HOT GASEOUS CORROSION OF SILICON NITRIDES IN CARBURIZING, SULPHIDIZING AND OXIDIZING ENVIRONMENTS
The gaseous corrosion mechanisms of some silicon nitrides were studied. The compositions and essential processing parameters of the materials are described; two of these were hot pressed (one with Y-2O-3 and the one with MgO as sintering aids) and two were pressureless sintered (both with Y-23 and the MgO). Corrosion experiments were carried out in autoclaves designed especially for use up to 5 bar pressure and 1500 degrees C. Tests were conducted in modal atmospheres of H-2 - CH-4 and H-2/H-2S at temperatures in the range of 900- 1300 degrees C. Samples were monitored intermittently up to 1000 hrs for weight changes and by surface XRD analysis. Structural analysis to assess the nature and extent of the chemical and mineralogical alterations characteristic of the corrosion were carried out normally at the end of the experiment by XRD, optical microscopy, SEM, ESCA and TEM. In general the HPSN performed better than the pressureless sintered SN. The individual results of each experiment were discussed in detail and the corrosion properties of the different materials are critically compared.
Bibliographic Reference: CERAMIC MATERIALS AND COMPONENTS FOR ENGINES, LUEBECK - TRAVEMUENDE (GERMANY), APRIL 14-17, 1986 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32853 ORA
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Record Number: 1989124135800 / Last updated on: 1987-01-01
Available languages: en