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Effect of Isostatic GAS Pressure on Optical Quality of MgAl2O4 Spinel

Published online by Cambridge University Press:  15 February 2011

S.E. Hsu ,
C.T. Wang ,
D.S. Tsai  and
S.J. Yang
S.E. Hsu
Affiliation:
Materials Research and Development Center, CSIST, P.O. Box 90008-8, Lung-Tan, Taiwan, 32526, R.O.C.
C.T. Wang
Affiliation:
Materials Research and Development Center, CSIST, P.O. Box 90008-8, Lung-Tan, Taiwan, 32526, R.O.C.
D.S. Tsai
Affiliation:
Materials Research and Development Center, CSIST, P.O. Box 90008-8, Lung-Tan, Taiwan, 32526, R.O.C.
S.J. Yang
Affiliation:
Materials Research and Development Center, CSIST, P.O. Box 90008-8, Lung-Tan, Taiwan, 32526, R.O.C.
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Abstract

Optical transparent MgAl2O4 spinel is obtained by processing with high gas pressure to eliminate or reduce the residual pores. Both hot–pressed and sintered specimens are post–treated by the high argon hipping process here. The densities of all the specimens before hipping are over 99% theoretical density. In the high gas pressure process, the pressure ranges from 2000 to 30000psi at 1500°C for 2hrs. The transmittance from visible to IR are measured before and after gas pressure treatment. The transparency from visible to IR increases significantly with the HIP process. When applied pressure less than 6000psi, bulk density is proportional to the logarithm of the pressure and the logarithm of the absorption coefficient is proportional to the porosity. Bimodal grain–size distribution exists in the sintered and hipped specimens but is not observed in the uniaxial–hot–pressed–only samples. XRD analysis indicates the width of the diffraction peaks in the HIP specimens is less than that in UAHP specimens. The result illustrates the HIP process improves the spinel crystallinity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 251: Symposium S – Pressure Effects on Materials Processing and Design , 1991 , 257
Copyright
Copyright © Materials Research Society 1992

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References

REFERENCES

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