Preparation of BN/SiO2ceramics by PIP method①
来源期刊：中南大学学报(英文版)2005年第1期
论文作者：王静 温广武 孟庆昌
文章页码：31 - 34
Key words：BN/SiO2ceramics; composites; properties
Abstract: The precursor infiltration and pyrolysis(PIP) method for preparation of BN/SiO2 composites was used to improve mechanical properties, dielectric properties and feasibility of high temperature dielectric parts with large dimensions and complex shapes. In the processing procedure, the porous BN ceramic matrix was first successfully prepared by compacting the mixed powders of B and BN and then sintering them at a certain temperature under normal pressure of N2.The polycarbosilane(PCS) solution was vacuum infiltrated into porous BN ceramics at the room temperature and then at 800℃in the air to depolimerize out amorphous SiO2, and sintered further at 1 300℃in N2 to get BN/SiO2 composites. The microstructure of materials was studied by means of X-ray diffraction and electron probe micro analysis. The thermo-decomposition mechanism of PCS was investigated by a TG-DTA and infrared (IR) spectrum analysis. The flexural strengths were measured by the three-point bending method. The dielectric constant and the loss tangent were measured by the wave-guide method. The results show BN/SiO2composites were fabricated. The obtained composites posses a flexural strength of 61.96 93.31 MPa, the dielectric constant in the range of 3.50 3.78 and the order of magnitude of the loss tangent at 10-3, which are good for the high temperature dielectric parts with large size and complex shapes.
