter of the hole or gap in the screen basket, i. the sieve opening to be adjusted.
    It is possible to coat a finished Siebkorbkonstruktion, for example a screen drum or a perforated drum in which the required support rings are mounted. Alternatively, the separate wear parts may be coated, such as Endstützringe and / or screen wires prior to the manufacture of the screen panel. The finished screen panel is cylindrical prior to being bent into a drum shape, just prior to assembly of the screen basket construction. In particular, the coating method is suitable for the coating of wire mesh baskets. The coating process can also be used for re-coating worn screen baskets.
    The double coating according to the invention is also preferably suitable for use in screen baskets in which the sieve openings present on their screen surface 2 have a diameter of less than 15 mm, but at least 0.1 mm. The diameter of the holes is for example 0.1 to 15 mm and the width of the sieve gaps 0.1 to 0.8 mm.
    In the first phase of the double coating, the surface of the part or a part of the surface of the part is coated with chemical nickel EN (EN = Electroless Nickel Plating). More specifically, a controlled autocatalytic precipitation of the nickel is carried out with a reducing agent on the surfaces of the part. For the coating process, the term autocatalytic chemical nickel plating can also be used. The coating formed in the first phase is referred to as the first coating layer. According to one embodiment, at least part of the screen surface 2 and the wall length of the screen openings 3, 8 on the feed side S are coated with the first coating layer containing chemical nickel. The thickness of the first coating layer may be, for example, 5 to 80 μm, more preferably 10 to 60 μm, most preferably 10 to 40 μm. In the chemical coating with nickel, no external power supply is needed, but the electrons are generated by the chemical reactions in the electrolyte. With the method, for example, a nickel plating may be precipitated on the surface of the screen basket made of a metal material with a reducing agent (reduced nickel plating). The reducing agent may be a phosphorus or boron compound. The cathode used is the part to be coated. The part to be coated also serves as a catalyst. The nickel coating reduced on the surface of the part is catalytic, thus further catalyzing the reaction, i. the coating reaction continues and thick coatings can be produced. If the coating is not catalytic, the coating reaction stops when the surface of the part to be coated is covered by a coating metal.
    A chemically nickel-plated coating is not pure nickel, but the coating always contains, depending on the reducing agent, either phosphorus, boron or tin. One exception is hydrazine, which acts as a reducing agent, precipitating the nickel on the surface of the part to be coated as pure nickel. A coating as pure nickel is rare.
    In the chemical nickel coating, i. in the first coating layer, besides nickel, there is always a second substance, i. it is a combination coating containing nickel, depending on the reducing agent, for example, boron or phosphorus in addition to nickel. In addition to phosphorus and / or boron, cobalt or tungsten may also be present in the chemical nickel coating. Also, alloying elements such as alumina, diamond particles, boron nitrogens or silicon carbide may be added to the bath, whereby various dispersion coatings can be obtained. The nickel coating consists mainly of nickel, the amount of which is 100% minus phosphorus, boron and / or other additives.
    On the composition of the chemical nickel coating, both the composition of the nickel plating bath and process parameters act. The nickel plating bath may contain, inter alia, stabilizers, accelerators, complexing agents, buffering agents and / or surface-active substances. Among other things, the pH of the bath and the reducing agent used act on the coating temperature. The coating temperature can be between 60 and 100 ° C. If the coating temperature is below 60 ° C, the coating speeds are generally very low, for example below 5 pm / h. A fast coating time is advantageous in terms of energy saving. In acidic hypophosphite based electrolyte baths, the coating temperature is more preferably 80 to 90 < €.
    The part can be coated, for example by oxidation with a Phosphitbad, wherein serving as reducing agent, for example, hydrogen hypophosphite or sodium hypophosphite. The chemical nickel plating bath contains about 2 to 8 g / l nickel. In the nickel plating bath, for example, nickel sulfate or nickel chloride may be used as the nickel. The pH in the bath may be, for example, between 4 to 5 or 8 to 11. The pH in the bath can be adjusted, for example, with ammonia, sodium hydroxide or sulfuric acid. The Phosphitbad is easy to control, advantageous and allows a run without heavy metals. The phosphorus content in the bath can be between 1 and 14%. The molar ratio of nickel and hydrogen hypophosphite in the Ni 2+ / H 2 PO 2 bath should be set in a range of 0.25 to 0.60, more preferably in a range of 0.30 to 0.45. The phosphorus content of the coating can contain phosphorus-poor 1 to 7 wt .-% phosphorus, an average content of 7 to 10 p-% phosphorus or phosphorus rich 10 to 14 wt .-% phosphorus. The temperature of the nickel bath and in particular the pH of the bath act on the phosphorus content. By reducing the pH of the nickel bath, the phosphorus content in the nickel bath and accordingly also the nickel coating to be formed in the nickel bath increases. The phosphorus content of the nickel coating generally forms the phosphorus content of the nickel bath. Alternatively, the nickel bath may contain as reducing agent boron compounds, for example sodium borohydride or dimethylamine borane. Depending on the content of the boron compounds in the nickel bath, 1-6% boron forms on the first coating layer. For applications requiring hardness and wear resistance, at least 2% is selected as the boron content for the coating. As a reducing agent, for example, dimethylamine borane can serve between 0.2 and 4%. Alternatively, sodium borohydride can be used between 4 and 7%. For example, the pH of a boron-containing bath may be between 5 and 14.
