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Open AccessArticle

Numerical and Experimental Analysis of Material Removal and Surface Defect Mechanism in Scratch Tests of High Volume Fraction SiCp/Al Composites

by Xu Zhao 1,2, Yadong Gong 1,*, Ming Cai 1 and Bing Han 2
1
School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China
2
School of Mechanical Engineering and Automation, University of Science and Technology Liaoning, Anshan 114051, China
*
Author to whom correspondence should be addressed.
Materials 2020, 13(3), 796; https://doi.org/10.3390/ma13030796
Received: 6 January 2020 / Revised: 28 January 2020 / Accepted: 3 February 2020 / Published: 10 February 2020
(This article belongs to the Special Issue Metal Matrix Composites)
This paper addresses a comprehensive and further insight into the sensitivity of material removal and the surface defect formation mechanism to scratch depth during single-grit scratch tests of 50 vol% SiCp/Al composites. The three-dimensional (3D) finite element model with more realistic 3D micro-structure, particle-matrix interfacial behaviors, particle-particle contact behaviors, particle-matrix contact behaviors and a Johnson-Holmquist-Beissel (JHB) model of SiC was developed. The scratch simulation conducted at scratch velocity 10 mm/min and loading rate 40 N/min revealed that the scratch depth plays a crucial role in material removal and the surface forming process. Brittle fracturing of SiC particles and surface defects become more deteriorative under a large scratch depth ranging from 0.0385 to 0.0764 μm. The above phenomenon can be attributed to the influence of scratch depth on SiC particles’ transport; the increase in the amount of SiC particle transport resulting from an increase of scratch depth raises the occurrence of particle-particle collision which provides hard support and shock for the scratched particles; therefore, brittle fracturing gradually becomes the major removal mode of SiC particles as the scratch depth increases. On the deteriorative surface, various defects are observed; i.e., lateral cracks, interfacial debonding, cavies filled with residually broken particles, etc. The von Mises stress distribution shows that SiC particles bear vast majority of load, and thus present greater stress than the surrounding Al matrix. For example: their ratio of 3 to 30 under the scratch depth of 0.011 mm. Namely, SiC particles impede stress diffusion within the Al matrix. Finally, the SEM images of the scratched surface obtained from the single-grit scratch experiments verify the numerical analysis’s results. View Full-Text
Keywords: SiCp/Al composites; scratch test; 3D finite element model; material removal; surface defect SiCp/Al composites; scratch test; 3D finite element model; material removal; surface defect
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Zhao, X.; Gong, Y.; Cai, M.; Han, B. Numerical and Experimental Analysis of Material Removal and Surface Defect Mechanism in Scratch Tests of High Volume Fraction SiCp/Al Composites. Materials 2020, 13, 796.

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