Millimeter-Wave Assisted Sintering of Polycrystalline Yttria for Laser Host Material

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We report an investigation of millimeter-wave processing of yttria for fabrication of transparent, high-strength polycrystalline laser hosts for high energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal laser host materials, include lower processing temperature, higher gain with flexibility of higher dopant concentrations, cheaper fabrication, and larger-size devices. Millimeter-wave processing is an alternative method to solve the problems of both conventional vacuum and low-frequency microwave sintering, such as low heating rate, poor coupling and thermal gradients. A major component of the millimeter-wave processing facility is a 20-kW, continuous-wave, 83-GHz gyrotron oscillator. Yttria has been successfully sintered with millimeter-wave beams with up to 99% theoretical density. A partially transparent yttria sample has also been achieved using the millimeter-wave sintering process [1]. Several factors impact the quality of the sintered material including the presence of agglomerates, impurities, processing atmosphere, sintering aids, and thermal gradients. Efforts to improve the transparency will be discussed.

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Periodical:

Materials Science Forum (Volumes 561-565)

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Edited by:

Young Won Chang, Nack J. Kim and Chong Soo Lee

Pages:

511-514

Citation:

M. K. Hornstein et al., "Millimeter-Wave Assisted Sintering of Polycrystalline Yttria for Laser Host Material", Materials Science Forum, Vols. 561-565, pp. 511-514, 2007

Online since:

October 2007

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$38.00

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