    In an acidic operating environment, the corrosion resistance of a low-phosphorus nickel coating is weaker than that of a phosphorus-rich nickel coating. In a basic, i. In alkaline operating environments, the corrosion resistance of a low-phosphorus nickel coating is better than that of a phosphorus-rich nickel coating. The pH of an acidic operating environment is below 7 and the pH of a basic operating environment is above 7. In practice, the weaknesses of phosphorus contents occur at a pH below 4 or above 9. In some sieve sorting processes the pH is below 4 or above 9, but in more conventional sieve sorting processes the pH is between 4 and 9.
    A thermal treatment weakens the corrosion resistance of the low-phosphorus nickel coating, since almost all of the phosphor forms separate, hardness-forming compounds together with nickel. This results in phosphorus-rich and low-phosphorus areas, between which forms a potential difference promoting corrosion. For phosphorus-rich nickel, the effect of the thermal treatment is less or irrelevant.
    By heat treatment of the phosphorus nickel coating, the hardness for the coating can be significantly increased. For example, hard compounds such as Ni3P form on the phosphorus-containing nickel coating during the thermal treatment. The hardness of the coating is adjusted by means of time and temperature of the thermal treatment. A boron-containing nickel coating is particularly hard without heat treatment, but this can also be improved by thermal treatment. In one embodiment, phosphor-containing nickel is used to coat wear parts requiring corrosion resistance, for example, a high-phosphorus nickel coating containing 10 to 14% phosphorus. The thermal treatment can also achieve an optimum coating in terms of corrosion resistance and hardness.
    A micro Vickers hardness of the nickel chemical coating may be about 500 HV (1 N load). The hardness can even be raised to a value of 1,100 HV (1 N load) with the thermal treatment. The microhardness is determined according to DIN 50133. For the coated part, the thermal treatment can be carried out, for example, at a temperature of 200 to 500 Ό. For example, the coated part is subjected to a thermal treatment of 450 ° C for one hour, whereby about 1,000 HV can be achieved as the Vickers hardness of the coating. By advantageously selecting the temperature and time for the thermal treatment, the desired hardness and corrosion resistance are achieved for the first coating layer. The thermally treated chemical nickel coating is golden in color. The golden yellow color can be used as an indicator of wear in estimating a post-coating requirement. The color of the first coating layer makes it visually easy to determine when the profile of the part is still recoverable according to the original profile, for example by means of a post-coating. By passivation, the nickel coating can alternatively be formed black in color. The black color can be used accordingly as a visual indication of wear. The black color is achieved without thermal treatment, which can be advantageous if, for example, the effect of the thermal treatment on the corrosion and on the thermal treatment possibly following deformation of the screen basket are taken into account. The microhardness of a non-chemically treated Ni-P nickel coating containing 10 to 14% phosphorus may be 500HV200, for example. The hardness of a corresponding coating may be thermally treated, for example 900HV200. The microhardness AT13 675U1 2014-06-15 te is determined according to DIN 50133 and HV200 = 200g / 2N.
    Magnetization of the nickel chemical coating can exacerbate the production of the second coating layer. A hard chrome coating is produced using electric current, whereby the magnetization of the nickel coating can affect the current density and / or can unfavorably align its vector direction. The magnetization may also cause unfavorable turbulence in the jet of thermal spraying since molten metal and gas may be partially ionized or otherwise polarized. Of the nickel-phosphorus coatings, a low-phosphor coating is most ferromagnetic, a medium-phosphor coating ten times less magnetic than a low-phosphor nickel coating. A phosphorus-rich nickel coating is not magnetic. The thermal treatment can quintuple the magnetization as a result of a rearrangement caused by phase changes. Nickel-boron coatings are significantly less ferromagnetic than nickel-phosphorus coatings. Taking into account the impairing effects of magnetization, it is thus advantageous with regard to the manufacturability of the double coating to form the first coating layer with medium-phosphorus nickel and even more advantageously with phosphorus-rich nickel.
