Diamond composite material for binder jetting and additive manufacturing method thereof

Abstract

The present application provides a diamond composite material for binder jetting and an additive manufacturing method thereof, which belongs to the field of additive manufacturing technology. The diamond composite material for additive manufacturing includes diamond powder and Mn-(10.5-13.5 wt%)Si alloy powder, wherein the content of the Mn-(10.5-13.5 wt%)Si alloy powder is 15-45 vol.% of the diamond powder; the additive manufacturing method includes first printing a diamond composite green body using a binder jetting additive manufacturing technology, and then obtaining a high-density diamond composite sintered part by a degreasing-sintering process. The Mn-(10.5-13.5 wt%)Si alloy powder introduced in the present invention has a lower sintering temperature, good wettability with diamond particles, and can undergo metallurgical reaction during high-temperature sintering to form a carbide layer to ensure stable bonding, and sufficient liquid phase during the sintering process, which is conducive to significantly improving the density and mechanical properties of the diamond composite printed-sintered parts.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a diamond composite material for binder jetting and an additive manufacturing method thereof. Background Art

[0002] Diamond composites have good mechanical properties and thermal conductivity, and show great application potential in high-performance cutting tools, abrasive tools, and heat dissipation of electronic devices. With the rapid development of additive manufacturing technology in recent years, the preparation of high-performance complex-structure diamond composite tool devices combined with additive manufacturing technology has also become a research hotspot.

[0003] Binder Jetting (BJ, also known as 3DP) is an additive manufacturing technology based on powder bed inkjet. It sprays binder on the surface of the powder bed, and stacks the complex structure of the printed green parts layer by layer by bonding the powder layer by layer. Then, the final molding of the printed and sintered parts is completed by curing-debinding-sintering and other processes. Different from the current mainstream laser powder bed technology (LPB) and light-stereolithography technology (ST), 3DP technology not only has higher molding efficiency and does not require support structures, but also has the advantage of being able to prepare large-size samples. It has received widespread attention and research in current additive manufacturing technologies.

[0004] 3DP technology has high requirements for the quality of powder bed laying. Generally, raw material powders with a particle size of 10-200 μm can achieve good powder laying and molding. However, coarse particles with larger particle sizes are prone to produce larger pores and severe shrinkage after subsequent degreasing treatment. The sintering activity is low during the sintering process, and the pores are difficult to be fully filled. Therefore, the final printed-sintered parts cannot achieve high density and mechanical properties. Summary of the invention

[0005] Based on the above problems, the purpose of the present invention is to provide a diamond composite material for binder injection and an additive manufacturing method thereof, which effectively controls and lowers the sintering temperature by introducing Mn-(10.5-13.5 wt%) Si alloy powder with good wettability with the diamond phase, and provides sufficient liquid phase to fill the pores, thereby solving the above-mentioned problem of difficulty in obtaining high density and mechanical properties of printed-sintered parts.

[0006] A first aspect of the present invention provides a diamond composite material for binder jetting.

[0007] Specifically, a diamond composite material for binder injection comprises diamond powder and Mn-(10.5-13.5wt%) Si alloy powder, wherein the content of the Mn-(10.5-13.5wt%) Si alloy powder is 15-45vol.% of the diamond powder.

[0008] The diamond powder has a particle size of 10-50 μm, and the Mn-(10.5-13.5 wt%) Si alloy powder has a particle size of 0.5-5 μm.

[0009] The Mn-(10.5-13.5 wt%) Si alloy powder introduced in this application has the following advantages:

[0010] (1) The Mn-(10.5-13.5 wt%) Si alloy has a reasonable ratio of Mn and Si and a low melting point, which can reduce the sintering temperature and ensure that thermal decomposition such as graphitization does not occur in diamond during the sintering process.

[0011] (2) Both Mn and Si have good wettability with the diamond phase. During the sintering process, metallurgical reactions can occur to generate a transition interface layer of Mn3C and SiC. The good bonding performance can significantly improve the density and mechanical properties of the printed-sintered parts.

[0012] (3) Compared with other alloys (such as Ti-Si alloy), the metallurgical reaction between Mn-Si alloy and diamond is more significant and it is easier to form stable carbides, which makes the bonding strength between the diamond matrix and the alloy bonding phase higher.

[0013] The second aspect of the present invention provides a method for additive manufacturing of the diamond composite material according to the first aspect of the present invention.

