Pyrophoric behaviour of ultrafine Mo powder

The pyrophoric behaviour of as-reduced ultrafine Mo powder at 873 K was investigated. The dew point of the H2 gas used in the preparation process had a significant effect on the pyrophoric behaviour of the resulting Mo powder as well as the product compositions. A low dew point of H2 resulted in pyrophoric behaviour and the formation of γ-Mo2N with a small amount of MoO3 forming outside; in contrast, a high dew point of H2 inhibited the pyrophoric behaviour. The morphology of the pyrophoric product was the same as that of the MoO2 raw material.