Effect Of Fabrication Processing On Microstructure And Properties Of SiCp/Al Composites

In this paper,SiCp/Al composites were fabricated with the method of thecombination of the sintered shaping of SiCp preform and pressureless infiltrating.TheSiCp/Al composites which include three different pore-forming agents of starch、stearic acid and graphite,two different bondings of binder bonding and oxidationbonding were fabricated.Test methods of TG-DTA/DSC、SEM、EDS and XRD and soon have studied oxidized characteristic of starch、stearic acid、graphite and the SiCp,micro-structure of performs, fractographs of composites, element composition ofsintering neck and SiCp/Al composites phase.The bending strength、 thermalconductivity and hermeticity of SiCp/Al composites were tested by mechanical testinginstrument,theremal conductivity apparatus and helium mass spectrometer leakdetector.The results show, starch、stearic acid and graphite of pore-forming agentsoxidize to end at different temperature and SiCp produces oxidation in air atmosphere,and SiCp surface product approximately thickness of0.4μm SiO2. Along with thedifference of the pore-forming agents, two kinds of SiCp bonding methods whichfabricated SiCp performs of three different pore-forming agents differ in SiCp volumefraction、porosity、compressive strength and change of size. SiCp volume fraction andcompressive strength of SiCp preforms with pore-forming agent of graphite are higherthan with pore-forming agent of starch and stearic acid, porosity and change of size aresmaller than starch and stearic acid, two kinds of SiCp bonding methods whichfabricated SiCp performs else make a difference in SiCp volume fraction、 porosity、compressive strength and change of size when the pore-forming agent are the same,SiCp volume fraction and compressive strength of performs which fabricated withoxidation bonding are smaller than with binder bonding, and porosity and change ofsize are higher than with binder bonding. Strength of performs with oxidation bondingis low and the dimension precision of performs decreases. SiCp and porosity in theperforms distribute uniformly.Along with the same of the pore-forming agents, SiCp/Al composites withoxidation bonding in the bending strength、thermal conductivity and hermeticity isbetter than with binder bonding, and residual porosity is the smallest, and properties ofSiCp/Al composites with pore-forming agent of graphite are the best: Relative densityis to up98.63%, the bending strength is278MPa,the thermal conductivity is124W·m-1·K-1and hermeticity is less than5×10-9Pa·m3·s-1. SiCp/Al composites produces Mg2Si and MgAl2O4phase.Thoughness dimples appear in the fracture of SiCp/Alcomposites,and brittle rupture is still major in the fracture.