    In view of the durability of the double coating, it is important that the connection between the base material and the first coating layer be permanently formed. In addition, the double coating has the effect of firmly adhering the second coating layer to the first coating layer. The phosphorus-rich first coating layer improves the adhesiveness of the first coating layer to the base material. The adhesiveness of the second coating layer to the first coating layer is in turn improved as the phosphorus content of the first coating layer decreases. This is due to the reduction of compressive stress forming in the coating. With regard to the adhesive strength of the second coating layer, it would thus be advantageous to produce the first coating layer with an average phosphorus content. In general, the highest possible phosphorus content is sought, so that a good corrosion resistance is achieved in an acidic environment, which is why it is preferable to choose a coating rich in phosphorus. The phosphorus content of the first coating layer is then chosen to be lower (for example, with an average phosphorus content) if the adhesiveness of the second coating layer is dominant or if the operating environment is alkaline.
    Chemical nickel plating is a dip coating process in which the part to be coated is immersed in a tank and the coating forms uniformly on all surfaces of the part. With the chemical nickel plating a uniformly thick coating layer can be achieved on the part. The coating can be located, for example, on each side of the screen basket, also in the gap spacing or screening gaps 3 on the sides 14, 16 of the screen wires of the screen basket. If it is desired not to coat any area, it may be covered with a mask which prevents adhesion of the coating. In dip coating, the coating thickness increases as a function of time, for example 16 to 25 pm / h, 5 to 15 pm / h or 4 to 10 pm / h. The rate of growth of the coating thickness is affected, inter alia, by the composition of the bath, the pH, and other coating parameters, such as coating temperature and mixing of the bath. The mixing can be carried out, for example, mechanically or with filtered air. The coating thickness of the part may be, for example, 5 to 100 μm. According to one embodiment of the invention, the coating thickness is at most about 60 to 80 pm. For thicker coatings, internal tensile stresses form on the coating, which can cause embrittlement and cracking in the coating. By adjusting the coating thickness for the first coating layer, the gap distance of the screen basket can also be adjusted, i. the diameter of the sieve opening. For example, the gap distance can be reduced by twice the coating layer if both walls of the gap have the same amount of coating.
    The size of the particles loading the walls of the openings 3, 8 on the screen surface 2 of the screen basket corresponds at most to the hole diameter or the gap width. The thickness of the first coating layer to be formed on the walls of the sieve surface 2 and of the sieve openings on the side of the feed flow S of the fiber mass in the sieve basket is preferably at least 5%, more preferably at least 8/22 Austrian Patent Office AT 13 675 U1 2014-06-15 10% of the gap diameter, whereby the coating layer structurally forms a sufficiently thick layer that can withstand the load caused by the surface loading particles. The smallest measure of the hole or gap of the opening on the screen surface of the screen basket, i. of the channel, such as the screen gap 3, can be preferably adjusted to 10 to 120 μm, more preferably to 20 to 80 μm, by means of the first coating layer. The thickness of the first coating layer is in this case preferably 5 to 60 μm and more preferably 10 to 40 μm. The thickness of the coating layer may also be 5 to 20 μm. For smaller layer thicknesses, such as less than 5 pm, the base material of the screen surface, which is weaker in terms of properties, causes a greater deformation load on the coating layer, which can lead to a shortened life of the coating layer. On the other hand, if the coating layer is too thick, the coating is brittle and is more easily damaged. With the first coating layer, a firm and wear-resistant coating, in particular in the openings on the sieve surface of the sieve basket, can be achieved. By means of the first coating layer, therefore, the wear resistance of certain parts of the piece can be regulated and increased. For example, the wear resistance by means of the coating layer can be controlled in a controlled manner on the parts on the side of the feeding surface of the screen basket. In addition, with the first coating layer, the openings on the screen basket can be adjusted to a desired hole or gap size or opening size or dimension. For example, the wear resistance for the gap distance on the screen surface can be improved by making a gap distance greater than the nominal value, i. larger diameter, and the gap distance is adjusted by coating to the nominal value. With the coating layer and the profile of the sieve opening can be adjusted.
    The first coating phase may be an expedient measure associated with the production of a new screen basket, with which a wear-resistant coating combination is formed on the new screen basket in such a way that the desired opening size or opening shape is achieved. Alternatively, the coating may be corrective, with the worn screen basket restored to its original size by coating, or the gauge and profile of the opening of an existing screen basket being adjusted by a combination of coatings suitable for the application. For example, the coating can correct for a too large gap distance, which may result from excessive electrolytic smoothing or corrosion wear of the gap.
    The surface quality of the chemical nickel coating is generally smooth and even, whereby the surface roughness Ra can be, for example, 0.5 μm. The surface roughness may also be lower, for example 0.2 μm. This may also be, for example, 2.1 pm or even 5 pm. The surface roughness of the chemical nickel coating mainly affects the surface roughness of the base material. The more general Ni-P and Ni-B coatings conform to the surface roughness of the base material. Greater surface roughness can be achieved if the coating contains large particles (> 1 pm), for example, boron carbide, and the particles are irregularly distributed in the coating.
