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Seeking an aqueous rust inhibitor that won't burn on from heat treatment

We manufacture jet engine parts and I have an issue concerning cleaning parts prior to heat treat.
The parts are mostly nickel alloys, and we clean the parts in a cleaning machine with alkaline spray degreasing.
My problem is that I have to use iron based fixtures in the cleaning machine. Due to rust problems on the fixtures and some of the parts, I am forced to use a rust inhibitor in the last rinse water. This leaves staining on the parts which burns into the part in heat treat. Our solution so far is to wipe of the rust inhibitor by hand prior to heat treat. This is very time consuming and often gives various results.
The parts are dried at 110 degrees C prior to heat treat.
Is there an aqueous rust inhibitor that will evaporate from the part in the drying process and not leave staining, and at the same time protect the fixtures in the cleaning cycle?

Linda Hauknes
Chemical Engineer - Norway
September 30, 2010

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Linda,

It seems to me that you do not need to change your inhibitor, more so that you need to change your jigging. Consider stainless steel or titanium jigging and then you can drop the inhibitor altogether.

Brian Terry
Aerospace - Yeovil, Somerset, UK
October 4, 2010

I've looked into changing the fixtures. But the cost is very high due to large parts and complex configuration.

Linda Hauknes
- Kongsberg, Buskerud, Norway
October 5, 2010

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Linda,

OK, if changing your jigging is not an option then changing the chemistry has to be your next step. I cannot say whether one inhibitor is any better than another but one I have had some experience with is a material called VpCI from Cortec Inc. It may be worth having a word with them to see if they can help. I'm sure other contributors may have other solutions and I would take their advice as well.

Brian Terry
Aerospace - Yeovil, Somerset, UK
October 6, 2010