TW201900896A - Cemented carbides comprising an fe-cr binder based metallic binder - Google Patents

Abstract

The present disclosure relates to a cemented carbide with a Fe-Cr based metallic binder, a method for manufacturing the cemented carbide and a use of the cemented carbide as a cutting tool, a wear part, a seal ring, a bushing, a component e.g. automotive, a die or a tool for handling radioactive parts.

Description

 Cemented carbide containing metal binder based on Fe-Cr binder  

The present invention relates to a cemented carbide comprising a Fe-Cr-based metal binder, a method for producing the cemented carbide, and the cemented carbide as a cutting tool, a wear member, a seal ring, a bushing, for example The use of components, dies or tools for handling radioactive components.

The cemented carbide typically has a metal binder based on cobalt or nickel. However, it is desirable to find a metal for the replacement of cemented carbides that does not contain any cobalt or nickel but which replicates the physical and mechanical properties and properties of the cobalt and nickel based metal binders as specified in the intended application. Adhesive.

It is an object of the present invention to provide a solution to the above problems.

Accordingly, the present invention therefore provides a cemented carbide comprising a hard phase and an iron-chromium (FeCr)-based metal binder phase, characterized in that the chromium content of the iron-chromium based metal binder phase is based on iron-chromium 1 to 10% by weight (wt%) of the total amount of the metal binder phase.

Furthermore, the present invention relates to a method of producing a cemented carbide comprising the steps of: a. providing a hard phase powder and at least one powder consisting of FeCr and optionally a powder consisting of Cr ₃ C ₂ ; Grinding the powder together with an organic binder to obtain a powder mixture; c. extruding the ground powder mixture; and d. sintering the extruded powder mixture to obtain a sintered cemented carbide; The Cr content is 1 to 10% by weight based on the total amount of the FeCr powder and the Cr ₃ C ₂ powder added.

Furthermore, the invention relates to the use of cemented carbides as described above or below for the manufacture of cutting tools, wear parts, sealing rings, bushings, components such as automobiles, or moulds. The invention further relates to the use of cemented carbide as described above or below for the manufacture of a tool for treating a radioactive component.

According to one aspect, the invention relates to a cemented carbide comprising a hard phase and an iron-chromium (FeCr)-based metal binder phase, characterized in that the chromium content of the iron-chromium metal binder phase is based on iron-chromium The total amount of the metal binder phase is from 1 to 10% by weight, such as from 2 to 10% by weight.

The present inventors have found that if the Cr content of the Fe-Cr based metal binder phase is from 1 to 10% by weight, such as from 2 to 8 wt%, of the total amount of the metal binder phase, it has the same particle size and metal binder content. The resulting cemented carbide will have surprisingly high wear resistance, lateral burst strength and thermal conductivity compared to cemented carbides based on cobalt or nickel binders.

In the present invention, the term "iron-chromium-based metal binder" means that the metal binder phase contains more than 50% by weight (% by weight) of iron-chromium based on the total amount of the metal binder phase. The remaining metal binder phase consists of cobalt, nickel, molybdenum carbide, vanadium carbide, titanium carbide, tantalum carbide, tantalum carbide, tungsten carbide, zirconium carbide, tantalum carbide or a mixture thereof.

If the chromium (Cr) content is less than 1% by weight, the effect of adding Cr to improve corrosion resistance and flame retardancy cannot be achieved. It is also assumed that Cr in the metal binder phase acts as a hardener. If the Cr content is > 10% by weight, the stability of the cemented carbide at higher temperatures is lowered, which is particularly important in metal cutting applications. Further, if the Cr content is out of the range of the present invention, the two-phase composition will not be realized. The term "two-phase composition" is used to describe a composition containing a minimum amount of graphite precipitate, ie less than 2 vol%, and no significant ternary phase, ie less than 2 vol% M ₆ C or M ₅ C ₂ , where M is hard Phase metal. The problem with the presence of a ternary phase is that the presence of such phases may reduce the lateral burst strength of the material due to its more brittleness, so that, for example, when used as a cutting tool, the tool is more likely to experience catastrophic failure.

