Effect of CeO₂ addition on the microstructure, hardness, and abrasive wear behaviour of flame-sprayed Ni-based coatings

Abstract

This article describes the effect of addition of CeO 2 on the microstructure, hardness, and abrasive wear behaviour of Ni-based flame-sprayed coatings. These coatings are economical but not frequently used because of their high porosity, low hardness, and bigger grain size. The mechanical and tribological properties of the coatings are governed by the microstructure, grain size, and distribution of various elements. Rare earth elements (oxides) refine the microstructure. The commercially available Ni-based powder was modified with the addition of CeO 2 (0.4, 0.8, 1.2, 1.6, and 2 %wt). The conventional Ni-based coatings and those containing various amounts of CeO 2 were compared in terms of grain size and distribution of various elements, hardness, porosity, and abrasive wear behaviour. The addition of an optimal amount of CeO 2 (0.8 %wt) refines the grain size and improves hardness and abrasive wear resistance of the coatings. X-ray diffraction of the conventional and modified coating with an optimum addition of CeO 2 (0.8 %wt) was also carried out to identify the various phases present in the coating.

Effect of La2O3 addition on the microstructure, hardness and abrasive wear behavior of flame sprayed Ni based coatings

“…The presence of such type of phases in NiCrBSi coatings has also been reported [15,20,21]. The XRD pattern of the coating with optimum addition of La 2 O 3 (1.2%) and the various phases such as Ni, Ni 3 Si, CrB, Cr 2 B, La 2 Ni were identified in the modified coating as shown in Fig.…”

“…Flame sprayed Fe-Ni coatings with rare earth elements have also been reported to increase microhardness and wear resistance [14]. In earlier work, refinement in microstructure, increase in micro-hardness and abrasive wear resistance of NiCrBSi flame sprayed coatings with the optimum addition of CeO 2 (0.8 wt.%) has been reported by the author [15]. Literature did not reveal any systematic study of La 2 O 3 addition and the effect of La 2 O 3 addition on the NiCrBSi flame sprayed coating on microstructure, hardness and abrasive wear resistance.…”

“…However, the extent of cutting on this coating is less as compared to other coatings due to less penetration of the conical abrasive due to high hardness and refined grain structure of this coating. The coarse-grain size of nickel solid solution provides longer free-mean path for abrasive wear as compared to small grain size [15,20]. As the grain size reduces the grain boundary area increases.…”

Effect of CeO2Addition on Wear Behavior of Flame Sprayed Coatings

“…In earlier work, refinement in microstructure, increase in microhardness, and abrasive wear resistance of NiCrBSi flame sprayed coatings with the optimum addition of CeO 2 (0.8%wt.) and La 2 O 3 (1.2%) have been reported [17,18]. In the present work, effect of CeO 2 (1%wt.)…”

Effect of CeO2 addition on thermal shock resistance of WC–12%Co coating deposited on ductile iron by electric contact surface strengthening

“…Therefore, the refining effect of CeO 2 on microstructure of WC-12Co coatings is mainly due to the characteristics of Ce, which composed of the surface active elements with a rather large atomic radius. The rare earth itself may become particles of heterogeneous nucleation, which can increase the number of crystal nuclei and hinder the growth of grains [21,22]. What is more, due to the large ionic radius of Ce 4+ (0.087 nm), the existence of CeO 2 within the solid solution will surely cause a great distortion and mismatch of lattice, which increases the energy of the system [23].…”