PURPOSE: To use parts directly exposed to the flame that are excellent in heat resistance and corrosion resistance at high temperature by forming the peripheral members of a combustion chamber positioned in or near the combustion area by a ferrous alloy material in which Ni content and Cr content are specified.

CONSTITUTION: A nozzle 6 and an ignition plug 7 are installed to a combustion cylinder 3 through a cover 5. For fuel kerosene that is atomized is supplied to the nozzle 6 through a pipe 8. The flame that is ignited by an ignition plug 7 is blown out towards a target 9. In this case the heat exchange of the air is carried out through the back side of the target 9. The peripheral members of a combustion chamber 4 that are positioned in or near the combustion area, namely the nozzle 6, ignition plug 7, target 9 are formed by a ferrous alloy material that consists of the following ingredients, This ferrous alloy material contains Ni (20% to 50%), Cr (about 20%), and, in addition, the alloy contains a suitable amount of C, Si, Mn, Al, Ti, and Fe.