Ornamental part for watches and method of producing the same
OwnerNobuo Nishidainventor
Life of this patent
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Abstract
An ornamental part for watches such as a watch case having a composite coating layer consisting essentially of titanium and titanium nitride, the ratio of the two components being varied in the direction of the thickness of the layer. The composite coating may be formed by the physical vapor deposition method in which the titanium in the vapor phase is reacted with nitrogen under a glow-discharge condition. The coating thus formed has a gold color and excellent physical and chemical properties.
Claims20
An ornamental part for watches comprising a substrate and a composite coating essentially consisting of titanium nitride and titanium formed by physical vapor deposition, said coating including an amount of titanium which continuously decreases from the portion adjacent said substrate to the surface thereof wherein said coating has a color tone with a brightness value of from 10 to 22 for a mirror surface test piece defined by a color difference measuring unichromatic system, with a ratio of red color to green color of from -5 to +5 and with a ratio of a yellow hue to blue color of from 0 to +5.
The ornamental part for watches according to claim 4, wherein said substrate is composed of any one of brass, a copper alloy containing nickel silver, aluminum and aluminum alloy, a ferro-alloy containing stainless steel, ceramics, or plastics having a thermal deformation temperature of higher than 150.degree. C.
The ornamental part for watches comprising a substrate and a coating layer containing titanium nitride represented by TiNx and formed by the physical vapor deposition method, the value of said x ranges from 0 to about 0.5 in a portion closest to said substrate, and lying over a range of from about 0.5 to 1 in the outer surface portion wherein said coating has a color tone with a brightness value of from 10 to 22 for a mirror surface test piece defined by a color difference measuring unichromatic system, with a ratio of red color to green color of from -5 to +5 and with a ratio of a yellow hue to blue color of from 0 to +5.
In the method of forming a coating essentially consisting of titanium nitride and titanium on the surface of a substrate by the physical vapor deposition method, a method of producing an ornamental part for watches comprising;
- evaporating titanium from a source of evaporation at a substrate temperature ranging from about 100.degree. to about 300.degree. under the condition in which a voltage sufficient for producing glow discharge is applied across said substrate and said source of evaporation placed in a vacuum vessel;
- feeding a nitrogen gas into said vacuum vessel;
- and
- changing a ratio of the partial pressure of titanium vapor to the partial pressure of said nitrogen gas in said vacuum vessel depending upon the progress of the vaporization, such that the ratio of titanium to titanium nitride contained in the resulting coating continuously decreases from the portion closest to said substrate toward the outer surface.
In a method of producing an ornamental part for watches for forming on a substrate a coating essentially consisting of titanium and titanium nitride by a physical vapor deposition method, the method of producing the ornamental part comprising:
- placing the substrate in a vacuum vessel in which a voltage sufficient for producing a glow discharge is applied across the substrate and a source of evaporation;
- feeding a nitrogen gas into the vacuum vessel;
- and
- controlling the ratio of the partial pressure of titanium vapor to the partial pressure of nitrogen in said vacuum vessel with the process of the deposition in such a manner that the ratio of titanium to titanium nitride in the resulting coating continuously decreases from the portion adjacent said substrate to the surface thereof;
- the ratio of titanium to titanium nitride being from about 3:1 to 1:1 at a portion closest to said substrate and from about 1:1 to 1:5 at the outer surface of the coating;
- and
- said coating having a color tone with a brightness value of from 10 to 22 for a mirror surface test piece defined by a color difference measuring unichromatic system, with a ratio of red color to green color of from -5 to +5 and with a ratio of a yellow hue to blue color of from 0 to +5.
Dependencies are inferred from the claim text.