[0014] Specifically, the additive manufacturing method of the diamond composite material for additive manufacturing comprises the following steps:

[0015] (1) diamond powder and Mn-(10.5-13.5 wt%) Si alloy powder are mixed in proportion, mixed with a binder, and then granulated to obtain granulated raw material powder;

[0016] (2) pre-sintering the granulated raw material powder in step (1) to obtain a pre-sintered raw material powder, wherein the pre-sintering process includes degreasing at 200-600° C. and pre-sintering at 600-800° C.;

[0017] (3) Printing, curing, degreasing and sintering the raw material powder of any one of steps (1) to (2) by binder jet additive manufacturing technology to obtain a diamond composite material printed-sintered part.

[0018] Preferably, the granulation process includes but is not limited to spray granulation, fluidized bed granulation, and compression-crushing granulation.

[0019] Preferably, the binder in step (1) comprises at least one of paraffin, PEG, PVA or rubber.

[0020] Preferably, the particle size of the granulated raw material powder in step (1) is 40-80 μm.

[0021] Preferably, the degreasing atmosphere in the pre-sintering treatment process is hydrogen, argon, nitrogen or vacuum; or / and the pre-sintering atmosphere is hydrogen, argon or nitrogen.

[0022] Through the granulation process, the diamond composite material powder raw material described in the present invention can be prepared into a raw material powder particle size range that is more suitable for 3DP printing, thereby ensuring the powder spreading quality during the printing process.

[0023] At the same time, pre-sintering the granulated powder can also provide a certain basic strength for the raw material powder, which is more conducive to subsequent printing and provides good strength for the printed-green parts.

[0024] Preferably, the printing process parameters of the binder jetting additive manufacturing technology include: powder layer thickness of 20-200 μm, binder saturation of 35%-150%, compaction roller speed of 150-500 rpm, powder roller speed of 200-300 rpm, and powder bed heating temperature of 25-300 °C.

[0025] Preferably, the printing-green part curing process includes a curing temperature of 120-300° C. and a curing time of 0.5-18 hours.

[0026] Preferably, the printing-green part degreasing process includes a degreasing temperature of 300-1000°C, a heating rate of 0.1°C / min-0.5°C / min, a holding time of 1-8 hours, and a degreasing atmosphere of one of hydrogen, nitrogen or argon.

[0027] Preferably, the printing-debinding part sintering process includes a sintering temperature of 1040-1150° C., a heating rate of 0.1° C. / min-0.5° C. / min, a holding time of 0.5-15 hours, and a sintering atmosphere of one of vacuum, nitrogen or argon.

[0028] Beneficial effects of the present invention:

[0029] (1) The introduced Mn-(10.5-13.5 wt%) Si alloy powder has good wettability with diamond powder. During high-temperature sintering, it can produce a metallurgical reaction with diamond particles to form a carbide transition layer, ensuring stable bonding. In addition, its sintering temperature is low, and thermal decomposition phenomena such as graphitization of diamond powder will not occur during the sintering process.

[0030] (2) The diamond composite material powder raw material of the present invention can be prepared into a raw material powder particle size range that is more suitable for 3DP printing through a granulation process, which is more conducive to ensuring the powder spreading quality during the printing process.

[0031] (3) The density of the diamond composite material 3DP printed-sintered parts prepared by the additive manufacturing method of the present invention can reach 95-98%, while the density of the parts prepared by other mainstream additive manufacturing technologies is only 68-86%.

[0032] (4) The Mn-(10.5-13.5 wt%) Si alloy powder has a reasonable ratio of Mn and Si, and its performance in improving the density of diamond composite 3DP printed-sintered parts is significantly better than that of pure Mn powder.

[0033] (5) Compared with other alloys (such as Ti-Si alloy), the metallurgical reaction between Mn-Si alloy and diamond is more significant and it is easier to form stable carbides, which makes the bonding strength between the diamond matrix and the alloy bonding phase higher. DETAILED DESCRIPTION

[0034] In order to further clearly express the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0035] Example 1

[0036] 1. Mix 30 vol.% of Mn-11 wt% Si alloy powder (2 μm) and 70 vol.% of diamond powder (15 μm) evenly, and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0037] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0038] 3. Using the pre-sintered raw material powder as the raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 85%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0039] 4. The printed green part is cured and powder removed. The curing process includes: curing temperature of 160 °C and curing time of 10 hours;

[0040] 5. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of argon; the sintering process includes: sintering temperature of 1080 °C, holding time of 2 hours, and sintering atmosphere of vacuum;

[0041] 6. Conduct density test on printed and sintered parts.