    In a spray coating, a rougher surface gives better adhesion, for example a roughness Ra of 3 to 6 μm. In the case of a second coating layer, if the layer is sprayed on, it is advantageous that before the chemical nickel plating that forms the first coating layer, the base material of the surface 12 on the feed side is roughened, for example, by grain blowing. Thereby, the adhesiveness of the second coating layer to the first coating layer can be improved because the surface roughness of the base material copies to the first coating layer, which is a chemical nickel plating. If the second coating layer is a hard chrome coating, then the roughness of the first coating layer on the face 12 on the feed side or the base material is a drawback. The roughness of the surface 12 on the feed side does not affect the surface roughness of the sieve nips or openings when the shape of the profile obscures the gap and when using a sufficiently large particle size aluminum -oxidoxidgrit, whereby no abrasive particles pass through the columns.
    If the surface roughness in the openings or gaps in the strainer basket is low, the risk of blockage of the strainer basket during the manufacturing process of the fiber mass is minimized. However, such a smooth surface is not a particularly good support for the second coating layer when it has been sprayed onto the coating. In this case, it may be necessary to roughen the first coating layer on the surface 12 on the feed side before the production of the second coating layer. If the size or diameter of the holes or gaps in the sieve basket is at least 0.3 mm, the surface roughness of the openings in the sieve basket can be greater because the sieve basket is less susceptible to clogging.
    The surface of a part may also be treated prior to coating the part with the first coating layer to improve adhesion to the surface such that the surface is cleaned of, among other things, grease, marking ink, dust and oxides. Also, a surface insulating oxide film is generally broken chemically by covering the surface, for example, in a hydrochloric acid-containing solution or electrochemically in an electrolytic solution, thereby better activating the surface for spraying metal. The composition of the coating can also influence the adhesion of the coating. With a phosphorus-containing nickel coating, for example, better adhesion to a steel surface can be achieved as compared with a boron-containing nickel coating. The adhesion of the phosphorus-rich nickel coating to the base material is better than that of a low-phosphorus or intermediate phosphorus content nickel coating.
    According to one embodiment, a carbide-containing coating is formed in a second coating phase on the chemical nickel plating by thermal spraying. The coating produced in the second coating phase is referred to as the second coating layer. With the second coating layer, a large wear margin for the screen surface 2 can be formed on the feed side S, which is subject to a wearing load and wear. According to one embodiment, the second coating layer is formed only on the feed side of the screen surface 2 on the screen basket 1, for example on the surface 12 of the screen wire or on the surface 18 of the screen plate.
    The carbide-containing coating may for example consist of a tungsten or chromium carbide-containing hard metal coating. Also, basic elements, such as Ti, V, Nb, Mo, Ta and Hf, may be present as carbide and these may be used in carbide-containing coatings. The carbide-containing coating contains hard carbides in a tough metal matrix. Cobalt, chromium and nickel can be used as the metal matrix (bonding matrix) since these carbides moisturize well. For a carbide-containing coating, the term carbide coating can be used. In this application, however, a ceramic-containing coating does not mean ceramic-dominant ceramic-metal composites, metal ceramics. During thermal spraying, it is possible to coat the corresponding areas on a wearing part, for example a screen basket, as in hard chrome plating.
    With reference to FIG. 12, during thermal spraying, the coating material (rod, wire, powder), wholly or partly molten or plasticized, is finely distributed as particle mist 38 by means of a gas flow onto the surface of the part to be coated, where it is sprayed distributed on impact. Upon cooling, the multi-particle lamellar coating 42 adheres mechanically to the surface of the member 40 to be coated. Any material having a stable melted state, such as metal, ceramic or their alloys, can serve as the coating material. Various thermal spraying processes include flame spraying, electric arc spraying, plasma spraying, vacuum plasma spraying, high-speed flame spraying, and detonation spraying or explosion spraying 11/22 Austrian Patent Office AT 13 675 Ul 2014-06-15. For example, high speed flame spraying (HVOF, HVAF) can be used to form cemented carbide coatings, such as, but not limited to, WC-Co (Cr) and Cr3C2-NiCr. HVAF spraying can produce thicker and denser coatings than HVOF spraying. A thicker and denser coating is advantageous compared to hard chrome because its tightness becomes weaker as cracks and coating thickness increase. The properties of the cemented carbide coating can be suitably tailored by means of the composition of the coating material to be used, the shape and size of the particles of the coating powder and the parameters for the spraying process.
