Silver surface treatment applicable to bolts for motorcycles

In motorcycles, the exposed mechanical parts play important roles in the styling design. The bolts that fasten these parts a good appearance in addition to the fastening function. Since many parts of a motorcycle are designed so as to appeal the mechanical and metallic beauty, needs are higher for silver-color bolts. Motorcycle bolts are exposed to the external environment, so they are required to have also cosmetic durability. Though there is a surface treatment having a higher cosmetic durability such as the chromium plating, due to its metallic gloss like a mirror, chrome-plated bolts are applicable only to specific models and parts. In this study, we developed a surface treatment that enhance the appearance and cosmetic durability required of bolts for motorcycles. The layer of developed surface treatment is dip coating with thin film polyorganosiloxane material on zinc plating. Clarified a zone where both the appearance and the cosmetic durability are attainable through the studies on the amount of aluminum flakes in the dip paint and the amount of chemical conversion coating. Clarified that the friction coefficient can be adjusted to the same level as the previous plating by maintaining the amount of friction modifier within a specific zone. With the above-mentioned, we achieved surface treatment for bolts that has a generally applicable silver color appearance and cosmetic durability.