3Y-TZP/BN纳米复相陶瓷的显微组织及其性能

利用化学包覆和热压烧结制备出晶界型3Y-TZP/BN纳米复相陶瓷,并与机械混合相同工艺热压烧结的微米复相陶瓷对比。结果表明:3Y-TZP/BN纳米复相陶瓷较对应的微米复相陶瓷保留了更多的t-ZrO2,并且形成精细均匀的显微组织;纳米h-BN第二相在基体中高度弥散,使引入的缺陷尺寸降低到100nm以下。这是造成材料能够获得优良力学性能的主要原因。在BN弥散相的体积分散达到20%时,3Y-ZrO2/BN纳米复相陶瓷保持了优异的强韧性,具有高质量的可加工性,并显示出类似塑性加工的特征。

Microstructures and properties of machinable 3Y-ZrO2/BN nanocomposites

Inter-type 3Y-TZP/BN ceramic nanocomposites with nano-sized BN dispersoids were successfully fabricated by hot-pressing turbostratic BN (t-BN) coating 3Y-ZrO2 powders, which were prepared through in situ reaction between boric acid and urea in nitrogen.XRD analysis and TEM observations revealed that the nano-sized hexagonal BN (h-BN) particulates were dispersed at ZrO2 grain boundaries. The outstanding strengthening and toughening of 3Y-TZP/BN nanocomposites, in comparison to 3Y-TZP/BN microcomposites, are attributed to keeping more tetragonal zirconia and possessing a finely microstructure caused by inhibition of the grain growth of ZrO2 by nano-BN coating on ZrO2 surface in the hot-pressing procedure. The nanocomposites with BN content more than 20 vol.% were ready for machining, which could be easily drilled with high quality conventional WC drills. The result reveals some plastic removal characteristic of the 3Y-ZrO2/BN nanocomposites.