    According to one embodiment of the invention, the spray jet of the thermal fuel can be selected with regard to the object to be coated in such a way that a part of the object to be coated protects the other part of the object to be coated. The spraying angle can be chosen, for example, with regard to the wires or openings of the screen basket in such a way that the profile of the wire or the opening of the perforated plate protects the gap gap 3, 8 remaining therebetween, the gap spacings remaining open. In Fig. 10, an example of the adjustment of the spray angle is shown in such a manner that the profile of the wire 22 protects the gap distance 3 between the wire meshes. In the figure, the spray angle is approximately at a profile angle A of the wire screen in the bevel, wherein the beam 36 is located substantially with respect to the profile surface 12 in the vertical. The spray angle may also be smaller than the profile angle A, preferably about half of the profile angle. The adhesion of the spray coating is also dependent on the spray angle. With regard to the adhesion of the coating, the vertical is the best spraying direction.
    In Fig. 11, an example of the construction for the screen surface is shown in which the screen wire profile is ground at the tip, whereby at the first tip 12 of the wire two level surfaces 32 and 34 are formed. For example, if the level surfaces 32 and 34 have 0 degrees (ground point) and 20 degrees (profile angle), the spray angle may be smaller than the profile angle A. During spraying, the spray jet 36 is moved back and forth along the profile 12. When the spray angle deviates from the vertical direction against the surface 12, the coating result may be weaker, i.e., less than the surface area. The coating adheres less to the surface. In addition, the inner structure of the coating may be weaker. The coating may contain, for example, porosity.
    For the second coating layer of the screen basket, the composition of the coating is essential, with both an optimal hardness and a fracture toughness can be achieved. The second coating layer may contain, for example, nanosize particles of 200 to 800 nm, tungsten carbide (WC) particles in a cobalt matrix (CoCr). For the particle size of carbide, the term grain size can also be used when the outer dimensions of the particle are meant. In some cases, the grain size can be used to describe the fine graininess of the internal structure of the particle. The WC-Co-Cr coating composition may contain, for example, 4 to 12% by weight of cobalt and 2 to 5% by weight of chromium and tungsten carbide so as to obtain 100% of the total amount of the substance. For example, the hardness of a WC-Co based hard metal coating may be about 1,000 HV. Wear-resistant, thermally sprayed carbide coatings can contain not only carbide but also other hard particles, such as nitrides, oxides or borides. With a carbide coating can also reduce the fracture toughness of the coating and thus erosion wear of the part to be coated. The second coating layer may also be a double carbide layer, the coating containing, for example, both tungsten carbide and chromium carbide. The particle size of chromium carbide is typically 2 to 10 pm. The second coating layer may consist of a hard metal alloy whose chemical composition is one of the following: WC-10Co-4Cr, Cr3C2-25NiCr, WC-20Cr3C2-7Ni or Cr3C2-37WC-18NiCo. The Cr3C2-37WC-18NiCo hard metal alloy may contain 18% of another metal alloy instead of NiCo.
    With thermally sprayed hard metal coatings, for example, following Austrian Patent Office AT13 675U1 2014-06-15
    Vickers hardness: WC-10Co-4Cr 1000-1200HV300, Cr3C2- 37WC-18Metal 900-1050HV300, CrC3C2-25NiCr 800-950HV300 (HV300 = 300g / 3N).
    The wear resistance of the thermally sprayed cemented carbide coating can be improved by brushing or grinding the surface of the second coating layer with, for example, a diamond brush or an abrasive belt. Brushing or sanding the surface smoothes out the large peaks of the surface causing the coating to crumble. A smoothed surface also prevents adhesion of fibers and contaminants to the surface. A brushed or polished surface reduces drag, which most advantageously results in energy savings in sorters in which the screen basket rotates and where the screen basket cleaning wings are secured to a stator fixed in place. Such a sorter is referred to as an inflow screen; its counterpart is an Outflow sieve.
    In one embodiment, the second coating layer of the double coating is a hard but brittle material. The second coating layer is more brittle than the tough nickel coating of the first coating layer. The second coating layer is positioned mainly on the surface 12, 18 on the side of the supply flow of the screen surface 2 on the screen basket and in turn simultaneously forms the so-called profile of the screen surface on the screen basket. Depending on the material to be sorted, for example, a load caused by the diameter of on average 1 to 3 mm particles is directed onto the screen surface 2 on the side of the feed surface S of the screen basket. For preventing a brittle fracture penetrating the second coating layer, the second coating layer is formed sufficiently thick, preferably at least 5%, more preferably at least 10%, of the average diameter of the particles. The second coating layer may be made of a carbide-containing cemented carbide and may have a thickness of, for example, 50 to 500 μm. Alternatively, the second coating layer may be made of hard chrome whose thickness is between 50 to 400 μm.
    In one embodiment, the second coating layer of the screen surface is made of hard chrome. The hard chrome plating can be made electrochemically by hard chrome plating, i. by precipitating pure chromium from an electrolyte solution onto the surface of the first coating layer.
