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Method for controlling sintering densification and grain sizes of metal materials

A technology of grain size and metal materials, which is applied in the field of powder metallurgy, can solve the problems of difficult control of grain size, poor structure uniformity, and low mechanical properties, and achieve narrow grain size distribution, reduced grain growth, and uniform density distribution Effect

Active Publication Date: 2019-04-26
UNIV OF SCI & TECH BEIJING
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  • Abstract
  • Description
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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for sintering densification and grain size control of metal materials. The technical problem to be solved is that the existing tungsten metal sintered products are difficult to densify, the grain size is difficult to control and the structure uniformity is poor resulting in poor mechanical properties

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  • Method for controlling sintering densification and grain sizes of metal materials
  • Method for controlling sintering densification and grain sizes of metal materials
  • Method for controlling sintering densification and grain sizes of metal materials

Examples

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Embodiment 1

[0055]Using 50nm pure tungsten powder as raw material, a high-speed screw blade mixer was used to deagglomerate the raw material powder, the blade speed was 3000 rpm, and the crushing time was 1 hour to obtain a deagglomerated raw material powder with a narrower particle size distribution. The polyethylene glycol and deionized water are uniformly mixed to prepare a solution A, the binder content in the solution A is 15wt.%, and then 50nm raw material tungsten powder is added to the solution A and mechanically stirred until the mixture is uniform to prepare Slurry, the solid phase content in the slurry is 85wt.%; the obtained slurry is spray granulated by a centrifugal spray dryer, the rotational speed range is 15000r / min, the atomization pressure is 300kPa, and the drying temperature is 90°C ; Put the granulated powder into a tube furnace and pass high-purity hydrogen for degreasing and reduction treatment. The treatment temperature is 700 °C, the heating rate is 5 °C / min, and ...

Embodiment 2

[0057] Using 50nm pure tungsten powder as raw material, a high-speed screw blade mixer was used to deagglomerate the raw material powder, the blade speed was 3000 rpm, and the crushing time was 1 hour to obtain a deagglomerated raw material powder with a narrower particle size distribution. The polyethylene glycol and deionized water are uniformly mixed to prepare a solution A, the binder content in the solution A is 15wt.%, and then 50nm raw material tungsten powder is added to the solution A and mechanically stirred until the mixture is uniform to prepare Slurry, the solid phase content in the slurry is 85wt.%; the obtained slurry is spray granulated by a centrifugal spray dryer, the rotational speed range is 15000r / min, the atomization pressure is 300kPa, and the drying temperature is 90°C ; Put the granulated powder into a tube furnace and pass high-purity hydrogen for degreasing and reduction treatment. The treatment temperature is 700 °C, the heating rate is 5 °C / min, and...

Embodiment 3

[0059] Using 200nm pure tungsten powder as raw material, a high-speed screw blade mixer was used to deagglomerate the raw material powder. The speed of the blade was 2500 rpm, and the crushing time was 1 hour to obtain a deagglomerated raw material powder with a narrower particle size distribution. The polyethylene glycol and deionized water are uniformly mixed to prepare a solution A, and the binder content in the solution A is 10 wt. Slurry, the solid phase content in the slurry is 70wt.%; the obtained slurry is spray granulated by a centrifugal spray dryer, the rotation speed range is 12000r / min, the atomization pressure is 200kPa, and the drying temperature is 120°C ; Put the granulated powder into a tube furnace and pass high-purity hydrogen for degreasing and reduction treatment. The treatment temperature is 600 °C, the heating rate is 5 °C / min, and the holding time is 120 min to obtain nearly spherical granulated powder; The granulated powder is subjected to bidirection...

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Abstract

The invention provides a method for controlling sintering densification and grain sizes of metal materials. The method includes the steps that firstly, raw material powder is deagglomerated, and deagglomerated powder with good dispersity is obtained. The deagglomerated powder is subjected to spray granulation, so that the flow performance of the powder and the density uniformity of a pressing blank are improved. The granulated powder is subjected to high-pressure pressing and cold isostatic forming. After the pressing blank is subjected to two steps of pressureless sintering, high-density fine-grain refractory metal is obtained. According to the first step of sintering, the pressing blank is rapidly heated to the temperature T1, heat preservation is carried out, the density is controlled at 75-85%, then the pressing blank is reduced to the temperature T2, then time heat preservation is carried out, and residual holes are further eliminated. By means of the two steps of sintering, the sintering temperature can be greatly reduced, almost full densification of the metal blank can be achieved at low temperature, rapid growth of grains in the densification later period in the conventional sintering process can be effectively restrained, the prepared refractory metal product is almost fully dense, the grains are fine, the grain sizes are evenly distributed, and the mechanical performance is excellent.

Description

technical field [0001] The invention belongs to the technical field of powder metallurgy, and particularly provides a method for sintering densification and grain size control of metal materials. Background technique [0002] Refractory metals are irreplaceable key materials for special applications such as national defense, nuclear engineering, aerospace, electronics, and high-end equipment. Tungsten and molybdenum targets are important basic raw materials for semiconductor large-scale integrated circuits, high-end display, solar photovoltaic and other industries. They are used to make electrodes, wiring metals, shielding metal materials, and barrier materials. Tungsten and molybdenum targets require high density and small grain size to ensure the uniformity of the coating. Metal tungsten is also the most promising plasma-facing first wall material and spallation neutron source target. However, the low-temperature brittleness of tungsten has always been a bottleneck restr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F1/00B22F3/02B22F3/04B22F3/10
CPCB22F3/02B22F3/04B22F3/1017B22F2999/00B22F1/14B22F1/10B22F2201/11B22F2201/013
Inventor 章林曲选辉李星宇董岩皓秦明礼王光华龙莹钟伟
Owner UNIV OF SCI & TECH BEIJING
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