Where the
world gathers for metal finishing
Q&As since 1989


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Phosphating

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Dear Reader :

I am manufacturing phosphating chemicals (I started this as a hobby). I use phosphoric acid with zinc oxide [affil links] and little nickel nitrate with Sodium Nitrate [affil links]. This in a hot bath does not work. Can anyone guide me?

Regards,

Harish Chitkara
- Chennai, India
2001

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2002

Try sodium nitrite as an accelerator rather than sodium nitrate.

Ron Zeeman
Continuous Colour Coat - Brampton, ON, CAN

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Can anyone suggest material sources for Class 4 phosphating as per DOD-P-16232 [ed. note: replaced by MIL-DTL-16232 [from DLA] ]?

Aryeh Asher
- Ashkelon, Israel
2000

Can you put your specifications in detail? Based on your requirement we can suggest for the chemical or the process.

DR.D.SEN
- calcutta, INDIA
2000

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Dr. Aryeh Asher,

You might give Ted a wrong impression that there are no suppliers in your country....-:)

Sara Michaeli
Tel-Aviv-Yafo, Israel
2000

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Country? I thought Israel was a city.
(only joshing, folks)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2000

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Which is the best phosphating method for powder coated product? hot or cold.

K.L.Nemade
irrigation systems - Jalgaon, M.S. INDIA
2006

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The best is usually the most difficult and most expensive, K.L. Zinc phosphate with a final chrome rinse is probably the 'best'.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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I want to know the right pretreatment & powder coating process for metal irrigation water filters AS these filters will be always in contact with water & soil may have some contact with fertilisers ( specially in case of fertiliser tanks ) & of course always in open sunlight & mounted in the farm itself for paint durability & resistance to corrosion ,protection against weathering effect ?

I have already done experiments of existing seven tank pretreatments ? & various ( epoxy & pure polyester & hybrids )

if someone know specific way of coating of water filters & fertiliser tanks pl. tell me.

V.R.PATIL
irrigation systems - Jalgaon, MS, India
2007

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We buy some spherical plain bearings from market & dealers give different brands according to availability. Japanese makes looks deep black colour, local makes are light grey. Catalogues say only phosphated. What is better? Black oxide also acceptable? Please clarify.

Regards,

S M Sundaram
- Tamilnadu, India
2002

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Hi, go for manganese phosphate it blackish in colour and secondly it is recommended for the parts where some lubrication is required eg: bearings, pinnion etc. Grey finish is of zinc phosphate and zinc phosphate looks grey in colour.

Qutubuddin Saify
- U.A.E.
2002

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2002

Dear Mr Saify,

Thanks for the reply. Would you suggest the cycle time for Mn Phosphating, because it is eating the material, or should we have to keep stock considering erosion. Pl advise for bearing steel material SAE52100, High Carbon High Chromium steel erosion pattern

Regards,

S MEENAKSHI SUNDARAM
- Chennai, Tamilnadu, India

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Mn phos time should be 10 mins. The imported bearings are not Mn Phos, they get the dark tone on account of different heat treatment process.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2002

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Dear Mr. Sundaram,

Keep the bath pointage around 30 35 ml, control iron to minimum and immerse the component when temp is 95 C and above for 10 min.

Prabhakar Gupta
- Kanpur, U.P., India
2004