Ho, Fang-YuanFang-YuanHoWei, Wen-Cheng J.Wen-Cheng J.Wei2008-12-312018-06-282008-12-312018-06-28199900027820http://ntur.lib.ntu.edu.tw//handle/246246/95369https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032625273&doi=10.1111%2fj.1151-2916.1999.tb01971.x&partnerID=40&md5=0d5e591f2468923111f2ffe39d2aff4dIn order to understand the reactions of yttria-containing zirconia powder in aqueous solution, the dissolution behavior of yttrium and the formation of the monoclinic (m) phase of the Y-TZP powder were investigated. The tests were conducted in aqueous solution at temperatures up to 95°C. The results showed that the reaction order of yttrium dissolution from the surface of TZP powder is 5-9, and the activation energy is about 8.4 kJ/mol. However, the value of the reaction order is different from that (0.96-1.20) of the formation of m-phase. However, the yttrium dissolution of the slurries with the addition of 2 mol% dispersant (D-134) was reduced greatly to an extremely low (<2 ppm) level up to 24 h at the testing temperatures. The results also showed that the amounts of m-phase formation were nearly the same for the powders in the slurries with or without D-134 addition. The decrease of yttrium content in the presence of D-134 and the formation of the m-phase of the TZP powder were not closely related. The degradation mechanism, or the formation of m-phase, should not be directly related to the dissolution of yttrium ions from a zirconia surface.application/pdf212349 bytesapplication/pdfen-USActivation energy; Ceramic materials; Dissolution; Phase transitions; Powders; Solutions; Surfaces; X ray diffraction analysis; Yttrium; Monoclinic phase; Yttria containing zirconia; Zirconiajournal article2-s2.0-0032625273http://ntur.lib.ntu.edu.tw/bitstream/246246/95369/1/27.pdf