"Thermal expansion, thermal hysteresis, and the monoclinic tetragonal phase transformation of ZrO₂ have been studied with high temperature x-ray diffractometry. The initial transformation temperature in pure ZrO₂, on heating, is about 1150ºC. The transformation occurs over a 100ºC temperature range and thermal hysteresis occurs on heating and cooling. The mechanism of the transformation is related to preferred vibrational modes of atoms on the AO -CO plane of the monoclinic structure. Because the monoclinic BO axis is parallel with the tetragonal  axis, structural relationships can be seen to be a controlling factor in the transformation. Initiation of the transformation is probably related to the vibrational energy of the atoms, and formation energy of tetragonal domains; hysteresis behavior is the result of development of strain energy between semi-coherent monoclinic and tetragonal domains. The effects of addition of CaO on the monoclinic [overlapping]→← tetragonal transformation of ZrO₂ and some phase relationships in the system ZrO₂-CaO were studied by high temperature diffractometry, and heating and quenching techniques. Addition of 1 mole % CaO lowered the initial transformation from 1150º to 1100ºC on heating and from 1050º to 1000ºC on cooling. Further addition of CaO affects the hysteresis characteristics but not initiation of the mono- clinic-tetragonal transformation. Increasing CaO content causes widening of the hysteresis loopage This phenomenon is explained by formation of a cubic solid solution, semi-coherent with the tetragonal phase. The thermal history of the samples also affects the width of the hysteresis loops, possibly related to difference in defect concentration. Phase equilibria of the system Zro₂-CaO was studied in some detail. A cubic solid solution and the compound CaZrO₃ are stable binary phases in this system. The stability field of the cubic solid solution is wider at higher temperatures. The phase boundary of the cubic field at 20 mole % CaO is almost vertical and exists to low temperatures"--Abstract, pages ii-iii
Sorrell, Charles A.
Moore, Robert E., 1930-2003
Materials Science and Engineering
M.S. in Ceramic Engineering
Thailand. Civil Service Commission, Office of the
University of Missouri--Rolla
106 pages in various pagings
© 1972 Damri Sukhotanang, All rights reserved.
Thesis - Open Access
Phase transformations (Statistical physics)
High temperature superconductivity
Thermal conductivity -- Measurement
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Sukhotanang, Damri, "Phase transformations in the system ZrO₂-CaO" (1972). Masters Theses. 6716.