High strength Y2O3-stabilized zirconia continuous fibers up to 1500°C: Crystalline phase and microstructure evolution as well as grain growth kinetics

Abstract

For zirconia continuous fibers, tensile strength is a very important performance parameter, which is affected by the crystal phase, its stability, grain size, processing temperatures, and so on. In this paper, the crystalline phases were adjusted through the Y2O3 contents and heat treatment temperatures in the range of 1000–1500°C. We found that interfacial segregation of Y3+ at high temperatures led to crystal phase instability, which was observed near the grain boundaries of the 13.8YSZ fibers. At high temperatures, the grain growth of different fibers occurred to different degrees. The regularities between the tensile strength, the strength retention and temperature, Y2O3 contents were discussed in detail. According to the highest tensile strength of a single fiber and Weibull modulus m, we found that the 5.4YSZ fibers were the most stable with the highest tensile strength and slow grain growth rate. The average strength was 1.6 GPa after heat-treating at 1500°C and the strength retention rate was about 54% under 1500°C for 60 min. Finally, the twistable 5.4YSZ continuous fibers with high strength were obtained by dry spinning technology. These results can provide reliable theoretical support and data sources for its high-temperature applications.