Research Progress and Development Trend of Ground Heavy Duty Gas Turbine and Its Thermal Barrier Coatings
Thermal barrier coating technology,an internationally recognized cutting-edge technology for heavy-duty gas turbine manufacturing,is mainly used on the surface of the hot section components of gas turbines to enhance their efficiency by increasiag the working temperature of the hot section components.However,at high temperatures,thermal barrier coatings frequently experience issues including CMAS(CaO-MgO-Al2O3-SiO2)corrosion,oxidation,phase transitions,and sintering.Key properties such as CMAS corrosion resistance affect the coating life,which affects the efficiency of gas turbines.Therefore,this paper first presents the current situation and development trends of heavy-duty gas turbines worldwide.The background of the research on thermal barrier coatings is then presented;thermal barrier coatings are classified according to their different coating structures.The characteristics and properties of commonly used coating materials such as the ceramic top coat and bond coat materials are compared,and the principles,advantages and disadvantages of several typical preparation processes of thermal barrier coatings such as air plasma spraying,electron beam-physical vapor deposition,plasma spraying-physical vapor deposition,and the morphological characteristics of the prepared coatings are summarized and analyzed.Aiming at some challenges that are often encountered in thermal barrier coatings for gas turbines at high temperatures,such as oxidation,CMAS corrosion,among others,the importance of several key properties of thermal barrier coatings,such as thermal insulation,oxidation resistance,and thermal shock resistance,is emphasized,and these key properties are explained and their research progress is reviewed.Finally,focusing on the high-temperature CMAS corrosion resistance of thermal barrier coatings,the mechanism of CMAS corrosion in terms of the thermochemical and thermomechanical aspects is described,along with five protective research methods to improve the CMAS corrosion resistance of thermal barrier coatings:identifying and developing new ceramic top coat materials,doping and modifying thermal barrier coating materials,preparing a protective layer on the surface of the ceramic top coat,adopting a double-layer ceramic top coat structure,and optimizing the coating surface structure.Based on a summary of the research progress and development trends of heavy-duty gas turbines and their thermal barrier coating,the following conclusions are drawn.Compared with developed countries,there is still a wide gap in the manufacturing technology and maintenance level of heavy-duty gas turbines in China,which will be developed towards high parameters,high performance,low pollution,and large-scale in the future.In general,the thermal barrier coating is preferred in the form of a double-layer structure;the material is preferred to be 8YSZ and MCrAlY,and the preparation process is preferred for air plasma spraying.Despite the fact that thermal barrier coatings have been widely used with the rapid development of industry,traditional thermal barrier coatings have failed to meet the service requirements of next-generation heavy-duty gas turbines;therefore,improving the performance of thermal barrier coatings has become a key issue.The materials,structures,and preparation processes of thermal barrier coatings are critical for improving their performance.To ensure the safe operation of heavy-duty gas turbines at higher temperatures for a longer period of time,we should continue to search,design,and develop new thermal barrier coating materials with low thermal conductivity,good oxidation resistance,thermal shock resistance,and corrosion resistance,increase investments in the structural design research of thermal barrier coatings,regulate the structural parameters of thermal barrier coatings,and improve and develop new preparation processes for thermal barrier coatings.This paper reviews several key properties of thermal barrier coatings for gas turbines and proposes that the performance of thermal barrier coatings is closely related to their materials,structures,and preparation processes.Methods to improve the performance of thermal barrier coatings are presented,and there is a lack of such review articles to lead the field of thermal barrier coatings for gas turbines.
gas turbinethermal barrier coatingsresearch progressCMAS corrosion
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