Prevention of Spline Wear by Soft Metallic Coatings
Abstract
The purpose of this cooperative program between MIT, Naval Air Development Center (NADC) and Foxboro-Analytical is to study the mechanism of wear and increase the wear resistance of aircraft splines. In addition to testing a much larger number or splines under a variety of conditions than has been done so far, optical microscopy, scanning electron microscopy and ferrography have been extensively used to identify the wear mechanism. Test specimens of aircraft splines were coated with Au, Ni, Ag and Cd with various thicknesses (0.1 - 10 micron m) and tested in the SwRI spline wear tester with and without grease. The gold coated splines exhibited induction periods of 250 hours, which is four times that exhibited by the uncoated splines. Ni, Ag and Cd failed to increase the induction period. Unlubricated splines wore exactly at the same rate as the post-induction wear rates of the grease lubricated splines. Optical and scanning electron microscopy results indicate that the mode of wear is by subsurface deformation, crack nucleation and growth processes (i.e., by the delamination mechanism) both in the induction and the post-induction periods. Analysis of the splines by the energy dispersive X-ray analysis showed that the metallic coatings did not react with grease. This and other evidence indicate that the costing/substrate bond strength is an important factor in the wear of splines. Methods for improving the bond strength and reducing the cost of the coatings are suggested.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1980
- Accession Number
- ADA091861
Entities
People
- Hyo-chol Sin
- Nam P. Suh
- Nannaji Saka
Organizations
- Massachusetts Institute of Technology