Fabrication And Performance Of High Volume Fraction Of Fly Ash /Aluminum Composites

In this experiment, 7075 aluminum alloy as the matrix material, by squeeze casting method to pressed the melt aluminum into the fly ash particles accumulate body, produce composite materials. In the preparation of composite materials to the fly ash is preheated to improve wetting of ceramic and aluminum alloy, and then under the action of the pressure die casting machine of aluminum alloy die-casting melting under the liquid into the ceramic foam, finally get the composite material. In the preparation process, to study the performance of the material mainly control pressure, pouring temperature and the volume fraction of fly ash etc. In this study, squeezing casting method was used to fabricate fly ash particle reinforced Al matrix composites. metallographic, SEM, density analysis, hardness and friction and wear properties tests were used to investigate the effect of pressure, pouring temperature and the fly ash volume fraction of the composite materialon on the microstructures and physical property of fly ash reinforced aluminum composites, and compared it’s performance with basis material. And has a preliminary analysis of the microstructure of friction surface of composite material,and then discuss abrasive wear mechanism of composite material.It has been shown that:(1) High volume fraction of fly ash / aluminum composites could be done with squeezing casting method. The greater pressure, the smaller grain generally. But it may make some defect such as crush fly ash;(2) The higher pouring temperature, the more uniform distribution of fly ash, and fly ash and metal will contact more closely, but at the same time with the high temperature will have defects such as bubbles and shrinkage cavity;(3) The addition of fly ash to improved the wear performance of material, and made the material of the friction coefficient increases at the same time, the coefficient of friction stability was improved. With the increase of fly ash volume fraction, friction performance of composites was improved. The friction performance is the best when fly ash volume fraction is 20%;(4) The wear resistance of 7075 Al alloy reinforced narrow size range(106-212 μm) fly ash particles were superior to that of the composite having the same volume fraction of particles in the wide size range(0-400 μm);(5) Composite material of the critical wear time is 10 minutes, when the wear time more than 10 minutes, wear rate increase, wear faster;(6) Fly ash particles fell off from composite material play the role of "ball" between the two pairs of mill, called "Three body" friction which can reduce the effect of friction bearing.