[0042] Example 2

[0043] 1. Mix 30 vol.% of Mn-11 wt% Si alloy powder (1 μm) and 70 vol.% of diamond powder (15 μm) evenly, and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0044] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0045] 3. Using the pre-sintered raw material powder as the raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 95%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0046] 4. The printed green part is cured and powder removed. The curing process includes: curing temperature of 160 °C and curing time of 10 hours;

[0047] 5. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of argon gas; the sintering process includes: sintering temperature of 1120 °C, holding time of 2 hours, and sintering atmosphere of argon gas;

[0048] 6. Conduct density test on printed and sintered parts.

[0049] Example 3

[0050] 1. Mix 30 vol.% of Mn-13 wt% Si alloy powder (1 μm) and 70 vol.% of diamond powder (15 μm) evenly, and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0051] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0052] 3. Using the pre-sintered raw material powder as the raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 95%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0053] 4. The printed green part is cured and powder removed. The curing process includes: curing temperature of 180 °C and curing time of 10 hours;

[0054] 5. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of nitrogen; the sintering process includes: sintering temperature of 1150 °C, holding time of 2 hours, and sintering atmosphere of nitrogen;

[0055] 6. Conduct density test on printed and sintered parts.

[0056] Example 4

[0057] 1. Mix 30 vol.% of Mn-13 wt% Si alloy powder (1 μm) and 70 vol.% of diamond powder (15 μm) evenly, and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0058] 2. Using granulated raw material powder as raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 95%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0059] 3. Curing and cleaning the printed green parts. The curing process includes: curing temperature of 180 °C and curing time of 10 hours.

[0060] 4. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of nitrogen; the sintering process includes: sintering temperature of 1150 °C, holding time of 2 hours, and sintering atmosphere of nitrogen;

[0061] 5. The density of the printed and sintered parts was tested and the density was 81.6%.

[0062] Comparative Example 1

[0063] 1. Evenly mix 30 vol.% pure Mn powder (1 μm) and 70 vol.% diamond powder (15 μm), and granulate them with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0064] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0065] 3. Using the pre-sintered raw material powder as the raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 95%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0066] 4. The printed green part is cured and powder removed. The curing process includes: curing temperature of 160 °C and curing time of 10 hours;

[0067] 5. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of argon; the sintering process includes: sintering temperature of 1300 °C, holding time of 2 hours, and sintering atmosphere of argon;

[0068] 6. Conduct density test on printed and sintered parts.

[0069] Comparative Example 2

[0070] 1. Evenly mix 30 vol.% Ti-8.5wt.%Si alloy powder (1 μm) and 70 vol.% diamond powder (15 μm), and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0071] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0072] 3. Using the pre-sintered raw material powder as the raw material, diamond composite material printing-green parts were prepared by binder jet printing. The printing process included: powder layer thickness of 100 μm, binder saturation of 95%, compaction roller speed of 150 rpm, powder roller speed of 300 rpm, and powder bed heating temperature of 55 °C;

[0073] 4. The printed green part is cured and powder removed. The curing process includes: curing temperature of 160 °C and curing time of 10 hours;

[0074] 5. Degreasing and sintering the printed green parts after curing. The degreasing process includes: degreasing temperature of 500 °C, holding time of 2 hours, and degreasing atmosphere of nitrogen; the sintering process includes: sintering temperature of 1450 °C, holding time of 2 hours, and sintering atmosphere of nitrogen;

[0075] 6. Conduct density test on printed and sintered parts.

[0076] Comparative Example 3

[0077] 1. Mix 30 vol.% of Mn-13 wt% Si alloy powder (1 μm) and 70 vol.% of diamond powder (15 μm) evenly, and granulate them after mixing with a binder to obtain a granulation raw material powder, which can be granulated by a spray method. The particle size range of the granulation raw material powder is 40-80 μm, and the binder is an organic binder PVA;

[0078] 2. Pre-sintering the granulated raw material powder to obtain pre-sintered raw material powder, wherein the pre-sintering process includes hydrogen degreasing at 600°C and hydrogen pre-sintering at 700°C;

[0079] 3. Using the pre-burned raw material powder as the raw material, the powder bed laser melting technology (LPBF) was used to print and prepare the diamond composite material. The printing process included: laser power 250 W, scanning rate 900 mm / s, slice layer thickness 100 μm, scanning interval 65 μm;

[0080] 4. Conduct density test on printed and sintered parts.

[0081] The relevant performances in Examples 1-4 of the present invention and Comparative Examples 1-3 were measured and compared, and the specific test performance results are shown in Table 1.

