Bimodal cemented carbide powders for additive manufacturing and structured bodies made therefrom

Abstract

Sintered cemented carbide powder compositions for use in the production of various articles by additive manufacturing are disclosed. The individual particles of the powder composition comprise metal carbide particles sintered together with a metal binder. The sintered cemented carbide particles comprise at least a bimodal particle size distribution wherein the first mode comprises spherical sintered cemented carbide particles having a D50 of 15 [mu] m to 45 [mu] m and the second mode comprises non-spherical cemented carbide particles having a D50 of 5 [mu] m to 15 [mu] m. The metal binder may be present in an amount of from 9% to 11% by weight based on the total weight of the sintered cemented carbide particles. A sintered cemented carbide body that is additively manufactured from the sintered cemented carbide powder composition is disclosed. A method of making the sintered cemented carbide powder composition and a method of making the sintered cemented carbide body are also disclosed.

Description

Technical Field

[0001] The present invention relates to a cemented carbide powder composition for additive manufacturing and a sintered cemented carbide body additively manufactured using the cemented carbide powder. Background Art

[0002] Additive manufacturing offers an efficient and cost-effective alternative to traditional molding-based product manufacturing techniques. With additive manufacturing, the significant time and expense of mold and / or die construction and other processing can be avoided. Furthermore, additive manufacturing technology allows for efficient material utilization by allowing for recycling within the process. Most importantly, additive manufacturing offers significant freedom in product design. Products with highly complex shapes can be produced without significant expense, allowing a range of product designs to be developed and evaluated before a final design is selected. Summary of the Invention

[0003] A sintered cemented carbide powder composition for producing various articles by additive manufacturing is provided. The individual particles of the powder composition comprise metal carbide particles sintered together with a metal binder. The sintered cemented carbide particles comprise at least a bimodal particle size distribution, wherein a first mode comprises spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm, and a second mode comprises non-spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm. The metal binder may be present in an amount of 9 wt % to 11 wt % based on the total weight of the sintered cemented carbide particles. A sintered cemented carbide body additively manufactured from the sintered cemented carbide powder composition is provided. A method of making the sintered cemented carbide powder composition and a method of making the sintered cemented carbide body are also provided.

[0004] Disclosed herein is a powder composition for binder jet printing, the powder composition comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising sintered cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles.

[0005] Also disclosed herein is a method for preparing a powder composition for binder jet printing, the method comprising: forming a slurry by grinding metal carbide particles and 9 wt % to 11 wt % of a metal binder based on the total weight of the slurry; spray drying the slurry to form a powder; sintering a first portion of the powder; grinding and sieving the first portion of the powder to a D50 of 15 μm to 45 μm; and sintering the first portion of the powder a second time in a partially liquid state to form a first pattern; forming a second pattern by grinding a second portion of the powder to form non-spherical cemented carbide particles with a D50 of 5 μm to 15 μm; and combining the first pattern and the second pattern.

[0006] Also disclosed herein is a binder jet printed sintered cemented carbide body comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising non-spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metallic binder based on the total weight of the sintered cemented carbide particles, and the sintered cemented carbide body has a theoretical density percentage of 99% or greater. The binder jet printed sintered cemented carbide body is formed by binder jet printing the sintered cemented carbide particles to form a green body, and then sintering the green body.

[0007] Also disclosed herein is a method for forming a sintered cemented carbide body, the method comprising binder jet printing a powder composition comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising non-spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles, and the sintered cemented carbide body has a theoretical density percentage equal to or greater than 99%, and the sintered cemented carbide body has a printed binder to form a green body; and sintering the green body to provide the sintered cemented carbide body. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a scanning electron microscope (SEM) image of a cross section of a sample of GU1 powder.

[0009] Figure 2 is a SEM of a cross section of a sample of C2 powder.

[0010] Figure 3 is a SEM of a cross section of F1 powder.

[0011] Figure 4 is the microstructure of sintered sample 1.

[0012] Figure 5 is the microstructure of sintered sample 2.

[0013] Figure 6 is the microstructure of sintered sample 3. DETAILED DESCRIPTION

[0014] The present invention disclosed herein is directed to a powder composition for binder jet printing, comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising non-spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles.

