Process of manufacturing an article comprising a body of a cemented carbide and a body of a metal alloy or of a metal matrix composite, and a product manufactured thereof

Abstract

The present disclosure relates to a process of manufacturing an article comprising at least one body of a cemented carbide and at least one body of a metal alloy or at least one body of a metal matrix composite and to a product manufactured thereof and wherein the article also comprises an interlayer between the at least one body of a cemented carbide and at least one body of a metal alloy or at least one body of a metal matrix composite in order to prevent deleterious interface phases from forming.

Claims

1. A hot isostatic pressing process for manufacturing an article comprising at least one body of a cemented carbide and at least one body of a metal alloy or of a metal matrix composite, comprising the steps of: a) providing at least one body of a metal alloy or a metal matrix composite and at least one body of a cemented carbide; b) positioning a metallic interlayer between a surface of the at least one body of a cemented carbide and a surface of the at least one body of a metal alloy or of a metal matrix composite or positioning a metallic interlayer on at least one surface of the at least one body of a metal alloy or of the at least one body of a metal matrix composite or of the at least one body of a cemented carbide; c) enclosing a portion of the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the at least one body of a cemented carbide in a capsule or enclosing the at least one body of a metal alloy with the metallic interlayer on at least one surface or the at least one body of a metal matrix composite with the metallic interlayer on at least one surface or the at least one body of a cemented carbide with the metallic interlayer on at least one surface in a capsule; d) optionally evacuating air from the capsule; e) sealing the capsule; and f) subjecting a unit to a solid state diffusion process, wherein the unit comprises the capsule, a portion of the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the least one body of a cemented carbide or comprises the capsule, the at least one body of a metal alloy or the at least one body of a metal matrix composite with the metallic interlayer on at least one surface or the at least one body of a cemented carbide with the metallic interlayer on at least one surface, wherein the solid state diffusion process exposes the unit to a predetermined temperature of above about 1100° C. and below a melting temperature of the metallic interlayer and a predetermined pressure of from about 300 to about 1500 bar during a predetermined time, wherein the metallic interlayer is formed by an alloy having a composition consisting essentially of copper, nickel, and less than 3 wt % total other elements, where each other element is at an impurity level, wherein the composition of the alloy of the metallic interlayer has a copper content from 20 to 98 wt %, and wherein the metallic interlayer has a thickness of from about 50 to 500 μm.

2. The process according to claim 1, wherein the copper content is from 30 to 90 wt %.

3. The process according to claim 1, wherein the metallic interlayer is formed by a foil or a powder.

4. The process according to claim 1, wherein the predetermined temperature is from about 1100 to about 1200° C.

5. The process according to claim 1, wherein the at least one cemented carbide body consists of a hard phase comprising one or more of titanium carbide, tantalum carbide, and tungsten carbide, or a mixture thereof and a metallic binder phase selected from cobalt, nickel and iron or a mixture thereof.

6. The process according to claim 1, wherein the at least one metal alloy body is a steel body.

7. The process according to claim 1, wherein the metallic interlayer is formed by electrolytic plating.

8. The process according to claim 1, wherein the article comprises more than or equal to two cemented carbide bodies.

9. The process according to claim 1, wherein the copper content is from 50 to 90 wt %.

10. The process according to claim 1, wherein the predetermined temperature is also below a melting temperature of the at least one body of the unit.

11. The process according to claim 1, wherein (i) the portion of the at least one body of the metal alloy or the at least one body of the metal matrix composite and the metallic interlayer and the least one body of the cemented carbide or (ii) the at least one body of the metal alloy or the at least one body of the metal matrix composite with the metallic interlayer on at least one surface or the at least one body of the cemented carbide with the metallic interlayer on at least one surface define components of the unit, and wherein the predetermined temperature is below a melting temperature of the components of the unit.

12. The process according to claim 1, wherein the predetermined time is from 30 minutes to 10 hours.

13. The process according to claim 1, further comprising: after step (f), cooling the unit and optional removing the capsule, wherein the article includes the at least one body of the cemented carbide and the at least one body of the metal alloy or of the metal matrix composite joined by diffusion bonds, and wherein the diffusion bonds are formed by elements of the metallic interlayer and of elements of the bodies.

