研究了以氮化铝(AlN)为助烧剂的碳化硅晶片(SiC_(pl))增韧二硼化锆(ZrB_2)复合陶瓷材料的制备工艺,并测定其抗弯强度、断裂韧性、致密度和显微硬度.利用扫描电子显微镜(SEM)观察了样品的表面及断面形貌.复合陶瓷中SiC晶片的添加量分别为5%, 10%, 15%以及20%(体积分数, 下同),AlN作为烧结助剂添加量为3%.结果表明:适量SiC晶片的添加提高了SiC_(pl)/ZrB_2复合陶瓷的烧结致密度;SiC_(pl)/ZrB_2复合陶瓷的力学性能比纯ZrB_2陶瓷有所提高,抗弯强度和维氏硬度在5%SiC晶片添加量时达到最大,分别为(625.34±21.46) MPa和(14.60±0.84) GPa;断裂韧性在15%SiC晶片添加量时达到最大值(8.35 ± 0.26) MPa·m~(1/2).断口形貌观察表明主要增韧机制为裂纹偏转与晶片拔出.
The preparation and mechanical properties of zirconium diboride matrix composites reinforced by silicon carbon platelets (SiC_(pl)/ZrB_2 composites) have been investigated using 3vol% AlN as sintering additive. Bending strength, fracture toughness, density and Vickers hardness were tested, respectively. Electron Scanning Microscope was used to observe the surface and the ruptured cross section. The additions of SiC platelets were 5 vol%, 10 vol%, 15 vol% and 20 vol%, respectively. The results showed that an adequate addition of SiC platelets could promote the sintering densification of the SiC_(pl)/ZrB_2 composites. The mechanical properties of the SiC_(pl)/ZrB_2 composites are higher than those of the monolithic ZrB_2 ceramic. Bending strength and Vickers hardness of the SiC_(pl)/ZrB_2 composites reached maximum values, (625.34±21.46) MPa and (14.60±0.84) GPa, respectively, at an addition of SiC platelets of 5 vol%, while fracture toughness of the SiC_(pl)/ZrB_2 composites reached a maximum value of (8.35 ± 0.26) MPa·m~(1/2) at an addition of SiC platelets of 15 vol%. According to the observation on fractograph of the SiC_(pl)/ZrB_2 composites, crack deflection and platelet pulling-out were thought as main toughening mechanisms.
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