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1 Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur-721302, India
2 Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad-500058, India
| Attempts are made to fabricate Si3N4 - MoSi2 in situ composites by reactive milling and reactive sintering of milled powders. 10 hours of milling Mo and Si3N4 powder mixtures shows the substantive increase in reactivity, which reaches to maximum after 30 hours of milling. The milling however even up to 104 hours does not by itself lead to the formation of MoSi2 phase. The pyrolysis of milled powder mixture with varying amount of sintering aid in the temperature range of 1000-1400 °C indicates that MoSi2 phase forms only at 1400 °C in argon, whereas 1350 °C in vacuum. SEM analysis of milled and pyrolised samples shows uniform distribution of 0.5-1 micron size MoSi2 in Si3N4 matrix. Longer hours of milling often leads to formation of SiC and it also played by large amount of WC contaminations. |
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