Mechanical properties and wear strengths in aluminium-alumina composites
Abstract
In this study, after producing metal matrix composite materials reinforced with ceramic particles by adding hard Al2O3 particles into a selected ageable aluminum alloy, the wear strengths were investigated. Composites of aluminum alloys containing 2 to 10 wt of Al2O3 particles in the size range of 23.4 to 108 mu m were prepared by adding alumina particles to a partially-solid vigorously-agitated matrix alloy. For a given tribologic system, the sizes and ratios of optimum particles were determined from the point of the wear strengths of these materials, of which the wear strengths greatly increased according to the matrix materials. Alumina particles were subjected to preheating at 500 degrees C for 8 hours. Particles were added into the alumina alloy heated up to semi-solid/ semi-liquid phase interval in an argon medium by using a mixer. Then furnace temperature was raised up to 800 degrees C step by step. Later the composite materials were die cast and solidified and aged. The behavior of the composites was studied by using a pin-on-disk type machine. The largest wear strengths were obtained at an average particle size of 76.5 mu m and percentage of 4% wt Al2O3. Increase in the wear strength of the composites was obtained as 3.85 times the wear strength of the matrix material.