Microstructure and Wear Resistance of Laser Cladded Ni-based Coatings with Nanometer La 2 O 3 Addition

Abstract

Ni-based coatings with nano-sized feedstock rare earth element (RE, La2O3) addition were produced by laser cladding. Bed of high energy ball milling mixed Ni60A and La2O3 powders were pre-placed onto the substrate 30CrMnSiNi2A before laser cladding. Results show that La segregates in inter dendrite and thus secondary dendrites growth and ripening are limited. The microstructure is refined. Top surface of the cladded coatings displays better refined microstructure which is caused by high La concentration, and this phenomenon is verified in EPMA results. The cracks and pores cannot be found in cladded coatings in which microstructure refinement and purifying effect caused by RE is clearly reflected in SEM microstructure, hardness and especially the wear resistance test results. The COF (coefficient of friction) of the coatings is apparently lower than that of substrate steel; the wear volume loss rate and the microhardness of coatings are less than 1/10 and about 4 times higher than that of substrate metal, respectively. This research forms the basement of metal surface anti-wear layer on the work surface of high speed heavy duty gear set in helicopter transform system.

Effect of the Rare Earth Oxide CeO2 on the Microstructure and Properties of the Nano-WC-Reinforced Ni-Based Composite Coating

“…The cross sections also present different morphologies, and some obvious porosity can be observed in each case. During the laser cladding process, the CO and CO2 gases are generated by the reaction of WC and CeO2 [20], as shown in Equation (1). Figure 3 shows the cross-sectional morphology of five single coatings with different CeO 2 contents under identical processing parameters.…”

Lanthanides: The Key to Durable and Sustainable Corrosion Protection

“…The inorganic oxides of Ln have been used to mitigate galvanic corrosion either by incorporating them into the metallic materials or by making different types of electrodes. Moreover, these oxides strongly impact mechanical properties, as the wear resistance of 30CrMnSiNi2A steel increased 4 times by adding the Ln-based oxides into laser cladding nickel-based coatings . Thus, La-based coatings are considered the best alternative for chromate coatings, providing corrosion resistance and toxicity levels at a minimal scale. ,, Although La is not directly involved in the biological activities of the human body, it is somehow associated with some bacteria as an essential component.…”

Laser Cladding of Ni-Co-W Composite Coating on Stainless Steel to Enhance Wear Resistance

“…The study by Liang et al [24] on the Ni-based alloy coating modified with rare earth showed that there were no cracks and pores in the coatings contained 4 %CeO2, 5 % Y2O3, and 5 % La2O3 respectively, and the microstructure was refined, but the study did not mention the effect on properties. Zhao et al [25] reported that the microstructure of Ni-based coating with nanometer La2O3 addition was refined because of La segregates in inter dendrite and thus limiting secondary dendrites growth and ripening, the hardness and wear resistance of the coating were improved in comparison with the base steel.…”