Early-stage Sintering of Alumina in Vacuum and Nitrogen Atmosphere

Abstract

The initial sintering kinetic of alumina have been studied in different heating rate and doped with metallic oxide (TiO2 or MgO) However sintering in atmosphere is barely discussed In this study green compacts of alumina were produced by slip casting and doped with 500 ppm Mg2+ by infiltration The ?-alumina powder dispersed in deionized water by PAA-NH4 After pre-heated at 800℃ for 12 h the compacts sintered in air vacuum and nitrogen atmosphere at 1300-1450℃ and held for 0-4 h The samples sintered in vacuum and in nitrogen could reach high density (~98%) at 1400℃ and grain size could be ~1 μm The activation energy of sintering during densification is analyzed by Arrehnius equation The results of densification activation energy in vacuum nitrogen and air are 67 4 kJ/mol 46 8 kJ/mol and 194 7 kJ/mol respectively After fitting the form with various sintering atmosphere grain growth exponent n of vacuum and nitrogen sintering are 2 and conventional sintering is 3 The activation energy of grain growth in different atmosphere can be analyzed It is 268 4 kJ/mol for vacuum sintering and 269 3 kJ/mol 512 5 kJ/mol for nitrogen and conventional sintering respectively

Date of Award	2020
Original language	English
Supervisor	Chi-Yuen Huang (Supervisor)