Numerical Model of Microstructure and Fracture of Coated Aluminum Alloys: A Novel Design Approach

Abstract:

Al/Si alloys are considered to be one of the most promising light weight alloys that can be used extensively in aerospace and automotive industry except for the poor tribological behaviour. However, with advancement and precision of the surface coating depositing techniques, new coating design which significantly enhances the tribological properties of the light weight alloys becomes attainable. In this paper, an innovative coating design is presented and thoroughly analyzed using finite elements method. The proposed model consists of Al/Si 319 as a matrix within which the geometrically defined hard Si particles are dispersed on the surface, and a hard coating layer then deposited in between the Si particles so that the lateral movement of the Si particles is constrained. ABAQUS is utilized to model and address the effects of different parameters, such as coating material, the hard coating thickness, and geometrical shape of the Si particles on the fracture and deboning of the entire structure. Two Si particles shapes are studied: circular and elliptical. Three coating materials are investigated: DLC, CrN and Al2O3. Besides, four coating thicknesses of 4 µm , 8µm, 15µm and 20µm are tested. It is found out that there is no single significant parameter which affects the fracture and deboning of Si particles, yet it is the combination of different parameters. The Si particle geometry plays a major role in determining the critical fracture stress with a circular shape outperforms the elliptical shape. The combination the circular Si particles and the CrN as coating material gives the highest critical fracture stress. Finally, DLC does not perform well with the circular Si Particle and it show the highest possible fracture stress with elliptical Si particle

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 2640-2645
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.2640
• Online since: January 2012
• Authors: Ola Rashwan, Vesselin Stoilov
• Keywords: Al/Si Alloys, Coating, Finite Element, Microstructure

References

[1] K. Gall, M. Horstemeyer, D. L. McDowell, J. Fan, Mechanics of Materials 32 (2000) 277-301.

[2] L. Qian, H. Toda, S. Nishido, T. Akahori, M. Niinomi, T. Kobayashi, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science 36 (2005) 2979-2992.

DOI: 10.1007/s11661-005-0071-x

[3] A. F. Bower, M. Oritz, Journal of the Mechanics and Physics of Solids 38 (1990) 443-480.

[4] K. Byung-Nam, M. Watanabe, M. Enoki, T. Kishi, Engineering Fracture Mechanics 59 (1998) 289-303.

[5] A. Erdemir, Proceedings of the Institution of Mechanical Engineers, Part J (Journal of Engineering Tribology) 216 (2002) 387-400.

[6] L. Zheng, S. Ramalingam, Multi-layer and composite structures for advanced coatings, in: vol 81, Elsevier, Switzerland, 1996, pp.52-71.

[7] C. Donnet, M. Belin, J. C. Auge, J. M. Martin, A. Grill, V. Patel, Surface and Coatings Technology 68-69 (1994) 626-631.

DOI: 10.1016/0257-8972(94)90228-3

[8] J. M. Martin, C. Donnet, T. Le Mogne, T. Epicier, Physical Review B (Condensed Matter) 48 (1993) 10583-10586.

DOI: 10.1103/physrevb.48.10583

[9] J. L. Beuth Jr, International Journal of Solids and Structures 29 (1992) 1657-1675.

[10] R. Nair, J. Wenping, P. Molian, Surface & Coatings Technology 202 (2008) 2935-2944.

[11] http: /www. sv. vt. edu/classes/MSE2094_NoteBook/97ClassProj/exper/gordon/www/fractough. html, Fracture Toughness and Fracture Design in: Accessed May 13, (2009).

[12] B. Tang, X. Zhu, N. Hu, J. He, Study on the structure and tribological properties of CrN coating by IBED, in: vol 131, Elsevier, Switzerland, 2000, pp.391-394.