High Proportion Tungsten Alloy Preparation by Two Times Sintering Process

The present sintering process of high proportion tungsten alloy is generally used in primary sintering. The high ratio of waste products and low utilization ratio of raw materials make high production cost of high gravity tungsten alloy. For example, the utilization ratio of raw material for 90WNiFe alloy by existing technology is only 60%, and the raw materials of 93WN iFe alloy sintered by existing technology are used. The utilization rate is only 63%, and the waste of raw materials is serious.

A two times sintering process has been proposed by some researchers. Two times sintering is used to reduce the amount of sintering deformation, improve the utilization of raw materials, reduce the production cost of the products, the alloy prepared by the sintering process, the rate of waste products is very low, the utilization ratio of raw materials is greatly improved, and the alloy prepared is in accordance with the requirements of the related materials. The process includes the following steps:

(1) According to the nominal composition of high proportion tungsten alloy 90WNiFe alloy, the 90WNiFe alloy compact is obtained after regular mixing.

(2) The 90WNiFe alloy blank is sent into the muffle furnace, the sintering temperature is 1400 ～1420°C, the boat speed is 7mm/s ～ 10mm/s, and the pre sintered blank is obtained with the cooling of the furnace. Or the 90WNiFe alloy blank in the first step is placed in the medium frequency induction sintering furnace and the sintering temperature is 1400 ～1420°C. Sintering at a temperature of 30min ~ 50min, and then cooling with the furnace, the pre sintered billet is obtained.

(3) The presintered billet was sent into the muffle furnace. The sintering temperature was 1410 ~ 1430°C and the speed of the boat was 7mm/s ~ 10mm/s for two times, and the 90WNiFe alloy was obtained after the cooling of the furnace.

Compared with the first sintering process, the two times sintering process can effectively control the amount of the sintering liquid phase in the tungsten alloy, increase the viscosity of the sintered body, reduce the fluidity of the sintered body, and make the sintered billet at high temperature have the ability to maintain the shape of the original press, and no larger deformation occurs. The utilization ratio of raw materials is increased, thereby reducing the production cost of products. 

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