Phosphating

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phosphating

[′fäs‚fād·iŋ]
(metallurgy)
Forming a phosphate coating on a metal. Also known as phosphatizing.

Phosphating

 

the creation of a conversion coating of insoluble phosphates (phosphate coating) on metal articles. When covered by paint or varnish, the conversion coating inhibits corrosion. Phosphating is used mainly on low-alloy and carbon steels and on cast iron. The phosphate coating (thickness, 2–5 micrometers) retains lubricant, a feature that acts to lower the coefficient of friction. Owing to their high electrical resistivity, the coatings can withstand potential differences of 300–500 volts, and they are stable at temperatures up to 400°–500°C.

Phosphating is carried out by immersing the article in a solution of iron, manganese, zinc, and cadmium phosphates that has been heated to 90°–100°C. Industry produces manganese ferric phosphate mixture in a form designed expressly for phosphating. The process usually takes approximately one hour. After being dried, the article is passivated in a weak chromate solution. Phosphating can also be carried out electrochemically with alternating or direct current; here, the process takes 15–20 min.

REFERENCES

Lainer, V. I. Zashchitnye pokrytiia metallov. Moscow, 1974.
V. I. LAINER
References in periodicals archive ?
Ramezanzadeh, "Studying corrosion performance, micro structure and adhesion properties of a room temperature zinc phosphate conversion coating containing Mn2+ on mild steel," Surface and Coatings Technology, vol.
Among all the treatment methods, phosphate conversion coating was easier to acquire and more environmentally friendly.
Rouhaghdam, Corrosion and cathodic disbondment resistance of epoxy coating on zinc phosphate conversion coating containing Ni2+ and Co2+, J Ind.
(2.) Tegehall, PE, Vannerberg, NG, "Nucleation and Formation of Zinc Phosphate Conversion Coating on Cold Rolled Steel." Corr.
Huang et al., "Preparation and corrosion behaviors of calcium phosphate conversion coating on magnesium alloy," Surface and Coatings Technology, vol.
Bonderite[R] 952 is a zinc phosphate conversion coating formulated for a spray application on substrates such as steel, galvanized and electrogalvanized, zincalloy, and aluminum.
Phosphate conversion coating involves the formation of a surface layer of hydrated metal phosphate crystals whose coverage approaches 100%.
These processes are capable of both removing fabricating soils and developing an iron phosphate conversion coating in one operation.
First significant advantage of the process is that there is no effluent to dispose of after the degreasing stage because the oils and greases removed from the components being treated are absorbed and become part of the polymeric phosphate conversion coating on steel, aluminium or zin coated steel.
The goal can be achieved with the help of innovative phosphate conversion coatings which can synchronize with light-weight initiative.
[ClickPress, Fri May 10 2019] Looking at the current market trends as well as the promising demand status of the " Phosphate Conversion Coatings Market ", it can be projected that the future years will bring out positive outcomes.