[0015] The powder composition can be used in any suitable additive manufacturing technology to form three-dimensional parts. The term "additive manufacturing technology" refers to a process for forming a three-dimensional object by continuously adding material to the object layer by layer. The layered construction on a layer by layer basis enables easy formation of undercuts and complex geometries that could not be formed using previous conventional manufacturing methods or required considerable effort and expense. The three-dimensional object can be based on a 3D model of the component object, which can be electronically designed as an electronic file with design parameters. Additive manufacturing may also be referred to as 3D printing. The additive manufacturing technology of the present invention comprises a process for forming a ceramic powder into a sintered cemented carbide body.

[0016] Additive manufacturing processes can include, for example, binder jetting. As used herein, "binder jetting" or "binder jet" refers to a method of producing a component by selectively spraying droplets of a liquid binder onto a bed of powder (e.g., ceramic powder) based on a 3D model of the component, causing the particles to adhere to the cross-section, depositing additional powder, and then depositing the binder to form the next layer of the object, and repeating this process until the green component is complete. For example, a binder jetting device spreads a layer of metal, ceramic, or cermet powder in a build box, moves a print head over the powder layer, depositing a liquid binder according to the design parameters of the layer, dries the layer, lowers the build box, spreads a new layer of ceramic powder, and repeats the process until the green article (body) is complete. Although binder jetting is primarily described herein as an additive manufacturing process for making the materials of the present invention, other types of additive processes may be suitable for use herein.

[0017] The sintered cemented carbide particles comprise individual metal carbide grains sintered and bound together by a metallic binder.

[0018] The sintered cemented carbide particles include one or more metal carbides. The metal carbide can include IVB group metal carbide, VB group metal carbide, VIB group metal carbide or its combination. For example, the sintered cemented carbide particles can include tungsten carbide, chromium carbide, titanium carbide, vanadium carbide, tantalum carbide, niobium carbide, zirconium carbide and / or hafnium carbide. The sintered cemented carbide particles can include tungsten carbide and a second metal carbide. The tungsten carbide can exist in an amount of at least 85 wt % to 90 wt % based on the gross weight of the sintered cemented carbide particles. If present, the second metal carbide can exist in an amount of 0.1 wt % to 5 wt % based on the gross weight of the sintered cemented carbide particles.

[0019] The sintered cemented carbide particles may not contain multiple metals and / or non-stoichiometric metal carbides. Bimetallic carbides and / or low-metal carbides include, but are not limited to, η phase (Co3W3C or Co6W6C), W2C, and / or W3C. Additionally, the sintered cemented carbide particles may exhibit a uniform or substantially uniform microstructure.

[0020] The sintered carbide particles include a metal binder. The metal binder may include cobalt, a cobalt alloy, nickel, a nickel alloy, iron, an iron alloy, or a combination thereof. The metal binder may further include one or more additives, such as a precious metal additive. Examples of precious metal additives that can be used in the present invention include, but are not limited to, platinum, palladium, rhenium, rhodium, and ruthenium, and alloys thereof. Other additives include molybdenum, silicon, or a combination thereof. If present, the additive may be present in the metal binder in an amount of 0.1% to 10% by weight of the sintered carbide particles based on the total weight of the sintered carbide particles.

[0021] The metal binder can be present in the sintered cemented carbide particles in an amount of at least 9 wt %, such as at least 9.1 wt %, such as at least 9.5 wt %, such as at least 9.8 wt % based on the total weight of the sintered cemented carbide particles. The metal binder can be present in the sintered cemented carbide particles in an amount of not more than 11 wt %, such as not more than 10.9 wt %, such as not more than 10.5 wt %, such as not more than 10.2 wt % based on the total weight of the sintered cemented carbide particles. The metal binder can be present in the sintered cemented carbide particles in an amount of 9 to 11 wt %, such as 9.1 to 10.9 wt %, such as 9.5 to 10.5 wt %, such as 9.8 to 10.2 wt % based on the total weight of the sintered cemented carbide particles. The metal binder can be present in the sintered cemented carbide particles in an amount of 10 wt % based on the total weight of the sintered cemented carbide particles.

[0022] As previously described, the sintered cemented carbide particles comprise a first mode. The first mode may comprise substantially spherical particles. As used herein, "spherical" means that the particles are generally spherical, have a convex curved outer surface with substantially no flat or concave surface areas, and have an aspect ratio of 1:1.

