Corrosion behaviors and electrochemical mechanisms of laser-cladded NiCrAlMo/nano-CeO₂ composite coatings in chloride-enriched environments

Abstract

Q235 steel is a low-cost material widely applied in modern industrial constructions. However, electrochemical degradation is the main drawback for its applications in chloride-enriched environments. To address this problem, NiCrAlMo and NiCrAlMo + 2 wt% nano-CeO2 composite coatings were laser-cladded on Q235 steel substrates. Characterization methods were used to investigate the microstructures, corrosion behaviors, and electrochemical mechanisms of the obtained coatings. The results showed that adding nano-CeO2 is conductive for removing residual gas pores and for refinement of grains, effectively improving the passive and electrochemical properties of the NiCrAlMo coating in both chloride-enriched solutions. Furthermore, the NiCrAlMoCeO2 composite coating exhibits a significantly reduced icorr of 0.4919 µA cm2 and an increased resistance ( Rp) of 175,310 Ω cm2 in a neutral solution, demonstrating the good anti-corrosion properties for its application in marine engineering structures.

Ni-Mo-P coatings on thrust plate of a gear pump to enhance its mechanical, tribological, and corrosion resistance properties

“…The least corrosion wear rate is obtained for the sample of Mo concentration 32 g L 21 (~2 mm/year for flowing condition and 1.7 mm/year for stationary condition), while, uncoated substrate offers the highest corrosion wear rate of 14 and 10.5 mm/year in flowing and stationary conditions respectively. The reduction of corrosion rate in present study is significantly lower as compared to previous researches performed by Wang et al, 24 Haixiang et al, 25 and Kumar et al 43 The reason behind this is forming a solid lubricating layer composed of Ni-Mo and Ni 3 Si phases during the electroless coating process. Figure 15 also suggests that the corrosion in flowing conditions is more than in stationary conditions.…”

“…Molybdenum (Mo) has become a popular research material in the past few years owing to its excellent corrosion and wear resistance properties. 24,25 Among all the elements suitable for electroless Ni-P coating, Molybdenum (Mo) shows good anti-H 2 S corrosion resistance. 26,27 Molybdenum has high hardness, a high melting point, good thermal conductivity, and resistance to corrosion.…”