This study set three kinds of situation and observed the various states such as carbonization by experimenting damages by fire of electric iron. The results of this study are as follows: The fire did not occurred when the unpowered iron over mattress and cotton shirts was com busted completely by external flame because the temperature of surface of soleplate and mattress did not reach the minimum ignition energy and when the powered electric iron over mattress and cotton shirts was left for an hour with its temperature dial set to high because the temperature of combustibles did not reach the minimum ignition energy. The fire occurred when the electric iron in which the outer box, bi-metal switch, and temperature fuse were removed over mattress and cotton shirts was powered by through heater terminal, and then the electric iron, mattress, and cotton shirts were combusted by the fallen combustibles because the temperature of combustibles reached to the minimum ignition energy with the help of active transfer of heat.

A new process of pulsed electric current sintering was developed. It combines compaction with activated sintering effectively and can manufacture bulky nano-crystalline materials very quickly. A nano-structured steel is obtained with high relative density and hardness by this process. The average grain size of iron matrix is 58nm and the carbide particulate size is less than 100 nm. The densification temperature of ball-milled powders is approximately lower than that of blended powders. When the sintering temperature increases, the density of as-sintered specimen increases but the hardness of as-sintered specimen first increases and then decreases.