SiBON陶瓷中BN晶片的析出与力学性能

Precipitation of BN crystals in SiBON ceramics and its mechanical properties

在Si-O网络中掺杂B、N元素形成一种新型陶瓷材料SiBON,以便抑制SiO2析晶及提高SiO2耐热温度,并且通过从SiBON非晶粉末烧结中析出BN增强相的途径提高熔石英基陶瓷的力学性能。研究表明,烧结体物相组成为析出的h-BN和非晶态基体,其中1400、1600和1700℃烧结析出的h-BN形貌特征为近等轴颗粒、大片晶和小片晶。SiBON陶瓷具有远高于熔石英陶瓷的力学性能。强化机制为析出相对基体的界面切向压应力作用,而韧化机制为片晶的桥接和拔出。

A new type of ceramics, SiBON, was fabricated by introducing B and N into Si-O network with purposes of inhabiting crystallization and increasing melting point of silica based materials. A route to improve mechanical properties of silica based materials was also presented, which is in-situ formation of reinforcement by means of crystallization of BN grains during the sintering of SiBON amorphous powder. Results show that the sintered SiBON is composed of precipitated h-BN grains and amorphous matrix. The morphology of precipitated h-BN is featured by nearequiaxised grains, big sized flakes and small sized flakes, which is corresponding to the sintering temperatures of 1400℃, 1600℃ and 1700℃, respectively. The SiBON ceramics have much higher mechanical properties than fused silica. The main strengthening mechanism is believed to be the interfacial compression stress of the matrix acted by the precipitations, and the toughening is attributed to the bridging and pull-out of the BN flakes.