Sintering method of low-Co WC

A technology of cobalt tungsten carbide and sintering method, which is applied in the sintering field of low-cobalt tungsten carbide, which can solve the problems of slow heating rate, low hardness of cemented carbide, and long sintering time, and achieve high relative density and strong fracture toughness.

Inactive Publication Date: 2017-03-22
SHANGHAI MARITIME UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The sintering method used is hot pressing sintering. Due to the slow heating rate of hot pressing, long sintering time, and sufficient dissolution-precipitation process, the grain size of WC grows obviously, and the grain size is not uniform. Part of the grains grow abnormally, so the hardness of the cemented carbide obtained by sintering is low, at 1800-2000HV; the fracture toughness is not high, at 7.5-9.5MPa∙m 1 / 2

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] (1) Ingredients: Prepare TiB 2 WC powder with a content of 0.1w% and a Co content of 0.2w%. 49.85g nanometer WC powder, 0.05gTiB 2 Put 0.10g of Co powder into a ball mill, add an appropriate amount of alcohol, set the rotation speed to 400 rad / min, take out the slurry after 48 hours, put it in an oven, bake at 90°C for 24 hours, and pass through a 100-mesh sieve.

[0025] (2) Firing: Take an appropriate amount of the above-mentioned dried powder and put it into a graphite mold with an inner diameter of 20mm for compaction, then place it together with the mold between the upper and lower electrodes of the SPS device, and vacuum it (vacuum degree reaches 6Pa) Turn on the power at a rate of 200°C / min and pressurize to reach the sintering temperature of 1700°C. The axial pressure is 50MPa and then keep warm for 5 minutes. After turning off the power and cooling, the sample is taken out.

[0026] (3) Cleaning: Grinding and cleaning the products after they are released from...

Embodiment 2

[0029] (1) Ingredients: Prepare TiB 2 WC powder with a content of 0.4w% and a Co content of 0.5w%. 49.55g nanometer WC powder, 0.20gTiB 2 Put 0.25g of Co powder into a ball mill, add an appropriate amount of alcohol, set the rotation speed to 400 rad / min, take out the slurry after 48 hours, put it in an oven, bake at 90°C for 24 hours, and pass through a 100-mesh sieve.

[0030] (2) Firing: Take an appropriate amount of the above-mentioned dried powder and put it into a graphite mold with an inner diameter of 20mm for compaction, then place it together with the mold between the upper and lower electrodes of the SPS device, and vacuum it (vacuum degree reaches 6Pa) Turn on the power at a rate of 200°C / min and pressurize to reach the sintering temperature of 1600°C, keep the temperature for 5 minutes after the axial pressure is 50MPa, and take out the sample after turning off the power and cooling.

[0031] (3) Cleaning: Grinding and cleaning the products after they are releas...

Embodiment 3

[0034] (1) Ingredients: Prepare TiB 2 WC powder with a content of 0.7w% and a Co content of 0.8w%. 49.25g nanometer WC powder, 0.35gTiB 2 Put 0.40g of Co powder into a ball mill, add an appropriate amount of alcohol, set the rotation speed to 400 rad / min, take out the slurry after 48 hours, put it in an oven, bake at 90°C for 24 hours, and pass through a 100-mesh screen.

[0035] (2) Firing: Take an appropriate amount of the above-mentioned dried powder and put it into a graphite mold with an inner diameter of 20mm for compaction, then place it together with the mold between the upper and lower electrodes of the SPS device, and vacuum it (vacuum degree reaches 6Pa) Turn on the power at a rate of 200°C / min and pressurize to reach the sintering temperature of 1500°C, keep the temperature for 5 minutes after the axial pressure is 50MPa, and take out the sample after turning off the power and cooling.

[0036] (3) Cleaning: Grinding and cleaning the products after they are relea...

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Abstract

The invention discloses a sintering method of low-Co WC. The sintering method comprises steps as follows: step 1, nano-WC powder, TiB2 and Co powder are subjected to ball mill mixing uniformly and are dried, mixed powder is obtained, wherein the content of TiB2 is 0.1w%-0.7w%, and the content of Co powder is 0.2w%-0.8w%; step 2, the mixed powder is put in a graphite die and compacted, then the mixed powder and the die are both put between an upper electrode and a lower electrode of an SPS (spark plasma sintering) device, subjected to vacuum pumping, powered-on, heated at a speed of 200 DEG C/min and pressurized, a product is subjected to heat preservation for 5-10 min after sintering temperature reaches 1,500-1,700 DEG C and axial pressure reaches 50 MPa, and a sample is taken out after power-off cooling; step 3, the product out of the furnace is polished and cleaned, and a finished product is obtained. Co is added during sintering of WC, so that fracture toughness of a hard alloy can be enhanced; then TiB2 is added, the hardness of the hard alloy is not affected by Co by the aid of the characteristic of high hardness of TiB2, and TiB2 can also change electrical conductivity of the powder and change sintering performance; under the synergy with the SPS technology, the sintering effect is better, crystalline grains cannot grow up, and the density and the hardness are higher.

Description

technical field [0001] The invention belongs to the field of cemented carbide powder sintering, and relates to a sintering method of low-cobalt tungsten carbide, specifically nano-tungsten carbide (WC) and titanium diboride (TiB 2 ) as the main raw material, using spark plasma sintering (SPS). Background technique [0002] Tungsten carbide (WC) is the most commonly used cemented carbide material. The mechanical properties of cemented carbide are closely related to the grain size of WC and the composition of the alloy. It is generally believed that when the grain size is reduced from micron to submicron (<0.5 μm), the hardness, fracture toughness and impact toughness of the alloy can be significantly improved. When preparing cemented carbide with WC grain size smaller than submicron, the finer the original WC powder, the larger its surface area, the greater its activity, and the easier it is to grow during the sintering process. Since the melting point of WC is as high a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/56C04B35/645
CPCC04B35/5626C04B35/6455C04B2235/3813C04B2235/405C04B2235/666C04B2235/77C04B2235/96
Inventor 赵煊陈海束晨阳董丽华尹衍升
Owner SHANGHAI MARITIME UNIVERSITY
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