Synthesis of light composites reinforced with cenospheres
Piotr Długosz, Paweł Darłak, Robert M. Purgert, Jerzy J. Sobczak
Quarterly No. 4, 2011 pages 288-293
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abstract The paper presents a method of casting metal matrix composite materials based on light alloys reinforced with cenospheres. The cenospheres, which are a product of fly ash processing by flotation, were formed into porous ceramic shaped elements and subjected to pressure infiltration with a liquid metal on a specially designed hydraulic press. The infiltration process was recorded with an infra-red camera. The obtained composite samples have been tested with the following inspections: density and hardness, X-ray and microstructure. The thermography inspection showed the temperature distribution on the surface of the preheated ceramic preforms. The X-ray examination revealed in the castings a few cracks caused probably by a high value of squeeze pressure. Numerous spheres filled with a solidified metal in the microstructure images were observed. The degradation of the cenospheres was directly connected to the infiltration process parameters, namely: the temperature of the preform and molten metal, too high squeeze pressure or too invasive process of the preform preparation. Despite the anticipations, only a slight decrease in composite density in comparison to the density of the monolithic alloy has been found. However, an increase in the composite hardness has been observed. As a result of the described work, instructions for further tests, which involve slight changes in the process parameters namely: casting pressure, temperature of the molten metal and the ceramic preforms, in order to achieve proper structural and mechanical characteristics of the composite products have been established.