Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
  • B22F7/062—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts
  • B22F7/064—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts using an intermediate powder layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
  • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C2204/00—End product comprising different layers, coatings or parts of cermet

Definitions

• a method for manufacturing a wear resistant component comprising mechanically interlocked cemented carbide bodies.
• the present invention relates to a method for manufacturing a wear resistant component by Hot Isostatic Pressing according to the preamble of claim 1 .
• the invention also relates to a wear resistant component according to the preamble of claim 15.
• Hot Isostatic Pressing is a method which is very suitable for Net Shape manufacturing of individual components.
• HIP Hot Isostatic Pressing
• a capsule which defines the final shape of the component is filled with a metallic powder and subjected to high temperature and pressure whereby the particles of the metallic powder bond metallurgically, intergranular voids are closed and the material is consolidated.
• the main advantage of the method is that it produces components of final, or close to final, shape having strengths comparable to forged material.
• the HIP method may be used for manufacturing wear resistant components. For example, tube bends or impellers for transporting sand or sand/water slurries.
• the wear resistance of the component may thereby be increased by mixing hard particles, such as tungsten carbide powder, in the metallic powder from which the component is manufactured.
• Cemented carbide bodies consist of a large portion hard particles and a small binder phase and are thus very resistant to wear.
• M 6 C-phase a.k.a. eta-phase
• W 2 C-phase brittle phases
• US4764255 shows a method of integrating cemented carbide drillbits in a cast iron matrix by enclosing the drillbits in a steel cup prior to casting.
• EP0169718 shows a roller bit cutter in which hard metallic inserts having an anchor portion are embedded in the core material of the roller bit cutter.
• a further object of the present invention is to provide a method that allows for manufacturing of components having high wear resistance.
• a further object of the present invention is to provide a method which allows for manufacturing, by Hot Isostatic Pressing, of wear resistant components in which cemented carbide bodies are securely retained with no or very little formation of brittle phases.
• Yet a further object of the present invention is to provide a method which allows for cost effective manufacturing of wear resistant components.
• a method for manufacturing a wear resistant component (100) comprising the steps: - providing a metallic base material (1 ) and at least one wear resistant cemented carbide body (2), wherein the cemented carbide body (2) comprises a top portion (3) which is adopted to extend over at least a section of the surface of the metallic base material (1 ) and an anchoring portion (4) which is adopted to be retained mechanically by the metallic base material (1 ) in the final wear resistant component (100);
• the HIP process takes place at high pressures and a high temperature and achieves thereby a metallurgical bond between surfaces of the cemented carbide body and the metallic base material.
• the metallurgical bond may be described as a flawless interface between the cemented carbide body and the metallic base material free of any pores, oxides or films.
• the surfaces of the cemented carbide body and base material adhere fully to each other at the interface and essentially form a homogenous body.
• the forming of the metallurgic bond takes place under various diffusion processes whereby, amongst other things, alloy elements diffuse between the wear resistant body and the metallic base material.
• the carbides in the surface of the cemented carbide body dissolves and forms a complex phase, M 6 C -phase or eta-phase with alloy elements in the metallic base material.
• inventive method allows for selective wear protection of components. This since only areas which are subjected to wear are provided with cemented carbide bodies. This allows for reduced manufacturing costs.
• properties, e.g. the mechanical properties, of the component may be tailored to suit a particular application by selecting specific materials for the body of the component and specific materials for the wear resistant cemented carbide bodies.
• Figure 1 shows schematically a perspective view of a wear resistant component manufactured with the inventive method.
• Figures 2a -2d shows schematically wear resistant cemented carbide bodies used in the inventive method.
• Figures 3a and 3b shows schematically steps of the inventive method according to a first alternative.
• Figures 4a - 4c shows schematically steps of the inventive method according to a second alternative.
• Figure 5 shows schematically a component manufactured according to the first or the second alternative of the inventive method.
• Figures 6 and 7 shows SEM-pictures of a sample of a component manufactured in a first test with the inventive method using a layer of AI 2 O 3 .
• Figure 8 shows a SEM-picture of an uncoated cemented carbide reference body used in a second test with the inventive method using a layer of hBN.
