Chrome plating refers to the act of plating chromium as a coating onto other metals.
Chromium is a kind of silver-white metal with microstrip blue. Chromium metal is easily passivated in the air, and a very thin passivation film is formed on the surface, thus showing the properties of precious metals.
The chromium plating layer has high hardness, and its hardness can vary within a wide range of 400-1200HV according to the composition of the plating solution and process conditions. The chrome-plated layer has good heat resistance. When heated below 500 °C, its gloss and hardness have no obvious change. When the temperature is higher than 500 °C, it begins to oxidize and discolor, and when it is higher than 700 °C, the hardness begins to decrease. The friction coefficient of the chrome layer is small, especially the dry friction coefficient, which is the lowest among all metals. So the chrome layer has good wear resistance.
Certain aluminum alloys can be chrome plated or anodized. Chrome plating can improve wear resistance, such as aluminum engine cylinders have chrome plating.
Chrome plating has no leveling properties, and the substrate has a high finish, and the finish of electroplating is also high.
Anodizing, the finish can be improved by chemical polishing/electropolishing, followed by anodizing. Chrome plating costs more than anodizing.
Some aluminum alloys can be chrome-plated, but they are definitely not pure aluminum, but basically silicon-aluminum alloy die-casting or cast-turned parts. Its mechanical strength is definitely at a certain level. For example, with the current price increase of zinc alloy, many lock-making companies have changed the raw materials to aluminum alloy parts, the cost is much lower, and the most important thing is that the repair rate is higher.
The electroplating is also different in the pretreatment, because the problem of aluminum bonding force needs to be well solved, which is the key to electroplating. Therefore, the process of dipping zinc is added in the pretreatment, and the nickel after dipping is added. Treatment, then the sequence is similar to other electroplating.