14. The process according to claim 13, wherein no eta phase is present in the metallic interlayer of the article.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A shows a SEM picture of an article obtained from the present process—the interface between the body of the metal alloy, the metallic interlayer (Cu/Ni) and the body of the cemented carbide is shown;

(2) FIG. 1B shows a SEM picture of an article obtained from the present process, wherein an enlargement of the interface between the metallic interlayer (Cu/Ni) and the body of the cemented carbide is shown;

(3) FIG. 2A shows a SEM picture of an article containing a metallic interlayer of Ni, wherein the interface between the metallic interlayer and the cemented carbide is shown;

(4) FIG. 2B shows a SEM picture of an article containing a metallic interlayer of Ni, wherein an enlargement of the interface between the metallic interlayer and the body of the cemented carbide is shown;

(5) FIG. 3 shows a SEM picture of an article containing no metallic interlayer wherein the interface between the metal body and cemented carbide body is shown.

DETAILED DESCRIPTION

(6) The present disclosure relates to a hot isostatic pressing process for manufacturing an article comprising at least one body of a cemented carbide and at least one body of a metal alloy or of a metal matrix composite, comprising the steps of:

(7) a) providing at least one body of a metal alloy or a metal matrix composite and at least one body of a cemented carbide;

(8) b) positioning a metallic interlayer between a surface of the at least one body of a cemented carbide and a surface of the at least one body of a metal alloy or of a metal matrix composite or

(9) positioning a metallic interlayer on at least one surface of the at least one body of a metal alloy or of the at least one body of a metal matrix composite or of the at least one body of a cemented carbide;

(10) c) enclosing a portion of the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the least one body of a cemented carbide in a capsule or

(11) enclosing the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the at least one body of a cemented carbide in a capsule;

(12) d) optionally evacuating air from the capsule;

(13) e) sealing the capsule;

(14) f) subjecting a unit comprised by the capsule, a portion of the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the least one body of a cemented carbide or

(15) subjecting a unit comprised by the capsule, the at least one body of a metal alloy or the at least one body of a metal matrix composite and the metallic interlayer and the at least one body of a cemented carbide

(16) to a predetermined temperature of above about 1000º C. and a predetermined pressure of from about 300 to about 1500 bar during a predetermined time; wherein the metallic interlayer is formed by an alloy essentially consisting of copper and nickel. During the process, the different bodies and the metallic interlayer will by diffusion bonding become one article. By using the metallic interlayer as defined hereinabove or hereinafter, the diffusion of carbon will be limited/reduced and thereby the formation of detrimental phases, e.g. eta-phase, in the interface of the bodies is avoided or reduced. As can be seen from FIG. 1A, which shows a SEM image of the interface between a body of a cemented carbide (3) and a body of a metal alloy (1) and the interlayer having a metallic interlayer (2) consisting essentially of Cu and Ni. As can be seen from the FIG. 1A, no eta phases (4) have been formed to be compared with FIG. 2A which shows the interface of a Ni interlayer (5) and a cemented carbide (3) and FIG. 3 which shows the interface of a steel body (1) and cemented carbide (3) without an interlayer. Furthermore, the present process will provide for that there will be no dissolution of the tungsten carbide in the body of cemented carbide (see FIG. 1B) to be compared with FIG. 2B and FIG. 3 which both show that the cemented carbide is dissolved in the interface and forms a continuous phase. In the present disclosure, the term “surface” is intended to mean the contact surface, i.e. the surfaces to be bonded/joined, on the at least one body of hard metal which is intended to form a diffusion bond with the at least one body of metal or MMC through the metallic interlayer and vice versa. At least a part of the contact surface has to be covered with the metallic interlayer.

(17) A metal matrix composite (MMC) is a composite material comprising at least two constituent parts, one part being a metal and the other part being a different metal or another material, such as a ceramic, carbide, or other types of inorganic compounds, which will form the reinforcing part of the MMC. According to one embodiment of the present process as defined hereinabove or hereinafter, the at least one metal matrix composite body (MMC) consists of hard phase particles selected from carbides, such as titanium carbide, tantalum carbide and/or tungsten carbide, but also from oxides, nitrides and/or borides and of a metallic binder phase which is selected from cobalt, nickel and/or iron. According to yet another embodiment, the at least one body of MMC comprising essentially of hard phase particles of tungsten carbide and a metallic binder of cobalt or nickel or iron or a mixture thereof.

