Influence of Solid Chromizing Doped with Various Rare Earths on Microstructures and Properties of Cr-RE Coatings Fabricated by Pack Cementation

TANG Xiang-guo, DAI Ming-jiang, WEI Chun-bei, KUANG Tong-chun, LIN Song-sheng, HOU Hui-jun

Surface Technology ›› 2018, Vol. 47 ›› Issue (10) : 157-164.

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Surface Technology ›› 2018, Vol. 47 ›› Issue (10) : 157-164. DOI: 10.16490/j.cnki.issn.1001-3660.2018.10.021
Surface Friction Wear and Lubrication

Influence of Solid Chromizing Doped with Various Rare Earths on Microstructures and Properties of Cr-RE Coatings Fabricated by Pack Cementation

  • TANG Xiang-guo1, DAI Ming-jiang2, WEI Chun-bei2, LIN Song-sheng2, HOU Hui-jun2, KUANG Tong-chun3
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Abstract

Thework aims to improve the surface properties of GCr15 bearing steel to meet the service requirements under severe load conditions. The chromizing treatment was conducted on GCr15 bearing steel surface by pack cementation. Three kinds of Cr-RE chromizing coatings were obtained by adding different rare earth oxides (such as La2O3,Y2O3 and CeO2). The surface and cross-section morphologies, phase composition, chromizing coating composition, microhardness, bond strength and friction and wear properties of the Cr-RE coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), Micro Vickers tester, Rockwell-C hardness tester and ball-on-disc wear tester. From the results, the addition of any rare earth could form a uniform, continuous and compact rare earth modified chromizing coating with thickness of 10 μm on the surface of GCr15 bearing steel. The Cr-La coating had the best toughness and adhesion, and its indentation grade was HF1. The coatings were mainly composed of Cr7C3,Cr2C and (Cr,Fe)7C3.The Cr-RE coating significantly increased the surface hardness, and the Cr-Y coating had the highest surface hardness of 1520HV. These three Cr-RE coatings could improve friction and wear resistance. The Cr-La coating showed the best tribological properties with average friction coefficient of 0.4714 and wear rate of 4.4806×10?7 mm3/(N?m) and the wear mechanism was adhesion transfer and oxidation wear. Chromizing doped with rare earth can improve the toughness and wear resistance of the chromizing layer and Cr-La coating has the best comprehensive performance.

Key words

GCr15 bearing steel; Cr-RE coatings; rare earth oxide; friction and wear property; pack cementation

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TANG Xiang-guo, DAI Ming-jiang, WEI Chun-bei, KUANG Tong-chun, LIN Song-sheng, HOU Hui-jun. Influence of Solid Chromizing Doped with Various Rare Earths on Microstructures and Properties of Cr-RE Coatings Fabricated by Pack Cementation[J]. Surface Technology. 2018, 47(10): 157-164

Funding

Guangdong Science and Technology Program (2017A070702016), Guangzhou Science and Technology Program (201807010027)
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