[0023] The D50 of the first mode particles may be at least 15 μm, such as at least 20 μm, such as at least 25 μm, such as at least 27 μm. The D50 of the first mode particles may be no greater than 45 μm, such as no greater than 40 μm, such as no greater than 35 μm, such as no greater than 30 μm. The D50 of the first mode particles may be from 15 μm to 45 μm, such as from 20 μm to 40 μm, such as from 25 μm to 35 μm, such as from 27 μm to 30 μm. As used herein, "D50" means the point of the particle size distribution at which 50% or more of the total volume of the material in the sample is contained. For example, a D50 of 15 μm means that 50% of the particles in the sample are less than 15 μm in size.

[0024] The D10 of the first mode particles may be at least 10 μm, such as at least 12 μm, such as at least 15 μm. The D10 of the first mode particles may be no greater than 25 μm, such as no greater than 23 μm, such as no greater than 20 μm. The D10 of the first mode particles may be from 10 μm to 25 μm, such as from 12 μm to 23 μm, such as from 15 μm to 20 μm. As used herein, "D10" means the point of the particle size distribution at which 10% or more of the total volume of the material in the sample is contained. For example, a D10 of 10 μm means that 10% of the particles in the sample are 10 μm or smaller in size.

[0025] The D90 of the first mode particles may be at least 25 μm, such as at least 30 μm, such as at least 35 μm. The D90 of the first mode particles may be no greater than 55 μm, such as no greater than 50 μm, such as no greater than 45 μm. The D90 of the first mode particles may be from 25 μm to 55 μm, such as from 30 μm to 50 μm, such as from 35 μm to 45 μm. As used herein, "D90" means the point of the particle size distribution at which 90% or more of the total volume of the material in the sample is contained. For example, a D90 of 25 μm means that 90% of the particles in the sample are less than 25 μm in size.

[0026] The particle size distribution of powders described and claimed herein can be measured using a laser diffraction particle size analyzer (S-3500, commercially available from Microtrac MRB).

[0027] The average individual particle porosity of the first mode particles may be no greater than 10 volume %, such as no greater than 8 volume %, and such as no greater than 6 volume %. As used herein, "individual particle porosity" refers to the volume % of pores in an individual particle based on the total volume of the particle. That is, if the particle porosity of the individual particles is 10 volume %, 90 volume % of the particles contain materials such as metal carbides and / or metal binders.

[0028] The first mode particles may be present in the powder composition in an amount greater than 60 wt %, such as at least 62 wt %, such as at least 65 wt %, based on the total weight of the powder composition. The first mode particles may be present in the powder composition in an amount less than 75 wt %, such as not greater than 73 wt %, such as not greater than 70 wt %, based on the total weight of the powder composition. The first mode particles may be present in the powder composition in an amount greater than 60 wt % to less than 75 wt %, such as 62 to 73 wt %, such as 65 to 70 wt %, based on the total weight of the powder composition.

[0029] The sintered cemented carbide particles comprise a second mode. The second mode may comprise non-spherical particles. As used herein, "non-spherical" means that the particles are not spherical, but may comprise a flat or multi-faceted surface. The edges may have an indented portion. The aspect ratio of the non-spherical particles may or may not be 1:1. For example, the aspect ratio of at least a portion of the particles may be greater than 1:1, such as greater than 1.1:1, such as greater than 1.2:1, such as greater than 1.5:1.

[0030] The second mode particles may be formed by grinding the first mode particles to prepare particles of smaller size.

[0031] The D50 of the second mode particles may be at least 5 μm, such as at least 6 μm, such as at least 8 μm. The D50 of the second mode particles may be no greater than 15 μm, such as no greater than 12 μm, such as no greater than 10 μm. The D50 of the second mode particles may be from 5 μm to 15 μm, such as from 6 μm to 12 μm, such as from 8 μm to 10 μm.

[0032] The D10 of the second mode particles may be at least 0.5 μm, such as at least 1 μm, such as at least 1.5 μm. The D10 of the second mode particles may be no greater than 5 μm, such as no greater than 3 μm, such as no greater than 2 μm. The D10 of the second mode particles may be from 0.5 μm to 5 μm, such as from 1 μm to 3 μm, such as from 1.5 μm to 2 μm.

[0033] The D90 of the second mode particles may be at least 10 μm, such as at least 12 μm, such as at least 15 μm. The D90 of the second mode particles may be no greater than 30 μm, such as no greater than 25 μm, such as no greater than 20 μm. The D90 of the second mode particles may be from 10 μm to 30 μm, such as from 12 μm to 25 μm, such as from 15 μm to 20 μm.

[0034] The average individual particle porosity of the second mode particles may be no greater than 20 volume %, such as no greater than 18 volume %, such as no greater than 15 volume %.