• Figures 9 and 10 - 12 shows SEM-pictures of samples of components manufactured in a second test with the inventive method using a layer of hBN.
• Figure 13 show a SEM-picture of a sample from a comparative example.
• Figure 14 shows the EDS-analysis of the chemical composition of the reaction phase in the sample of figure 13.
• Figure 15 shows a SEM-picture of a sample from a wear resistant component manufactured in a fourth test with the inventive method.
• Figure 1 shows schematically a wear resistant component 100 manufactured with the inventive method.
• the wear resistant component 100 is a-Grouser bar.
• the wear resistant component could have any form.
• the wear resistant component may be a pipe, or crushing equipment such as an impact hammer or a crusher tooth, or slurry handling equipment or mineral handling equipment.
• the wear resistant component 100 comprises a body 1 which consists of metallic base material.
• the metallic base material may be any type of metallic material which is suitable to form the main structural body of the component in question.
• the metallic base material may be a steel alloy, for example an iron based steel alloy, or a nickel based steel alloy or a cobalt based steel alloy.
• the metallic base material is a ferritic steel alloy such as a ferritic iron based steel alloy, for example the commercially available steel 41 OL.
• Ferritic steels have low coefficient of thermal expansion, which minimizes stress in the metallic base material during cooling from the HIP temperature.
• Further non-limiting examples of the metallic base material are the steel grades S355JR or S235JR.
• the metallic base material may also comprise hard particles in order to increase the overall hardness or strength of the component, for example the metallic base material may be Metal Matrix Composite (MMC).
• MMC Metal Matrix Composite
• Wear resistant cemented carbide bodies 2 are arranged on a surface of the component which is to be protected against wear, such as protection from abrasive wear, erosive wear, impacts or corrosion.
• the wear resistant bodies 2 have a top portion 3 which extends over a section of the surface of the body 1 of metallic base material.
• the cemented carbide bodies 2 further have an anchoring portion 4 which protrudes from the top portion 3.
• the anchoring portion 4 is enclosed by the metallic base material and is, as will be further described below, due to its design locked mechanically in the metallic base material.
• the number and shape of the wear resistant cemented carbide bodies depends on the type and shape of the component 100. Therefore, the component could comprise merely one wear resistant body or several wear resistant bodies such as two wear resistant bodies or any other number, for example 1000 wear resistant bodies.
• a wear resistant cemented carbide body 2 is provided.
• Figure 2a shows schematically a wear resistant body 2 which has a top portion 3 which is adopted to extend over at least a portion of the component in order to protect that portion of the component from wear.
• the top portion 3 of the wear resistant cemented carbide body may have any shape suitable for protecting the underlying section of the component from wear.
• the top portion may for example be rectangular, or triangular or have any other geometrical form which allows several wear resistant bodies 2 to be placed adjacent each other such that their top portions 3 together form a continuous, unbroken surface.
• the upper surface of the top portion 3, i.e. which faces away from the anchoring portion 2 is flat, but depending of the field of application it may have other shapes, such as convex.
• the lower surface of the top portion 3, i.e. that faces the anchoring portion may have any shape, such as flat or convex or concave .
• the wear resistant body 2 further comprises at least one anchoring portion 4 which protrudes from the top portion 3.
• the anchoring portion 4 protrudes from the lower side of the top portion 3 of the wear resistant body.
• the anchoring portion 4 is in the form of an elongated profile and extends over the entire middle section of the top portion 3.
• the anchoring portion 4 may also only extend over a portion of the top portion 3 of the wear resistant body 2.
• Figure 2b shows an alternative design of the wear resistant body 2.
• the anchoring portion 4 is a discrete, protruding element which protrudes like a stem from the center of the lower side of the top portion 3.
• the advantage thereof is that the top portion 3 covers the entire anchoring portion 4 and thus protects the anchoring portion from wear.
• the anchoring portion is designed such that it will be mechanically locked in the consolidated metallic base material after HIP. In general, this may be achieved by designing the anchoring portion 4 so that the cross-section of the upper end of the anchoring portion (i.e. adjacent the top portion 3) is narrower than the cross- section of the lower end of the anchoring portion 4, i.e. distal from the top portion.
