Silicon Powder Mixtures Research Articles

A novel brazing technique for aluminum and other metals

In this brazing technique, at least one of the metal surfaces to be joined is coated with a powder-mixture of silicon and a potassium fluoroaluminate flux. Brazing of aluminum is carried out by heating at ∼600 °C in nitrogen gas. During heating, the flux melts and dissolves the oxide layers on the contacting surfaces, thus allowing the silicon to come into intimate contact with bare aluminum. At a temperature exceeding the Al–Si eutectic temperature of 577 °C, the silicon diffuses rapidly into the aluminum and generates in situ a layer of Al–Si liquid alloy of near-eutectic composition. The filler material then flows into the joint and forms a fillet. This brazing technique may be exploited with aluminum using intermediary elements other than Si, and may be used for joining a variety of metals.

Metallographic Development and Thermal Reaction of 304L—Silicon Powder Mixtures During Sintering

The metallographic development and thermal reaction of 304L stainless steel powder with silicon additions during sintering has been investigated. On heating to 850°C a marked diffusion zone appears on the edge of silicon particles. This reaction zone grows inwards, and then transforms into some kind of eutectic liquid at 950°C. Upon futher sintering the silicon particles melt completely, the liquid phase dissolves and penetrates the boundaries of the 304L particles. The wettability and fluidity of the liquid phase are improved with increasing sintering temperature

四塩化珪素による金属珪化物の生成反応（第2報）四塩化珪素とモリブデンの反応

Molybdenum can berenderd highly resitsant to oxidation by treatment with a hydrogen-silicon tetrachloride atomosphere so as to produce a molybdenum disilicide coating on its surface. The effects of time, temperature and concentration of silicon tetrachloride on the rate of reaction were investigated at 1000∼1800°. By treating a powder mixture of silicon and molybdenum (in the stoichiometric ratio of MoSi2) either in hydrogen or in silicon tetrachloride atmosphere, the formation of molybdenum disilicide was observable only at the high temperature of 1300° in the former, but at a lower temperature as 1000° in the latter atmosphere. The mechanism of the reaction between molybdenum and silicon tetrachloride, and the process of sintering of molybdenum-silicon powder was interpreted by the formation of silicon dichloride at high temperature.