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Thermal barrier coatings ( TBC ) are regularly used today to protect and extend the service life of several superalloys which are extensively used in high temperature applications .
 Thermal barrier coatings, TBC, service life, superalloys, temperature
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 Thermal barrier coatings, TBC, service life, superalloys, temperature