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3D printing preparation method of high-density hard alloy block

A cemented carbide block, 3D printing technology, applied in additive manufacturing, additive processing, improving energy efficiency, etc., can solve the problems of holes, cracks, high residual stress, and large differences in thermal expansion coefficients in printed parts

Pending Publication Date: 2022-01-21
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these two additive manufacturing technologies have many problems in printing and preparing cemented carbide materials. For example, the extremely high energy density of electron beams and lasers will cause WC to decompose and decarburize, resulting in brittle WC. 2 C phase; and because of the large difference in melting point and thermal expansion coefficient between WC and Co, Ni and other metals used as the binder phase, in the rapid solidification process of the multiphase melt, the volume shrinkage of different precipitated phases is often uncoordinated, which is very easy to produce high temperature. Residual stress, which leads to a large number of holes, cracks and other defects in the printed part, its mechanical properties are difficult to compare with the cemented carbide block prepared by powder metallurgy

Method used

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  • 3D printing preparation method of high-density hard alloy block
  • 3D printing preparation method of high-density hard alloy block
  • 3D printing preparation method of high-density hard alloy block

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Ball mill the spherical WC-Co powder of 5-20 μm and the nylon powder of 25-85 μm for 4 hours to mix them evenly. The quality of the nylon powder is 5% of the mass of the WC-Co powder; Dry to remove water vapor, and then use powder-spreading selective laser sintering equipment to print the mixed powder into a green body of the desired shape. This process is to perform laser sintering on the mixed powder layer for each layer of mixed powder. The sintering temperature is 170°C; the green body is degreased and pre-sintered under the protection of the atmosphere, firstly at a rate of 3°C / min from room temperature to 200°C, and then at a rate of 0.6°C / min to 550°C, And keep it at 550°C for 2h, then raise the temperature to 1390°C at a rate of 4°C / min and keep it for 1h, then slowly cool down to 800°C at a rate of 2°C / min, keep it at 800°C for 0.5h, and then heat it at 2°C Cool down with the furnace at a rate of 400°C / min, in which the protective atmosphere is a hydrogen-argon...

Embodiment 2

[0022] Ball mill the spherical WC-Co powder of 5-20 μm and the nylon powder of 25-85 μm for 5 hours to mix them evenly. The quality of the nylon powder is 7% of the mass of the WC-Co powder; Dry to remove water vapor, and then use powder-spreading selective laser sintering equipment to print the mixed powder into a green body of the desired shape. This process is to perform laser sintering on the mixed powder layer for each layer of mixed powder. The sintering temperature is 170°C; the body is degreased and pre-sintered under the protection of the atmosphere, firstly at a rate of 4°C / min from room temperature to 250°C, and then at a rate of 0.7°C / min to 600°C, And keep it at 600°C for 2.5h, then raise the temperature to 1420°C at a rate of 4.5°C / min and keep it for 1.5h, then slowly cool it down to 800°C at a rate of 3°C / min, and keep it at 800°C for 0.5h, then Cool down with the furnace at a rate of 3°C / min to 400°C, in which the protective atmosphere is a hydrogen-argon mixt...

Embodiment 3

[0024]Ball mill the spherical WC-Co powder of 5-20 μm and the nylon powder of 25-85 μm for 6 hours to mix them evenly. The quality of the nylon powder is 8% of the mass of the WC-Co powder; Dry to remove water vapor, and then use powder-spreading selective laser sintering equipment to print the mixed powder into a green body of the desired shape. This process is to perform laser sintering on the mixed powder layer for each layer of mixed powder. The sintering temperature is 170°C; the body is degreased and pre-sintered under the protection of the atmosphere, firstly at a rate of 5°C / min from room temperature to 300°C, and then at a rate of 0.8°C / min to 650°C, And keep it at 650°C for 3 hours, then raise the temperature at a rate of 5°C / min to 1480°C for 2 hours, then slowly cool it down to 800°C at a rate of 4°C / min, keep it at 800°C for 0.5h, and then heat it at 4°C Cool down with the furnace at a rate of 400°C / min, in which the protective atmosphere is a hydrogen-argon mixtu...

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Abstract

The invention discloses a 3D printing preparation method of a high-density hard alloy block, and belongs to the technical field of alloy preparation. The preparation method comprises the following steps: spherical WC-Co powder of 5-20 microns and nylon powder of 25-85 microns are taken as raw materials, firstly, the raw material powder are uniformly mixed through ball milling; then, powder laying type selective laser sintering equipment is adopted for conducting layer-by-layer printing forming on the mixed powder, and in the process, after the nylon powder is heated and melted, the WC-Co powder is bonded into a blank in the needed shape; degreasing and pre-sintering are carried out on the obtained green body to completely decompose and remove nylon, and most of open and communicated holes in the green body are changed into closed holes; and after the pre-sintered body is cooled to the room temperature, secondary sintering is conducted on the pre-sintered body under the pressurization condition, internal closed holes are removed through the dual effects of high temperature and pressure, and finally the 3D printing hard alloy product which is pure in phase, nearly fully compact and good in comprehensive mechanical property is obtained.

Description

technical field [0001] The invention belongs to the field of cemented carbide additive manufacturing, and in particular relates to a high-density cemented carbide 3D printing preparation method. Background technique [0002] Cemented carbide is widely used in metal cutting, mining, drawing die processing and other fields because of its high hardness and strength, excellent wear resistance and corrosion resistance. With the development of modern manufacturing industry, for some new application conditions, the traditional powder metallurgy preparation process is difficult to meet the requirements of complex shape and structure of cemented carbide products, which greatly restricts the expansion of the application field of cemented carbide. In recent years, the rapid development of 3D printing technology in China has great potential to overcome the above bottlenecks and develop new high-performance cemented carbide products. Using computer-aided design modeling, model files are...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/04B22F10/28B22F3/10B33Y10/00
CPCB22F9/04B22F10/28B22F3/1025B33Y10/00B22F2009/043Y02P10/25
Inventor 王海滨宋晓艳张焱垚赵治刘雪梅邢明
Owner BEIJING UNIV OF TECH