Tableware and method for surface treatment thereof, substrate having hard decorative coating film and method for production thereof

A process for surface treatment of tableware, comprising:

• heating titanium or titanium alloy tableware in a vacuum chamber to anneal the tableware,
• hardening the tableware by introducing a mixed gas containing nitrogen as a main component and an oxygen component into the vacuum chamber after the heating to anneal step, and further heating the vacuum chamber at a temperature of 700 to 800° C. for a given period of time under a given reduced pressure to diffuse nitrogen and oxygen inside the titanium or titanium alloy tableware from the surface so as to form a solid solution,
• cooling the titanium or titanium alloy tableware to room temperature after the hardening treatment step, and
• polishing the tableware after the cooling step.

A process for surface treatment of tableware, comprising:

• placing titanium or titanium alloy tableware in a vacuum chamber, evacuating the vacuum chamber, then introducing an inert gas into the vacuum chamber, and heating the tableware under reduced pressure to anneal the tableware,
• hardening the tableware by evacuating the vacuum chamber to remove the inert gas after the heating to anneal step, then introducing a mixed gas containing nitrogen as a main component and an oxygen component into the vacuum chamber, adjusting the pressure in the vacuum chamber to atmospheric pressure, and further heating the vacuum chamber to a temperature of 700 to 800° C. for a given period of time to diffuse nitrogen and oxygen inside the titanium or titanium alloy tableware from the surface so as to form a solid solution,
• cooling the titanium or titanium alloy tableware to room temperature after the hardening treatment step, and
• polishing the tableware after the cooling step.

A process for producing a substrate having a hard decorative coating film, comprising:

• heating a substrate comprising titanium or a titanium alloy in a vacuum chamber to anneal the substrate,
• hardening the substrate by introducing a mixed gas containing nitrogen as a main component and an oxygen component into the vacuum chamber, and further heating the vacuum chamber to a temperature of 700 to 800° C. for a given period of time under given reduced pressure to diffuse nitrogen and oxygen inside the titanium or titanium alloy substrate from the surface so as to form a solid solution,
• cooling the titanium or titanium alloy substrate to room temperature,
• polishing the substrate surface,
• washing the substrate,
• placing the substrate in a vacuum chamber and evacuating the vacuum chamber,
• introducing argon into the vacuum chamber, ionizing the argon and ion bombarding the substrate surface,
• forming by sputtering an intermediate layer comprising a metal or a metallic carbide on the substrate surface,
• exhausting the argon the vacuum chamber and introducing a gas containing carbon into the vacuum chamber, and
• generating a plasma in the vacuum chamber and forming by plasma CVD treatment a diamond-like carbon coating film on the surface of the intermediate layer.

A process for producing a substrate having a hard decorative coating film, comprising:

• heating a substrate comprising titanium or a titanium alloy in a vacuum chamberto anneal the substrate,
• hardening the substrate by introducing a mixed gas containing nitrogen as a main component and an oxygen component into the vacuum chamber, and heating the vacuum chamber to a temperature of 700 to 800° C. for a given period of time under given reduced pressure to diffuse nitrogen and oxygen inside the titanium or titanium alloy substrate from the surface so as to form a solid solution,
• cooling the titanium or titanium alloy substrate to room temperature,
• polishing a surface of the substrate,
• washing the substrate,
• placing the substrate in a vacuum chamber and evacuating the vacuum chamber,
• introducing argon into the vacuum chamber, ionizing the argon and ion bombarding the substrate surface, and
• forming a hard decorative coating film comprising a nitride, a carbide, an oxide, a nitrido-carbide or a nitrido-carbido-oxide of a 4a, 5a or 6a Group element of the periodic table on the substrate surface by ion plating or sputtering.