Opportunity
Precious metals and copper alloys are widely used in decorative applications such as watches, jewelry, souvenirs, and coins due to their aesthetic appeal. However, these materials are prone to deformation, wear, and loss of brightness or color when exposed to external forces, chemical substances, moisture, exhaust gases, or sweat. Traditional surface protection methods like electroplating and organic coatings fail to meet the stringent requirements of decorative designs. Physical vapor deposition (PVD) techniques, while environmentally friendly, introduce structural defects such as pinholes and droplets, compromising surface quality. Additionally, PVD coatings are non-homogeneous on objects with complex shapes due to the directional nature of particle deposition (shadowing effect). These limitations create a significant need for a robust, transparent, and homogeneous protective coating that preserves the original appearance of precious metals and copper alloys while enhancing their durability.
Technology
The patent addresses these challenges by introducing a pulsed chemical vapor deposition (PCVD) or plasma-enhanced PCVD (PE-PCVD) method to form homogeneous and transparent protective coatings on precious metals and copper alloys. The innovation lies in the use of ionic oxide films (e.g., aluminum oxide, titanium oxide) deposited via PCVD/PE-PCVD at low temperatures (100–300°C). The process involves injecting metal organic precursors (e.g., aluminum isopropoxide, titanium isopropoxide) into a vacuum-sealed reactor chamber in timed pulses, followed by pump-down periods to remove unreacted gases. This cyclic approach ensures uniform coverage even on non-planar surfaces, eliminates defects like pinholes, and enhances adhesion. The resulting coating is optically transparent, chemically inert, and resistant to oxidation, corrosion, and wear. The PCVD/PE-PCVD process also avoids the shadowing effect of PVD, making it ideal for 3D objects with intricate geometries.
Advantages
- Uniform Coverage: Ensures homogeneous coating thickness on complex shapes.
- Defect-Free: Eliminates pinholes and droplets common in PVD coatings.
- Transparency: Preserves the original brightness and luster of the underlying metal.
- Durability: Enhances hardness, wear resistance, and corrosion/oxidation resistance.
- Low-Temperature Process: Safe for heat-sensitive substrates (100–300°C).
- Karatage Preservation: Does not affect the purity value of precious metals after melting.
- Versatility: Compatible with gold, silver, platinum, palladium, copper, and alloys.
Applications
- Jewelry and Watches: Protects against scratches and tarnishing while maintaining aesthetics.
- Decorative Items: Coins, souvenirs, and luxury goods.
- Eyewear and Lenses: Scratch-resistant coatings for glasses and optical devices.
- Biomedical Implants: Corrosion-resistant coatings for metal implants.
- Electronics: Protective layers for displays and conductive components.
- Industrial Tools: Wear-resistant coatings for molds and precision instruments.