[0082] Table 1 Experimental related data and comparative data in Examples 1-4 and Comparative Examples 1-3 of the present application

[0083] Material Sintering atmosphere Sintering temperature Density Example 1 Diamond + 30vol.% Mn-11wt.% Si (3DP) vacuum 1080℃ 95.5% Example 2 Diamond + 30vol.% Mn-11wt.% Si (3DP) Argon 1120℃ 97.8% Example 3 Diamond + 30vol.% Mn-13wt.% Si (3DP) Nitrogen 1150℃ 98.9% Example 4 Diamond + 30vol.% Mn-13wt.% Si (3DP) (granulated raw material powder is not pre-sintered) Nitrogen 1150℃ 81.6% Comparative Example 1 Diamond + 30vol.% Mn (3DP) Argon 1300℃ 52.5% Comparative Example 2 Diamond + 30vol.% Ti-8.5wt.%Si (3DP) Nitrogen 1450℃ 78.6% Comparative Example 3 Diamond + 30vol.% Mn-13wt.% Si (LPBF) / / 58.5%

[0084] From Table 1, it can be seen that by adopting the present invention, the density of the prepared diamond composite material can reach 95-98% by combining the introduction of Mn-(10.5-13.5 wt%) Si alloy powder and the binder jet additive manufacturing printing-curing-degreasing-sintering process; while the density of pure diamond and diamond composite materials prepared by the binder jet additive manufacturing printing-curing-degreasing-sintering process of diamond-Mn and diamond-Ti-Si powders prepared by conventional granulation method is obviously lower, and Comparative Examples 1 and 2 fully demonstrate that Mn-13 wt% Si alloy powder is significantly better than pure Mn powder and Ti-Si alloy powder in improving the density of diamond composite printed-sintered parts; and from Comparative Example 3, it can be seen that the density of diamond composite materials prepared by other mainstream LPBF additive manufacturing technology processes can only reach 58.5%. Obviously, the density performance of the diamond composite material prepared by using the diamond composite material for binder injection and the process flow scheme of the additive manufacturing method thereof described in the present invention is significantly better than that of the conventional granulated powder system and the mainstream additive manufacturing process scheme.

Claims

1. A method for additive manufacturing of diamond composite materials for binder jetting, characterized in that: include: (1) diamond powder and Mn-(10.5-13.5 wt%) Si alloy powder are mixed, and the mixture is mixed with a binder and then granulated to obtain a granulated raw material powder, wherein the content of the Mn-(10.5-13.5 wt%) Si alloy powder is 15-45 vol.% of the diamond powder, the powder particle size of the diamond powder is 10-50 μm, and the particle size of the Mn-(10.5-13.5 wt%) Si alloy powder is 0.5-5 μm; Alternatively, the granulated raw material powder in step (1) is pre-sintered to obtain a pre-sintered raw material powder, wherein the pre-sintering process includes degreasing at 200-600° C. and pre-sintering at 600-800° C.; (2) The granulated raw material powder or the pre-sintered raw material powder in step (1) is subjected to a binder jetting additive manufacturing technology for printing, curing, degreasing and sintering to obtain a diamond composite material printed-sintered part.

2. The additive manufacturing method of diamond composite material for binder jetting according to claim 1, characterized in that: In the step (1), the binder includes at least one of paraffin, PEG, PVA or rubber.

3. The additive manufacturing method of diamond composite material for binder jetting according to claim 1, characterized in that: The particle size of the granulated raw material powder in step (1) is 40-80 μm.

4. The additive manufacturing method of diamond composite material for binder jetting according to claim 1, characterized in that: In the step (1), the degreasing atmosphere of the pre-sintering process is hydrogen, argon, nitrogen or vacuum; or / and the pre-sintering atmosphere is hydrogen, nitrogen or argon.

5. The additive manufacturing method of diamond composite material for binder jetting according to claim 1, characterized in that: The printing process parameters of the binder jetting additive manufacturing technology in step (2) include a powder layer thickness of 20-200 μm, a binder saturation of 35%-150%, a compaction roller speed of 150-500 rpm, a powder roller speed of 200-300 rpm, and a powder bed heating temperature of 25-55 °C.

6. The additive manufacturing method of diamond composite material for binder jetting according to claim 1, characterized in that: The curing process in step (2) includes a curing temperature of 120-300°C and a curing time of 10-18 hours; or / and the degreasing process in step (2) includes a degreasing temperature of 300-1000°C, a heating rate of 0.1°C / min-0.5°C / min, a holding time of 1-8 hours, and a degreasing atmosphere of one of hydrogen, nitrogen or argon; or / and the sintering process in step (2) includes a sintering temperature of 1040-1150°C, a heating rate of 0.1°C / min-0.5°C / min, a holding time of 2-15 hours, and a sintering atmosphere of one of vacuum, nitrogen or argon.