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为研究超二氧化锆(ZrO2)陶瓷的冲击增韧特性,利用能量为35 J的激光脉冲对ZrO2陶瓷试样进行冲击试验,并对试样进行扫描电镜(SEM)检测。结果表明试样表面产生了约90μm厚的无裂纹的致密层,后表面出现了层裂破坏,在非致密层内则产生大量微观裂纹,微裂纹密度越靠近试样后表面越大。X射线物相分析结果表明部分材料发生了从四方相到单斜相的冲击相变,而这一相变过程会导致组织体积增加。发生在裂纹尖端的冲击相变因体积增加产生残余压应力,阻碍裂纹的扩展,使裂纹具有非扩展性。大量非扩展性微裂纹的存在可提高ZrO2陶瓷的冲击韧性,利用10 J能量的激光脉冲对试样进行多点冲击预处理,然后利用42 J的激光脉冲对试样进行冲击,结果表明预处理后的试样后表面仅出现层裂倾向,而没有发生层裂破坏。说明激光冲击预处理达到了增加冲击韧性的目的。
In order to study the impact toughening properties of ZrO2 ceramics, a laser pulse with energy of 35 J was used to perform impact test on ZrO2 ceramic samples. The samples were examined by scanning electron microscopy (SEM). The results show that the crack-free compact layer with a thickness of about 90μm is formed on the surface of the sample. The crack appears on the back surface and a large number of microcracks are generated in the non-dense layer. The closer the microcrack density is to the surface of the sample, the larger the surface is. X-ray phase analysis shows that some materials undergo an impact phase transition from tetragonal phase to monoclinic phase, and this phase transformation process will lead to the increase of tissue volume. The impact phase transition at the tip of the crack produces residual compressive stress due to the increase of volume, hinders the expansion of the crack and makes the crack non-expandable. The presence of a large number of non-expanding microcracks can improve the impact toughness of ZrO2 ceramics. The laser pulse of 10 J energy was used to pretreat the sample with multi-point impact, and then the laser pulse of 42 J was used to impact the sample. The results show that pretreatment The posterior surface of the sample showed only a tendency of delaminations without delaminations. This shows that laser impact pretreatment has achieved the purpose of increasing the impact toughness.