激光重熔Al2O3-TiO2涂层的强韧性能
Strength and toughness of laser-remelted Al2O3-TiO2 coatings
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摘要: 采用等离子喷涂和激光重熔复合工艺在Ti-6Al-4V基体上制备了Al2O3-TiO2涂层,通过X射线衍射(XRD)、扫描电镜(SEM)、显微硬度试验和压痕试验等方法研究了激光重熔对涂层的组织及强韧性能的影响.结果表明,等离子喷涂Al2O3-TiO2涂层中的主相为γ-Al2O3,而相应重熔涂层中的主相为α-Al2O3.激光重熔可消除喷涂态涂层内部的孔隙、微裂纹和层状堆垛等微观缺陷,获得致密化的组织,并使涂层与基体形成良好冶金结合.重熔涂层的硬度比相应喷涂态涂层约提高了50%,裂纹扩展抗力相比喷涂态涂层提高了近两倍.激光重熔纳米涂层中的未熔增强颗粒和纳米结构特性等对涂层起到了协同强化和韧化作用.Abstract: Laser-remelted Al2O3-TiO2 coatings were prepared on Ti-6Al-4V alloy substrates by plasma spraying and laser remelting.X-ray diffraction (XRD),scanning electron microscopy (SEM),micro-hardness and indentation tests were carried out to investigate the effects of laser remelting on the microstructure and properties of the coatings.The results showed that the major phase in the as-sprayed Al2O3-TiO2 coatings was γ-Al2O3, while that in the remelted coatings was α-Al2O3.After laser remelting,pores,micro-cracks,lamella structure and other defects in the as-sprayed coatings could be eliminated to form compact microstructure as well as good metallurgical bonding between the coating and substrate.The hardness and crack propagation resistance of the remelted coatings were approximately 50%, which were twice higher than those of the corresponding assprayed coatings,respectively.The unmelted particles and nanostructure in the laser-remelted nanostructured coatings contributed to the strength and toughness.
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