Improved Threaded Fastener Coatings for Turbine Engine Applications

Period of Performance: 01/03/1995 - 12/31/1996

$733K

Phase 2 SBIR

Recipient Firm

Surfaces Research & Applications, Inc.
8330 Melrose Drive
Lenexa, KS 66214
Principal Investigator

Research Topics

Abstract

The objective of this Phase II SBIR program is to furter develop improved coatings for turbine engine threaded fasteners that will prevent seizure upon removal for maintenance. Most engine hot section fasteners currently use silver plate as an antiseize coating. Silver must be replaced. It is known to be a cause of galvanic and stress corrosion of engine parts. It adversely reacts with common fastener assembly aids. It is also limited to 1200 degrees F operation. In Phase I, we demonstrated the first dry film antiseize coatings to have antiseize performance and reusability identical to or better than silver plate after 1200 degrees F exposure, in torqued fastener screening tests. These new Surfaces Research coatings were formulated to be inert towards engine materials and the engine environment. The coating components are stable to 1800 degrees F. One of the new coatings provides the additional benefit of room temperature spray-on or brush-on application and cure. In Phase II, we will demonstrate an overall fastener system -- antiseize coating, fastener material and fastener design -- in which the antiseize coating has greater compatibility with engine materials, prevents seizure, galling and breakage after use for one engine overhaul interval, and is usable at significantly higher temperatures than silver. We will develop a test method to demonstrate the performance of the fastener system which incorporates all signficant variables of the engine environment. This method will provide confidence that the performance of the fastener system in our proof tests will translate directly to its performance in engines. We will be ready for engine tests and commercial production at the conclusion of Phase II.