Zinc Yellow [ASTM B633]

Zinc Yellow refers to a specific type of chromate conversion coating applied to steel or aluminum and its alloys. Zinc Yellow plating, as specified by ASTM B633, is commonly used for several reasons:

• Corrosion Resistance: The yellow chromate conversion coating enhances the corrosion resistance of the zinc plating, making it suitable for harsh environments, including marine and outdoor applications.
• Durability: This type of plating provides a durable finish that can withstand wear and tear, extending the lifespan of the coated parts.
• Aesthetic Appeal: The yellow chromate gives the metal a distinctive, iridescent appearance, which can be desirable for certain applications where appearance matters.
• Cost-Effectiveness: Compared to other types of corrosion-resistant coatings, Zinc Yellow plating is relatively cost-effective, providing good protection at a reasonable price.
• Versatility: It can be used on a variety of metal components, making it a preferred and versatile choice for different industries, including automotive, construction, and industrial settings.

Let’s dive into the details:

               Purpose:

                               Corrosion Protection: Zinc yellow coatings enhance the material’s resistance to corrosion.

                               Adhesion Promotion: They act as an adhesion promoter for paint or adhesive bonding.

                               Conductivity: These coatings exhibit low electrical resistance.

                               Appearance: The color is typically a bright yellow with an iridescent look.

               ASTM B633 Classifications:

                               Type I: Zinc, as plated (no chromate). It remains in its natural state.

                               Type II: Zinc with a yellow hexavalent chromate coating.

                               Type III: Zinc with a colorless trivalent chromate coating (standard clear).

                               Type V: Zinc with a colorless trivalent passivate (high corrosion clear).

                               Type VI: Zinc with a yellow trivalent passivate.

Minimum Plating Thickness: Thickness varies based on the severity of the environment the parts will operate in (ranging from mild to very severe).

RoHS Compliance:

Trivalent finishes (like the “clear” trivalent chromate) are RoHS compliant.

Hexavalent chromate finishes (like “yellow”) are not RoHS compliant due to restricted substances.

Remember, zinc yellow coatings strike a balance between protection and aesthetics.