【摘要】 将商用纳米Al2O3与TiO2粉末混合制浆,通过喷雾造粒技术重构成大颗粒纳米Al2O3-13%TiO2团聚粉体,然后采用不同加热温度进行烧结,制备用于热喷涂的纳米喂料。采用等离子喷涂技术沉积形成纳米涂层。利用XRD和SEM对纳米粉末和涂层的形貌、显微结构和晶相进行表征。结果表明,在烧结过程中纳米氧化铝没有发生相变,而纳米氧化钛则由锐钛矿相转变为金红石相;在等离子喷涂过程中,部分α-Al2O3发生熔化转变为γ-Al2O3,且转变量与喷涂工艺参数有关;而TiO2相只在较低喷涂工艺参数下存在衍射峰,在较高喷涂工艺参数下则以χ-Al2O3·TiO2固溶体存在;涂层在热处理过程中会发生γ-Al2O3向α-Al2O3的转变,且有TiO2相析出。更多还原

【Abstract】 Commercial nanosized alumina and titania particles were selected as raw materials to prepare the blended slurry with composition of Al2O3-13%TiO2(mass fraction), which were reconstituted into micrometer-sized granules by spray drying, subsequently sintering at different temperatures to form nanostructured feedstock for thermal spraying, and then Al2O3-13%TiO2nanocoatings were deposited by plasma spraying. The evolution of morphology, microstructure, and phase transformation of the agglomerated powder and as-sprayed coatings were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The results show that Al2O3 retains the same α phase as the raw material during sintering, while TiO2 changes from anatase to rutile. During plasma spraying, some α-Al2O3 phases solidify to form metastable γ-Al2O3, and the volume fraction of α-Al2O3decreases as CPSP increases. However, peaks of the TiO2 phase are not observed from the as-sprayed coatings except for the coatings sprayed at the lower CPSP. As the CPSP increases, nanostructured TiO2 is dissolved easily in γ-Al2O3 or χ-Al2O3·TiO2 phase. After heat treatment, γ-Al2O3 in the coatings transforms to α-Al2O3, and rutile is precipitated.更多还原