[0035] The second mode particles may be present in the powder composition in an amount greater than 25 wt %, such as at least 27 wt %, such as at least 30 wt %, based on the total weight of the powder composition. The second mode particles may be present in the powder composition in an amount less than 40 wt %, such as not greater than 38 wt %, such as not greater than 35 wt %, based on the total weight of the powder composition. The second mode particles may be present in the powder composition in an amount greater than 25 wt % to less than 40 wt %, such as 27 to 38 wt %, such as 30 to 35 wt %, based on the total weight of the powder composition.

[0036] The theoretical density percentage of the powder composition can be at least 99%, such as at least 99.1%, such as at least 99.2%, such as at least 99.3%, such as at least 99.5%. The theoretical density percentage is calculated by dividing the sintered HIP density as measured by ASTM B311 by the theoretical density. As used herein, "theoretical density" means the maximum achievable density of a sample.

[0037] The powder composition may have a tap density of at least 6.5 g / cm 3 , such as at least 6.7 g / cm 3 , such as at least 6.8 g / cm 3 , such as at least 6.9 g / cm 3 The tap density of the powder composition may be no greater than 8.0 g / cm 3 , such as not more than 7.5 g / cm 3 , such as not more than 7.3 g / cm 3 , such as not more than 7.2 g / cm 3 The tap density of the powder composition may be 6.5 g / cm 3 Up to 8.0g / cm 3 , such as 6.7 g / cm 3 Up to 7.5 g / cm 3 , such as 6.8 g / cm 3 Up to 7.3 g / cm 3 , such as 6.9 g / cm 3 Up to 7.2 g / cm 3 As used herein, "tap density" means the mass per unit volume of a powder once the powder has been tapped a defined number of tapping cycles. Tap density can be determined according to ASTM B527 Standard Test Method for Tap Density of Metal Powders and Compounds.

[0038] The powder composition may have an apparent density of at least 5.0 g / cm 3 , such as at least 5.2 g / cm 3 , such as at least 5.3 g / cm 3 The apparent density of the powder composition may be no greater than 6.0 g / cm 3 , such as not more than 5.8 g / cm 3 , such as not more than 5.6 g / cm 3 The apparent density of the powder composition may be 5.0 g / cm 3 Up to 6.0 g / cm 3 , such as 5.2 g / cm 3 Up to 5.8 g / cm 3 , such as 5.3g / cm 3 Up to 5.6 g / cm3 As used herein, "apparent density" means the mass per unit volume of a powder or granules in a loose state. Apparent density may also be referred to as bulk density. Apparent density can be determined using a Hall flowmeter funnel according to ASTM B212 Standard Test Method for Apparent Density of Free-Flowing Metal Powders.

[0039] The ratio of the tap density to the apparent density ("Hausner ratio") of the powder composition may be at least 1.18, such as at least 1.19, such as at least 1.20. The Hausner ratio of the powder composition may be no greater than 1.30, such as no greater than 1.29, such as no greater than 1.28. The Hausner ratio of the powder composition may be from 1.18 to 1.30, such as from 1.19 to 1.29, such as from 1.28 to 1.28.

[0040] When the carbide comprises tungsten carbide and the metallic binder comprises cobalt, the sintered density of the powder composition may be at least 14.30 g / cm 3 , such as at least 14.31 g / cm 3 , such as at least 14.32 g / cm 3 , such as at least 14.33 g / cm 3 The sintered density of the powder composition may be no greater than 14.40 g / cm 3 , such as not more than 14.38 g / cm 3 , such as not more than 14.37 g / cm 3 , such as not more than 14.36 g / cm 3 The sintered density of the powder composition may be 14.30 g / cm 3 to 14.40 g / cm 3 , such as 14.31 g / cm 3 to 14.38 g / cm 3 , such as 14.32 g / cm 3 to 14.37 g / cm 3 , such as 14.33 g / cm 3 to 14.36 g / cm 3 Sintered density can be measured by ASTM B311 density determination for powder metallurgy (P / M) materials containing less than two percent porosity.

[0041] The present invention further relates to a method for preparing a powder composition for binder jet printing, the method comprising: forming a slurry by grinding metal carbide particles and 9 wt % to 11 wt % of a metal binder based on the total weight of the slurry; spray drying the slurry to form a powder; sintering a first portion of the powder; grinding and sieving the first portion of the powder to a D50 of 15 μm to 45 μm; and sintering the first portion of the powder a second time in a partially liquid state to form a first pattern; forming a second pattern by grinding a second portion of the powder to form non-spherical cemented carbide particles having a D50 of 5 μm to 15 μm; and combining the first pattern and the second pattern.

