Pressureless Infiltration Preparation Of Sicp / Al Composites

SiCp/Al composite has good and attentive applying perspective; through SiC particulate reinforcing Al matrix, this composite possesses good properties that solo component hasn抰. Pressureless infiltration technique is a novel way to producing metal matrix composites (MMC), and is characterized by simplified process and low cost. In this paper. the fabrication of SiCp/Al composite employing this technique is stated and the process conditions of molten Al alloy infiltrating into SiCp reinforcement is explored, too. The effects of factors on wetting and infiltrating are studied, these factors that can influence the composition and microstructure of composite comprise the content of Mg and Si, process time and process temperature et al. The nature of the extent of reactions with the change of these factors is researched. Microstructure in the interface of SiCp/A1 system and the effect of it on mechanical propel-ties of composite are analysized. The most difficulty in this experiment lies in the bad wettability of SiCp/Al system. For bettering the wettability of this system, these following two ways are used: (i) Mg, Si elements are entered to Al matrix; (ii) SiC particulate is heated in air so that a stable, impervious film of Si02 is formed. The experiment proves that the entering of Mg element can improve the wettability and infiltration of SiCp/Al system; Si element in Al matrix can slowdown the interficial reactions; the Si02 film can enhance wettability and infiltration to some extent. At the SiCp/Al system interface, the reaction products of Si, Al203 et al and segregation of Mg as well as Si can be found by EDS analysis. When the extent of interfacial reactions is controlled properly, molten Al will attack SiC particulate and cause mechanical bonding between matrix and reinforcement. It is just this mechanical bonding that improves the properties of composite. The effect of segregation of Si element on mechanical properties is lower than that of interfacial reactions on them; so this effect does not play major faction and is in second station.