Accession Number : AD0717059

Title :   Effect of Additives of Rare Earth Oxides on the Polymorphism of Zirconium Dioxide,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Glushkova,V. B. ; Sazonova,L. V.

Report Date : 28 OCT 1970

Pagination or Media Count : 14

Abstract : Zirconium oxide, which melts at 2700 C, is a promising material for high temperature technology. The sharp volume changes which occur during phase transformations lead to cracking of objects made of zirconia. Consequently, stabilization of zirconium oxide in cubic or tetragonal modifications has been treated in a large number of investigations, but the solution of this problem has not been obtained up to the present time. The article presents data on changes of free energy of zirconium dioxide and its solid solutions as a function of temperature, changes of linear dimensions of specimens as a function of temperature and composition of solid solutions. In addition, the article gives phase diagrams for given zirconium oxide systems. It is concluded that the best stabilizers of zirconium oxide in cubic form are oxides of heavy rare earth elements and yttrium oxide. With the use of these compounds a minimum amount of additives are necessary (3-7 mole percent), and the solid solutions which are formed are stable in a variety of gaseous media and do not suffer phase changes up to 2000C. (Author)

Descriptors :   (*ZIRCONIUM OXIDES, *PHASE STUDIES), REFRACTORY MATERIALS, PHASE DIAGRAMS, ADDITIVES, RARE EARTH ELEMENTS, SOLID SOLUTIONS, USSR

Subject Categories : Physical Chemistry
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE