Analysis of porosity in high volume fraction SiCp/Alcomposites fabricated by pressureless infiltration

摘要

Porosity was found in the local area of high volume fraction SiCp/Al composites fabricated bypressureless infiltration at times, which seriously affects the performance and results in waste ofresources. In this paper, the microscopic feature and the phase composition of the porosity areain the composites were studied by scanning electron microscope, energy-dispersive x-rayspectroscopy and X-ray diffraction. The formation of new phases on the surface of SiC particlesextracted from the composites with porosity by using chemical dissolution method wasinvestigated by scanning electron microscope, energy-dispersive x-ray spectroscopy and X-raydiffraction. The effect of porosity on the mechanical property of composites was investigated bythree-point-bending tests. The results showed that the pores existing among the gaps of SiCparticles in the porosity area were in different sizes and shapes. Additionally, the aluminiumoxides in different states formed on SiC particles surface in the porosity area without infiltrationby aluminium. The porosity degrades the composites mechanical performance. The formationmechanism of porosity in the composites was discussed to provide the view for avoiding theporosity.