Poor adhesion of underlayers (nickel or copper). Excessive polishing pressure. High internal stress in chrome layer.
Chrome plating is widely used for decorative finishes, corrosion resistance, and wear protection. However, defects can arise due to process variations, contamination, or improper substrate preparation. Below is a detailed breakdown of common chrome plating defects, their causes, and corrective measures.
The chrome layer separates from the substrate or underlying nickel layer.
Poor adhesion of undercoat (nickel or copper) due to inadequate cleaning or activation.
Hydrogen embrittlement (common in high-strength steels).
Excessive stress in the chrome layer (from high current density or bath temperature).
Contamination (oil, grease, or oxides on the substrate).
✔ Improve pre-plating cleaning (ultrasonic degreasing, electrolytic cleaning).
✔ Optimize nickel strike layer (ensure proper adhesion before chrome plating).
✔ Reduce current density to minimize stress.
✔ Post-plate baking (for hydrogen embrittlement-sensitive parts).
Chrome deposit lacks brightness and appears hazy or cloudy.
Low chrome concentration in the bath.
High sulfate-to-chromate ratio (affects plating quality).
Organic contamination (decomposed brighteners or oils).
Incorrect temperature or current density.
✔ Adjust bath chemistry (maintain proper CrO₃:H₂SO₄ ratio, typically 100:1).
✔ Purify bath (activated carbon treatment for organics).
✔ Optimize temperature (50–60°C) and current density (15–40 A/dm²).
Fine cracks visible under magnification; excessive cracking reduces corrosion resistance.
High internal stress (due to improper bath composition).
Excessive current density.
Low bath temperature.
Poor nickel underlayer (if cracks propagate from base metal).
✔ Adjust bath composition (add stress reducers if needed).
✔ Optimize current density & temperature.
✔ Use a ductile nickel underlayer (semi-bright or bright nickel).
Dark, rough, or powdery deposits, usually at high-current-density areas.
Excessive current density.
Low bath temperature.
Insufficient agitation.
Poor conductivity (low chromic acid concentration).
✔ Reduce current density.
✔ Increase bath temperature (55–60°C for hard chrome).
✔ Improve agitation (air or mechanical stirring).
Areas where chrome fails to deposit, exposing the underlayer.
Poor throwing power (due to bath imbalance).
Shielding effect (from racking or part geometry).
Low catalyst (sulfate) content.
Contaminated substrate (passive oxide films).
✔ Adjust sulfate content (if too low, add sulfuric acid).
✔ Use conforming anodes for complex shapes.
✔ Improve activation (acid dip before plating).
Raised bumps where chrome lifts from the substrate.
Trapped hydrogen gas (from high current density).
Poor rinsing after nickel plating (residual salts).
Substrate porosity (trapping plating solution).
✔ Reduce current density.
✔ Improve rinsing & drying before chrome plating.
✔ Pre-plate baking (for cast or porous materials).
A milky-white film on the chrome surface.
Overheating during plating.
High organic contamination.
Excessive brightener additives.
✔ Control bath temperature.
✔ Purify bath (carbon treatment).
✔ Reduce brightener concentration.
Chrome layer chips or flakes off after buffing.
Poor adhesion of underlayers (nickel or copper).
Excessive polishing pressure.
High internal stress in chrome layer.
✔ Ensure proper nickel adhesion (use a nickel strike layer).
✔ Use gentler polishing techniques.
✔ Optimize chrome plating parameters (reduce stress).
✅ Maintain bath chemistry (regular analysis of CrO₃, sulfate, and catalysts).
✅ Use high-purity anodes & chemicals (avoid metallic contamination).
✅ Optimize pre-treatment (cleaning, activation, and rinsing).
✅ Control process parameters (current density, temperature, agitation).