| Autor: |
Yo Tajima, Satoshi Iio, Tomonori Niwa, Masakazu Watanabe, Jun Otsuka |
| Rok vydání: |
1994 |
| Předmět: |
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| DOI: |
10.1016/b978-0-444-81991-8.50060-1 |
| Popis: |
Corrosion behavior of gas pressure sintered silicon nitride with alumina and yttria additives was investigated in sulfuric acid solution with respect to the initial stage of the corrosion in which drastic strength degradation and fairly large weight change were observed in our previous study. Thickness of the corroded layer, in which glassy grain boundary phase was dissolved in the solution, was affected by the surface finishing of samples. The corroded layer was thicker in as-ground specimen than in specimen whose surface layer of about 30μm or more was removed by polishing. Residual stress introduced by surface machining was determined by an X-ray diffraction analysis for the as-ground specimen and the polished specimen. It was observed that the compressive stress of about 70MPa remained on the as-ground specimen surface and that the residual stress was gradually removed by polishing. To clarify the effect of surface condition on the corrosion behavior, annealing was employed as an alternative method to eliminate the residual stress and the same corrosion test was conducted. The similar result was obtained for the annealed specimens as for the polished specimens. From these results, the strength degradation and weight change at initial stage for the as-ground specimens are considered to be related to the surface damage by machining. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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