Microstructure, wear and electrochemical behaviors of laser cladding Fe-based coatings with various molybdenum contents

Abstract

Fe-based alloy coatings with different Mo contents were fabricated on 45 steel substrates by laser cladding. X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to analyze the phase composition and microstructural evolution of the coatings. The effects of Mo addition on the wear and electrochemical behaviors of the coatings were analyzed by ball-on-disc wear tester and electrochemical workstation. The results showed that the addition of Mo could help refine grains and promote the transition of dendrites to equiaxed grains. With the increase of Mo content, the hard phases changed from Fe2B to Mo2FeB2. Mo and Cr tend to aggregate in the intercrystalline regions in the form of hard phases. When the Mo content was 4.8 wt.%, the hardness increased by 3.6 times compared with that of the substrate. The wear resistance of the coatings increased with the Mo addition. Mo played the role of fine grain strengthening and solid solution strengthening, which was beneficial for the improvement of the hardness and wear resistance. Polarization curves and electrochemical impedance spectroscopy test results revealed that the addition of Mo could improve the corrosion resistance of Fe-based coating.

Effect of the Molybdenum Content on Wear and Corrosion Behavior of Fe-B-Based Surface-Alloyed Layer

“…For this reason, the increasing amount of block-structured or eutectic hard phase acts in the direction of the increasing wear resistance. Similar results have been reported in previous studies [27]. In the study, it was determined that micro-abrasive, adhesive, and oxidative wear were the dominant wear mechanism.…”

“…Coatings 2023, 13, x FOR PEER REVIEW 13 of 20 increasing wear resistance. Similar results have been reported in previous studies [27]. In the study, it was determined that micro-abrasive, adhesive, and oxidative wear were the dominant wear mechanism.…”

“…The similarity of the EIS curves seen in Figure 11c indicates that similar corrosion mecha- Tafel curves obtained from the samples subjected to the electrochemical corrosion test in the 0.5 M NaCl solution are given in Figure 11b. The corrosion potential obtained from these curves gives information about the direction of corrosion [27,60]. According to the curves, there was no big difference in corrosion potentials.…”

“…There are various studies in the literature where molybdenum is used as a coating material [23,24]. In these studies, it is generally seen that the wear or corrosion properties on the surface are improved after hardfacing [25][26][27][28][29]. On the other hand, some studies have reported that molybdenum increases corrosion resistance in the presence of an element such as chromium or nickel, but its effect alone is still ambiguous [30,31].…”