The main objectives of this project are :
- to develop European source of SiC whiskers and Al2O3 platelets which could also be used
- to improve the technology developed to produce ceramic matrix composites for cutting tools, tips and wear parts.
The main aims of this research are:
to develop a European source of silicon carbide whiskers and aluminium oxide platelets which could also be used;
to improve the technology developed to produce ceramic matrix composites for cutting tools, tips and wear parts.
The reinforcing phases synthesized were:
silicon carbide whiskers with a mean diameter of 2.5 um and a mean length between 20 and 200 um (these whiskers show very smooth surfaces and do not present cracks);
alpha-alumina platelets witha diameter of approximately 5 um and a thickness of 0.7 um.
Silicon carbide whisker toughened alumina, alumina reinforced by alumina or silicon carbide platelets, and mullite reinforced by alumina platelets were developed. The best density, and consequently the best mechanical behaviour, was obtained using hot pressing. The mechanical properties of alumina silicon carbide whisker composites were higher than those of pure alumina, particularly toughness and bending strength. For platelet containing composites, an increase in toughness is obtained to the detriment of strength.
Wear and cutting tool tests show the high potential of whisker or platelet reinforced ceramic composites. The most promising results were achieved in the cutting tool field where alumina silicon carbide whisker composites were suitable for machining superalloys employed in the aeronautical industry.
The use of SIC whiskers-reinforced alumina has proved an attractive way of producing wear parts and ceramic cutting tools. Tools are used more and more in the aeronautical industry for high-speed machining of super alloys, and the development of reinforced wear parts is forecast. Ceramix Matrix Composites cutting tools are mainly produced in the USA and Japan. SiC whiskers are also produced in those two countries.
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