[0042] The density and individual particle porosity of the powder composition disclosed herein can be achieved by applying one or more sintering processes to the particles. The sintering process can be performed without using a sintering inhibitor to reduce particle sticking or adhesion. The sintered carbide particle characteristics described herein can be achieved in the absence of a sintering inhibitor. Sintered carbide particles can be prepared by sintering the grade powder composition at a temperature of 1100° C. to 1400° C. for 0.5 to 2 hours to provide a sintered compact. The sintered compact is then ground to provide individual sintered carbide particles. Depending on the particle morphology and density, the sintered carbide particles can be further heat treated to further densify. The further heat treatment can include plasma densification, such as plasma spheroidization using an RF plasma torch or a DC plasma torch. Alternatively, the sintered carbide particles can be re-sintered to form a second compact. The second compact is ground to provide sintered carbide particles. Any desired number of additional densification treatments may be applied to provide sintered cemented carbide particles having a desired apparent density, tap density, and / or individual particle density. The sintering time and temperature may be selected based on several considerations, including but not limited to the binder content of the cemented carbide particles, the desired sintered particle density, and the sintering stage. In some embodiments, an early sintering stage is performed at a lower temperature and / or for a shorter time to aid in grinding the sintered compact. For example, an initial or early sintering process may be applied at a temperature below the liquefaction temperature of the binder. A later or final sintering process may reach a higher temperature, such as a temperature at which liquid phase sintering occurs.

[0043] The present invention further relates to a binder jet-printed sintered cemented carbide body comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising non-spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles, and the sintered cemented carbide body has a theoretical density percentage equal to or greater than 99%.

[0044] When the sintered cemented carbide body comprises tungsten carbide and cobalt binder metal in the amounts disclosed herein, the sintered cemented carbide body may have a sintered density equal to or greater than 14 g / cm 3 , such as at least 14.1 g / cm 3 , such as at least 14.2 g / cm 3 , such as at least 14.3 g / cm 3 , such as about 14.4 g / cm 3 Sintered density can be measured by ASTM B311 density determination for powder metallurgy (P / M) materials containing less than two percent porosity.

[0045] The sintered cemented carbide body may have a percent theoretical density equal to or greater than 99%, such as greater than 99.1%, such as greater than 99.3%, such as greater than 99.5%, such as greater than 99.7%, such as greater than 99.9%. The percent theoretical density is calculated as described above.

[0046] The sintered porosity grade of the sintered cemented carbide body may be A02B00C00, A01B00C00, or A00B00C00. The sintered density may be determined by the procedure of ASTM B276: Standard Test Method for Apparent Porosity in Active-Only Cemented Carbides.

[0047] The present invention further relates to a method of forming a sintered cemented carbide body, the method comprising: binder jet printing a powder composition comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first pattern comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second pattern comprising spherical sintered cemented carbide particles having a D50 of 5 μm to 15 μm. μm non-spherical sintered cemented carbide particles, wherein the sintered cemented carbide particles contain 9 wt% to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles, and the first mode and the second mode are present in a weight ratio of 1:9 to 3:2, and the theoretical density percentage of the sintered cemented carbide body is equal to or greater than 99%, and the sintered cemented carbide body has a printed binder to form a green body; and sintering the green body to provide the sintered cemented carbide body.

[0048] A method for forming a sintered cemented carbide body may comprise sintering the green body by a sinter-HIP process.The green body may be formed from any of the powder compositions described above.

[0049] The green body is formed by binder jetting one of the powder compositions described herein and a printing binder. Any organic binder known in the art can be used as the printing binder. In one embodiment, the organic binder can include one or more polymeric materials, such as polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), or a mixture thereof. The organic binder can be curable, which can enhance the strength of the green body. The polymeric binder can be an aqueous binder or a solvent binder. The green body can exhibit a binder saturation of at least 80%, such as 100% or greater.

