Skip to main content
European Commission logo print header

THE DEPOSITION OF IMPROVED CORROSION RESISTANT COATINGS ONTO SURFACES OF COMPLEX SHAPE

Objetivo

The objectiv es of this project are: to optimize an ion plating technique for the deposition of dense, corrosion resistant coatings of uniform thickness and structure onto substrates of prescribed shapes; to develop a model of the coating process which will predict the process parameters required for the deposition of such coatings onto substrates of complex shape.
Optimisation of ion plating parameters for aluminium coating of specially designed samples, which contain features relevant to industrial components, has been performed.
Coating experiments were done using diode ion plating, triode ion plating and radio frequency (RF) ion plating techniques. Gaseous and aqueous corrosion tests were carried out on specimens coated under different conditions. The RF ion plating technique was found to give substantially improved coating quality on metallic substrates compared with the diode ion plating technique.
Coating of uniform thickness on a complex shape could only be attained by manipulating the specimen during coating. Certain features were identified, principally sharply reentrant cavities, which could not be coated under conventional ion conditions.
A general model of the coating process could not be developed, only general guidelines for the coating of complex shapes could be established.

The technique of direct current (DC) and radio frequency (RF) ion plating have been used to coat components incorporating various common engineering features such as internal and external radii, reentrant cavities and masked surfaces. The effects of the process parameters on the thickness distribution and coating quality have been investigated.
It has been shown that there are certain features, principally sharply reentrant cavities which can not be plated under any conventional ion plating conditions. This is attributed to high local electric fields which preclude the net deposition of coating material.
Components coated under different conditions have been corrosion tested in both gaseous and salt spray environments. There is little significant correlation between coating quality and any of the process parameters on any shape of specimen when using conventional DC diode ion plating. It has been found tha the use of RF boas ion plating gives coatings which are superior in quality to those obtained using DC bias.
When evaporating from molten sources, approximately uniform coverage of a complex shape could only be obtained by manipulating the speciment during coating. An attempt to coat similar components using triode ion plating was unsuccessful.
THE PRIMARY AIM OF THIS PROJECT IS THE DEVELOPMENT OF NEW PVD COATINGS WITH GREATER CORROSION RESISTANCE THAN PURE ALUMINIUM, TO DERIVE A MODEL OF COATING THICKNESS AND QUALITY AS A FUNCTION OF ANGLE OF INCIDENCE AND DEGREE OF SHADOWING, AND TO DEVELOP THE PVD TECHNIQUE TO ALLOW THE DEPOSITION OF FULLY DENSE COATINGS OF UNIFORM THICKNESS ONTO SURFACES OF COMPLEX SHAPE.

THE PROGRAMME WILL PROCEED IN THE FOLLOWING STAGES:

- USE OF THE DIODE ION PLATING TO COAT A SERIES OF COMPLEX SHAPED SPECIMENS. IN PARALLEL WITH THIS, A MATHEMATICAL MODEL RELATING COATING THICKNESS DISTRIBUTION AND STRUCTURE TO SUBSTRATE GEOMETRY GEOMETRY WILL BE DEVELOPED.
- OPTIMISATION OF A TECHNIQUE FOR THE PRODUCTION OF ADHERENT AND NON-POROUS COATINGS OF PURE ALUMINIUM ON A RANGE OF STEEL SUBSTRATES.
- DEPOSITION OF A RANGE OF ALIMINIUM-MAGNESIUM ALLOYS USING THE TECHNIQUES DEVELOPED, ONTO BOTH MILD STEEL AND OTHER SUBSTRATE MATERIALS OF INDUSTRIAL INTEREST.
- INVESTIGATION OF COATING THICKNESS AND QUALITY ON A VARIETY OF COMPLEX SUBSTRATE SHAPES, INCLUDING SCREW THREADS, BELLOWS AND BLIND HOLES OF DIFFERENT ASPECT RATIOS.
- CORROSION TESTS ON EACH COATING, BOTH AS DEPOSITED AND AFTER STANDARD DAMAGING TREATMENT.

THE RANGE OF ALLOY COMPOSITIONS STUDIED WILL INCLUDE NOVEL METASTABLE ALLOYS WHICH CANNOT BE FORMED BY ANY TECHNIQUE OTHER THAN CO-DEPOSITION FROM THE VAPOUR PHASE.
THE MATHEMATICAL MODEL TO BE DEVELOPED WILL PROVIDE A SCIENTIFIC BASIS FOR THE COATING OF COMPLEX SHAPES, WHICH HAS PREVIOUSLY BEEN DONE BY EMPIRICAL METHODS.
ECONOMIC BENEFITS INCLUDE THE PRODUCTION OF NEW COATINGS TO REPLACE ELECTRO-PLATED CADMIUM: THIS WOULD BE BOTH ENVIRONMENTALLY AND ECONOMICALLY BENEFICIAL AS IT WOULD REMOVE THE PROBLEM OF THE SAFE DISPOSAL OF TOXIC WASTES.
THE POTENTIAL BENEFITS IN EXTENSION OF COMPONENT LIFE WILL BE GREAT. THE AEROSPACE AND NUCLEAR INDUSTRIES ARE PARTICULARLY LIKELY TO BENEFIT.

Tema(s)

Data not available

Convocatoria de propuestas

Data not available

Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

Centec GmbH
Aportación de la UE
Sin datos
Dirección
Stetternicher Staatsforst
52428 Jülich
Alemania

Ver en el mapa

Coste total
Sin datos

Participantes (4)