【摘要】 热障涂层的残余应力是影响其服役寿命的关键因素,过去,对纳米结构热障涂层的残余应力研究不多。在45钢基体上,用超音速火焰喷涂NiCoCrAlY打底层,再用大气等离子喷涂ZrO2-8%(质量分数)Y2O3(8YSZ)工作层,制备了纳米结构与传统结构2种类型的热障涂层(TBC)。采用SEM、XRD对这2种涂层的粉末及涂层进行了组织结构分析,用纳米压痕仪测得了2种涂层的弹性模量。用X射线衍射应力测试仪测得了2种涂层的表层残余应力。结果表明:喷涂工艺参数相同条件下,对于打底层及工作层的厚度均相同的2种涂层,纳米结构热障涂层的表层残余应力比传统结构热障涂层约低24.7%;相同打底层的纳米结构热障涂层表层残余应力随着陶瓷层厚度增加而增加,陶瓷层厚度在240μm以下时,表层为残余压应力;厚度超过300μm时,表层为残余拉应力。最后提出了相应的物理力学模型。更多还原

【Abstract】 Nano-structured feedstock of ZrO2-8wt% Y2O3 used for plasma spraying was obtained success-fully by making use of reconstituting nanoparticle technique. Then nano-structured and conventional ZrO2-8wt% Y2 03 (8YSZ) thermal barrier coatings (TBC) were prepared by atmos-pheric plasma spraying (APS) on NiCoCrAlY coated 45 steel substrates. The microstructure and phase composition of the two types of feedstock and corresponding plasma sprayed coatings were analyzed by means of scanning electron microscopy ( SEM) and X-ray diffraction (XRD). The elastic modulus of the coat-ings was measured using a nano-indenter. The surface residual stresses of the coatings were tested using an XRD stress test de-vice,and a physical model was put forward to explain the causes leading to varied residual stresses. Results show that the nano-structured 8YSZ coating had a lower elastic modulus than the con-ventional 8YSZ coating,and the surface residual stress of nano-structured 8YSZ coating is lower than that of conventional 8YSZ coating by 24. 7%. Moreover,the residual stresses of the coat-ngs increased with increasing thickness of the ceramic coating. The coatings with a ceramic coating below 240 μm had compres-sive residual stress,while those with a ceramic coating of above 300 μm had tensile residual stress.更多还原