Wear Behavior and Microstructure of Thermally Sprayed NiCrBSiFeC and Composite NiCrBSiFeC-WC(Co) Coatings

Abstract

In this work, a study was carried out on the friction and wear behavior of flame thermal sprayed NiCrBSiFeC-WC(Co) composite and NiCrBSiFeC coatings subjected to severe wear conditions. For this purpose, flame remelted samples were tested in reciprocating wear conditions based on a cylinder-on-flat configuration. The wear assessment of the coatings was achieved using scanning electron microscopy (SEM) and 3D optical profilometry. The microstructure and the mechanical properties of the coatings were investigated using SEM, EDS and XRD techniques as along with indentation tests. The tribological behavior of the substrate and the coatings was successfully studied thanks to wear tests conducted on an adapted multi test apparatus. The results show that both NiCrBSiFeC and composite coatings induced a significant increase in the steel substrate hardness and wear resistance due to the formation of precipitates with high hardness well dispersed within an ultra-crystalline structure. Besides, adding WC(Co) to NiCrBSiFeC leads to a composite coating with hardness and wear resistance further improved. In return, it increases the coefficient of friction (COF) and the coatings’ roughness. Furthermore, improvements in the surface hardness, the roughness and the coating-substrate adhesion were attained after the remelting process for both NiCrBSiFeC and NiCrBSiFeC-WC(Co) coatings. Wear tracks investigations indicated that reciprocating dry sliding based on cylinder-on-flat test configuration promote several wear mechanisms that may occur simultaneously.

Comparison of Wear Resistance of Overlay Welded Layers and Thermal Sprayed Coatings in Real Conditions

“…The chemical composition and hardness of the coating sprayed with this powder are presented in Table 4. Compared to the layers deposited by arc welding with self-shielded flux cored wire, coatings flame-sprayed with self-fluxing powders after melting are characterized by a much greater surface smoothness, which may contribute to an increase in the durability of the friction pair [20]. The technological parameters of deposited layers and coatings are presented in Tables 5 and 6.…”

“…The available literature presents the results of laboratory tests of abrasion resistance of both overlay welding layers with high-alloy chromium cast iron [6,8,[15][16][17][18][19] and flamesprayed coatings with nickel-based powder [20][21][22][23][24]. However, there was no quantitative data enabling the comparison of the wear intensity of layers and coatings applied to guides and active armour in real conditions.…”