In order to clarify the degradation mechanism of gas turbine bucket coating, 25000hr serviced bucket with Pt-Al coating was destructively evaluated. Degraded phase, which is called breaching, was identified in the substrate of the tip section of the bucket and was figured out to be an Al-rich phase. Based on this evaluation result, Monte Carlo simulation analysis was carried out to simulate the formation of breaching by using an Al-cluster diffusion model. The results obtained are as follows: (1) The degradation phenomena in the serviced coated bucket were successfully simulated by using an Al-cluster diffusion model in a simple Ni-Al alloy system. (2) By using this simulation method, inverse problem analyses of actual complex degradation phenomena were performed. The results are as follows; (a) Preferential formation temperature of breaching was identified. (b) Effects of surface temperature and temperature gradient on the formation of breaching were identified. The gradient shifted the peak breaching formation temperature to the higher surface temparature and also increased the amount of breaching. (c) Effect of orientation on the probability of breaching formation was identified. The probability tended to be high at the direction of Al-cluster diffusion.
|ジャーナル||Journal of the Society of Materials Science, Japan|
|出版ステータス||Published - 1994|
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