Abstract: Disclosed are DC plasma assisted chemical vapor deposition (DC PA-CVD) apparatus operable in the absence of a positive column, a method for depositing a material by DC PA-CVD in the absence of a positive column, and a diamond thin film fabricated thereby. In the method for depositing a material in the absence of a positive column, a discharge is generated between a cathode and an anode disposed to face each other in a reaction chamber by applying a DC voltage therebetween, and introducing reaction gas into the reaction chamber, thereby depositing a material on a substrate mounted on the anode and serving as a part of the anode, wherein the deposition of the material on the substrate is performed under a state that a cathode glow and an anode glow exist in a form of thin layers coating respectively the surfaces of the cathode and the substrate, while a positive column does not exist or is so small as to be negligible.

Abstract: A diamond film depositing apparatus and method are disclosed in which a uniform and large plasma is formed on a substrate having a diameter of larger than 100 mm without using a heated filament cathode, without applying a magnetic field thereto, and without using a ballast resistance. The thusly formed plasma is maintained stably for a long time, so that a diamond thick film having a diameter of larger than 4 inches and a thickness of over hundreds of &mgr;m can be deposited on a flat or curved substrate and also on a Si wafer.

Abstract: A diamond film depositing apparatus and method are disclosed in which a uniform and large plasma is formed on a substrate having a diameter of larger than 100 mm without using a heated filament cathode, without applying a magnetic field thereto, and without using a ballast resistance. The thusly formed plasma is maintained stably for a long time, so that a diamond thick film having a diameter of larger than 4 inches and a thickness of over hundreds of &mgr;m can be deposited on a flat or curved substrate and also on a Si wafer.

Abstract: In order to provide an excellent toughness and a sufficient adhesive force without any limit in the content of other carbides in the substrate material and Co and in the size of the cemented carbides grains, the present invention provides a diamond film coated cutting tool, comprising a surface layer which cemented carbide grains are grown abnormally on the cemented carbide substrate, and a diamond film formed on the surface layer, and also a method for manufacturing a diamond film coated cutting tool, comprising the steps of heat-treating a surface of a cemented carbide substrate under a decarburizing atmosphere until the surface changes to a &eegr; phase, heat-treating the surface-decarburized cemented carbide substrate under a carburized atmosphere, depositing a diamond film on the carburized surface of the cemented carbide substrate.

Abstract: A diamond film depositing apparatus and method are disclosed in which a uniform and large plasma is formed on a substrate having a diameter of larger than 100 mm without using a heated filament cathode, without applying a magnetic field thereto, and without using a ballast resistance. The thusly formed plasma is maintained stably for a long time, so that a diamond thick film having a diameter of larger than 4 inches and a thickness of over hundreds of &mgr;m can be deposited on a flat or curved substrate and also on a Si wafer.

Abstract: In order to provide an excellent toughness and a sufficient adhesive force without any limit in the content of other carbides in the substrate material and Co and in the size of the cemented carbides grains, the present invention provides a diamond film coated cutting tool, comprising a surface layer which cemented carbide grains are grown abnormally on the cemented carbide substrate, and a diamond film formed on the surface layer, and also a method for manufacturing a diamond film coated cutting tool, comprising the steps of heat-treating a surface of a cemented carbide substrate under a decarburizing atmosphere until the surface changes to a &eegr; phase, heat-treating the surface-decarburized cemented carbide substrate under a carburized atmosphere, depositing a diamond film on the carburized surface of the cemented carbide substrate.

Abstract: A diamond film depositing apparatus and method are disclosed in which a uniform and large plasma is formed on a substrate having a diameter of larger than 100 mm without using a heated filament cathode, without applying a magnetic field thereto, and without using a ballast resistance. The thusly formed plasma is maintained stably for a long time, so that a diamond thick film having a diameter of larger than 4 inches and a thickness of over hundreds of &mgr;m can be deposited on a flat or curved substrate and also on a Si wafer.

Abstract: A fabrication method for a diamond-coated cemented carbide cutting tool includes electrolytically etching the surface of a cemented carbide cutting tool with a NaOH or KOH aqueous solution or chemically etching the surface of the cemented carbide cutting tool with a KMnO.sub.4 +KOH aqueous solution, and depositing a diamond film on the cemented carbide cutting tool. A stronger etching effect than by using a Murakami solution can be achieved, and no poisonous material is included in the etchant. In addition, disposal of the waste etchant is made simpler, and the adhesion between the diamond film coating and the cemented carbide cutting tool can be strengthened.

Abstract: There is disclosed a method for depositing a diamond film on a substrate which utilizes high density direct current glow discharge at a glow-arc transition region to form plasma between a cathode and an anode in a reactor, wherein the cathode maintains its temperature at a range of 2,100 to 2,300.degree. C. and is composed of a plurality of U-shaped filaments which are aligned parallel to one another to form an array and each of which is made by bending a conductive wire.