Study On The Preparation Of SiCp/AZ91D Composite Materials By Mechanical Agitation Method

The application of magnesium alloy was limited, because of lower strength and wear resistance. The tensile properties and the friction and wear behavior of magnesium alloy was improved by introducing SiC particle into magnesium alloys. But there is difference in the performance and structure of the SiC and magnesium alloy, and mechanical agitation device was imperfect, it was difficult to achieve the full mixture of reinforcement and matrix in liquid or semi-solid, and the microstructure of SiC reinforced magnesium composites was not uniform and compact, it will lead to the gap between performance and project needs.In this paper, mechanical stirring compound furnace was designed and manufactured, there were mainly heating system, stirring system and vacuum system in the experimental equipment, and the main performance parameters were the effective heating zone size (f80mm×120mm), the size of stirring vessel(f70mm×80mm), the maximum temperature (900℃), power(1kW), stirring speed(0 ~ 2500r/min) and limited vacuum(0.1Pa)SiC_p/AZ91D composite materials was prepared by mechanical stirring method. The stirring temperature, stirring time and stirring speed were discussed, the tensile and wear properties of composite materials were tested at room temperature. The microstructure of composite materials, the fracture morphology and the morphology of wear defect were analyzed by optical microscopy (OM) and scanning electron microscopy (SEM).The results indicated that: in this experimental conditions, at 580℃, stirring 30min speed 1500r/min, SiC particles relatively dispersed uniformly, and were better to link up with the AZ91D matrix; at580℃, stirring30min, with the stirring speed increased, the distribution of SiC particles showed the variation of reunion - part of the reunion - a relatively uniform, when the stirring speed was up to 1500r/min, SiC particles relatively distributed uniformly, the speed exceed 1500 r/min, with the stirring speed increased, the distribution of SiC particles showed non-uniform, and the pore appeared; at 580℃, stirring speed 1500r/min, with the increase of stirring time, the distribution of SiC showed more and more relative uniformity, but more than 40min, SiC particle distributed unevenly, and there were a large number of pores.In 10vol%, 15vol%, 20vol% composite materials, with the content of SiC increased, the distribution of SiC showed the changes of relatively uniform - small group distribution - the chain distribution, and the trend of the fracture strength and relative elongation decreased. The fracture strength of 10vol% composite material was 156.2MPa, and the relative extension rate was 4.4%. The tensile curve of composites had no obvious yield point, the tensile fracture was mixture of cleavage and touph dimple.In 10vol%, 15vol%, 20vol% composites, with increasing volume fraction monotonously increased, the average coefficient of friction and the wear volume appeared monotonous increasing trend. Compared with AZ91D, the average friction coefficient of 10vol%, 15vol%, 20vol% composite materials respectively increased 10.3%, 15.7% and 31.7%, the abrasion resistance of 10vol%, 15vol% composite increased 19.6% and 5.5%, and the abrasion resistance of 20vol% was slightly less than AZ91D. The wear mechanism of 10vol% composites included two kinds of adhesive and abrasive wear, and the abrasive wear accounted for the main part in 15vol%, 20vol% composites.