DEVELOPMENT AND EVALUATION OF TRANSPARENT MAGNESIUM OXIDE
Abstract
The densification parameters for hot pressing MgO to a theoretically dense polycrystalline body was studied. Two experimental approaches were followed; using pure MgO powders, and pressing mixtures of MgO plus small amounts of LiF. In the former case specimens having 60% total transmission (adequate for in line observation) were obtained by very precise control of the fabrication conditions followed by a long term anneal in hydrogen. The MgO - LiF process yielded thin specimens having 85% total transmission in the visible, and 3/8 inch thick specimens possessing a maximum transmission of 70%. A post hot pressing anneal at temperatures greater than 1200C and heating rates less than 28C/hour were required to produce maximum transparency. Evidence obtained by grain growth studies, weight loss experiments and lattice parameter determinations suggest that the densification mechanism for this process was pressure-enhanced diffusion through a solid solution grain boundary layer and a grain boundary phase. At temperatures above the melting point of LiF a pressure-enhanced liquid phase sintering mechanism probably operates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1967
- Accession Number
- AD0650621
Entities
People
- D. Sellers
- T. Vasilos
- W. Rhodes