Accession Number : ADP007745

Title :   Microwave (Hybrid) Heating of Alumina at 2.45 GHZ: II. Effect of Processing Variables, Heating Rates and Particle Size,

Corporate Author : FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : De, Arindam ; Ahmad, Iftikhar ; Whitney, E. Dow ; Clark, David E.

Report Date : 27 APR 1992

Pagination or Media Count : 11

Abstract : Microwave (hybrid) heating (MHH) is a novel combination of microwave (MW)-material interaction and conventional radiant/conduction mechanisms that facilitates the attainment of very high heating rates In a 2.45 GHz. multimode MW cavity. Dry-pressed green samples of pure, undoped alumina were fired under similar conditions by MHH and conventional fast firing (CFF). The effect of processing variables (temperature, time) and heating rates on MHH and CFF were Investigated. The effect of particle size on the MHH phenomena was also studied. MHH has been shown to result in accelerated densification (higher densification to coarsening ratios) relative to CFF under the same conditions of temperature and time. Higher heating rates with MHH result in higher densities and smaller grain sizes. Smaller starting particle sizes with MHH also culminate In the highest densities and the largest grain sizes similar to conventional firing.

Descriptors :   *MICROWAVES, *CERAMIC MATERIALS, *ALUMINUM OXIDES, CAVITIES, HEATING, INTERACTIONS, MATERIALS, MULTIMODE, PARTICLE SIZE, PARTICLES, PROCESSING, RATES, RATIOS, STARTING, TEMPERATURE, TIME, VARIABLES, FIRING(CERAMICS), GRAIN SIZE, PROCESSING, DENSITY, SYMPOSIA.

Subject Categories : Ceramics, Refractories and Glass
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE