The Evolution of Decorative Trivalent Chromium Plating
May 05, 2023
May 05, 2023
For decades, hard chrome and decorative chrome plating from chromic acid baths have been widely accepted plating processes. However, the industry has been searching for more efficient and safer alternatives for the environment and human health. That's where decorative trivalent chromium plating comes in.
Initially, researchers were not trying to create a substitute for hard or decorative chrome plating. Instead, they discovered that electroless nickel could achieve similar hardness characteristics with a pre-bake procedure. Additionally, alloy techniques can produce deposits resembling a hexavalent chrome flash.
Despite these alternatives, hard chrome plating from the hexavalent bath remains a mainstay in many commercial applications, including the printing industry, drilling equipment, aerospace, and military. It offers unique characteristics such as high deposition thickness, lubricity, and hardness that are difficult to replicate with other plating processes.
Efficiency of hexavalent chrome
However, hexavalent chrome has an efficiency of only 10% to 15% due to wasteful electrochemical side reactions. Some of these side reactions produce significant amounts of gas, leading to fine mist. According to clinical studies, long-term exposure to chromic acid solution and airborne mists can harm human health.
In contrast, trivalent chromium salts are not carcinogenic but are an essential mineral in human nutrition. That's why trivalent chromium passivates have become popular since the 1980s and comply with RoHS and REACH directives.
Decorative Trivalent chromium plating has several advantages over decorative hexavalent chromium plating. It allows double the production rate as it requires less space to stack more parts. The deposit throw and efficiency have significantly increased, and post-plate rinsing is more efficient, resulting in less metal waste. Electrical contact making and breaking are no longer issues, making it easier to handle parts like a nickel bath.
The trend toward replacing hexavalent chromium-containing processes with trivalent chromium plating will continue for years. At PAVCO, we offer a full range of decorative trivalent chromium plating systems and resources to help you stay informed about the global metal finishing market.
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