In one embodiment, the wt% of the Fe-Cr based metal binder phase is from 3 to 35 wt% of the total cemented carbide composition, such as from 3 to 25 wt%. If the binder phase is less than 3% by weight of the total cemented carbide composition, the cemented carbide may not be completely sintered, and the cemented carbide may have a porous microstructure. This can have an adverse effect on the properties of the material, such as a decrease in the hardness and toughness of the cemented carbide. If the content of the binder phase is more than 35 wt%, the contiguity of the hard phase may be lowered, which may adversely affect the properties of the material, such as a decrease in hardness and toughness.

In one embodiment of the cemented carbide, the hard phase particles are selected from one or more of WC, TiC, TaC, NbC, VC, ZrC, Mo ₂ C, or HfC, or mixtures thereof.

In one specific example of cemented carbide, the hard phase consists essentially of WC. In the present invention, the term "consisting essentially of" means that the hard phase contains more than 90% by weight of a given carbide particle based on the total amount of the hard phase.

A small amount of other elements such as V, Mo or Mn may also be added to the cemented carbide composition, such as in an amount of less than or equal to 3% by weight. These elements added to further improve the properties of cemented carbide, for example, such elements may contribute to grain refinement or M ₆ C phase is stabilized.

Another aspect of the invention relates to a method of making a cemented carbide comprising the steps of: a. providing a hard phase powder, at least one powder consisting of FeCr, and optionally consisting of Cr ₃ C ₂ a powder; b. grinding the powder together with an organic binder to obtain a powder mixture; c. extruding the ground powder mixture; and d. sintering the extruded powder mixture to obtain a sintered cemented carbide; It is characterized in that the Cr content is 1 to 10% by weight based on the total amount of the FeCr powder and the Cr ₃ C ₂ powder added.

In the process of the present invention, the term "percent by weight (wt%)" means the relative weight of the weighed powder compared to the total amount of powder added.

The hard phase powder, the Fe-Cr based metal binder powder and any additional powder are typically ground together using a ball mill and then sintered, for example using a sintered HIP oven. However, other grinding and sintering methods can also be employed. Fe is usually added in the form of a prealloy because the treatment element Fe is not practical due to the risk of oxidation due to the element Fe. The desired Fe:Cr ratio is achieved by providing one of: a pre-alloyed Fe-Cr powder having a desired Cr content; a pre-alloyed Fe-Cr metal binder having a lower Cr content, added An appropriate amount of Cr ₃ C ₂ ; or two pre-alloyed Fe-Cr powders having a higher and lower Cr content, achieve the desired Cr content in a suitable ratio.

In a specific embodiment of the method, the chromium content is from 2 to 8 wt% based on the total amount of the iron-chromium based metal binder phase.

In a specific embodiment of the method, the cemented carbide comprises from 3 to 35 wt% of the iron-chromium based metal binder phase of the total cemented carbide composition.

In one embodiment of the method, the hard phase particles are selected from one or more of the group consisting of WC, TiC, TaC, NbC, VC, ZrC, Mo ₂ C, or HfC, or mixtures thereof.

In one embodiment of the method, the hard phase consists essentially of WC.

Another aspect of the invention is the use of a cemented carbide as described above or below for the manufacture of cutting tools, wear parts, seal rings, bushings, components or molds such as automobiles.

Another aspect of the invention is the use of a cutting tool, a wear component, a seal ring, a bushing, such as an automotive component, mold or tool, manufactured from cemented carbide as described above or below.

Another aspect of the invention is the use of a cemented carbide as described above or below for the manufacture of a tool for treating a radioactive component. However, it should be understood that the cemented carbides described above or above are not limited to such use and may be used in other applications.

The following examples are illustrative, non-limiting examples.

Example

A cemented carbide having a Fe-Cr-based metal binder is prepared by providing WC powder, FeCr powder, and C powder to adjust the carbon content to form a material having a two-phase composition. The desired Cr content is achieved by providing a pre-alloyed FeCr powder having the desired wt% of Cr. The variants were then milled in a 250 ml ball mill with 1200 g of grinding media (WC based cylpebs) in 50 ml ethanol slurry for 8 hours. The obtained powder was then dried at 75 ° C, sieved using a 500 μm mesh sieve, and extruded using a TOX press to a target extrusion pressure of 80 MPa to a sample piece having a size of about 5.5 × 6.5 × 20 mm. . The obtained sheet was then vacuum sintered at a temperature of 1450 ° C and an Ar bar pressure of 1 bar for 1 hour. After sintering, the samples were mounted in Bakerlite and the hardness and toughness were determined according to ISO 28079 using a 50 kg indentation.

