Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Zinc Phospate in steel

Zinc Phospate in steel

Zinc Phospate in steel

We have some carbon steel parts which need to be protected from corrosion. The part has internal threaded section about and inch in diameter. The parts are to be installed under the car and will be exposed to contaiminates. We are looking for the best and cost effective way to protect the part from corrosion. One way is to apply zinc phospate to prime the part than apply paint on top. The zinc phospate provides corrosion protection for everywhere(e.g. thread) where paint cannot reach. From internet search, some site mentioned this coating forms abrasive crystalline. My concerns is if zinc phospate is applicability to bolted joint. Would the friction and abrasive characteristic damage the threaded joint. Would structural integrity (e.g. preload) be maintained with the crystal structure damaged? If oil is needed to lub the joint, would it be compatible with thread locking compound, e.g. Loctite 243.

RE: Zinc Phospate in steel

Zinc phosphate forms crystals, but they are not abrasive to steel. This coating is used widely for threaded fasteners. It does not provide enough corrosion protection for steel parts underneath vehicles subjected to chloride ion from deicing salts. A better coating would be a non-electrolytically applied zinc coating, such as Magni 565 or similar competing ones (e.g. Delta Protekt, Zintek, and Geomet). If you do continue with zinc phosphate and need a lubricant and a thread locking compound, you need to coat the parts in this order:

thread locker

This is how we specify similar parts, although they are for use inside driveline housings, not exposed to the outside environment. For external applications, we use the zinc-based coatings.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close