Testing Methods For Alumina Fibers

Applying tension during sintering can significantly improve the straightness and tensile strength of alumina fibers, inhibit axial shrinkage, and promote the phase transformation from γ-Al₂O₃ to α-Al₂O₃. Compared to pressureless sintering, the application of 0.9 MPa axial tension increased the average tensile strength of alumina fibers sintered at 1,500°C for 3 minutes from 0.35 GPa to 1.16 GPa-an increase of 231%.
The phase-field method was employed to simulate the growth of α-Al₂O₃ grains during the high-temperature sintering of alumina fibers prepared via the sol-gel process. Both phase-field simulations and experimental results indicate that within the sintering temperature range of 1,200–1,500°C, the Al₂O₃ grain size increases with rising temperature, with a particularly marked increase observed between 1,400°C and 1,500°C. Therefore, to control Al₂O₃ grain size, the sintering temperature should not exceed 1,400°C.
A national standard project titled "Test Methods for Dielectric Properties of Continuous Alumina Fibers" is currently being drafted. The project is administered by the National Technical Committee on Glass Fiber Standardization, with key drafting organizations including the Institute of Aerospace Special Materials and Processing Technology, Nanjing Glass Fiber Research & Design Institute Co., Ltd., and Beihang University.