Özet:

   Mullite is a material used for advanced structural and functional ceramics due to its favourable properties such as low thermal expansion, low thermal conductivity, excellent creep resistance, high-temperature strength and good chemical stability. Several studies have been performed to coat metallic materials or Si3N4, SiC ceramics that have potential usage in aviation industry with mullite based ceramics. In this study, porous mullite ceramics for used as coating layers for turbine engine components were fabricated by partial sintering and pore former addition. PMMA sphere and carbamide were added as pore formers and the effects of pore former type and size were investigated. Three different pore formers: PMMA with two different particle sizes and carbamide were used 5 vol. % as pore former additives. The average particle size PMMA spheres were 40 and 400 mm, carbamide was 1000 mm. The porosity of fabricated components varied between 30-40 % whereas pore size changes from 1-500 mm depending on the pore former type. Elastic modulus of the components was measured by ultrasonic method, microstructural development was investigated by scanning electron microscopy (SEM), pore size and distribution was determined by mercury porosimeter.

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