[0050] The green body can then be sintered under conditions and for a period sufficient to provide a sintered body having the desired density. The green article can be vacuum sintered or sintered under a hydrogen or argon atmosphere at a temperature between 1300°C and 1560°C. Furthermore, sintering times can typically range from 10 minutes to 5 hours. Hot isostatic pressing (HIP) can optionally be added to the sintering process. HIP can be performed as a post-sintering operation or applied during vacuum sintering. HIP can be applied at a pressure of 1 MPa to 300 MPa and a temperature of 1300°C to 1560°C for up to 2 hours. The microstructure of the sintered cemented carbide body can be uniform. The sintered cemented carbide body can exhibit volume shrinkage in the sintered sample compared to a 40 to 60 volume percent pre-printed sample.

[0051] The sintered cemented carbide bodies produced according to the methods described herein can be used in a variety of industries, including petrochemical, automotive, aerospace, industrial tool processing, metal cutting tools and manufacturing. The sintered cemented carbide bodies can be used as parts exposed to wear environments or abrasive operating conditions, such as flow control parts, pumps, bearings, valves, valve parts, centrifuge parts, disk stacks and / or fluid handling parts. The sintered cemented carbide bodies can also include one or more internal fluid flow channels formed by additive manufacturing techniques. The sintered cemented carbide bodies can be near net shape and / or require minimal post-sintering processing to place the body in its final form.

[0052] Examples

[0053] A spherical porous coarse powder (C1) was produced by grinding a mixture of 90 wt.% tungsten carbide (WC) particles, 10 wt.% cobalt (Co) powder and organic additives. The slurry was then spray dried and heated at 1200-1250 °C in the solid state under vacuum (<10 -3 The C1 powder was sintered in a vacuum (<10-3 Torr) for 1-2 hours to form a slightly sintered powder. The sintered powder was ground and sieved to the desired powder size distribution. A spherical, dense coarse powder (C2) was produced by re-sintering the C1 powder at 1260-1320°C in a partially liquid state in a vacuum (<10-3 Torr) for 1-2 hours to increase the density. A non-spherical, porous fine powder, F1, was produced by ball milling the C1 powder for 10 hours. After milling, the powder size was significantly reduced compared to GU1, while the porosity level remained similar.

[0054] Table 1 shows the powder particle size distribution (D10, D50, and D90), porosity, and morphology of the C1, C2, and F1 powders. The powder particle size distribution was measured by laser scattering using a laser diffraction particle size analyzer (S-3500, commercially available from Mackey Claytsch). Powder samples were mounted, polished, and imaged to characterize porosity and morphology. Figure 1 、 2 Scanning electron micrographs (SEM) of the cross sections of the C1, C2, and F1 powders are given in Figures 3 and 4, respectively. Image processing software Image J was applied to the SEM images to calculate the porosity.

[0055] Table 1

[0056] Characteristics of WC-10Co powder

[0057]

[0058] Eight batches of bimodal powder mixtures were examined. Samples were prepared in 100 g batches by mixing in sealed cylindrical glass jars. The sealed jars were oriented to be located on the underside of a vibration table. The table was vibrated at 100 Hz to 300 Hz for at least 5 minutes to allow for thorough mixing of the powder. 11 g of bimodal powder from each batch was placed in a graphite crucible coated with a graphite-based release agent and tapped 300 times. The crucibles with powder were sintered at a temperature of 1441°C and a pressure of 5.5 MPa in an Ar atmosphere using a Sinter-HIP vacuum furnace for 45 minutes. The target minimum sintered density was 14.33 g / cm 3 Or 99.5% of theoretical density. The results are provided in Table 2. As shown, the density decreases with increasing weight % of GU2 powder. Batches containing 70% or less GU2 powder exhibit excellent sintered density.

[0059] Sintered density was determined using the Archimedes procedure described in ASTM B311. Apparent density was measured using a Hall flowmeter funnel according to ASTM B212 Standard Test Method for Apparent Density of Free-Flowing Metal Powders. Tap density was measured according to ASTM B527 Standard Test Method for Tap Density of Metal Powders and Compounds. Particle size was measured as described above.

[0060] Table 2

[0061] Characterization of bimodal powder mixtures

[0062]

[0063] Comparison samples

[0064] 1 Reference density: 14.42 g / cm 3

[0065] A 25 mm x 25 mm x 12 mm block was printed from bimodal powder batches 4, 5, 6, and 7 using a binder jetting machine "Desktop P1" with SPJ-04 binder. The binder droplet size was approximately 20 pL. The layer thickness was 50-60 μm, and the binder saturation was 30% to 45%.

