Preparation and properties of SiO2 matrix composites doped with AlN particles

SiO2 matrix composites doped with AlN particles were prepared by hot-pressing process. Mechanical properties of SiO2 matrix composites can be greatly improved by doping with AlN particles. Flexural strength and fracture toughness of 30 vol%AlN-SiO2 composite sintered at 1400°C reached 200 MPa and 2.96 MPa·m1/2. XRD analysis indicated that, up to 1400°C, no chemical reaction occurred between SiO2 matrix and AlN particles suggesting an excellent chemical compatibility of SiO2 matrix with AlN particles. The influences of hot-pressing temperature and the content of AlN particles on dielectric properties of SiO2-AlN composites were studied. The temperature and frequency dependency of dielectric properties of SiO2-AlN composites were also studied. Residual flexural strength of SiO2-AlN composites decreased with increasing temperature difference. The critical temperature difference was estimated about 600°C.