• the anchoring portion it is also possible to achieve a mechanical lock by designing the anchoring portion so that the cross-section of the middle of the anchoring portion may be thicker, or narrower than adjacent portions.
• the anchoring portion 4 is an elongated drop-shaped profile.
• the discrete anchoring portion 4 is drop-shaped. Both designs thereby achieve a mechanical lock in the final component.
• Figure 2c and 2d shows alternative designs of the anchoring portion.
• figure 2c shows an anchoring portion 4, having projections 4b which extends perpendicular from the anchoring portion 4 and parallel with the top portion 3 of the wear resistant body.
• Figure 2d shows a design in which the anchoring portion 4 forms a wall around a hollow space under the top portion 3. The bottom end of the wall is undercut.
• the wear resistant body 2 is manufactured from sintered cemented carbide.
• the cemented carbide consist of 75 - 99%, preferably 90 - 95 %, of hard carbide particles, typically tungsten carbide (WC) and remainder binder phase such as cobalt. However, it may also consist of other carbides, such as TiC and other binder phase such as nickel or combinations of chromium, nickel and cobalt.
• WC tungsten carbide
• TiC titanium carbide
• other binder phase such as nickel or combinations of chromium, nickel and cobalt.
• the wear resistant bodies 2 may be manufactured by molding a blend of carbide and binder powders into a green body with a desired shape and subsequently sintering of the green body in a sintering furnace. Sintering may take place at a temperature above the melting point of the binder material, which melts and during solidification cements the hard carbides into a rigid wear resistant body.
• Profile shaped eleongated wear resistant bodies such as shown in figure 2a, may be formed by uniaxial pressing into a green bodies followed by sintering, thus allowing for effective production.
• a metallic base material 1 is provided.
• the metallic base material is in the form of a volume of powder, for example a volume of powder having a particle size of 10-250 ⁇ .
• the metallic base material may also be a forged or a cast body. It is of course possible that the metallic base material is constituted by both powder and forged and/or cast bodies.
• the wear resistant cemented carbide bodies 2 and the metallic base material 1 are arranged such that the top portions 3 of the wear resistant cemented carbide bodies 2 extends over at least a portion of the surface of the metallic base material 1 .
• a capsule 10 which at least partially defines the shape of the component 100 is provided.
• the capsule 10, see figure 3a, is manufactured from steel sheets that are welded together.
• the capsule 10 may have any shape, in figure 3a the capsule defines the shape of a brick shaped component and has thus a bottom plate 1 1 and a circumferential wall 12.
• Wear resistant cemented carbide bodies 2 are placed in the capsule 10 so that the upper surface of the top portion 3 of the wear resistant bodies are supported on the bottom plate 1 1 of the capsule whereby the anchoring portion 4 protrudes in a direction towards the interior of the capsule.
• the capsule 10 is filled with a powder of a metallic base material 1 .
• the powder 1 thereby encloses the anchoring portion 4 of the wear resistant cemented carbide bodies and embeds the anchoring portions and the lower side of the top portion 3 of the wear resistant cemented carbide bodies 2. It is of course also possible to first fill the capsule with a volume of powder and then placing the wear resistant bodies 2 on the surface of powder volume and pushing the anchoring portion into the powder.
• the wear resistant bodies can of course be arranged on any surface of the metallic base body.
• the capsule is sealed by a lid 13 which is welded to the circumferential wall of the capsule, see figure 3b.
• the capsule 13 Prior to HIP, the capsule 13 may be evacuated. Thereby, a vacuum may be drawn through an opening in the capsule (not shown) whereupon the opening is closed and sealed.
• the metallic base material is a solid metallic body see figure 4a.
• the solid metallic body may for example be a forged solid body, a cast solid body or a solid body manufactured from consolidated metallic powder.
• the solid body 1 is provided with recesses 15, such as bores formed by drilling and/or milling, on a surface that shall be protected against wear.
• the wear resistant cemented carbide bodies 2 are arranged such the top portion 3 extends over the surface of the solid body of metallic base material and such that their anchoring portions 4 are inserted into the recesses 15 and thereby enclosed by metallic base material 1 , see figure 4b. Subsequently, a lid 13 is placed over the wear resistant bodies 2 and welded to the metallic base body 1 , see figure 4c. It is important to seal the arrangement of metallic base material and wear resistant bodies since the body of metallic material otherwise not will be compacted by the pressure in the H IP-chamber. Prior to HIP, the arrangement of soild metallic material and wear resistant bodies may be evacuated. Thereby, a vacuum may be drawn thorugh an opening (not shown) in the lid 13 whereupon the opening is closed and sealed.