    In one embodiment, it is advantageous that in the double coating, the relative proportion of the first coating layer, such as a nickel chemical coating, to the total coating thickness is less than the portion of the second coating layer, i. the proportion of carbide or hard chrome coating. The thickness of the cemented carbide coating is at least 100 μm, for example.
    Any of the above-described two-phase coating process steps may optionally be repeated, for example, to repair the damage or deterioration of the surface on the screen basket. It is also possible to repeat both coating phases.
    According to one embodiment, the renewal of the coating comprises the simultaneous removal of the two coating layers present in the screen basket before the first and second coating phases are carried out. The coating to be removed contains, in particular, the first coating layer, which consists of chemical nickel, and the second coating layer, which consists of thermally sprayed hard metal. The coating can be removed mechanically or by means of a water jet. The coating layer is preferably removed by chemically dissolving the first coating layer (chemical nickel coating) of the double coating from the underlying base material (from the surface of the profile wire), with the second coating layer (thermally sprayed hard metal) also being dissolved. For example, dissolution may be accomplished by immersing the screen basket in a chemical solution which reacts with and dissolves the first coating layer from the base material underlying the coating layer. The chemical solution does not react with the base material under the first coating layer and the surface in question is not damaged. The shape of the sieve profile remains undamaged. The chemical solution may include, for example, chemicals such as amino carboxylic acid, sulfonic acid, sodium and potassium carbonate. The coating layer containing low-phosphorus chemical nickel can be removed more quickly with a chemical wash than phosphorus-rich chemical nickel. The dissolution of the coating can be accelerated with electric current and / or by spraying high-pressure water onto the coating. The use of high pressure water when dissolving hard metal coatings is difficult and in some cases impossible. The electric current-intensified chemical dissolution process is advantageous for the phosphorus-rich chemical nickel plating. For accelerating the dissolution of the first coating layer, for example, an electrochemical method may be used in which the sieve basket is set as the anode and the solution tank as the cathode. The magnitude of the rectified electric current may be about 20 A / sqft ~ 21mA / cm 2. Preheating the part may also be beneficial to dissolving the nickel chemical coating. The preheating is particularly suitable for dissolving the phosphorus-rich chemical nickel coating. After removal of the coating, the first and second coating phases may be carried out to produce the new double coating.
    It is possible to remove only the second coating layer, for example by high pressure washing, in particular for the reason that the second coating layer is more brittle than the first coating layer.
    In Fig. 6, the structure of a double-coated screen wire 22 according to one embodiment is shown as a cross section viewed from the end of the wire screen. The first surface 12 of the wire screen, i. the surface of the wire on the supply flow S side of the fiber mass, and the first 14 and second sides 16 of the wire are coated with a first coating layer 24, i. with chemical nickel (EN). The nickel coating 24 extends on the sides 14, 16 of the wire to the support rod or support ring to which the profile wire is welded. The point of the wall length to which the first coating layer may extend is indicated by the letter L in the figure. The coating can thus be located in the screen openings only on a certain length on the side 14, 16 of the wire, such as in the screen gaps 3 on the side of the feed flow of the screen surface. The nickel chemical coating essentially forms the uniformly thick coating layer 24. The size of the gap 3 between the wires can be adjusted with the chemical nickel coating. On the nickel coating, the second coating layer 26 is formed by thermal spraying of the cemented carbide coating. The hard metal coating is formed on the first surface 12 of the wire. The sprayed coating layer has a substantially more uniform thickness compared to the hard chrome coating.
    In Fig. 7, the structure of a double-coated screen wire 22 according to one embodiment is shown as a cross section seen from the end of the wire screen. The first surface 12 of the wire screen, i. the surface of the wire on the supply flow side of the fiber mass, and the first 14 and second sides 16 of the wire are coated with a first coating layer 24, i. with chemical nickel (EN). The nickel coating may extend on sides 14, 16 of the wire to point L of the wall length. The nickel chemical coating forms the substantially uniformly thick coating layer 24. On the nickel coating, the second coating layer, the hard chromium coating 28, is formed by electrochemical hard chrome plating. Due to the chrome plating process, the coating 28 is uneven in thickness and the chrome plating can not be formed on the sides 14, 16 of the wire, i. on the surfaces of the adjacent wires that form the gap.
    In Fig. 8, the structure of a double-coated screen wire 22 according to one embodiment is shown as a cross section viewed from the end of the wire screen. The first surface 12 of the wire screen, i. the surface of the wire lying on the side of the supply flow of the pulp is coated with electrolytic nickel 30 constituting the first coating layer 14/22 Austrian Patent Office AT 13 675 Ul 2014-06-15. Due to the nickel plating process, the coating 30 is uneven in thickness. Nor can the nickel coating be formed on sides 14, 16 of the wire. On the nickel coating, the second coating layer is formed by thermally spraying the uniformly thick hard metal coating 26. The hard metal coating is only on the first surface 12 of the wire.
