Influence of spraying conditions on microstructures of Al-SiC p composites by plasma spraying

Abstract

Air plasma spraying was used to produce Al-SiC p composites as electronic packaging material. Ballmilled Al with 55 and 75 vol. pct SiC powders was repeatedly deposited onto a graphite substrate, and then mechanically removed to get free-standing 100 ϫ 100 mm composite plates of about 2-mm thickness. Different input electrical powers were employed at two spray distances of 100 and 120 mm. The SiC volume fraction and porosity in the sprayed composites were found to be dependent on spray conditions, especially input electrical power. Maximal SiC volume fraction can be obtained at a low input electrical power for the composite sprayed from the Al-55SiC powder and a high input electrical power for Al-75SiC powder. The variation of the SiC level in the composites with spray conditions and SiC size is discussed based on the characteristic of feedstock, the characteristic of deposited surface, and the heat and momentum transfer between particle and plasma flame. Pores in the sprayed composites were found inside one sprayed layer (inner-layer pore) and at the boundary between two sprayed layers (interlayer pore). The formation mechanisms of two types of pores are also explained. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses indicate that Si phase is formed in the sprayed composites for most spray conditions. The Si resulted from the decomposition of SiC particles in high-temperature plasma flame.

Enhanced dielectric and microwave absorption properties of Cr/Al2O3 coatings deposited by low‐power plasma spraying

“…Thus, it is difficult for the solid Al 2 O 3 particles to be deposited on the substrate, resulting in a certain amount of loss. Similar results have also been reported by other researches . Besides, there was no other phase formed during plasma spraying, including Cr 2 O 3 , can be found.…”

“…Similar results have also been reported by other researches. 20 Besides, there was no other phase formed during plasma spraying, including Cr 2 O 3 , can be found.…”

Thermal expansion behaviour of plasma sprayed Al–SiCp composites

“…A previous study demonstrated that the Si phase in the composites resulted from the decomposition of SiC particle in the feedstock at high temperature of plasma flame. 20 Based on OM image analysis, 2-5% porosity existed in the as sprayed composites, and Al-75SiC composites contained higher porosity. The arrows in Fig.…”

Archives of Metallurgy and Materials

“…In surface engineering field, surface MMCs have been synthesized through various methods like plasma spraying [9], cold spraying [10], laser melting [11][12][13][14], cast sinter [15][16] and electron beam irradiation method [17] etc. These fabrication techniques have many disadvantages such as particle agglomeration, formation of detrimental phases and interfacial reactions because of processing above melting point temperatures of respective metal alloys.…”