• a layer 5 of Al 2 0 3 (alumina) or hBN (hexagonal boron nitride) is arranged between at least the anchoring portion 4 and the metallic material which encloses the anchoring portion.
• the layer of Al 2 0 3 or hBN also extends between the metallic base material and the lower surface of the top portion 3 of the wear resistant body 2. More preferably, the layer of Al 2 0 3 or hBN is arranged between all interfacing surfaces of metallic base material and wear resistant cemented carbide bodies.
• the layer of Al 2 0 3 or hBN is suitably applied on the wear resistant body, see figure 3a which shows a layer 5 that is applied on the anchoring portion 4 of the wear resistant cemented carbide body 2.
• the layer of Al 2 0 3 or hBN may be applied either on the surfaces of the metallic body or on the wear resistant body 2.
• a first layer of Al 2 0 3 is applied on the wear resistant body and then a second layer of hBN is applied on top of the Al 2 0 3 layer.
• the advantage thereof is that the Al 2 0 3 layer ensures that no metallurgical binding occurs between the wear resistant body and the metallic base material wheras the hBN layer allows for relative motion between the wear resistant body and the metallic base material.
• the two layers may be applied either on the soild body or on the wear resistant body.
• a layer of Al 2 0 3 or hBN is applied on the surface of the wear resistant body 2 and another layer of Al 2 0 3 or hBN is applied on the surface of the solid metallic body.
• the layer or the layers of Al 2 0 3 and hBN are applied on the wear resistant body rather than on the solid metallic base material.
• the reason therefore is that the wear resistant cemented carbide bodies are more formstable during HIP than the metallic base material. So, if the layers of Al 2 0 3 and hBN were applied on the metallic material, they could crack due to deformation of the metallic material deform during HIP.
• Figure 4c show schematically a portion of a solid body, in which a layer 5 of Al 2 0 3 or hBN has been applied on the surface of the recess 15.
• the layer of Al 2 0 3 or hBN will prevent metallurgical bonding between the wear resistant cemented carbide bodies and the metallic base material and thus also prevent the formation of brittle M 6 C-phase.
• the layer of Al 2 0 3 or hBN may be applied by various methods.
• Al 2 0 3 is applied by CVD (Chemical Vapour Deposition). Being a gas- based coating method, CVD effectively reaches and covers all surfaces of the bodies to be coated. This method is therefor suitable for applying coatings on components with complex geometries. The method also allows for high coating speed and many components may be coated simultaneously. A further advantage with CVD is that dense coatings are achieved and the repeatability is high. Al 2 0 3 may also be applied by plasma spraying, which is a suitable method for coating of large surfaces. It is also possible to apply the layer of Al 2 0 3 by PVD (Physical Vapor deposition).
• PVD Physical Vapor deposition
• the thickness should be at least 2 ⁇ in order to ensure that interfacing surfaces of wear resistant body and metallic base material does not come in contact with each other.
• the resistance to metallurgical bonding is believed to increase with increasing layer thickness.
• the thickness of Al 2 0 3 layers should be 2 ⁇ - 10 ⁇ , preferably 4 ⁇ - 8 ⁇ .
• a further advantage of a layer of AI2O3 is that AI2O3 has good adhesion to the underlying surface and is resistant to mechanical wear which makes components with Al 2 0 3 layers easy to handle.
• a layer of hBN may be applied by brushing or spraying a suspension of hBN, a binder, such as a solgel and a solvent, such as ethanol or water, onto the wear resistant body. It is also possible to apply the hBN layer onto the wear resistant body by dipping the wear resistant body in the suspension. To achieve a layer of suitable thickness the wear resistant body need to be sprayed, painted or dipped several times. Between each application, the wear resistant body may be allowed to dry for at least 10 minutes in room temperature. The drying time must be adjusted in dependency of the solvent since, for example ethanol, evaporates faster than water.
