Tungsten Copper Activation Of Liquid Phase Sintering
Tungsten Copper Activation Of Liquid Phase SinteringTungsten copper activation of liquid phase sintering is in the use of tungsten copper alloy was added trace (0.1 to 0.5) a third metal element Pd, Ni, Co, Fe or the like means cause insoluble in copper tungsten phase is dissolved in the copper phase and in the liquid containing these metal elements 7-phase formed during sintering. Compared with the high-temperature liquid-phase sintering method, which not only reduces the sintering temperature and shortening the sintering time and the sintering density is greatly increased. J LJohnsonl1, who studied the use of transition elements Pd, Ni, Co, Fe sintered tungsten copper alloy activation effect. Studies have shown that Co, Fe activation effect is best, can significantly improve the density of tungsten copper materials, Ni, Pd activation effect in W-Cu in obvious than its activating effect in pure tungsten powder is worse, the reason for Ni, Pd and Cu solid solution formed unlimited, can not play activating effect, and Co, Fe and Cu is formed only limited solid solution, formed during sintering second encounter precipitation of trace elements in the grain boundaries, and the formation of intermetallic compounds promote densification tungsten. Study JL Johnson and RM German et al based on W-lOCu also show that when the Co content is 0.35, the sintering at 1300 ℃ good material properties after 1h.
The following describes two typical tungsten-copper-activated liquid phase sintering process:
1, W powder, Cu powder and a small amount of Ni, Co or Fe powder additive heptane after drying 24h in a ball mill and sieved, and then by press-forming, and finally the protection of the H2, sintered at 1250 ~ 1400 ℃ 1h conditions.
2, W powder milled in heptane after 24h drying sieved and added to the salt solution and the salt solution of Cu Ni, Co or Fe are additive mixture, after stirring at 95 ℃ conditions, evaporation, and then followed by crushing, H2 reduction under the protection of 800 ℃ 1h, press molding, and finally protection in H2, 1h sintering conditions under 1250 ~ 1400 ℃.
Activation of liquid phase sintering tungsten copper, tungsten copper alloy can get a higher relative density, hardness, flexural strength and other properties.黄金昌 and so will be less than 1% of Co added to the original copper tungsten powder mixed in vivo, significantly improved the performance of the final proceeds of tungsten-copper composite. Another study also confirms the activation properties within a certain range with increasing amount of added activator increases. Add Fe or Co, tungsten-copper composite density, strength and hardness in the range of 0.35% to 0.5% have experienced the best value. But it is worth noting that adding activator can affect high conductivity copper phase electrical and thermal conductivity, thereby significantly reducing the thermal conductivity of the material, which is detrimental to the requirements of high electrical and thermal conductivity of the material for microelectronics. Therefore, the material prepared by this method is only applicable to electrical conductivity, thermal conductivity is not critical.
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