[0066] The samples were cured at 195°C in a curing oven in an Ar atmosphere for 4 hours. After curing, de-powdering was performed by removing the surrounding unbound powder using vacuum. Samples from batches 5, 6 and 7 were able to be de-powdered, but the sample from batch 4 was not able to be de-powdered due to excessive fine powder in the mixture. The blocks were then placed on a graphite tray coated with a graphite-based release agent for de-binding and sintering in a sintering-HIP furnace. In the de-binding step, the samples were heated to 538°C in a hydrogen atmosphere. In the subsequent sintering step, the samples were sintered in an Ar atmosphere at a temperature of 1510°C and a pressure of 5.5 MPa for 45 minutes. A shrinkage of 50 to 60 volume % was observed in the sintered samples compared to the pre-printed samples. The characteristics of the pre-printed and sintered samples are provided in Table 3. Representative microstructures of samples 1, 2 and 3 are shown in Table 3, respectively. Figure 4 、 5 The results show that when the powder composition used contains 30 wt% or more of fine powder, the sample is almost completely dense. However, when the amount of fine powder is as low as 25 wt%, the sintered sample shows poor performance.

[0067] Table 3

[0068] Characteristics of WC-10Co samples printed using a bimodal powder mixture

[0069]

[0070] For the purpose of this specific embodiment, it should be understood that, unless clearly indicated otherwise, the present invention can take various alternatives and step sequences. In addition, except in any operating examples or when otherwise indicated, all numerals expressing the quantity of the components used in the present specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless indicated otherwise, the numerical parameters set forth in the following description and the appended claims are approximate values that can vary according to the desired properties to be obtained by the present invention. At least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0071] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0072] Furthermore, it should be understood that any numerical range recited herein is intended to include all subranges contained therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0073] As used herein, "including," "containing," and similar terms are understood in the context of this application to be synonymous with "comprising," and are thus open-ended and do not exclude the presence of additional, undescribed or unrecited elements, materials, ingredients, or method steps. As used herein, "consisting of" is understood in the context of this application to exclude the presence of any unspecified elements, ingredients, or method steps. As used herein, "consisting essentially of" is understood in the context of this application to include the specified elements, materials, ingredients, or method steps "as well as those that do not materially affect the basic and novel characteristics described."

[0074] In this application, unless specifically stated otherwise, the use of the singular includes the plural and the plural encompasses the singular. For example, although reference is made herein to "a" powder composition, "a" cemented carbide body, and "an" apparent density, combinations (i.e., a plurality) of these components may be used.

[0075] Additionally, in this application, the use of "or" means "and / or" unless specifically stated otherwise, even though "and / or" may be explicitly used in certain circumstances.

[0076] While specific aspects of the present invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details can be developed based on the overall teachings of this disclosure. Therefore, the particular arrangements disclosed are intended to be illustrative only and not limiting of the scope of the invention, which is to be given by the full scope of the appended claims and any and all equivalents thereof.

Claims

1. A powder composition for binder jet printing, the powder composition comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical cemented carbide particles having a D50 of 15 μm to 45 μm; and A second mode comprises non-spherical cemented carbide particles having a D50 of 5 to 15 μm, wherein the sintered cemented carbide particles comprise 9 to 11 wt% of a metal binder based on the total weight of the sintered cemented carbide particles. 2 . The powder composition of claim 1 , wherein the sintered cemented carbide particles comprise tungsten carbide and the metallic binder comprises cobalt.

3. The powder composition of claim 1 , wherein the powder composition has a sintered density of at least 14.3 g / cm 3 .

4. The powder composition of claim 1, wherein the metallic binder is present in an amount of 9.5 wt% to 10.5 wt% based on the total weight of the sintered cemented carbide particles. The powder composition according to claim 1 , wherein the D10 of the first mode is 10 μm to 25 μm. The powder composition according to claim 1 , wherein the D90 of the first mode is 25 μm to 55 μm. The powder composition according to claim 1 , wherein the first mode of particle porosity is no greater than 10% by volume.

8. The powder composition of claim 1, wherein the first mode comprises spherical sintered cemented carbide particles. 9 . The powder composition according to claim 1 , wherein D10 of the second mode is 0.5 μm to 5 μm. 10 . The powder composition according to claim 1 , wherein the D90 of the second mode is 10 μm to 30 μm.

11. The powder composition according to claim 1, wherein the second mode of particle porosity is no greater than 20% by volume.

12. The powder composition of claim 1, wherein the second mode comprises non-spherical sintered cemented carbide particles.