(18) A cemented carbide is an example of a metal matrix composite and comprise carbide particles in a metallic binder. Typically, more than 50 wt % of the carbide particles in the cemented carbide are tungsten carbide (WC), such as 75 to 99 wt %. Other particles may be TiC, TiN, Ti(C,N), NbC and/or TaC. According to one embodiment, the at least one body of cemented carbide consists of hard phase comprising titanium carbide, tantalum carbide and tungsten carbide and a metallic binder phase selected from cobalt, nickel and/or iron. According to one embodiment, the at least one body of cemented carbide body consists of a hard phase comprising more than 75 wt % tungsten carbide and a binder metallic phase of cobalt. The at least one body of cemented carbide may be either pre-sintered powder or a sintered body. The at least one body of cemented carbide may also be a powder. The at least one body of cemented carbide may be manufactured by molding a powder mixture of hard phase and metallic binder and then pressing the powder mixture into a green body. The green body may then be sintered or pre-sintered into a body which is to be used in the present process.

(19) The capsule may be a metal capsule which may be sealed by means of welding. The encapsulation is either performed on a portion of the at least one body of a metal alloy or a metal matrix composite and the metallic interlayer and the least one body of a cemented carbide or on the at least one body of a metal alloy or of a metal matrix composite and the metallic interlayer and the at least one body of a cemented carbide. It is to be understood that the capsule is at least enclosing the joint between the least one body of a cemented carbide and the at least one body of a metal alloy or of a metal matrix composite and the metallic interlayer.

(20) The terms “diffusion bond” or “diffusion bonding” as used herein refers to as a bond obtained through a diffusion bonding process which is a solid-state process capable of bonding similar and dissimilar materials. It operates on the principle of solid-state diffusion, wherein the atoms of two solid, material surfaces intermingle over time under elevated temperature and elevated pressure.

(21) According to the present process, the metallic interlayer may be formed from a foil or a powder. However, the application of the metallic interlayer may also be performed by other processes such as thermal spray processes (HVOF, plasma spraying and cold spraying). The metallic interlayer may be applied to either of the surfaces of the at least body of the metal alloy or MMC and the at least one body of hard metal or on both surfaces of the bodies or in between the bodies. For the parts to be HIP:ed, it is important that there are no areas where the at least one body of cemented carbide is in direct contact with the at least one body of metal alloy or the MMC. The metallic interlayer may also be applied by electrolytic plating. The metallic interlayer will thus form two interfaces, one together with the at least one portion or with the at least one body of metal alloy or of the MMC. The other interface is together with the at least one body or the portion of the cemented carbide.

(22) According to the present disclosure, the copper content of the metallic interlayer is of from 20 to 98 weight % (wt %). According to another embodiment, the Cu content is of from 25 to 98 wt %, such as from 30 to 90 weight % (wt %), such as 35 to 90, such as of from 50 to 90 wt %. The chosen composition of the metallic interlayer will depend on several parameters, such as the HIP cycle plateau temperature and holding time as well as the carbon activity in the materials to be diffusion bonded at the temperature where the bodies are to be bonded article. According to one embodiment, the metallic interlayer has a thickness of about 50 to about 500 μm, such as of from 100 to 500 μm. The term “essentially consists” as used herein refers to that the metallic interlayer apart from copper and nickel also may comprise other alloying elements, though only at impurity levels, i.e. less than 3 wt %. Examples of other alloying elements are Manganese and Iron.

(23) The bodies may be in the form of powders, loosely bound powders or as solid bodies. Additionally, according to one embodiment of the present process, the at least one body of cemented carbide is a more than or equal to two. Additionally, according to another embodiment, the at least one body of metal alloy or the at least one body of metal matrix composite is more than or equal to two. According to one embodiment, at least one recess may be created in the at least one body of metal alloy or in the at least one body of metal matrix alloy, said least one recess may have the same form or a similar form as the at least one body of cemented carbide. The interlayer is first placed in the least one recess and then the at least one cemented carbide is placed therein.

(24) In the present HIP process, the diffusion bonding of the at least one body or portion of the cemented carbide to the at least one body or portion of the metal alloy or body of the metal matrix composite and the metallic interlayer occurs when the capsule is exposed to the high temperature and high pressure for certain duration of time inside a pressure vessel. The high temperature, is a temperature which is below the melting temperature for all the articles. During this HIP treatment, the bodies/portions and metallic interlayer are consolidated and diffusion bonds are formed. As the holding time comes to an end, the temperature inside the vessel and consequently also of the consolidate article is returned to room temperature and atmospheric pressure. After cooling of the above-mentioned unit and optional removal of the capsule, the obtained article comprising diffusion bonded bodies will define a hot isostatic pressed article comprising at least one body of a cemented carbide and at least one body of a metal alloy or of a metal matrix composite, wherein said bodies are joined by diffusion bonds, and wherein said diffusion bonds are formed by the elements of the interlayer and of the elements of the bodies and wherein said metallic interlayer comprises an alloy essentially consisting of copper and nickel.

