Magnesium alloy is used as a material of the container of a personal computer and a cellular phone. Magnesium plays an important role in the field of the chemical synthesis as a raw material of an organic metal agent. However, the magnesium powder is involved in a fire and a dust explosion. In addition, it prevents the fire fighting in the magnesium fire because there is the possibility that it easily reacts with water and generates heat and hydrogen. The characteristics of heat flow of magnesium particles were investigated with a thermal activity monitor (TAM III) which was the high sensibility calorimeter. The measurement periods of most tests were several days. The particle size of magnesium powder of 99.6 wt % was below 150 µm. The TAM III demonstrated the heat flow increased in air, argon and nitrogen atmosphere when the magnesium powder was used as the sample. The heat flow was almost constant in various atmospheres when the magnesium turnings were used as the sample. It was elucidated the increase of heat flow had the relation with the surface area of magnesium particles. The reaction of magnesium with water was examined by the TAM III. The heat flow with the addition of water was approximately ten times larger than the heat flow without the addition of water.
Magnesium powder, Small heat release, High sensitive calorimeter.