Phosphatization Classification
Phosphatization is a method of chemically treating a material, such as metal, to form a protective layer of phosphate, also known as PTZ (Patina, prophylactic, zinc or PZ). It is the combination of a metal surface and phosphorus in an acid or alkaline solution, and then subjected to heat treatment. The most common metals used to phosphatize are carbon steel and alloy steel, but other metals and alloys can also be phosphatized.
Phosphatization can be classified into three main categories: reactive, inorganic, and organic.
Reactive Phosphatization
Reactive phosphatization refers to the process of reacting metals with phosphorus compounds in an acid or alkaline solution. This reaction results in the formation of a thin layer of phosphorus on the metal surface. The process is often used to increase wear resistance and corrosion resistance of the metal by forming an oxide layer. The most common form of reactive phosphatization is a hot-dip method, where the metal is preheated, a phosphate solution is applied, and then the metal is heated to a higher temperature. This process can be used to protect against oxidation, corrosion, and abrasion.
Inorganic Phosphatization
Inorganic phosphatization is the process of coating a metal surface with an inorganic phosphate compound. This process involves treating the metal with an acid or alkaline solution with a high concentration of phosphates, then adding a catalyst and heat. This process forms an inorganic layer of phosphate on the metal’s surface. This layer protects against corrosion, erosion, and wear.
Organic Phosphatization
Organic phosphatization is the process of coating a metal surface with an organic phosphate compound. This process involves applying a solution containing organic phosphate-based compounds onto the metal’s surface and then subjecting it to heat treatment. This process forms an organic layer of phosphate on the metal’s surface which provides protection against corrosion, erosion, and wear.
The advantages of phosphatization include: improved adhesion of paints and primers; improved corrosion resistance; improved wear resistance; and prevention of metal oxidation. The disadvantages of phosphatization include: cost; the need for continual maintenance; and increased thickness of the phosphate layer which can reduce the service life of the metal.
In conclusion, phosphatization is a process of chemically treating a material, such as metal, to form a protective layer of phosphate. It can be classified into three main categories: reactive, inorganic, and organic. The benefits of phosphatization include improved adhesion of paints and primers, improved corrosion resistance, improved wear resistance, and prevention of metal oxidation. It should be noted that this process comes with its own drawbacks, such as cost, continual maintenance required, and increased thickness of the protective layer that can reduce the service life of the metal. These issues must be taken into consideration when determining whether or not to use phosphatization on a particular surface.
