Nano tungsten powder injection molding method

Abstract

The invention provides a nano tungsten powder injection molding method and belongs to the technical field of powder injection molding. The nano tungsten powder injection molding method includes the technical steps that 1 wt%-5wt% of covering agents are added to nano tungsten powder, and the mixture and deionized water are prepared to be slurry; the slurry is subjected to spray drying for prilling so that nano tungsten prilling materials can be obtained, the prilling materials and binding agents are placed in a roller mixing roll for mixing according to the volume ratio from 50:50 to 60:40, a green tungsten billet is prepared through injection molding, and a tungsten product is obtained through degreasing and sintering. Prilling is conducted on the nano tungsten powder in advance, so that the mobility, apparent density and tap density of the powder are improved, and the loading capacity for tungsten feeding is improved; the tungsten product is obtained through the processes of injection molding, degreasing and sintering, and the loading capacity for injection molding is improved while the good sintering property of the nano powder is maintained; the nano tungsten powder injection molding method has the characteristics of small shrinkage distortion, high size precision, good surface quality, low sintering temperature and the like.

Description

technical field [0001] The invention belongs to the technical field of powder injection molding and provides a method for injection molding of nanometer tungsten powder. Background technique [0002] Metal tungsten has a high melting point (3410°C), high density (19.3g / cm 3 ), high strength and low expansion coefficient, occupy an important position in engineering applications such as defense electronics industry, and are widely used in aerospace, atomic energy and high temperature fields. Due to the high hardness, high brittleness, poor conductivity and difficulty in cutting and processing of metal tungsten, the traditional powder metallurgy pressing and sintering method cannot prepare thin-walled and complex-shaped tungsten products. Powder injection molding is a new type of near net size forming technology developed by combining traditional powder metallurgy and modern plastic injection molding technology. The biggest feature of this technology is that it can directly ma...

AI Technical Summary

Problems solved by technology

At present, the main problem of powder injection molding tungsten products is that due to the high melting point of tungsten, it is difficult to sinter and densify. Even at a temperature higher than 2000 ° C, it is difficult to obtain tungsten products with a density higher than 95%.

In order to solve the problem of sintering densification, the methods currently used: 1. By adding active elements such as Fe and Ni, liquid phase sintering can be formed at a lower temperature (1350-1450 °C) to reduce the sintering densification temperature, but Fe, Ni alloy elements The introduction will affect high temperature performance. 2. Nano tungsten powder is used as raw material. Nano tungsten powder has high specific surface area and high sintering activity, and high density pure tungsten products can be obtained at lower temperature. The main problems of nano tungsten powder It is due to the large specific surface area, serious agglomeration, low loose packing density, and difficulty in forming, resulting in low loading of the feed powder (low powder content), low density of the prepared tungsten green body, and severe shrinkage and deformation during the subsequent sintering process. , poor surface quality and dimensional accuracy

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