TRANSLUCENT AND TOUGHENED Dy-α-SiAlON CERAMICS WITH LiF AS SINTERING ADDITIVE

SiAlON ceramics show a great potential for application, with excellent thermal shock resistance, good oxidation resistance, good wear resistance, and high hardness. So the present research focusing on its transmittance improvement has been carried out by the application of LiF as a sintering additive and processing control. Also, the interaction relation among sintering, phase evolution, microstructure and optical property has been understood. The samples with a highest transmittance as 73% have been manufactured by hot-press(HP) sintering. A satisfied microstructure, such as a fully developed main phase, uniform morphology, and neat grain boundary, must be a suitable explanation for the transmittance improvement. From the view of microstructure, the duplex morphology of both elongated and equiaxed grains in the SiAlON samples should be responsible for the self-reinforced result, except for the optical transmittance. To a certain extent, the properties of the translucent Dy-alpha-SiAlON have been reasonably tailored by composition design and process control, with resultant samples possessed a higher transmittance of 65% and also kept a higher fracture toughness of 5.21 MPa.m(1/2) at the same time