等离子喷涂纳米结构与传统结构热障涂层的残余应力研究

【作者】 王亮； 王铀； 田伟； 杨勇； 周红霞；

【机构】 哈尔滨工业大学材料科学与工程学院；

【摘要】 本文以成熟的造粒技术,获得了能够用来进行等离子喷涂的纳米结构团聚体喂料。运用热喷涂技术,在45#钢基体上通过超音速火焰喷涂NiCoCrAlY打底层,再进一步通过大气等离子喷涂工作层的方法制备了纳米结构与传统结构两种类型的ZrO₂-8wt%Y₂O₃（8YSZ）热障涂层（TBC）。采用SEM,XRD对这两种涂层的喂料及涂层进行了组织结构分析,并运用纳米压痕仪测得了两种涂层的弹性模量。最后运用X射线衍射应力测试仪测得了两种涂层的表层残余应力,测量计算结果表明:在同种喷涂工艺参数条件下,对于打底层及工作层的厚度均相同的两种涂层,纳米结构的热障涂层的表层残余应力明显低于传统结构热障涂层的表层的残余应力约24.7%。对于具有相同打底层的纳米结构热障涂层,其表层残余应力的数值随着陶瓷层的厚度增加而增加,当陶瓷层厚度在240μm以下,表层为残余压应力,而当陶瓷层厚度超过300μm时,表层为残余拉应力。本文对这一结果提出了相应的物理力学模型并予以解释。更多还原

【Abstract】 The nano-structured agglomerates feedstock which can be used for plasma spraying was obtained success- fully with the maturity of the reconstituting nano-particle technique.Nano-structured and traditional ZrO₂-8wt% Y₂O₃ （8YSZ）thermal barrier coatings（TBC）have been prepared by atmospherically plasma spraying（APS）on NiCoCrAlY coated 45#steel substrates.The feedstock and its corresponding coatings was observed by SEM.The phase of feedstock and its corresponding coatings which experienced atmospherically plasma sprayed was characterized by SEM and XRD. The elastic modulus was also tested by The TRIBO indenter.The surface residual stresses was tested by XRD stress test instrument.The test result shows that the elastic modulus of nano-structured 8YSZ is lower than that of conventional 8YSZ coatings and the surface residual stresses of nano-structured 8YSZ coatings is 24.7% lower than that of conventional 8YSZ coatings.The value of residual stresses is increased as the thickness of the ceramic coatings increased.The coatings has been gained compressive residual stresses when the thickness of the ceramic coating is lower than 240μm and has been gained tensile residual stresses when the thickness of the ceramic coating reach to higher than 300μm under the same situ- ation（including the same bend coat,the same technological parameter and the same thickness）.A physical mechanical model was put forward to explain the causation of the vary of residual stresses.更多还原