Study On SPS Sintering & Joining Of Refractory Metals

Refractory tungsten(W)and molybdenum alloys(TZM)have excellent properties such as high melting point and high strength.In order to develop refractory metal products and study the sintering and bonding of tungsten and molybdenum alloys,the densification process of SPS sintering of tungsten and molybdenum alloys,the sintering-bonding process of powder and powder,bulk and powder,as well as the interface and structure of the alloy were studied in this paper,based on the application of X-ray anode target materials.And performance.The research scheme and technical route are reasonably designed,which provides theoretical and experimental basis for the study of SPS sintering and bonding of refractory metals.In SPS sintering of refractory metals,W and TZM powders are used as raw materials and spark plasma sintering system as the core equipment.The effects of sintering process(pressure,temperature,particle size)on the sintering of W and TZM were investigated.The results show that the sintering pressure has a significant effect on the densification behavior of pure W,when the sintering pressure is lower than40 MPa.However,the influence of sintering pressure on the densification is unobvious,when the sintering pressure is higher than 40 MPa.The density of sintered body increases with the increase of temperature at the same pressure.At 40 MPa,the relative density of raw material W powder sintered body increases from 92.5%(1600?)to 95.6%(2000?).After ball milling,the particle size of W powder decreases from 11.17?m to 1.66?m,and the relative density of sintered body can reach 97.1% at 1600?,which greatly reduces the sintering temperature and slightly increases the hardness.The melting point of TZM is lower than that of W,and the relative density of TZM can reach 96.7% at 1600?.After W powder + TZM powder SPS sintering--joining,the strength of W-TZM joint was tested.The experimental results show that the fracture mainly occurs on the W side,and the shear strength of the joint increases with the sintering temperature,from 186.7MPa(1600 ?)to 253.0MPa(1900?);the diffusion depth of elements increases from 5.0?m(1600?)to 10.0?m(1900?),and Mo from 16.0?m(1600?)to 18.0?m(1900?).In SPS sintering--joining of W block + TZM powder,the cooling rate has little effect on strength.The strength of joints obtained by rapid cooling is slightly higher than that by slow cooling.The maximum shear strength is 159.7MPa(1600?,40 MPa,rapid cooling).The diffusion depth of elements at the interface decreases obviously,with the highest W value being 3.5?m and the highest Mo value being 6.0?m.In the sintering--joining process of W powder + TZM block,the surface roughness of TZM has a significant effect on bonding strength: the higher the flatness of TZM,the better the bonding,and the maximum shear strength is 164.7MPa(1900?,40MPa).The diffusion depth of elements increases with the increase of temperature.The strength of WRe-TZM joint was further increased to 201.4MPa after adding 5% Re into pure W powder,and the shear strength of WRe-TZM alloy joint was almost unchanged by thermal shock test.