I. Electroplating Process Optimization
Electroplating Solution Composition:
Adjusting the concentration of chromium anhydride and the ratio of sulfate, and adding organic/inorganic additives (such as HHHF25, CR-10) can improve hardness.
For example, HHHF25 additive can significantly improve coating hardness and current efficiency.
Process Parameter Control:
Temperature: 50-60℃ (too high will reduce hardness).
Current Density: 15-50A/dm² (too high can easily cause cracking).
Time: 30-90 minutes, ensuring uniform coating.
II. Substrate and Post-treatment
Substrate Pre-treatment:
Select high-carbon steel such as 45# steel or 40Cr, ensuring the surface is free of oil and rust.
Polish to Ra≤0.8μm to improve coating adhesion.
Post-treatment:
Low-temperature tempering (200℃×1 hour) can eliminate hydrogen embrittlement and improve hardness stability.
Hydrogen removal treatment of HA oil significantly improves corrosion resistance.
III. Material Selection
45# High Carbon Steel: Smooth surface, high hardness, suitable for hydraulic cylinders, pneumatic cylinders, etc.
Q460C Cold-Drawn Round Steel: High strength, suitable for precision mold manufacturing.
IV. Precautions
When the coating thickness is >100μm, it is recommended to use a Rockwell hardness tester for measurement.
Avoid excessively thick coatings (>65μm), as the improvement in corrosion resistance is limited.