Table 1 shows a summary of the compositions of the examples tested, and Table 2 shows a summary of the physical and mechanical properties measured for the compositions of the examples. The WC types WC008, WC0095, WC020, and WC060 mean that the average particle size of the WC powder was 0.8 μm, 0.95 μm, 0.2 μm, and 6 μm as measured using a Fischer method.

The properties in Table 2 are measured according to the standards used in the field of cemented carbides, namely ISO 3369:1975 for density; ISO 3878:1983 for hardness; and ISO 28079:2009 for toughness. The examples show that it is possible to produce full density sintered cemented carbides having hardness, toughness and thermal conductivity which are advantageous compared to current WC-Co cemented carbides based on Fe-Cr based binders.

The wear test was performed according to the B611 standard method. The sample powders A, B and C were extruded at 42 metric tons into a geometry of 40 x 20 x 5 mm and sintered to a plate having a density of about 14.5 g/cm ³ at 1450 ° C and 50 bar argon pressure. It is done on both sides of the board. The Fargo plate was then fixed perpendicular to the grinding wheel, immersed in an alumina slurry while impacting the grinding wheel, which was rotated 1000 rpm at 100 rpm and applied a contact force of 196 N. The mass loss is then measured and then the volume loss is calculated using the formula density/mass loss to measure the number of wear. The results are shown in Table 2. The same test was performed on a comparative sample having a binder based on Ni or Co. The Fe-Cr variant has higher wear resistance when compared to samples having equal particle size and binder content. It is also noted that if the Cr content of the binder is not more than 10% by weight, the abrasion resistance is higher.

The transverse rupture strength (TRS) was determined according to the standardized method ISO 3327:2009. The tests were done on samples A, B and C. The results show that the highest TRS value is achieved when the Cr content of the binder is not more than 10% by weight.

The thermal conductivity measurement of the cemented carbide shows that for an equivalent WC particle size, the cemented carbide with the Fe-Cr based binder phase has a higher thermal conductivity than the cemented carbide with the Co based binder phase.

Claims (13)

A cemented carbide comprising a hard phase and an iron-chromium based metal binder phase, characterized in that the binder phase has a chromium content of 1 based on the total amount of the iron-chromium metal binder phase 10wt%.  The cemented carbide according to claim 1, wherein the chromium content is from 2 to 8 wt% based on the total amount of the iron-chromium-based metal binder phase.    The cemented carbide according to claim 1 or 2, wherein the cemented carbide comprises 3 to 35 wt% of an iron-chromium-based metal binder phase of the total cemented carbide composition.   The cemented carbide according to any one of the preceding claims, wherein the hard particles of the hard phase are any of WC, TiC, TaC, NbC, VC, ZrC, Mo ₂ C or HfC or a mixture thereof.  A cemented carbide according to any of the preceding claims, wherein the hard phase consists essentially of WC.   A method of producing a cemented carbide, comprising the steps of: a. providing a hard phase powder, at least one powder composed of FeCr, and optionally a powder composed of Cr ₃ C ₂ ; b. The organic binder is ground together to obtain a powder mixture; c. the milled powder mixture is extruded; and d. the extruded powder mixture is sintered to obtain a sintered cemented carbide; characterized in that the Cr content is added 1 to 10% by weight of the total amount of the FeCr powder and the Cr ₃ C ₂ powder. The method of claim 6, wherein the Cr content is 2 to 10% by weight based on the total amount of the FeCr powder and the Cr ₃ C ₂ powder added. The method of claim 6 or 7, wherein the total amount of added FeCr and Cr ₃ C ₂ powder is between 3 and 35 wt% of the total cemented carbide composition. The method of any one of claims 6 to 8, wherein the hard phase powder provided is selected from one or more of WC, TiC, ZrC, Mo ₂ C or HfC or a mixture thereof.  The method of any one of claims 6 to 9, wherein the hard phase consists essentially of WC.    Use of a cemented carbide according to any of the preceding claims for the manufacture of a cutting tool, a wear component, a seal ring, a bushing, an assembly such as an automobile, or a mold.    A cutting tool, a wear member, a seal ring, a bushing, a mold, an assembly such as an automobile, or a tool according to any one of claims 1 to 10.    Use of the cemented carbide of any one of claims 1 to 10 for the manufacture of a tool for processing a radioactive component.