• hBN and solvent are for example MYCRONID® BORON NITRIDE SUSPENSION which is available commercially from ESK Ceramics GmbH & Co. KG.
• MYCRONID® BORON NITRIDE SUSPENSION is available commercially from ESK Ceramics GmbH & Co. KG.
• HeBoCoat 401 E is commercially available from Henze Boron Nitride Products GmbH.
• the thickness of the hBN layer depends on the geometry of the component in question and also on the HIP process parameters. However, the thickness should be at least 10 ⁇ in order to ensure that interfacing surfaces of wear resistant body and metallic base material does not come in contact during HIP. However, too thick layers, may result in that the wear resistant bodies are not sufficiently retained in the metallic base material. A further disadvantage with thick layers is that the adhesion of thick layers to the base material is poor.
• the thickness of hBN layers should not exceed 500 ⁇ .
• the minimum thickness of the hBN layer may be 20 ⁇ or 40 ⁇ .
• the maxium thickness may be 400 ⁇ or 300 ⁇ or 200 ⁇ or 100 ⁇ .
• the thickness is 50 ⁇ - 80 ⁇ or 50 ⁇ - 80 ⁇ .
• An additional advantage with a layer of hBN is that due to its low friction coefficient the hBN layer allow relative motion between the metal and the cemented carbide as well as reduce stresses in the interface otherwise arising from the thermal elongation mismatch between the metal and the cemented carbide.
• the intermediate layer may also be a mixture of TiC and TiN.
• the layer of TiC and/or TiN may for example be 0.5 - 10 ⁇ , 2 - 10 ⁇ or 5 - 10 ⁇ and increases the adhesion between the cemented carbide and the Al 2 0 3 coating.
• the sealed arrangement of metallic base material and wear resistant cemented carbide bodies are subjected to Hot Isostatic Pressing (HIP) at a predetermined temperature, a predetermined isostatic pressure during a predetermined time so that the metallic base material closes around the anchoring portions of the wear resistant bodies and lock thereby these mechanically in the component.
• HIP Hot Isostatic Pressing
• the capsule is thereby placed in a heatable pressure chamber, normally referred to as a Hot Isostatic Pressing-chamber (H IP- chamber).
• the heating chamber is pressurized with gas, e.g. argon gas, to an isostatic pressure in excess of 500 bar.
• the isostatic pressure is 900 - 1200 bar.
• the chamber is heated to a temperature which is below the melting point of the metallic base material.
• the arrangement of metallic base material and cemented carbide bodies is held in the heating chamber at the predetermined pressure and the predetermined temperature for a predetermined time period.
• HIP The consolidation processes that take place between the metallic materials during HIP:ing are time dependent so long times are preferred.
• the HIP time also depends on the dimension of the component, i.e. heavy components require long HIP times.
• HIP is perfomed during a period of 0.5 - 3 hours, preferably 1 - 2 hours, most preferred 1 hour.
• FIG. 5 shows a HIP:ed component consisting of a solid body 1 of metallic base material and wear resistant bodies that are mechanically locked in the metallic base material.
• the capsule may be partly or completely stripped from the consolidated component by e.g. machining, grindning or grit blasting.
• FIG. 6 shows a Scanning Electron Microscope (SEM) image of the cemented carbide body 2 which consisted of two different types of hard particles 2a and 2b and a binder phase 2c.
• the chemical composition of the cemented carbide body was determined in the SEM.
• the first type of hard particles 2a was identified as tungsten carbide.
• the second type of hard particles 2b consisted of carbides of tungsten, Ti and Nb.
• the binder phase 2c consisted of mainly cobalt with a small addition of nickel.
• the cemented carbide body was embedded in commercially available 410L steel powder in a capsule of steel sheets that had been welded together.
• the 410L powder had the following composition: C: 0.023, Si: 0.52, Mn: 0.20; P 0.009, S: 0.008; Cr: 13.0; Ni: 0.27, balance Fe.
• the steel powder had the following Sieve analysis according to ASTM-E1 1 :
• the capsule was sealed by welding and subjected to Hot Isostatic Pressing (HIP) at a temperature of 1 150°C, at a pressure of 1000 bar. The capsule was held at this temperature and pressure for two hours and then allowed to cool down with a cooling rate of approximately 3-5 °C /min. After HIP:ing the capsule was cut through the center of the cemented carbide body and samples were taken for analysis. The samples were prepared prepared by polishing for analysis by scanning electron microscopy (SEM) which was performed in a Zeiss EVO 50 VPSEM.
