To make it possible to lower sliding resistance and to maintain a service life by forming a lubricating film of thermal decomposition carbon on the sliding surface of a sliding gate plate used for a sliding nozzle device.
A sliding gate plate body 20 is arranged in a heat treating furnace 10 and the temp. in the furnace is set at 800 to 1700°C. Gaseous hydrocarbon 16, such as gaseous propane and gaseous ethylene, and a carrier gas, such as hydrogen, are introduced into the furnace while the flow rate thereof is controlled by a flow meter 14 to allow the thermally cracked carbon to deposit on the sliding surface 20a of the sliding gate plate. The pressure in the heat treating furnace 10 is preferably reduced by a pressure reducing means. As a result, the sliding gate plate has a lubricating film of the thermal cracking carbon on its sliding surface 20a and, therefore, even if this surface receives heat, the easy dislodgment of the lubricating film does not arise and the small sliding resistance is maintained. The life is thus prolonged.
FUSHIMI TETSUO
OTSUKA HIROSHI
WAKITA TAMOTSU
WATANABE ISAO
