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Manganese Phosphating Problem

Hello All

We are doing Manganese Phosphating and we are maintaining the pointage between 40--45. Our Problem is that we are suffering from the rust problem. What we did is that after phosphating in the phosphating bath of about 100 ltrs. capacity for 20--30 mins., we immediately quench into the solution prepared from cutting oil and water.(Actually the quantity is of total 20 ltrs. i.e. 16--18 Ltrs. water and remaining cutting oil.)

If directly quench into diesel which is from our Genset (power backup), then we got problem of the sludge which shines more than that of cutting oil solution.

If we did chromic acid treatment then the sludge which comes out with the pieces got packed with chromic acid and too creates a big problem.

Please help.

Sean Aarchr
Engineer Q.A - Chandigarh
2007

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Cleaning prior to manganese phosphating is equally important. Also the surface activation just prior to phosphating delays the oxidation. Hence, give more information about the entire phosphating process being followed at your plant.

Use of cutting oil is not suggested. Proprietary rust preventive oil should be used.

BHAVESH SHAH
- Mumbai, India
January 8, 2008

I am looking for coating process for 50Cr V4 material (Chrome vanadium steel). My requirement is it should withstand at least 300 Hours of salt spray and the coating thickness should be less than 3 Microns. I tried the manganese phosphating process but its not withstanding the salt spray test. Please advise

Cibi Joseph
Product designer - Cochin, India
March 18, 2011