13. The powder composition of claim 1, wherein the sintered cemented carbide body comprises greater than 60 wt% to less than 40 wt% of the first mode, based on the total weight of the sintered cemented carbide body.

14. The powder composition of claim 1, wherein the sintered cemented carbide body comprises greater than 25 wt% to less than 40 wt% of the first mode, based on the total weight of the sintered cemented carbide body.

15. The powder composition of claim 1, wherein the powder composition has a tap density of at least 6.5 g / cm 3 .

16. The powder composition of claim 1, wherein the powder composition has an apparent density of at least 5.0 g / cm 3 .

17. The powder composition according to claim 1, wherein the powder composition has a Hausner ratio of 1.18 to 1.

30.

18. The powder composition of claim 1, wherein the powder composition has a percent theoretical density of at least 99.0%.

19. A method for preparing the powder composition according to claim 1, comprising: grinding metal carbide particles and the metal binder to form a slurry; spray drying the slurry to form a powder; sintering a first portion of the powder; grinding and sieving the first portion of the powder; and sintering the first portion of the powder a second time in a partially liquid state to form the first pattern; forming the second pattern by grinding a second portion of the powder; as well as The first mode and the second mode are combined.

20. A method of preparing a powder composition for binder jet printing, the method comprising: forming the slurry by grinding metal carbide particles and 9 to 11 weight percent of a metal binder based on the total weight of the slurry; spray drying the slurry to form a powder; sintering a first portion of the powder; grinding and sieving the first portion of the powder to a D50 of 15 to 45 μm; and sintering the first portion of the powder a second time in a partially liquid state to form a first pattern; forming a second pattern of non-spherical cemented carbide particles having a D50 of 5 μm to 15 μm by grinding a second portion of the powder; and The first mode and the second mode are combined.

21. A binder jet printed sintered cemented carbide body comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical particles having a D50 of 15 μm to 45 μm; and A second mode comprising non-spherical particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metallic binder based on the total weight of the sintered cemented carbide particles, and the sintered cemented carbide body has a theoretical density percentage of 99% or greater.

22. The sintered cemented carbide body of claim 21, wherein the sintered cemented carbide body has a sintered porosity grade of A02B00C00, A01B00C00, or A00B00C00.

23. The sintered cemented carbide body of claim 22, wherein the sintered cemented carbide particles comprise tungsten carbide and the metallic binder comprises cobalt.

24. The sintered cemented carbide body of claim 23, wherein the sintered density is greater than 14.0 g / cm 3 .

25. The sintered cemented carbide body of claim 21, comprising 9.5 to 10.5 weight percent of the metallic binder, based on the total weight of the sintered cemented carbide particles.

26. The sintered cemented carbide body of claim 21, wherein the first mode has a D10 of 10 to 25 μm and a D90 of 25 to 55 μm.

27. The sintered cemented carbide body of claim 21, wherein the second mode has a D10 of 0.5 to 5 μm and a D90 of 10 to 30 μm.

28. The sintered cemented carbide body of claim 21, wherein the second mode of grain porosity is no greater than 20 volume percent.

29. The sintered cemented carbide body of claim 21, wherein the sintered cemented carbide body comprises greater than 60 wt% to less than 40 wt% of the first mode, based on the total weight of the sintered cemented carbide body.

30. The sintered cemented carbide body of claim 21, wherein the sintered cemented carbide body comprises greater than 25 wt% to less than 40 wt% of the first mode, based on the total weight of the sintered cemented carbide body.

31. A method of forming a sintered cemented carbide body according to claim 21, the method comprising: binder jet printing a powder composition comprising the sintered cemented carbide particles to form a green body; and The green body is sintered to provide the sintered cemented carbide body.

32. A method of forming a sintered cemented carbide body, the method comprising: performing binder jet printing on a powder composition comprising sintered cemented carbide particles, the sintered cemented carbide particles comprising: a first mode comprising spherical sintered cemented carbide particles having a D50 of 15 μm to 45 μm; and a second mode comprising non-spherical cemented carbide particles having a D50 of 5 μm to 15 μm, wherein the sintered cemented carbide particles comprise 9 wt% to 11 wt% of a metallic binder based on the total weight of the sintered cemented carbide particles, and the sintered cemented carbide body has a percent of theoretical density of 99% or greater, and the sintered cemented carbide body has a printed binder to form a green body; and The green body is sintered to provide the sintered cemented carbide body.

33. The method of claim 12, wherein the green body is sintered by a sinter-HIP process.

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