• SEM scanning electron microscopy
• Figure 7 shows a SEM image of the interface between the surface zone of the cemented carbide body 2 and the surrounding steel matrix 1 .
• the layer closest to the surface of the cemented carbide body is TiC.
• the outermost layer, 5 is Al 2 0 3 .
• the hard phase particle size was roughly 3 ⁇ and below.
• the binder phase consisted mainly of cobalt but with an addition of chromium.
• the inserts were dipped eight times each in the hBN solution. Between each dipping the inserts were allowed to dry for 30 minutes in room temperature. The coating on the first insert was hardened at a temperature of 300 for 30 minutes after the final dipping.
• the coating on the second insert was not hardened. Instead it was only allowed to dry in room temperature for 30 minutes between each dipping.
• Figure 9 shows a SEM image of a sample from the first cemented carbide cutting insert.
• the black area 6 is hBN which appears in black due to that the SEM image is taken in backscattering mode.
• the black area 6 is of uniform cross-section and approximately 20 ⁇ thick.
• the "bridges" are believed to be formed by steel powder that penetrates through cracks in the hBN coating. The cracks may have been formed due to that the coating becomes brittle during hardening.
• a reaction zone is formed between steel and cemented carbide at the end of the "bridge".
• Figure 10 shows a SEM image of a sample from the second cemented carbide cutting insert. Also in this sample there is a black area 6 of hBN between the steel matrix 1 and the cemented carbide insert 2.
• Figure 1 1 is an enlargement of a portion of the image in figure 10.
• Figure 12 is a 1000 times magnification of figure 10, it is clearly visible that no reaction zone has formed where the hBN layer has separated steel powder and cemented carbide insert.
• the chemical composition of the uncoated cemented carbide insert was identical to the chemical composition of the inserts used in Test 2.
• Figure 13 shows a SEM-image of a sample from the HIP:ed uncoated cemented carbide insert.
• the uncoated cemented carbide insert 2 is metallurgically bound to the surrounding 410L steel matrix 1 and a reaction zone 7 of brittle carbide phases is formed in the outermost part of the cemented carbide insert 2.
• the chemical composition of the reaction phase 7 is shown in figure 14.
• a cemented carbide body was embedded in 410 L steel powder and subjected to HIP.
• the cemented carbide body had a design according to figure 2, i.e. it it comprised a flat top portion 3 and a drop-shaped anchoring element 4.
• the cemented carbide body was manufactured by sintering of the commercially available cemented carbide grade C15C. Thus comprising 6.6wt% Co, 7.5 wt% Ni 0.8 wt% chromium carbide and remainder WC.
• the cemented carbide body was provided with a hBN coating (HeBoCoat 401 E spray) from the company Henze.
• the coated cemented carbide body was embedded in 410 L steel powder in a HIP capsule, which was vacuumed and welded shut.
• the capsule was subjected to HIP at a temperature of 1 150°C and a pressure of 100 MPa for 2 hours. Thereafter, the capsule was divided into sections by spark maching and the sections were prepared for SEM.
• Figure 15 shows a SEM image of a sample taken from a corner of the flat top portion 3 of the cemented carbide body. It is appearant that the hBN coating has prevented contact between the steel powder 1 and the cemented carbide 3 during HIP. Only in one minor area (encircled) has the steel powder penetrated the hBN layer and caused a metallurgical bond with the cemented carbide.

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• 2013
  • 2013-07-04 EP EP13175106.7A patent/EP2821166B1/de not_active Not-in-force
• 2014
  • 2014-07-03 CA CA2912498A patent/CA2912498A1/en not_active Abandoned
  • 2014-07-03 US US14/900,635 patent/US20170203368A1/en not_active Abandoned
  • 2014-07-03 EP EP14734502.9A patent/EP3016767A2/de not_active Withdrawn
  • 2014-07-03 WO PCT/EP2014/064153 patent/WO2015001006A2/en active Application Filing

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