Fabrication And Properties Of SiC_p/Al Composite By Liquid Infiltration

SiC particle reinforced Al matrix composites(SiC_p/Al)get high modulus,high chemical stability,low density and excellent thermal properties.SiC_p/Al composites with high SiC volume fraction can provide the best performance for electronic packaging.The advantages of Si C_p/Al composites prepared by pressureless infiltration technology are simple process,controllable cost and easy industrial production and so on.In this paper,the fabrication and properties of SiC_p/Al composite by liquid infiltration in open air are discussed.Si C porous preform was prepared by molding process.The molding pressure and the relationship between particle ratio and preform volume fraction were studied,and the effect of pre-oxidation treatment of SiC particles was analyzed.In the infiltration process,the effects of Mg and Si on the wettability and the microstructure of the composites were investigated,and the effect of Si on the storage time of the composites was investigated.The thermal properties of the composites were analyzed.For single particle SiC,the smaller the particle size,the greater the surface friction,this resulted in a higher preform opening rate at the same applied pressure.As for the double-particle SiC,when the ratio of coarse to fine particles was 10:1,and the mass ratio was 4:1,the porosity of the preform was lower,the density was higher,and the SiC bulk was obviously improved.The pre-oxidation treatment of SiC particles is beneficial to the infiltration process.The thickness of SiC oxide layer increased with increasing holding time and temperature.Improving wettability between the substrate and the porous preform is important for the impregnation process.The addition of 14wt.%Mg in the alloy matrix can improve the wettability between the matrix and the porous preform.When the Mg content in the alloy was 10 wt.%,the addition of Si caused the metal to further expand on the SiC surface,and the extent of expansion and penetration increased with the Si content.When the Si content reached 10 wt.%,The porous preform could be completely penetration.The addition of Si element could suppress the chalking of the composites in the exposed air.Thermal properties of SiC reinforced 10 wt.%Mg-10wt.%Si-Al metal composites were analyzed.The thermal conductivities of the composites calculated was 146W/(m·k).And the thermal expansion coefficient of the composites calculated was in the range of11¹4×10^-6K^-1.