Origin of Unusual Sintering Phenomena in Compacts of Chloride-Derived 3Y-TZP Nanopowders

Authors

  • Sean M. Sweeney Dept. of Materials Science and Engineering, The Pennsylvania State University; Now at GE Global Research
  • Merrilea J. Mayo Dept. of Materials Science and Engineering, The Pennsylvania State University; Now at Mayo Enterprises, LLC

Abstract

After evaluating three alternative possibilities, the present study shows that seemingly minor amounts (at least as low as 0.06 wt%) of chlorine impurities are responsible for the poor sintering behavior observed in chloride-derived 3 mol% yttria stabilized zirconia (3Y-TZP) nanopowders. Models and quantitative estimates are used to explain the role of evolved HCl and ZrCl4 gases in such anomalous behaviors as reduced sintered densities for higher green densities, de-densification, improved sintering in nitrogen over oxygen, and formation of a dense shell microstructure. Two solutions to problematic residual chlorides are compared: 1) a thermal treatment composed of an extended hold at 1000°C to allow HCl gas removal before the onset of closed porosity, and 2) a chemical treatment performed by washing bisque-fired samples at room temperature using a concentrated ammonium hydroxide solution to remove chlorides. The thermal treatment was found to be superior.

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Published

2017-12-13

Issue

Vol. 46 No. 2 (2014)

Section

Articles

License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Authors retain copyright of the published papers and grant to the publisher the right to publish the article, to be cited as its original publisher in case of reuse, and to distribute it in all forms and media. Articles will be distributed under the Creative Commons Attribution International License (CC BY 4.0).