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

“…It is found that in the middle region, the average diameter of γ-(Ni, Fe) solid-solution is about 3 μm, larger than 1 μm for dendrites diameter in top region. The formation of fine dendrites by rare earth (RE) element in Ni-based alloy is thought to be a beneficial mechanism [14,15] . La segregates in interdendrite.…”

“…Rare earth element in Ni, Fe-based alloy melt pool react easily with sulfur and the sulfide is floatable and prone to float to the top surface of composite coatings. Hence the Table 3 EDS quantification analysis of locations labeled 1~3 in Fig.4 (at% content of sulfur remained in melt is decreased, which in turn increases the materials strength of coating alloy [15] . The coefficient of friction (COF) curves of coating specimens and substrate metal without laser cladded coatings in Fig.7 show that the COF of Ni60A-La 2 O 3 coatings is lower and the average value is about 0.56 under dry sliding condition.…”

“…Finally, in addition to promoting the formation of a fine dendrite, La has also the effect of desulfurization. RE element reacts with sulfur to form low density and high incipient melting temperature sulfides in melting [15] . Big La atoms with radius 0.1877 nm and active chemical properties attract sulfurs and phosphorus around them, the majority of low density compounds swimming to the surface of melt pool and some remaining between dendrites surfaces before solidifying.…”

“…Ni-based self-fluxing alloys are extensively used to produce abrasive resistance coatings [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . Nickel based alloy coatings combine excellent properties such as good corrosion resistance and low wear loss rate, and hard particles usually added in Ni-based alloy coatings are lanthanum oxide [7,8] , samarium oxide [9] , cerium oxide [10,11] , yttrium oxide [12][13][14][15] , WC [1,[4][5][6]8] and TiC [12] . RE added in Ni-based alloys is aimed at solid solution strengthening, microstructure refinement and structural purifying as well as corrosion resistance [7][8][9][10][11] .…”

“…RE added in Ni-based alloys is aimed at solid solution strengthening, microstructure refinement and structural purifying as well as corrosion resistance [7][8][9][10][11] . The mechanical properties such as coating hardness, wear, corrosion resistance and toughness of laser coatings can be improved by RE addition [7][8][9][10][11][12][13][14][15] . Song et al [16] found that the Ce-doped sample showed grain boundary segregation in heat-affected zones (HAZ) and made finer microstructure than the Ce-undoped sample.…”