Preparation, microstructure and toughening mechanism of superhard ultrafine-grained boron carbide ceramics with outstanding fracture toughness
Preparation, microstructure and toughening mechanism of superhard ultrafine-grained boron carbide ceramics with outstanding fracture toughness
复制标题
断裂韧性超硬超细晶碳化硼陶瓷的制备、显微组织及增韧机理
DOI：
10.1016/j.jallcom.2018.05.228
复制
发表时间：
2018
影响因子：
6.2
通讯作者：
Wang Weimin
中科院分区：
文献类型：
--
作者：
Zhang Xiaorong;Zhang Zhixiao;Sun Yang;Xiang Mingyu;Wang Guangshuo;Bai Yongmei;Mu Jingbo;Che Hongwei;Wang Weimin
采用放电等离子烧结技术在1700 °C和80 MPa条件下制备了具有超高硬度和优异断裂韧性的致密超细晶B4 C陶瓷。该工艺以高能球磨法制备的超细B_4C粉末为起始粉末。在烧结过程中，由于高压和粉末的高烧结活性的影响，致密化在1050 ° C开始较早，最大致密化速率在1500 °C出现较早。B4 C陶瓷具有超细晶粒，平均晶粒尺寸为370 nm，这是其超高硬度的主要原因。许多小于200 nm的小B4 C颗粒分散在大B4 C颗粒之间或聚集形成聚集区。小晶粒诱导裂纹偏转、颗粒脱出和裂纹桥接，从而提高陶瓷的韧性。B4 C陶瓷的相对密度、维氏硬度和断裂韧性分别达到99.4 ± 0.49%、41.1 ± 0.9GPa和4.57 ± 0.12MPam1/2。
Dense ultrafine-grained B4C ceramics with superhigh hardness and outstanding fracture toughness were fabricated via spark plasma sintering at 1700 °C and 80 MPa. This process used the ultrafine B4C powder prepared by high-energy ball milling as starting powder. During sintering, densification began earlier at 1050 °C and the maximum densification rate appeared earlier at 1500 °C under the influence of high pressure and high sintering activity of the powder. The B4C ceramics possessed ultrafine grains, with average grain size of 370 nm, which contributed to the superhigh hardness. Many small B4C grains with size of less than 200 nm were individually dispersed among large B4C grains or accumulated to form congregated areas. The small grains induced crack deflection, particle pullout and crack bridging, thereby enhancing the toughness of the ceramics. The relative density, Vickers hardness and fracture toughness of the B4C ceramics reached 99.4 ± 0.49%, 41.1 ± 0.9 GPa and 4.57 ± 0.12 MPa m1/2, respectively.