Aluminum Alloys with Ceramic Coatings
Development of Wear-Resisting Materials “Aluminum Alloy-Ceramic Coating” Produced by Shaped Casting and Plasmoelectrolitic Oxidation
Tech Area / Field
- MAT-ALL/High Performance Metals and Alloys/Materials
8 Project completed
Senior Project Manager
Mitina L M
MISIS (Steel and Alloys), Russia, Moscow
- Ilyushin Aircraft Association, Russia, Moscow
- Akita University, Japan, Akita
Project summaryAt present, aluminum alloys (particular, casting) are most promising structural materials for mechanical engineering, owing to their properties (low density, high specific strength, machinability) and almost unlimited resources of raw materials for aluminum production. However, low wear resistance, insufficient heat and corrosion resistance, and low elasticity modulus inhibit widespread use of components made of aluminum alloys.
It is known that the properties of a surface layer determine to a large extent the most important service characteristics of many components. Traditional methods of depositing special protective coatings on aluminum-made components are attended with considerable difficulties. The most promising method of plasmoelectrolitic oxidation allows to obtain the hard coatings (HV up to 20 GPa) with the thickness up to 200 m. Good results were obtained on wrought aluminum alloys with small content of silicon. However, plasma electrolytic oxidation of alloys with high silicon content (so called silumins which weight part in the total production of aluminum casting alloys is higher than 90%) faces certain problems, because particles of the silicon phase of solidification origin, emerging on the surface, have a screening effect on electric charges. So it is necessary to develop the new casting aluminum alloys combining the advantages of silumins (in castability) and low-Si alloys (in quality of ceramic coating).
Preliminary experiments showed that this task may be decided successfully if to use the new compositions (Si-free or Si <4%) on the aluminum base elaborated in Moscow State Institute of Steel and Alloys and new technology of plasma electrolytic oxidation elaborated in Russia by A. Shatrov and then developed and patented by KERONITE Ltd (UK).
To create the materials “aluminum alloy-ceramic coating” with the needing combination of properties it is necessary to carry out the complex of investigations focused on determination of quantitative dependencies of quality characteristics of coating versus composition and microctructural parameters of aluminum casting alloy and parameters of plasma electrolytic oxidation.
Works on the Project and expected results:
1. Analysis (on literature date) the quality and economic characteristics of wear-resistant coatings obtained by various methods. Selection of alloys for experimental study. Execution of preliminary experiments including alloy preparing, microstructural investigations, determination of mechanical and casting properties, obtaining of ceramic coating on the surface of castings by plasma electrolytic oxidation. Preliminary conclusion on desired microstructural parameters for ceramic coating.
2. Development of economical (“cheap”) casting alloys for their use without heat treatment. Study of their microstructure, determination of mechanical and casting properties. Preliminary experiments on obtaining of ceramic coatings.
3. Optimization of parameters of oxidation process for economical casting alloys. Study of structure and properties of obtained coatings. Development of wear-resisting materials “economical aluminum alloy-ceramic coating”, determination of their service properties and estimation of their using in various branches of industry.
4. Development of creep resisting casting alloys for their use at elevated temperatures (up to 350-400 °С). Study of their microstructure, determination of mechanical and casting properties. Preliminary experiments on obtaining of ceramic coatings.
5. Optimization of parameters of oxidation process for creep resisting casting alloys. Study of structure and properties of obtained coatings. Development of wear-resisting materials “creep resisting aluminum alloy-ceramic coating”, determination of their service properties and estimation of their using in civil branches of industry.
6. Development of high strength casting alloys for their use instead of wrought alloys of AA7075 type. Study of their microstructure, determination of mechanical and casting properties. Preliminary experiments on obtaining of ceramic coatings.
7. Optimization of parameters of oxidation process for high strength casting alloys. Study of structure and properties of obtained coatings. Development of wear-resisting materials “high strength aluminum alloy-ceramic coating”, determination of their service properties and estimation of their using in civil branches of industry.
8. Preparing of pilot sets details from new materials and their testing for determination of standard characteristics (mechanical, casting and physical). Preparing of technical and patent documentation.
Project Manager Zolotorevskiy V.S. – Professor, specialist on the field of physical metallurgy of aluminum alloys and composite materials, author of more than 150 publications.
Responsible executor Belov N.A. – Professor, specialist on the field of physical metallurgy of aluminum alloys and phase diagrams, author of more than 100 publications.
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