    In Fig. 9, the structure of a double-coated screen wire 22 according to one embodiment is shown as a cross section viewed from the end of the wire screen. The first surface 12 of the wire screen, i. the surface of the wire on the supply flow side of the fiber mass is coated with electrolytic nickel 30 constituting the first coating layer. Due to the nickel plating process, the coating 30 is uneven in thickness and the nickel coating can not be formed on the sides 14, 16 of the wire. On the nickel coating, the second coating layer, i. the hard chrome coating 28, formed by electrochemical hard chrome plating. Also, the hard chrome coating 28 is located only on the first surface 12 of the wire screen and is uneven due to the chrome plating process.
    Double coatings are particularly suitable for the coating of wires of the screen basket. However, double coatings shown in FIGS. 6 to 9 can also be produced on the surface 18 of the perforated plate 6 of the perforated screen basket, which is present in the screen basket construction on the side of the supply flow of the fiber mass and thus susceptible to wear. During the coating of the hole, a rapid and possibly non-uniform reduction of the surface volume of the open area of the hole during the coating must be taken into account.
    With the double coating according to the invention, in which the first coating layer is formed with a chemical nickel plating and the second layer is a thermally sprayed hard metal coating, a longer life of the coating can be achieved than for example with a conventional single-layer hard chrome coating. In addition, the wear resistance of the thermally sprayed hard metal coating is better than that of a conventional hard chrome coating. With the thermal sprayed (HVAF) hard metal coating, larger coating thicknesses can be achieved without cracks forming in the coating. The thickness of the sprayed HVAF coating may be, for example, 200 to 500 μm, the thickness of the sprayed HVOF coating is limited to less than 250 μm, which is due to cracking. It is also possible to improve the durability of the hard metal coating on the surface of the part with the double coating, i. the nickel chemical coating can improve the adherence of the cemented carbide coating without the need to treat the surface to be coated by, for example, roughening.
    According to one embodiment, the entire screen basket is coated in such a way that at least one first coating layer containing chemical nickel is present on both the screen surface 2 on the feed side S and in the screen gaps 3, 8. With the method, it is possible to achieve even a thickness uniform coating. The above circumstances substantially reduce the wear of wire nips, i. Among other things, the shape and dimensional accuracy of the profile of the screen wires and the screening gaps are preserved.
    Thus, a longer life of the screen basket can be achieved. The coating process also does not cause any hazardous waste.
    As shown above, the double coating can also consist of a chemical nickel coating (EN) and a hard chromium coating formed on this electrochemically formed, thus forming a second coating layer. Alternatively, the double coating may also consist of an electrolytically precipitated nickel coating (first coating layer) as well as a hard metal coating or electrochemically formed hard chromium coating (second coating layer) thermally sprayed thereon. For example, the hard chrome plating of the chemical nickel plating can be performed electrically by activating the metallic plating in a plating bath by exchanging the cathode and anode placements prior to the actual hard chrome plating. The thickness of the EN coating in hard chrome plating may be, for example, about 30 μm. With the double coating, whose first coating layer consists of chemical nickel, it is possible to reduce the wear of the gap spacing on the screen basket and to extend the service life of the screen basket. In addition, shape and dimensional accuracy of the gap distance can be better preserved.
    It is not intended to limit the invention to the embodiments presented above, but the invention should be widely used within the scope of the inventive idea defined in the claims. 16/22
    权利要求:
    Claims (19)
    [1]
    Austrian Patent Office AT13 675U1 2014-06-15 Claims 1. Screen basket (1) for treating fiber mass, wherein the screen basket on the side of a feed stream (S) of the fiber mass comprises a screen surface (2) and screen openings (3,8) on the supply side and the screen openings are arranged to direct a portion of the mass supplied to the feed side (S) of the screen basket to the accept side (AK) of the screen basket, characterized in that at least a portion of the screen surface (2) and a wall length of the screen openings (3 , 8) is coated on the supply side with a first coating layer (24) containing chemical nickel, and also at least a portion of the feed side screen surface (2) coated with the first coating layer (24) with a second one Coating layer is coated, which consists of a hard chrome coating (28) or a carbide-containing hard metal coating (26).
    [2]
    2. strainer basket according to claim 1, characterized in that the thickness of the first coating layer (24) is 5 to 80 pm, more preferably 10 to 60 pm, most preferably 10 to 40 pm.
    [3]
    3. strainer basket according to one of claims 1 or 2, characterized in that the thickness of the second coating layer (26,28) is 50 to 500 pm.
