Corrosion behavior of polymer-derived SiHfCN(O) ceramics in salt and acid environments

Powder particles of polymer derived SiHfCN(O) ceramics were pulsed electric current sintered at 1300 and 1500 °C to produce amorphous and partially crystalline ceramic pellets for corrosion studies in salt (NaCl or Na2SO4) and acid (HF) environments. While, sodium dramatically accelerated phase transformation and catalyzed the crystallization process, the open porosity acted as the main cause for sodium penetration in these materials. The samples, however, were completely disintegrated during fluoride acid tests. The cristobalite and HfO2 crystalline phases were severely corroded and it was found that the SiC grains were relatively stable in comparison with other phases in the system.