Hard Chrome Plating (HCP) is an electroplating process that is primarily used to improve the hardness, wear resistance, temperature resistance and corrosion resistance of metal parts
Author: Anna
Hard Chrome Plating (HCP) is an electroplating process that is primarily used to improve the hardness, wear resistance, temperature resistance and corrosion resistance of metal parts. Compared to decorative chrome plating, hard chrome plating provides a thicker coating, typically above 20 micrometers (μm), and a higher hardness (typically between 900 and 1200 HV), which makes it ideal for applications subject to high friction and wear.
The main features of the hard chrome plating process are as follows:
High cathodic current efficiency: The cathodic current efficiency of hard chrome plating is typically in the range of 50% to 65%, and even higher versions can reach 22% to 27%. This means that more current is efficiently converted to metal deposition, resulting in faster deposition rates.
Rapid Deposition: Due to the high current efficiency, hard chrome plating is able to deposit metal at a faster rate, which helps to shorten process cycle times.
Plating Hardness: Hard chrome plating has a very high hardness of 900 to 1200 HV, which gives it excellent wear resistance.
Crack Structure: Hard Chrome plating usually has a reticulated crack structure, which has a positive effect on reducing stress concentration and improving flaking resistance.
Dispersing ability: Hard chromium electrolytes have good dispersing ability, which ensures uniform thickness of the layer and reduces roughness and blisters.
Appearance: Hard chrome plating usually has a bright and smooth appearance.
The general flow of hard chrome plating process includes:
Pre-treatment: This includes steps such as cleaning and activation to ensure that the surface of the workpiece is clean and free of oil and oxides.
Preheating: Preheating the workpiece reduces the risk of plating stress and cracking.
Chromium plating: The workpiece is placed as a cathode in an electrolyte containing chromium ions and the chromium layer is deposited by direct current.
Post-treatment: This may include steps such as cleaning, drying and inspection.
Hard chrome plating is widely used in a variety of industrial applications, such as aerospace, automotive, mold making, machining, etc., especially on parts that require high hardness and wear resistance, such as piston rods, cylinders, gears, shafts, tools and molds. However, hard chrome plating has some limitations, such as potential contamination of the environment and potential impact on the health of the operator, and therefore alternative, environmentally friendly plating technologies are being explored in certain regions or industries.