激光重熔等离子喷涂Al_2O_3陶瓷层的相转变

PHASE TRANSFORMATION OF Al_2O_3CERAMIC COATING AFTER PLASMA SPRAYING AND LASER REMELTING

研究了锌铝基A12O3陶瓷层激光重熔区内陶瓷相的转变。采用METCO4MP等离子喷涂机对基体材料表面喷涂氧化铝(A12O3的质量分数为99%)陶瓷层。采用上海光学精密机械研究所HJ4工业用横流CO2激光器进行激光重熔。通过X射线衍射分析和透射电镜对Al2O3陶瓷的微观结构、成分和分布的研究,得到以下结论:在等离子喷涂过程中,喷涂层中陶瓷相发生αAl2O3γAl2O3+αAl2O3的转变。激光重熔后,试样表层的原αA12O3陶瓷相、γA12O3陶瓷相均转变为δA12O3陶瓷相,为体心四方结构。熔池区陶瓷相主要分布在表层,次表层和过渡区。

Ceramic phase transformation of A12O3 ceramic coating coated on Zn-Al based alloy by plasma spraying and laser remelting was investigated. Alumina (99% in mass) particles were sprayed on surface of parent materials by plasma spraying equipment, and the sprayed layer was remelten by transverse flowing CO2 laser. The microstructure, composition and distribution of ceramic phases were studied by XRD and TEM. Results show that during plasma spraying ceramic phase transformation is occurred as follows: α-A12O3 to γ-A12O3 + α-A12O3. Alpha-alumina and gamma-alumina ceramic phases in superficial layer transform into δ-A12O3 after laser remelting, which is in the structure of body-centered tetragonal. Ceramic-phase grains in molten pool are mainly distributed in the superficial layer, and there are also some ceramic grains of δ-A12O3 in subsurface and transition layers.