Plastic plating-the difference between hard chromium plating and decorative chromium plating.

Plastic plating-the difference between hard chromium plating and decorative chromium plating.

Hard chromium plating is generally used more often in high-temperature conditions of machinery, such as: moulds and so on.
As the name implies, the main purpose of chromium plating is for bright surface, beautiful appearance, anti-rust and so on.
Judge which kind of chromium to plating according to its purpose.
1. Relationship between chromic anhydride concentration and hardness.
When other process conditions are the same, the hardness is high when the concentration of chromic anhydride is low. But the concentration is low, the plating bath changes quickly and is unstable.
two。. Relationship between sulfuric acid content and hardness.
In the normal chromium plating process specification. The ratio of chromic anhydride to sulfuric acid should be kept at 100 per cent. When other concentrations remain constant, the hardness of the chromium layer increases with the increase of sulfuric acid content. However, when the ratio of them is 100 / 1.4, the hardness will decrease with the increase of sulfuric acid content.
3. Relationship between current density and hardness.
At normal temperature, the hardness of chromium layer increases with the increase of current density. When the current density reaches a certain limit, the hardness tends to be stable.
4. Relationship between Stability and hardness of Chromium plating Bath.
At a higher temperature (65-75 ℃), the hardness of the chromium layer plated from the dilute solution is 1520% higher than that of the chromium layer plated from the concentrated plating solution; at the lower temperature (35-45 ℃), the hardness of the chromium layer deposited from the dilute solution is not much different from that from the concentrated plating solution.
5. Relationship between thickness and hardness of Chromium plating layer.
In general, the hardness of hard chromium coating increases with the increase of thickness, and the highest hardness is about 0.2 μ m. In the future, even if the thickness is increased, the hardness will not increase.
6. The hardness of chromium coating decreases significantly with the increase of heating temperature.