What is the Difference Between Trivalent and Hexavalent Zinc Plating?

The main difference between trivalent and hexavalent zinc plating lies in their environmental impact, toxicity, and process efficiency. Here are the key differences:

1. Environmental Impact: Trivalent zinc plating is considered more environmentally friendly than hexavalent zinc plating. Trivalent chromium processes are less toxic, and hexavalent chromium plating produces several byproducts that are considered hazardous.
2. Toxicity: Trivalent chromium plating is more safely regulated than hexavalent chromium plating, reducing hazardous waste and other compliance costs.
3. Process Efficiency: Trivalent zinc plating has a higher efficiency with more uniform distribution compared to hexavalent zinc plating. It is also possible to barrel plate with trivalent chromium, which is not possible with hexavalent chromium.
4. Cost: Hexavalent zinc plating is generally less expensive than trivalent zinc plating, but the latter offers more advantages in terms of environmental impact and process efficiency.
5. Performance: Corrosion test numbers are significantly better for trivalent passivates over zinc than hexavalent chromium over zinc. Trivalent chromium plating is more versatile, and its plating distribution is more uniform.

In summary, trivalent zinc plating is a more environmentally friendly, less toxic, and more efficient process compared to hexavalent zinc plating. However, hexavalent zinc plating is less expensive. The choice between the two processes depends on factors such as environmental considerations, performance requirements, and cost constraints.

Comparative Table: Trivalent vs Hexavalent Zinc Plating

The key difference between trivalent and hexavalent zinc plating lies in their efficiency, environmental impact, and safety. Here is a comparison table outlining the differences between the two processes:

Trivalent zinc plating is a more modern process that offers higher efficiency, better uniformity, and is more environmentally friendly than hexavalent zinc plating. It is also safer to use and has a good throwing power, which allows for better coverage on complex shapes. Additionally, trivalent zinc plating can be used in barrel plating, making it more cost-effective for larger volumes of smaller parts. However, hexavalent zinc plating is less expensive and has some advantages in terms of throwing power and contamination tolerance.