热压烧结ZrB_2/Ni复相陶瓷的显微结构

Microstructure of ZrB_2/Ni composite ceramics prepared by hot-pressing

采用热压烧结法在1 950℃/50 MPa/1 h工艺条件下分别对二硼化锆(ZrB2)粗粉、高能球磨超细粉及两者均添加Ni烧结助剂的4种粉末进行烧结。采用阿基米德排水法测定不同烧结体的密度,采用扫描电子显微镜(SEM)及其附带的能谱仪(EDS)研究烧结体形貌及成分。研究结果表明,纯相ZrB2粗粉的烧结致密化过程为温度和压力作用下的球形颗粒切面接触及烧结颈传质;球磨细化后纯相ZrB2粉体的烧结致密化主要得益于粉体表面积及烧结活性的增大;金属Ni烧结助剂对ZrB2粗粉及细化粉体的烧结致密化均能起到促进作用;对ZrB2粗颗粒而言,Ni元素主要分布在粗颗粒交界处或残留孔隙内,起到增大ZrB2颗粒间的接触面积及烧结颈传质速率的作用;对ZrB2超细粉而言,Ni元素主要分布在ZrB2晶界处,促进了ZrB2晶粒间的互扩散及微细孔隙的进一步缩小。

Four kinds of zirconium diboride （ZrB2） powders were sintered at the same technical condition of 1950℃/50 MPa/1 h by hot-pressing. They were coarse monolithic ZrB2 powders, high energy milled powders with and without the sintering additive of metal nickel, respectively. The archimedes method was used to meas- ure the density of the as-sintered ceramic samples. The microstructure observation and element distribution mapping were performed by using scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS）, respectively. The results indicated that： the density process can be described as spherical surface con- tact and matter diffusion when the coarse monolithic ZrB2 powders were sintered at the condition of high tem- perature and high press. The density behavior was profited from the augmentation of surface area and sinter ac- tive when the powder was deal with high energy mill. The sintering additive of metal nickel was contributive to the sinter density for both thick ZrB2 powders and milled super-thin powders, but different density action be- tween them. The Ni element was distributed at the boundary of thick granules or rudimental cavity, and it had the operation to augment the contact area of thick ZrB2 grain and accelerate the matter diffuse between the con- tacted ZrB2 granules. Ni element was distributed at the common boundary of ZrB2 grain, and which had the con- tribution for the diffusion between ZrB2 grain and the reduction of superfine cavity.