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Title: STABILITY OF SOLID SOLUTIONS IN THE SYSTEMS ZrO$sub 2$-MgO ZrO$sub 2$-CaO HfO$sub 2$-MgO AND HfO$sub 2$-CaO

Abstract

The stability of solid solutions of ZrO/sub 2/ and HfO/sub 2/ with MgO and CaO was investigated. The starting materials were HfO/sub 2/ (97.2% pure), ZrO/ (98.45% pure), and chemically pure alkaline-earth carbonates. The chemical phase analysis of the pressed samples consisting of 80% HfO/sub 2/ (or ZrO/suyb 2/ ) and 20% alkaline-earth oxide which were anneaIed at 1750 deg C for 2 hr disclosed the formation of solid solutions in all samples. After additional annealing at 1200 C for 24 hr the solid solutions which cortained MgO were decomposed. In order to study the kinetics of this decomposition, samples of solid solutions were heated at 1200 C for various lengths of time. X-ray analysis and phase analysis confirmed the instability of the solid solutions in the systems ZrO/- MgO and HfO/-MgO, and a higher stability of the solid solutions with CaO. In the radiograph, the decomposition is manifest by the appearance of a monoclinic HfO/sub 2/ or ZrO/sub 2/ phase. On the assumption that the impurities contained in ZrO/sub 2/ and HfO/sub 2/ may influence the decomposition of solid solutions, special ZrO/sub 2/ and HfO/sub 2/ reagents of particularly high degree of purity were prepared (9S.5 to 99.8 ZrO/submore » 2/; 99.5 HfO/sub 2/). After annealing of these reagents with 20 mole% MgO or 20 mole% CaO no difference was found as compared with the initially used samples (98.45% ZrO/sub 2/, 97.2 HfO/sub 2/). After heating at 1200 deg C, x-ray analysis and chemical phase analysis disclosed, however, a higher stability of the solid solutions which were prepared from high-purity reagents. WWhile at 1200 deg C the solid ZrO/sub2/MgO solutions from commercial ZrO/sub 2/ (98.3% pure) completely decomposed into their components already after 15 to 20 hr, only 30% of the solid solution prepared from 99.8% ZrO/sub 2/ was decomposed after 200 hr. There was no substantial difference between the solid solutions of ZrO/sub 2/ and HfO/sub 2 with MgO and CaO. (OTS)« less

Authors:
;
Publication Date:
Research Org.:
Inst. of Silicate Chemistry, Academy of Sciences, USSR
OSTI Identifier:
4792892
NSA Number:
NSA-16-015219
Resource Type:
Journal Article
Journal Name:
Ogneupory (U.S.S.R.) For English translation see Refractories (USSR) (Engl. Transl.)
Additional Journal Information:
Journal Volume: Vol: 26: No. 9; Other Information: Orig. Receipt Date: 31-DEC-62
Country of Publication:
Country unknown/Code not available
Language:
English
Subject:
METALS, CERAMICS, AND OTHER MATERIALS; ALKALINE EARTH METALS; ANNEALING; CALCIUM OXIDES; CARBONATES; DECOMPOSITION; HAFNIUM OXIDES; HIGH TEMPERATURE; IMPURITIES; MAGNESIUM OXIDES; PHASE DIAGRAMS; QUALITATIVE ANALYSIS; RADIOGRAPHY; REACTION KINETICS; SAMPLING; SOLID SOLUTIONS; STABILITY; X RADIATION; ZIRCONIUM OXIDES

Citation Formats

Godina, N A, and Keler, E K. STABILITY OF SOLID SOLUTIONS IN THE SYSTEMS ZrO$sub 2$-MgO ZrO$sub 2$-CaO HfO$sub 2$-MgO AND HfO$sub 2$-CaO. Country unknown/Code not available: N. p., 1961. Web.
Godina, N A, & Keler, E K. STABILITY OF SOLID SOLUTIONS IN THE SYSTEMS ZrO$sub 2$-MgO ZrO$sub 2$-CaO HfO$sub 2$-MgO AND HfO$sub 2$-CaO. Country unknown/Code not available.
Godina, N A, and Keler, E K. Sun . "STABILITY OF SOLID SOLUTIONS IN THE SYSTEMS ZrO$sub 2$-MgO ZrO$sub 2$-CaO HfO$sub 2$-MgO AND HfO$sub 2$-CaO". Country unknown/Code not available.
@article{osti_4792892,
title = {STABILITY OF SOLID SOLUTIONS IN THE SYSTEMS ZrO$sub 2$-MgO ZrO$sub 2$-CaO HfO$sub 2$-MgO AND HfO$sub 2$-CaO},
author = {Godina, N A and Keler, E K},
abstractNote = {The stability of solid solutions of ZrO/sub 2/ and HfO/sub 2/ with MgO and CaO was investigated. The starting materials were HfO/sub 2/ (97.2% pure), ZrO/ (98.45% pure), and chemically pure alkaline-earth carbonates. The chemical phase analysis of the pressed samples consisting of 80% HfO/sub 2/ (or ZrO/suyb 2/ ) and 20% alkaline-earth oxide which were anneaIed at 1750 deg C for 2 hr disclosed the formation of solid solutions in all samples. After additional annealing at 1200 C for 24 hr the solid solutions which cortained MgO were decomposed. In order to study the kinetics of this decomposition, samples of solid solutions were heated at 1200 C for various lengths of time. X-ray analysis and phase analysis confirmed the instability of the solid solutions in the systems ZrO/- MgO and HfO/-MgO, and a higher stability of the solid solutions with CaO. In the radiograph, the decomposition is manifest by the appearance of a monoclinic HfO/sub 2/ or ZrO/sub 2/ phase. On the assumption that the impurities contained in ZrO/sub 2/ and HfO/sub 2/ may influence the decomposition of solid solutions, special ZrO/sub 2/ and HfO/sub 2/ reagents of particularly high degree of purity were prepared (9S.5 to 99.8 ZrO/sub 2/; 99.5 HfO/sub 2/). After annealing of these reagents with 20 mole% MgO or 20 mole% CaO no difference was found as compared with the initially used samples (98.45% ZrO/sub 2/, 97.2 HfO/sub 2/). After heating at 1200 deg C, x-ray analysis and chemical phase analysis disclosed, however, a higher stability of the solid solutions which were prepared from high-purity reagents. WWhile at 1200 deg C the solid ZrO/sub2/MgO solutions from commercial ZrO/sub 2/ (98.3% pure) completely decomposed into their components already after 15 to 20 hr, only 30% of the solid solution prepared from 99.8% ZrO/sub 2/ was decomposed after 200 hr. There was no substantial difference between the solid solutions of ZrO/sub 2/ and HfO/sub 2 with MgO and CaO. (OTS)},
doi = {},
journal = {Ogneupory (U.S.S.R.) For English translation see Refractories (USSR) (Engl. Transl.)},
number = ,
volume = Vol: 26: No. 9,
place = {Country unknown/Code not available},
year = {1961},
month = {1}
}