Decorative PVD Coatings

Agenda

1. Overview of decorative PVD coatings
2. Tutorial on how the coatings are made
3. Detailed discussion about types and materials of decorative PVD coatings
4. Discussion on color assessment
5. Q&A session

Overview of Decorative PVD Coatings

• Durable Decorative PVD: Chosen for applications needing wear resistance, hard surfaces, chemical, or corrosion resistance.

Types of Coatings

1. Natural Finishes: Mimic natural alloys like gold, copper, bronze.
2. Artificial Finishes: Include colors not typically found in nature like black, graphite, blue, rainbow.

Applications

• Jewelry: First use in the 80s (watches, rings).
• Door Hardware and Plumbing: Popular since the 90s (e.g., polished brass with zirconium nitride coatings).
• Sporting Goods and Firearms: Growing use in firearms.
• Consumer Electronics: Common in smartphones.
• Automotive: For both interior and exterior parts.

How Decorative PVD Coatings are Made

Physical Vapor Deposition (PVD)

• Process: Solid material (target) vaporized by energy (plasma or thermal) and deposited on a substrate in a vacuum chamber.
• Equipment: Large vacuum chamber with a central arc source (or cathode) for the target material.

Chamber Configuration

• Central Arc Source: Target material vaporized and ionized, leading to deposition on parts mounted on a carousel for uniform coating.
• Gas and Power Supplies: Control reactions and drive coatings, such as bias voltage on parts to attract ions.

Cathodic Arc vs. Magnetron Sputtering

• Cathodic Arc: High energy, high ionization, good for low-temperature reactions, less sensitive to target poisoning, more defects (macro particles).
• Magnetron Sputtering: Lower energy, lower ionization, fewer defects, more sensitive to target poisoning, often requires thermal energy.
• Usage: Cathodic arc preferred for decorative coatings; combination of both methods for multi-layer coatings.

Types of Decorative PVD Coatings

Natural Coatings

• Opaque Coatings: Colors defined by material properties and do not change with thickness.
• Common Uses: Mimic metals like gold, stainless steel, brass.

Artificial Coatings

• Optical Coatings: Transparent or semi-transparent, color dependent on thickness (e.g., blues, rainbows).
• Common Materials: Metal oxides, diamond-like carbons (DLCs).

Key Materials and Reactions

• Metals: Zirconium, titanium, chromium (main ones used).
• Gases: Nitrogen, oxygen, methane, acetylene (for creating compounds).
• Compounds: Nitrides, carbonitrides, oxycarbides.
• Properties: Ceramic-like, hard, brittle, and electrically conductive.

Zirconium-Based Coatings

• Popular Use: Best chemical and corrosion resistance.
• Colors: Wide range e.g., nickels, brasses, bronzes, stainless steel.
• Types: Zirconium nitride, zirconium carbonitride, zirconium oxycarbides.

Titanium-Based Coatings

• Longest Use History: Used since the 80s.
• Colors: Golds, rose golds, bronzes (less range compared to zirconium).

Chromium-Based Coatings

• Colors: Shades of gray and silver.
• Common Use: Mimics electroplated chrome finishes.

Diamond-Like Carbon (DLC)

• Durable Coating: Low friction, hard, commonly used in sporting goods.
• Colors: Dark gray to black.

Color Assessment

• Measurement: Use of a spectrophotometer to determine color coordinates in 3D space (L, A, B values).
• Delta E Value: Indicates distance between two colors in color space.
• Visual Standards: Light boxes for controlled assessment, qualified inspectors to avoid subjective bias and colorblindness.
• Surface Texture: Can affect perceived color; important to consider during judgment.

Final Notes

• Color and texture have significant effects on decorative PVD coatings.
• Ensure consistency and control during color assessment and judgment.