Synthesis and oxidation of Zr(3)Al(3)C(5) powders

Predominantly single phase Zr(3)Al(3)C(5) powders were synthesized in an Ar atmosphere using Zr-Al intermetallics and graphite as starting materials. The reaction path of Zr(3)Al(3)C(5) synthesis was discussed based on differential scanning calorimetry and X-ray diffraction results. Lattice parameters of Zr(3)Al(3)C(5) determined using the Rietveld method are a = 3.347 angstrom and c = 27.642 angstrom. In addition, the oxidation of Zr(3)Al(3)C(5) powders was tested by using thermogravimetry-differential scanning calorimetry. The starting and complete oxidation temperatures are 400 degrees C and 1200 degrees C, respectively. These temperatures are much higher than those for ZrC, suggesting that Zr(3)Al(3)C(5) has better oxidation resistance than ZrC. On the other hand, the oxidation degree of Zr(3)Al(3)C(5), defined for the complete carbideoxide transformation, overshot 100% during oxidation. This overshooting is attributed to the formation of amorphous carbon. The phase evolution during the oxidation of Zr(3)Al(3)C(5) was also investigated.