(25) The pre-determined temperature applied during the predetermined time may, of course, vary slightly during said period, either because of intentional control thereof or due to unintentional variation. The temperature should be high enough to guarantee a sufficient degree of diffusion bonding within a reasonable period of time between the bodies. According to the present process, the predetermined temperature is above about 1000° C., such as about 1100 to about 1200° C.

(26) The predetermined pressure applied during said predetermined time may vary either as a result of intentional control thereof or as a result of unintentional variations thereof related to the process. The predetermined pressure will depend on the properties of the bodies to be diffusion bonded.

(27) The time during which the elevated temperature and the elevated pressure are applied will, of course, depend on the rate of diffusion bonding achieved with the selected temperature and pressure for a specific body geometry, and also, of course, on the properties of the bodies to be diffusion bonded. Example of predetermined time ranges of from 30 minutes to 10 hours.

(28) According to one embodiment of the process as defined hereinabove or hereinafter, the at least one body of a metal alloy is a body of a steel alloy. The steel grade may be selected depending on functional requirement of the product to be produced. For example, the steel may be a tool steel such as AISI O1. Other examples are, but not limited to, stainless steel, carbon steel, ferritic steel, austenitic steel and martensitic steel. The at least one body of a metal alloy may be a forged and/or a cast body or a HIP:ed body.

(29) Examples but not limited thereto of an article of the present disclosure are a crusher part, a valve part, a roll and a nozzle.

(30) The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. With the expression “about” is herein meant ±10% of the indicated value.

(31) The present disclosure is further illustrated by the following non-limiting examples.

EXAMPLES

(32) Cylindrical solid rods with flat perpendicular end surfaces and Ø19 mm diameter were butt-joined using two different processes; HIP diffusion joining and induction brazing. The two materials were AISI O1 steel and a fine-grained (0.8 μm WC grain size) cemented carbide with roughly 10% cobalt binder phase.

(33) The induction brazing used a two-phase solder of chemical compositions roughly according to table 1 and the solder bond thickness was roughly 80-110 μm.

(34) TABLE-US-00001 TABLE 1 Chemical composition of the two phases in the solder used in the brazing trials. Solder phase Ag Cd Cu Zn Ni Light grey* 67 22 4 7 — Dark grey* 3 — 44 33 20

(35) In the HIPed counterpart, an interlayer of 200 μm Ni—Cu foil was used having a chemical composition of roughly 45% Ni, 1% Mn, 0.2% Fe and the remainder Cu (weight-%). A cylindrical tube with closed ends was used as the HIP capsule. The air was evacuated from the capsule prior to it being welded shut and placed in the HIP chamber. The HIP-cycle plateau was characterized by a 3 hour holding time at 1150° C. and 100 MPa pressure. SEM images of polished sections of the HIP articles are shown in FIGS. 1A and 1B.

(36) From these two types of bonded articles, cylindrical rod blanks of length 80 mm and diameter Ø6.7 mm were extracted using wire EDM. The bond was positioned at midlength. The blanks were circumferentially ground using a centerless circular grinding machine down to a diameter of Ø6.3 mm and a surface finish of roughly Ra=0.5 μm. These rods were then manually polished circumferentially with diamond paste down to a surface finish of roughly Ra=0.5 μm. These polished specimens were then exposed to four-point-bend-testing in a rig with the four cylindrical transverse supports (relative to the orientation of the specimens) equally spaced with 20 mm and a force was applied to the two central supports. The maximum force applied just prior to fracture for the two types of bonded specimens are given in Table A.

(37) TABLE-US-00002 TABLE A Results of four-point bend tests. Max force applied prior to fracture. Bond type 1 2 3 4 Brazed 1.2 kN 1.0 kN 1.0 kN 1.0 kN HIPed 4.3 kN 4.0 kN

(38) These results show that the HIP induction bonding process using a copper-nickel interlayer results in a stronger bond than ordinary induction brazing.