Properties and structure of periclase — Yttrium materials

Conclusions An analysis was carried out of the properties of a ceramic material in the system MgO-Y₂O₃ containing 5–64.8% yttrium oxide.The vaporization of a periclase-yttrium ceramic is attributable to its large surface area and to the state of the material (monocrystalline grains and a fine-ground component). The addition of yttrium oxide to the periclase material results in a lower weight loss in a vacuum of 1.5·10^–5 mm Hg at 1700°C, more especially in the case of a mix produced from chemically pure materials. The weight loss was lowest for a composition designed as a chemical compound, viz., 1.1% after holding for 20 h.Granular mixes (2-0, 1-0 mm) are more stable to vacuum than a fine-grain material. An analysis of the structure of the cylindrical surface of the specimens showed that the vaporization rate is greater for the fine-ground component.Translated from Ogneupory, No. 1, pp. 50–54, January, 1976.