等离子喷涂高强韧纳米TiO_(2)涂层的制备及其力学性能

Preparation and Mechanical Properties of Air Plasma Sprayed High Strength and Toughness Nano-TiO_(2) Coatings

为提高大气等离子喷涂(APS)TiO_(2)陶瓷涂层的结合强度及其摩擦磨损性能,采用喷雾造粒的纳米结构TiO_(2)粉末为原料,利用APS工艺制备出TiO_(2)陶瓷涂层,研究了涂层的显微组织、相组成、力学性能和摩擦磨损性能,并与常见的微米级TiO_(2)粉末制备的陶瓷涂层组织性能进行了对比。结果表明,微米TiO_(2)粉在喷涂前后相成分从板钛矿变为金红石和锐钛矿的混合相;而纳米团聚的TiO_(2)粉喷涂前后无明显的相成分变化,均以金红石相为主。纳米TiO_(2)涂层的孔隙率为1.4%,低于微米粉涂层的3.3%。纳米TiO_(2)涂层的力学性能优于微米涂层,微米涂层硬度为934.2 HV_(0.1),而纳米涂层的硬度为1349 HV_(0.1);纳米和微米涂层的弹性模量分别为203.1和185.8 GPa;纳米涂层的断裂韧性为2.1 MPa·m^(1/2),略高于微米涂层的2.0 MPa·m^(1/2);纳米涂层的结合强度可达46.8 MPa,是微米涂层的3.18倍(14.7 MPa)。此外,在相同的摩擦条件下,纳米TiO_(2)涂层的摩擦因数为0.69,比微米TiO_(2)涂层更低,纳米涂层的磨损体积也比微米涂层更少。综合来说,纳米TiO_(2)涂层相对于微米级TiO_(2)涂层体现出更好的综合力学性能。

In order to improve the bond strength and frictional wear performance of atmospheric plasma sprayed(APS)TiO_(2) ceramic coatings,the nanocrystalline TiO_(2) powder produced by spray-dry technology was adopted as the raw material and the TiO_(2) ceramic coatings were prepare applying APS technology.The microstructure,phase composition,mechanical properties,and frictional wear behavior of the coatings were investigated and compared with ceramic coatings prepared using commercial sintered-crushed micro-scale TiO_(2) powder.The results show that the phase composition of the micro-scale TiO_(2) coating(MT)changes from an anatase phase to a mixture of rutile and brookite phases after the APS process.However,there is no significant phase composition change occurred for the nano-scale TiO_(2) coating(NT),which predominantly remains in the rutile phase.The porosity of the nano-scale coating is 1.4%,lower than that of the micro-scale coating(3.3%).The mechanical properties of the nanometer-scale coating are better than those of the micrometer-scale coating.The hardness of the micro-scale coating is 934.2 HV_(0.1),lower than that of the nano-scale coating(1349 HV_(0.1)).The elastic module of the micro-and nano-scale coatings are 185.8 GPa and 203.1 GPa,respectively.The fracture toughness of the nano-scale coating is 2.1 MPa·m^(1/2),which is also slightly higher than that of the micro-scale coating(2.0 MPa·m^(1/2)).The bond strength of the nanometer-scale coating is 46.8 MPa,which is 2.18 times larger than that of the micro-scale coating(14.7 MPa).Furthermore,under the same sliding friction conditions,the friction coefficient of the nano-scale coating is 0.69,which is lower than that of the micro-scale coating.In addition,the comparison of friction volume data also favores the nano-scale coating over the micro-scale coating.In summary,TiO_(2) coatings produced from nanocrystalline powder exhibit superior comprehensive mechanical properties and friction resistance compared to those prepared from microcrystalline powder.