How will the number of micro cracks per inch effect the properties of hard chrome plating?
A. Yes, the number of “cracks” in a given distance affects the properties of chrome plating. Almost all electroplated hard chromium deposits are cracked. Cracking occurs during the plating cycle when internal stress exceeds the tensile strength of the chromium, which is hard and brittle. The width, depth and population density of these microcracks varies widely and is influenced by the following: the type of plating chemistry used (single-catalyst, mixed catalyst, proprietary), chromic acid concentration, type and concentration of catalyst, chromium-to-catalyst ratio, plating current-density, bath temperature, concentration of bath impurities (iron, copper, zinc, nickel, trivalent chromium, etc.) chromium deposit thickness surface condition of substrate. Generally speaking, a microcrack structure which is comprised of a high population density of narrow, shallow cracks is desirable, because the deposit tends to have a lower stress, higher lubricity, good wearability and better corrosio
