Evolution of alumina phase structure in thermal plasma processing

Alumina (Al2O3) remains one the most important engineering ceramic for industrial applications. In addition to the alpha phase, transition alumina phases have interesting characteristics. Controlling the obtained phase structure from alumina melt requires processes with extreme cooling rates and therefore limits the tailoring capabilities. This study investigates how the cooling rate of pure alumina affects its microstructural properties and phase structure in plasma-based processing. The paper reports phase changes in micron sized granulated alumina particles in high-temperature plasma spheroidization and compares the results to plasma sprayed alumina coatings. Both plasma processes involve melting of the material followed by subsequent rapid cooling. Direct comparison on the alumina phase transitions is obtained for the two methodically distinct processing routes, creating unique microstructures due to difference in their cooling rates.

Automated summary

This study investigates the influence of cooling rate on the microstructural properties and phase structure of pure alumina in plasma-based processing. The phase changes in alumina particles during high-temperature plasma spheroidization and plasma sprayed alumina coatings are compared, revealing unique microstructures due to different cooling rates.