TED-AJ03-280 DEVELOPMENT OF NONDESTRUCTIVE INSPECTION METHOD FOR THE DEGRADATION OF THERMAL BARRIER COATING : SERVICEABILITY EVALUATION OF THE DEVELOPED NDI METHOD
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概要
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Gas turbines are being operated at ever higher temperatures in order to increase their efficiency. As a result, thermal barrier technology to protect the hot parts of gas turbines from high-temperature gas is becoming increasingly important, making it necessary to evaluate the thermal barrier performance of the thermal barrier coating (TBC). The thermal barrier performance of TBC is a function of its thermal resistance (in other words, thickness and thermal conductivity). Both the reduction of TBC thickness by erosion and sintering of TBC degrade its thermal barrier performance. To date, however, no effective method for inspecting the thermal barrier performance of TBC has been developed. We propose an effective nondestructive inspection (NDI) method to evaluate the thermal barrier performance of TBC by infrared transient heating of the surface. The surface of TBC is heated by a CO_2 laser, and the temperature of the heated surface is measured by an infrared camera. In this method, the CO_2 laser and the IR camera are fixed, whereas the measured TBC specimen is traversed continuously. The temperature behavior is closely correlated with the thermal barrier performance of TBC. The results of numerical analysis and laboratory tests show that the proposed NDI method is effective for evaluating the thermal barrier performance of TBC. This paper evaluates the effectiveness of our proposed inspection method based on the inspection results for the combustor inner surface TBC and the measurement accuracy of the thermal barrier performance of TBC. The thermal barrier performance of the combustor inner surface TBC was quantitatively measured by our method. The inspection results revealed that TBC degradation affects the remaining life of the substrate because the ratio of the maximum value to the minimum value of TBC thermal barrier performance was about 3.5 times. The results also confirmed that the thermal barrier performance of combustor TBC can be measured to within ±5%, which was the target accuracy. This quantitative evaluation of the thermal barrier performance of combustor TBC is the first nondestructive inspection method of TBC. The method offers sufficient measurement accuracy for practical use, is easy and quick to perform, and so is useful for making repair decisions and acceptance inspections.[figure]
- 一般社団法人日本機械学会の論文
著者
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Morinaga Masahiko
Energy & Mechanical Engineering Department Central Research Institute Of Electric Power Industry
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Fujii Tomoharu
Energy & Mechanical Engineering Department Central Research Institute Of Electric Power Industry
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TAKAHASHI Takeshi
Energy & Mechanical Engineering Department, Central Research Institute of Electric Power Industry (C
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Takahashi Takeshi
Energy & Mechanical Engineering Department Central Research Institute Of Electric Power Industry