GI-Ⅱ型渗透陶瓷赫兹触压循环疲劳的实验研究

Cyclic fatigue of GI-Ⅱ glass infiltrated ceramic in Hertzian’s contact

目的:研究GI-Ⅱ型渗透陶瓷在赫兹触压循环加载下的疲劳模式。方法:应用半径3.18mm的碳化钨球,对GI-II型渗透陶瓷标准试件进行循环加载,测试加载后试件的残余三点弯曲强度,观测试件表面及次表面损伤,数据进行单因素方差分析。结果:当最大载荷为900N时,第一次循环后试件的强度从原始的(395.7±46.5)MPa下降至(318.6±40.3)MPa,当循环次数增加至105次时,试件的三点弯曲强度再次显著性降低至(203.6±18.7)MPa(P<0.05),此后持续下降;2×105次时,降至(170±33.9)MPa。疲劳损伤随加载周期依次表现为加载区的屈服、加载区外围即滑移区的虫蚀状磨损和片状剥落,以及随后出现大块脱落。而在最大载荷为500N时,即使当循环次数增加至105次,强度的下降仍无统计学意义。结论:GI-Ⅱ型渗透陶瓷在赫兹触压循环加载下的疲劳模式为剪切应力和张应力驱动的、以裂尖屏蔽以及晶体桥接效应机械降低过程为特征的类塑性模式。

PURPOSE： To investigate the cyclic fatigue damage modes of GI-Ⅱ glass infiltrated ceramic in Hertzian＇s contact, METHODS： All ceramic specimens were loaded by a r=3.18 mm WC ball to investigate their cyclic fatigue behavior in Hertzian＇s contact. Furthermore,the surviving stress was examined by three-point-flexure-test and morphological damages were observed, All statistical analysis were performed with one -way ANOVA. For all tests, a Pvalue less than 0.05 was considered to be significant. RESULTS： The strength of the specimens decreased from 395.7± 46.5MPa to 318.6±40,3MPa after the 1st cycle when the load was 900N, 203.6±18.7MPa after 105 cycles, and 170± 33.9MPa after 2×10^5 cycles. There was significant difference from that of the cycles （P〈0.05）.Aeeording to the loading cycles, the fatigue damage represented bend in loading area, worm-eaten abrasion or exfoliation around loading area and sequent massive exfoliation , But there was not significant different between the 1st cycle and the 105 cycles when the load was 500N. CONCLUSION： In Hertzian＇s contact ,the fatigue damage mode is characterized by a quasi-plastic mode caused by crack tip shiehl and crystal bridging decline which are driven by shear and tensile stress.