动态加压下自蔓延高温合成致密ZrC陶瓷

Dense ZrC Ceramics Fabricated by Self-propagating High Temperature Synthesis under Dynamic Pressing

在万能材料试验机平台的监控下,采用自蔓延高温合成/单向加压法(SHS/SAP)动态结合自蔓延高温合成/准热等静压法(SHS/PHIP)制备了ZrC陶瓷。研究了位移、负荷曲线变化规律与SHS/PHIP工艺参数之间的关系以及SHS/PHIP压力对产物显微结构与致密度的影响。通过万能材料试验机平台记录了位移、负荷曲线,利用XRD与SEM研究了产物的物相组成和显微结构,采用排液法测定了产物的密度。结果表明:位移、负荷曲线反映出了SHS反应结束的时间点和塑性时间段,可作为SHS/PHIP加压时机和保压时间的参数。随着压力的增大,ZrC晶粒表面挤压变形越加明显,在120 MPa时出现了烧结颈现象。致密度随压力增大呈增大的趋势,最高达到93.7%,其致密机理为晶粒重排和晶粒塑性变形共同作用。

Under the monitoring of the universal testing machine platform, ZrC ceramics were prepared by self-propagating high-temperature synthesis/single action pressing（SHS/SAP） dynamically combined with self-propagating high-temperature synthesis/pseudo-hot isostatic pressing（SHS/PHIP）. The relationship between rules of displacement, load curve changing and technical parameters of SHS/PHIP was investigated. The effects of pressure on microstructure and densification of the products were also studied. Displacement and load curve were recorded by the universal testing machine platform, XRD and SEM were used to demonstrate the phase constitution and microstructure of products, and the density was measured by the drain away liquid way. Results indicate that the ended time of SHS reaction and the plasticity period of time of products are demonstrated by displacement and load curves, which can be used as parameters of pressure applying moment and dwell time of SHS/PHIP. With the increasing pressure, extrusion deformation of ZrC grain surface is more obvious, leading to the sintering necks under 120 MPa. Density is increased with the pressure increasing, reaching a peak of 93.7%; the involved mechanism includes crystal particles rearrangement and plastic deformation.