Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions

Advances in Tribology, Feb 2018

The microstructures of subsurface layers of 20CrMnTi steel pins against chroming and nonchroming T10 under dry sliding tests were studied by means of OM (optical microscopy), XRD (X-ray diffraction), and SEM (scanning electron microscopy). Results showed that the chroming coating strengthened the disc surface and significantly affected microstructural evolution. Three layers—the matrix, deformation layer (DL), and surface layer (SL)—formed in 20CrMnTi for the chroming T10. The matrix and deformation layer (DL) formed in 20CrMnTi for the nonchroming T10. The formation of the microstructure was considered as a result of the shear deformation.

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Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions

Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions Xin Wang,1,2,3 Rulin Zhang,1 Tao Zhou,1 Xicheng Wei,2 Peter Liaw,4 Rui Feng,4 Wurong Wang,2 and Rongbin Li1,3 1School of Materials Science and Engineering, Shanghai Dian Ji University, 1350 Ganlan Rd., Shanghai 201406, China 2School of Materials Science and Engineering, Shanghai University, 149 Yanchang Rd., Shanghai 200072, China 3Institute of Energy Equipment Materials, Shanghai Dian Ji University, 1350 Ganlan Rd., Shanghai 201406, China 4Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37909, USA Correspondence should be addressed to Rongbin Li; nc.ude.ujds@bril Received 18 October 2017; Revised 5 January 2018; Accepted 11 January 2018; Published 7 February 2018 Academic Editor: Dae-Eun Kim Copyright © 2018 Xin Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract The microstructures of subsurface layers of 20CrMnTi steel pins against chroming and nonchroming T10 under dry sliding tests were studied by means of OM (optical microscopy), XRD (X-ray diffraction), and SEM (scanning electron microscopy). Results showed that the chroming coating strengthened the disc surface and significantly affected microstructural evolution. Three layers—the matrix, deformation layer (DL), and surface layer (SL)—formed in 20CrMnTi for the chroming T10. The matrix and deformation layer (DL) formed in 20CrMnTi for the nonchroming T10. The formation of the microstructure was considered as a result of the shear deformation. 1. Introduction Chroming is an interesting and intriguing coating technology. How the chroming coatings protect the substrate material interests both materials academic and technological communities [1–5]. Literature rarely reports the systematic study on the application of chroming coatings on carbon steel, the most important material for mechanical components and their tribological performance evaluation [6]. A reasonable database is provided for the further application of chrome-plating coating in tool steel engineering; it is worthwhile to investigate the friction and wear behaviors of chroming coatings and the substrate materials [7]. The microstructure evolution of ferrous alloy surface layer studied in [8] is beneficial to optimize the properties of surface chroming coatings on steels. Meanwhile, studying the chromium compounds layer of steel can help us extend the life of mechanical components. Our group has concentrated on improving surface properties of the T10 tool steel using the surface chroming coatings, which can satisfy the requirements of machining operation. The focus in this manuscript is to systematically investigate the microstructural evolution in advanced structural carbon steel friction pairs with and without chroming coatings under dry sliding testing conditions. 2. Methods2.1. Materials and Tribological Experiment The 20CrMnTi steel contains 0.2% C, 1.2% Cr, 0.1% Ti, 0.95% Mn, and Fe balance, and the T10 steel contains 0.98% C and Fe balance. The original 20CrMnTi steel pins have hardness of about 200 HB (, 0.05 μm to 0.1 μm). The chroming and nonchroming T10 steel discs have hardness of about 590 HB and 180 HB (, 0.05 μm to 0.33 μm), respectively. The conventional powder pack cementation method [9, 10] was applied to produce the chroming coating on T10 steel discs. The operation of the powder filling process is 1273 K and lasts 24 hours. This parameter is derived from the orthogonal test [11]. Friction and wear behaviors of chroming and nonchroming T10 steel discs were evaluated by laboratory tests, which were performed on the MM-W1 friction testing machine. All experiments were taken with a speed of 0.3 m/s, with load of 60 N, for 2 hours, and at 300 K. Friction coefficients were recorded online in a computer during the test. 2.2. Analysis and Characterization Methods The chroming coating of T10 was observed with a Nikon optical microscope. The constituents were detected with a MAX2550V X-ray diffractometer (XRD). Wear scars and the cross-section microstructures of chroming and nonchroming T10 discs and the worn surface layers of 20CrMiTi pins after the dry sliding test were observed by a HITACHI S-570 scanning electron microscope. A microhardness tester (MH-3) was used to measure the microhardness distribution across the cross-section of 20CrMnTi pins against the chroming and nonchroming T10 steel discs using a Vickers indenter under a load of HV0.01 with a dwell time of 20 s. 3. Results3.1. Microstructural Characterizations of Chroming T10 Steel Disc The coating sectional area OM image is shown in Figure 1(a). The results show that the chrome-plating layer is homogeneous and there is no obvious boundary between the interfaces. The average coating thicknes (...truncated)


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Xin Wang, Rulin Zhang, Tao Zhou, Xicheng Wei, Peter Liaw, Rui Feng, Wurong Wang, Rongbin Li. Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions, Advances in Tribology, 2018, 2018, DOI: 10.1155/2018/5962153