Effects of La2O3 on the microstructure and property of laser cladding Ni-based ceramic coating
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- 作者：Meiyan Li ; limeiyan@upc.edu.cn ; Bin Han ; Yong Wang ; Kejin Pu
- 关键词：Laser cladding ; Nickel based composite coating ; La2O3 ; Microstructure ; Property
- 刊名：Optik - International Journal for Light and Electron Optics
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：130
- 期：Complete
- 页码：1032-1037
- 全文大小：3134 K
- 卷排序：130
文摘
Nickel based composite coatings with La2O3 addition were fabricated on medium carbon steel by laser cladding processing. The microstructure, phase composition, microhardness and corrosion resistance of the laser cladding coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness tester and electrochemical workstation. The results show that the herringbone cracks generated in the deposited Ni-based ceramic coatings and the fracture mechanism exhibits quasi-cleavage fracture, while many tearing ridges and micro plastic deformations are present. A crack-free Ni-based composite ceramic coating is prepared with 0.6 wt% La2O3 addition, and refined dendritic microstructures are formed with higher microhardness (659HV0.2). However, the introduction of La2O3 addition has little effect on the phase composition of the Ni-based ceramic coating, composed of γ-(Fe, Ni) solid solution, CrB, Cr23C6, Cr7C3 and WC. In addition, the Ecorr values of two kinds of laser cladding Ni-based coatings are all more positive than that of the as-received medium carbon steel, while the Ecorr value of Ni-based cladding ceramic coating with 0.6 wt% La2O3 addition is more positive than that of Ni-based coating. Compared with Ni-based cladding coating, addition of 0.6 wt% La2O3 leads to lower corrosion current density, which indicates the improved corrosion resistance.