Study on Improvement of Fatigue Strength and Thermal Fatigue Strength of High Density Low Pressure Plasma Sprayed Material.

在893K和室温下对一种喷氧化锆304不锈钢进行了疲劳试验。利用激光散斑应变仪对疲劳试验过程中的表面应变进行了监测，考察了疲劳过程中亚表层的开裂和分层等疲劳过程。大气等离子喷涂(APS)氧化锆涂层试件的疲劳寿命与喷砂衬底的疲劳寿命相似。在疲劳破坏的早期阶段，陶瓷层出现了裂纹，裂纹向基材渗透。在低压等离子喷涂(LPPS)氧化锆涂层的情况下，疲劳寿命比喷砂基材的要长。由LPPS制成的粘结涂层被发现抑制了裂纹在基材中的萌生。

Fatigue tests were conducted at both 893K and room temperature for a zirconia-sprayed type 304 stainless steel. Surface strain was monitored by using a laser speckle strain gauge during the fatigue test to examine the fatigue processes such as cracking and, delamination of subsurface layer. Fatigue life of an Atomospheric Plasma Spraying(APS) zirconia-coated specimen was similar to that of a blasted substrate. A cracking occurred in the ceramics layer at the early stage of fatigue failure and the crack penetration into the substrate. In case of a Low Pressure Plasma Spraying (LPPS) zirconia-coated specimen, the fatigue life was longer than that of a blasted substrate. The bond coating layer made by LPPS was found to restrain a crack from initiating in the substrate.