Hard chrome plating is a traditional surface plating technology that has been used for more than 70 years. Chromium plating layer has high hardness, wear resistance, corrosion resistance and can keep the surface bright for a long time and the process is relatively simple and low cost.
Author: Anna
Hard chrome plating is a traditional surface plating technology that has been used for more than 70 years. Chromium plating layer has high hardness, wear resistance, corrosion resistance and can keep the surface bright for a long time and the process is relatively simple and low cost. For a long time, chrome plating is not only used as a decorative coating, but also widely used as a wear-resistant and corrosion-resistant coating for mechanical parts. Electroplated hard chrome plating technology is often used to repair damaged parts.
However, the electroplating hard chrome process can lead to serious environmental problems, chrome plating process using chromic acid solution, will produce chromium-containing acid mist and wastewater, and there are other shortcomings, such as: hardness is generally 800 ~ 900HV, hardness than some ceramics and cermet materials, and hardness will also be reduced with the temperature; chrome plating layer there are micro-cracks, inevitably produce penetrating cracks, resulting in corrosion media from the surface Penetration to the interface and corrosion of the substrate, resulting in rust spots on the surface of the plated layer or even flaking; plating process deposition speed is slow, plating 0.2 ~ 0.3mm thick plating often need 2 ~ 3 shifts, but also is not conducive to the application of thicker plating.
Therefore, the research field has been trying to find a new process to replace electroplating hard chrome. Many new processes have emerged and been applied and developed.
Single-layer chromium plating has good corrosion resistance only when it reaches a considerable thickness. However, when the thickness of chromium plating reaches 65 μm or more, increasing the thickness further does not improve the corrosion resistance further. Generally speaking, the plating time has a great influence on the thickness of the hard chrome layer, and the selection of the plating time depends on the process conditions such as the concentration of the main salt of the plating solution, the temperature and the current.
In the actual electroplating production process, in order to accurately control the thickness of the chromium plating layer and improve the uniformity of the plating of the outer round chromium-plated parts, the barrel plating anode is often used, and the alloy steel parts are turned over and switched to other positions at regular intervals during the plating process, so as to ensure that the hard chromium-plated layer is uniformly and meticulously obtained.