PURPOSE:To obtain a diamond film having high homogeneity and adhesion by a moving flame method over a large area at a high speed by heating a surface on which diamond is deposited with a small-sized burner precedent to a main burner. CONSTITUTION:A main burner 1 and a small-sized burner 2 are arranged with the nozzles downward at 10mm interval, acetylene and oxygen are sent to the burner 1 in about 0.92 ratio of oxygen to acetylene and a flame is formed by combustion. At the same time, acetylene and oxygen are sent to the burner 2 in 0.98 ratio of oxygen to acetylene and a flame is formed. These burners are set in a reaction vessel, the internal pressure of the vessel is regulated to 500Torr and a WC-Co substrate is kept at 900 deg.C. The burners are moved parallel to the substrate at 7mm interval from one end in the longitudinal direction at 0.35mm/min rate and the substrate is coated with diamond.
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