Tungsten alloy with high melting point, high density, high strength, thermal expansion coefficient is small, good corrosion resistance and oxidation resistance, good conductive heat conduction performance, good ductility, good machining performance and ray absorption ability, etc, in national defense, aerospace, electronic information, energy, metallurgy and mechanical processing has been widely applied in the industrial field. Traditional
tungsten alloy parts processing methods mainly include electrical discharge machining method, chemical vapor deposition, electroplating, etc., for complex shape precision parts processing, more with wire cutting and laser etching, but there is still a low yield, consuming materials, time consuming, processing is difficult, or even individual fine parts can't processing. Therefore, 3D cold printing technology has certain advantages to print tungsten alloy parts.
Metal 3D printing technology makes it possible to make metal parts "directly" instead of making non-functional molds. At present, the mainstream metal 3D printing technology includes selective laser sintering, selective laser melting, electron beam melting, etc., but the equipment is expensive, and many auxiliary protection processes are needed, so the overall technology is difficult. And 3D cold without using laser printing technology, direct forming under normal temperature or low temperature, which make use of low viscosity and high solid content of metal powder slurry instead of 3D printing raw material, at room temperature or low temperature conditions to implement step by step a body for the metal parts to print, print the parts of body after drying, debinding and sintering, with dense metal parts. The 3D cold printing technology is applied to the forming of tungsten alloy parts, which provides the basis for the production and application of tungsten alloy parts with low cost, high efficiency and higher precision.
Using military standard tungsten powder,
nickel powder and iron powder as raw materials, 90W-Ni-Fe alloy parts were prepared by 3D cold printing technology. The effects of binder content and solid content on the viscosity of metal paste were studied, and the microstructure uniformity of blank blank was analyzed. TG-DTA curve was used to optimize the degreasing sintering process, and the morphology, microstructure and density of the sintered body were analyzed. The results show that the W-Ni-Fe slurry with 4% binder and 70%~75% solid content is the most suitable for 3D cold printing. The vertical direction of the blank has a good uniformity of microstructure. The metal particles are more evenly filled in the three-dimensional network structure composed of PVB. The solid particles are evenly distributed and there is no obvious sedimentation phenomenon. During the printing process, the thickness of the blank increases non-linearly, the width is unstable, and the curing speed of the paste still needs to be improved. After degreasing the blank and sintering at 1440 ℃ for 2h, a sintered body with a density of 16.26 g/cm3 was obtained, with a density of 94.83%.
