Al_2O_3/TiO_2纳米复合粉体爆炸喷涂层微结构及纳米压痕力学特性

Microstructure and Nanoindentation Mechanical Properties of Detonation Sprayed Coatings Derived from Al_2O_3/TiO_2 Nanocomposite Powders

研究了纳米复合涂层(NCC)和传统涂层(MCC)的微观结构及纳米压痕力学性能. NCC孔洞小,具有良好的均质分布特征.MCC中存在多级尺度分布的孔洞及微裂纹等缺陷, 呈现明显的非均质分布特征.NCC中大量晶界、亚晶界和微裂纹使得涂层中Al2O3基质相细化为纳米晶粒,但MCC中存在大量未熔片层颗粒.NCC和MCC具有各向异性的弹性、塑性、硬度和弹性模量.NCC比MCC相应的断面和表面具有更优良的抵抗外加负载性能、弹性恢复能力,更高的纳米压痕硬度和弹性模量.

This paper researched the microstructrue and nanoindentation mechanical properties of detonation sprayed coatings derived from Al2O3/TiO2 nanocomposite powders. The pores of the nanocomposite coating （NCC） appeared to be generally equal-sized and showed a very homogeneous distribution, while the conventional microcomposite coating （MCC） appears an inhomogeneous pore distribution. The results also indicate that NCC has better chimerism between splat interfaces than MCC and more homogeneous melting condition. A mass of grain boundaries, subboundaries and nanosized microcracks in NCC lead the matrix Al2O3 to be nanoparticulate, while a mass of unmelted particles can be detected in MCC. Both of Al2O3/3wt.%TiO2 nanocompsite and conventional coatings exihibit apparently anisotropic nanoindentation mechanical behaviors, which are due to the anisotropic microstructure of the as-sprayed coatings. The mean values and distribution intervals of both nanoindentation hardness and Young＇s modulus of NCC are higher than those of corresponding surface and cross section of MCC. Therefore, NCC exhibits better nanoindentation mechanical properties than MCC, which is due to the reinforcing effect of TiO2 nanoparticles on the matrix Al2O3 particles of NCC.