It is the general name given to the forms of coating used to bring the desired performance of the metal surface with various ways and various derivatives with phosphate compound. It gets its special name according to the groups that make coating on the surface together with phosphate.
I. Iron Phosphate Coating Application and Chemicals
II. Zinc Phosphate Coating Application and Chemicals
III. Manganese Phosphate Coating Application and Chemicals
It can be applied to products with spray or dipping option, iron-steel derivative and galvanized surfaces, generally used indoors, where very high rust resistance is not desired. Since there is no protection resistance on its own, passivation or dyeing is performed after the Iron Phosphate coating. Depending on the application, the color of the iron phosphate coated surface can be different. However, the most common color is eggplant purple. Iron phosphate application is preferred because the number of baths is low, and the investment cost is low. It is easier to follow than other phosphate applications. Since the coating is in distinctive colors, it gives an insight into the health of the coating even with the eye. The product is more effective at low pH. Since it has a pressure effect, the spray application has a better effect if the surfaces of the products are also suitable. If we need to specify the working ranges on average, it can be worked at a temperature of 40̊C-60̊C in the pH range of 3.5-6 and a total acid note of 1.5-6.
It is suitable for products used outdoors that require long-term rust protection. It can be used in iron steel or galvanized. Its application and follow-up are sensitive and the initial investment cost is high.
Fine crystalline structure is required for undercoat application. If desired, passivation process is applied. This process removes some negativities before painting. The undercoat zinc phosphate process that provides the highest strength is trication zinc phosphate. Temperature, concentration, duration of action, amount of accelerator and amount of sludge are the precursors to be followed in the bath. It can be used as a spray or dipping depending on the complexity of the application surface. Adequate rust resistance can be achieved in the range of 2-5gr/m2.
Usage ranges;
Temperature: 45̊C-70̊C
Concentration: 4-5%
Effect Duration: 5-8 min.
It is used to reduce friction during cold drawing and to prevent rust on wires. Zinc phosphate can be applied to wires whose surface has been cleaned from various impurities in different ways. It is especially suitable for pulling high carbon hard wires. Depending on the requirement, coating can be made in the range of 4-14gr/m2. It can be used at temperatures of 65̊C-75̊C in the range of 30-120 total acid, with a duration of action of 4-10 minutes. Total and free acid balance is very important in the bathroom. Sludge is formed as a by-product of the reaction. In heavy use, there are grains of mud suspended in the bathroom. If these are not cleaned properly, they can have a negative effect on the rolling mills. The sludge that settles on the bottom of the bath should be cleaned at regular intervals. Or, mechanisms that clean this mud from moment to moment should be prepared. We also have zinc phosphate chemicals suitable for businesses where patenting is done for continuous lines. In the enterprises where the patenting process is performed, the effect time in the phosphate bath is low.
It is used to reduce friction and prevent rusting during cold drawing. Theoretically, its application is the same with wire drawing zinc phosphate chemical. The pipes, which are purified from oil and rust by various methods, are coated in the zinc phosphate bath within the time required by the desired coating thickness. It can work in the temperature range of 60-75̊C. Coating can be done in the range of 4-14gr/m2. It can be applied within 6-10 minutes of effect. Then the pH of the surface is increased or coated with protective oil. It can also be put into a soap bath according to the necessity of the process.
As can be expected, the corrosion resistance of this product is very high. It is used in fasteners and machine parts. After cleaning the oil and rust, which is the beginning of the surface treatment, it enters the zinc phosphate bath. Coating is done in the range of 12gr-40gr/m2. Processing time varies according to concentration, duration of action and temperature. The recommended temperature is 70-95̊C. Coated with protective oil after zinc phosphate bath
Manganese phosphate is used in applications where the use of oil is allowed in the internal parts of the moving machinery. Since the oil used penetrates the manganese phosphate coating, the oil may remain on the part for a long time. Besides rust resistance, abrasion resistance against rubbing is also partially achieved. It is used in machine parts, automotive industry, defense industry.
A coating thickness of around 15gr/m2 is seen when applied by dipping process on iron-containing parts. It gives a dark image like the image of gun barrels. Since it is a product that works on the iron side, the sludge problem is not as much as in zinc phosphate.
The operating conditions also vary depending on the concentration, type of part, temperature and duration of action. However, the recommended ambient conditions are:
80̊C-90̊C temperature
70-80 total acid
12-13 free acids