Ceramic Fibre Reinforced Aluminium Matrix Composites Made By Die-Casting Technique

In order to broaden the application of MMC on auto industry, die-casting technique were adopted to fabricate ceramic short fiber reinforced composites in this research and the suitable process parameters of die-casting were acquired as following: the pressure applied is about 80MPa, filling velocities of alloy liquid range from 15 to 20m/s, warm-up temperature of the perform is 400(C~700(C, and warm-up temperature of the mould is 150~200(C. Composite specimens with 5 percent to 50 percent fibre volume fraction were fabricated by die-casting technique under the process parameters above. The microstructure, hardness, tensile strength and wear behaviors of composites made by die–casting technique were investigated and analyzed. The results showed that aluminum alloy liquid could be preferably dipped into ceramic fibre perform, and the fibre distributed in the matrix relatively evenly and combined well with the matrix. But pores usually existed especially when fibre volume fraction was very high. The interfacial bonding between reinforced areas and unreinforced areas was well in the composite, whose overall hardness (HB) is higher than that of matrix and increase with the amount addition of fibre volume fraction. A certain existence of tensile strength remains even under high temperature(300(C or so).The main reason leading to the limitation of composite tensile strength is the existence of pores, inclusions and unevenly distribution of fibre as high fibre volume fraction. The fabricated aluminum matrix composites have much better wear behaviors than that of the matrix when lubricated with oil. Under dry friction condition, there are two phases named sliding abrasion and grinding-particle abrasion respectively, under which abrasion is relatively stable but abrasion rate is different. The sliding distance between the two phases is named as critical point. Composites have much better wear behaviors than that of the matrix under sliding abrasion phase, but the condition is changed under grinding-particle abrasion phase when the abrasion of composite get acutely and abrasion rate exceeds the matrix.