APPLICATION FIELDS OF ZINC-PHOSPHATE COATING
1. ZINC- PHOSPHATE COATING BEFORE PAINT
the most important factor that determines the performance of paint is the preparation of material surface. No matter how excellent the paint job is, a long-term protectiveness cannot be expected as long as the impurities (oil, grease, rust, oxide layer, etc.) are not cleaned from the material surface and a complete contact is not ensured between the paint and the surface. The impurities (oil, grease, rust, oxide layer, etc.) between the paint layer and the material surface will adversely affect the adherence (viscosity), hardness, brightness and resistance of the paint.
Therefore, fine and small grained and low weight (2-6 g/m2) phosphate coating process is applied to prepare the metal surfaces for paint process. Zinc phosphate coating process prepares a perfectly adsorbent surface (the roughness on the surface ensures perfect adherence of paint to the surface) in all kinds of paint applications (dipping method, electrodipping, hand painting, automatic painting, powder spraying method) and significantly increases corrosion protection.
It is commonly used in automotive, white appliances and household appliances industries. Phosphate layer significantly decelerates corrosion that progresses underneath the paint film and that starts from a weak point as a result of tiny scratches and deteriorations that may occur on the paint film. In brief, it increases corrosion resistance.
Photo 1: A metal ring which is phosphated before application of bonding agent
2. PROTECTIVE ZINC PHOSPHATE COATING
In order to protect metal materials against corrosion, the materials are coated with coarse grained, high-weight (5-15 g/m2) zinc-phosphate and phosphate crystals are impregnated with ANTI-CORROSIVE oil, emulsion or wax. Coarse and heavy phosphate crystal grains ensures excessive amount of anti-corrosive materials to be retained on the surface. Thus, it would have high protective effect.
Photo 2: A cover of clutch which is coated zinc-phosphate as protective coating..
3. ZINC- PHOSPHATE COATING FOR COLD-FORMING
In cold forming process of materials, high-weight (5-15 g/m2) zinc-phosphate is used. Here, zinc-phosphate absorbs the lubricant used in cold forming and facilitates the process. It is used in wire drawing, tube drawing, and cold press forming.