    [4]
    Screen basket according to one of the preceding claims, characterized in that the first and second coating layers form a double coating in which the relative proportion of the first coating layer (24) to the thickness of the double coating is less than the thickness of the second coating layer (26, 28 ).
    [5]
    5. Strainer basket according to one of the preceding claims, characterized in that the sieve opening (3,8) has a diameter which is at least partially formed from the thickness of the first coating layer (24) at least from the direction of the feed side (S).
    [6]
    6. strainer basket according to claim 5, characterized in that the diameter of the sieve opening is 0.1 to 15 mm, preferably 0.1 to 0.8 mm.
    [7]
    7. Strainer basket according to one of the preceding claims, characterized in that the first coating layer is chemical nickel containing 1 to 14% phosphorus or 1 to 6% boron.
    [8]
    Screen basket according to one of the preceding claims, characterized in that the second coating layer is a carbide-containing hard metal coating (26) which is produced by thermal spraying on the screen plate (2) on the first coating layer (24).
    [9]
    9. Screen basket according to claim 8, characterized in that the carbide-containing hard metal coating (26) contains tungsten carbide particles and / or chromium carbide particles. 17/22 Austrian Patent Office AT13 675U1 2014-06-15
    [10]
    10. Strainer basket according to claim 9, characterized in that the carbide-containing hard metal coating of the chemical composition is one of the following metal alloys: WC-10Co-4Cr, Cr3C2-25NiCr, WC-20Cr3C2-7Ni or Cr3C2-37WC-18.
    [11]
    11. A method of coating a screen basket (1) to be used in the treatment of pulp, wherein in the method at least a portion of a screen surface (2) and a wall length of screen openings (3,8) on the feed side (S) of the screen basket with chemical Nickel is coated to form a first coating layer (24) and at least a portion of the feed side screen surface (2) coated with the first coating layer (24) is formed to form a second hard chromium coating layer (26, 28) carbide-containing carbide is coated.
    [12]
    12. The method according to claim 11, characterized in that at least part of the wall length of the screen opening (3,8) from the direction of the feed side (S) to form the diameter of the screen opening with chemical nickel (24) is coated.
    [13]
    13. The method according to any one of claims 11 or 12, characterized in that at least 5%, preferably at least 10% of the diameter of the sieve opening is formed with chemical nickel.
    [14]
    14. The method according to any one of claims 11 to 13, wherein the first coating layer is formed with a dip coating in a nickel plating, wherein the phosphorus content in the bath 1 to 14% or the boron content is 1 to 6%.
    [15]
    15. The method according to any one of claims 11 to 14, characterized in that the first coating layer (24) is cured by a thermal treatment at 200 to 500 ° C.
    [16]
    16. The method according to any one of claims 11 to 15, characterized in that the second coating layer is formed by thermal spraying with carbide-containing cemented carbide (26).
    [17]
    17. The method according to claim 16, characterized in that the thermal spraying is carried out substantially in the vertical direction with respect to the profile (12,18) of the screen surface (2).
    [18]
    18. The method according to any one of claims 16 or 17, characterized in that the thermally sprayed hard metal coating is brushed or ground to increase the wear resistance
    [19]
    19. The method according to any one of the preceding claims 1 to 18, characterized in that the screen basket is immersed in a chemical solution prior to forming the first coating layer to simultaneously remove the existing first and second coating layer. 4 sheets of drawings 18/22
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    同族专利:
    公开号 | 公开日
    DE202013101853U1|2013-05-16|
    CN203451619U|2014-02-26|
    FI124364B|2014-07-15|
    FI20125668A|2013-12-16|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB451742A|1934-11-10|1936-08-11|Einar Andreas Lie|Improvements in or relating to strainer plates for the manufacture of wood pulp, cellulose or paper or the like|
    DE19627039A1|1996-07-05|1998-01-08|Gotek Gmbh|Sieve plate|
    US20040195158A1|2001-07-17|2004-10-07|Walter Gisin|Hard-chromed sieve basket|
    US10000993B2|2015-04-29|2018-06-19|Baker Hughes, A Ge Company, Llc|Multi-gauge wrap wire for subterranean sand screen|
    DE102017216579B4|2017-09-19|2019-06-19|Ford Global Technologies, Llc|Method of manufacturing a manufacturing device|
    DE102017127562A1|2017-11-22|2019-05-23|Voith Patent Gmbh|screen|
    WO2020219637A1|2019-04-26|2020-10-29|Kadant Black Clawson, Llc|Screen cylinder with improved slot width protection and method of removing solid contaminants from a solid suspension|
    法律状态:
    2019-01-15| MM01| Lapse because of not paying annual fees|Effective date: 20180531 |
    优先权:
    申请号 | 申请日 | 专利标题
    FI20125668A|FI124364B|2012-06-15|2012-06-15|Wear-resistant coating of a silk basket and method of manufacturing coating|
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