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BEHAVIOUR OF HARD COATINGS UNDER VIBRATIONAL CONTACT CONDITIONS

Objective


This project has addressed the following items:
the development of specific test rigs for the simulation of contact vibrations over a broad range of testing parameters,
the identification of the major parameters influencing the deterioration of hard coatings (like TiN, diamond and amorphous diamondlike carbon coatings) in vibrating contacts in which simultaneously normal static loading and additional tangentail static and cyclic loads are present,
the modelling of the crack risk in materials subjected to vibrational wear,
the set up of guidelines and selection criteria for the optimum use of hard coatings in vibrating contacts.

The resulting benefit is the availability of a methodology for the material selection for parts as vibrating contacts and its experimental validation. A method has been developed for the calculation of the crack risk in vibrating contacts, for the determination of the wear rate in vibrating contacts, and a database useful as a tool for material selection.
The aim of this research is to provide a scientific base for the understanding of the process of wear initiation and for the unravelling of damage mechanisms leading to failure of hard coatings used under vibrational contact conditions. Coating materials selected are representative of four types of hard coatings, some of them being under development, namely a superhard coating (diamond), a hard coating with a low coefficient of friction (diamond-like carbon), a hard coating already introduced in industry and used as reference material in this project (TiN), and an artificially structured coating (NiP/Sn compositionally modulated multilayer) included for modelling purposes.

Three actions are planned :

- the testing of hard coatings under oscillating contact conditions at low displacement amplitude, in a reciprocating mode, at small displacement combined with a tangential static loading, and with compounded fatigue loading. The complementary of the equipment available at the different partners offers a unique testing range in terms of normal load, displacement amplitude, frequency range, and controlled relative humidity,

- the on-line detection of wear initiation in vibrating contacts and off-line characterization of the wear induced on the hard coatings. In that respect selected state-of-the-art techniques will be supplemented by innovative methods like charged particle emission, lateral atomic force microscopy and Fourier transform demodulation profilometry,

- the modelling of the velocity accommodation mechanism in vibrating contacts.

Expected benefits are the development of in-situ monitoring of wear initiation in vibrating contacts and the set-up of guidelines for an optimum selection of hard coatings for use in vibrating contacts.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

KATHOLIEKE UNIVERSITEIT LEUVEN
Address
De Croylaan 2
3001 Leuven
Belgium

Participants (4)

FEDERAL INSTITUTE FOR MATERIAL RESEARCH AND TESTING
Germany
Address
87,Unter Der Eichen 87
12205 Berlin
Liverpool John Moores University
United Kingdom
Address
Byrom Street
L3 3AF Liverpool
UNIV UPPSALA
Sweden
Address
Po Box 534
751 21 Uppsala
École Centrale de Lyon
France
Address
36 Avenue Guy De Collongue
69131 Ecully