The wavelet transform is applied to the analysis of acoustic emission signals collected during tensile test of the ZrO2-8% Y2O3 (YSZ) thermal barrier coatings (TBCs). The acoustic emission signals are de-noised using ...The wavelet transform is applied to the analysis of acoustic emission signals collected during tensile test of the ZrO2-8% Y2O3 (YSZ) thermal barrier coatings (TBCs). The acoustic emission signals are de-noised using the Daubechies discrete wavelets, and then decomposed into different wavelet levels using the programs developed by the authors. Each level is examined for its specific frequency range. The ratio of energy in different levels to the total energy gives information on the failure modes (coating micro-failures and substrate micro-failures) associated with TBCs system.展开更多
The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the...The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.展开更多
基金Project(10525211, 50531060) supported by the National Natural Science Foundation of China
文摘The wavelet transform is applied to the analysis of acoustic emission signals collected during tensile test of the ZrO2-8% Y2O3 (YSZ) thermal barrier coatings (TBCs). The acoustic emission signals are de-noised using the Daubechies discrete wavelets, and then decomposed into different wavelet levels using the programs developed by the authors. Each level is examined for its specific frequency range. The ratio of energy in different levels to the total energy gives information on the failure modes (coating micro-failures and substrate micro-failures) associated with TBCs system.
文摘The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.
