Preparation method of unbonded-phase ultrafine WC hard alloy

A technology of cemented carbide and no binder phase, which is applied in the field of preparation of ultra-fine WC cemented carbide without binder phase, and achieves the effects of excellent comprehensive performance, good comprehensive performance, and avoiding uneven growth.

Inactive Publication Date: 2014-07-16
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, during the mixing process of ball milling, it is difficult to distribute the trace amount of Co and the grain growth inhibitor evenly in the raw material powder system, which can easily cause the component segregation of the trace amount of Co and the grain growth inhibitor, resulting in abnormal WC grains during the sintering process. Non-uniform growth makes the material exhibit unstable mechanical properties, which ultimately seriously affects the performance of ultrafine cemented carbide without a binder phase. Therefore, ultrafine cemented carbide without a binder phase has not been able to be widely used in practice.

Method used

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  • Preparation method of unbonded-phase ultrafine WC hard alloy

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] (2) The mixed powder is subjected to high-energy ball milling in a high-energy ball mill using cemented carbide balls. The speed of ball milling is 360 r min -1 , the ball milling time was 48 h, after the ball milling, the powder was vacuum-dried, ground and sieved.

[0022] (3) Hot pressing sintering of powder. Hot pressing temperature: 1750 ℃, holding time: 60 min, hot pressing pressure: 20 MPa.

[0023] (4) Measure the grain size and detect the mechanical properties of the sintered samples. The fracture toughness of the as-prepared superfine WC cemented carbide without binder phase is 7.15 MPa·m 1 / 2 , the Vickers hardness is 3150 HV 0.05 , the transverse fracture strength is 910 MPa, and the grain size is 390 nm.

[0024] Example 2:

[0025] (1) Weigh the mass of each powder component according to the mass percentage distribution (take the total powder mass of 100g as an example):

Embodiment 2

[0027] (2) The mixed powder is milled in a high-energy ball mill with cemented carbide balls at a speed of 300 r min -1 , the ball milling time was 36 h, after the ball milling, the powder was vacuum-dried, ground and sieved.

[0028] (3) Hot pressing sintering of powder. Hot pressing temperature: 1750 ℃, holding time: 60 min, hot pressing pressure: 20 MPa.

[0029] (4) Measure the grain size and detect the mechanical properties of the sintered samples. The fracture toughness of the as-prepared superfine WC cemented carbide without binder phase is 7.15 MPa·m 1 / 2 , the transverse fracture strength is 964 MPa, and the Vickers hardness is 3450 HV 0.05 , with an average grain size of 420 nm.

[0030] Example 3:

[0031] (1) Weigh the mass of each powder component according to the mass percentage distribution (take the total powder mass of 100g as an example):

Embodiment 3

[0033] (2) The mixed powder is milled in a high-energy ball mill with cemented carbide balls at a speed of 250 r min -1 , the ball milling time was 72 h, after the ball milling, the powder was vacuum-dried, ground and sieved.

[0034] (3) Preparation of powder compact. Compression pressure: 100 MPa.

[0035] (4) Vacuum pre-sintering of powder compacts. Sintering temperature: 1700 ℃, sintering time: 1 h.

[0036] (5) Hot isostatic pressing of vacuum pre-sintered body. Hot isostatic pressing temperature: 1550 ℃, hot isostatic pressure 1000 MPa, time: 1 h.

[0037] (6) Measure the grain size and detect the mechanical properties of the sintered samples. The fracture toughness of the as-prepared superfine WC cemented carbide without binder phase is 7.85 MPa·m 1 / 2 , the transverse fracture strength is 1178 MPa, and the Vickers hardness is 3050 HV 0.05 , with a grain size of 480 nm.

[0038] Example 4:

[0039] (1) Weigh the mass of each powder component according to the mas...

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Abstract

The invention discloses a preparation method of an unbonded-phase ultrafine WC hard alloy. The unbonded-phase ultrafine WC hard alloy comprises less than 0.5 percent by weight of Co, 0.3-1.0 percent by weight of grain growth inhibitor and the balance of WC. The method comprises the following steps: mixing ultrafine WC compound powder containing a small amount of grain growth inhibitor prepared by using a spray thermal reduction method and ultrafine WC-Co compound powder serving as raw materials in a certain ratio; adding less than 0.4 percent by weight of carbon black powder, and performing high-energy ball milling for 36-72 hours; and sintering by using a hot pressing or hot isostatic pressing or air pressure reactive sintering method at the temperature of 1,550-1,750 DEG C for 1-3 hours. The prepared unbonded-phase ultrafine WC hard alloy has superior comprehensive performance, the Vickers hardness is up to 3,000-3,500HV0.05, the fracture toughness is up to 7.1-8.0MPa.m<1 / 2>, the transverse fracture strength is up to 900-1,200MPa, and the grain size is 0.2-0.5 micron. The novel hard alloy can be widely applied to fields requiring high wear resistance and high corrosion resistance.

Description

Technical field: [0001] The invention relates to a preparation method of superfine WC hard alloy without binder phase. Background technique: [0002] Conventional cemented carbide is a very important tool material composed of WC hard phase and γ-Co binder phase. It has high strength, high hardness, high elastic modulus, wear resistance, corrosion resistance, and low thermal expansion coefficient. And high chemical stability and other characteristics, widely used as cutting tools, drilling tools, wear-resistant parts and so on. The strength and toughness of WC-Co cemented carbide increase with the increase of Co content, but at the same time, the increase of Co content also reduces the wear resistance and corrosion resistance of cemented carbide. Therefore, in some special occasions, such as the working environment that requires high hardness, high wear resistance and high corrosion resistance, the traditional WC-Co cemented carbide can no longer meet the requirements, so ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C29/08C22C1/05
Inventor 范景莲刘涛成会朝郑虎春田家敏
Owner CENT SOUTH UNIV
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