Thermal diffusivity and erosion resistance of ZrO2-8 wt-% Y2O3 coatings prepared by a laser hybrid spraying technique

The results of thermal diffusivity measurement revealed that post-treated thermal barrier coatings (TBCs), which contain a remelted dense layer with numerous vertical cracks, are not effective in reducing the heat transfer. However, laser-hybrid sprayed TBCs with segmented feather-like microcracks decreased the thermal diffusivity by 60% of the as-sprayed value at the specific laser-hybrid condition (P = 120 W mm(-2)). The post-treated TBCs with dense layers endured at the early stage of erosion but collapsed gradually due to consecutively impacting particles. On the other hand, weight losses of laser-hybrid sprayed coatings (P = 80 and 120 W mm(-2)) were decreased compared with the usual sprayed coatings and the erosion rates were also constant even if blasted by much more erodent than used for post-treated samples (erodent weight, 210 g). From the results of this work, it is suggested that the laser-hybrid spraying process can be a good choice for production of durable TBCs used in hot sandy environments. (C) 2002 Elsevier Science B.V. All rights reserved.