High temperature induced “glaze” layer formed in HVOF-sprayed NiCrWMoCuCBFe coating and its wear reduction mechanism

Abstract

The in-situ formation of oxides on alloy surface induced by high temperature can effectively reduce wear and resist oxidation. In consideration of the solid solution strengthening effect and great oxidation resistance of additional elements at elevated temperature, the NiCrWMoCuCBFe coating was prepared by high velocity oxygen flame (HVOF) spraying technology, and its tribological behavior was scrutinized from 25 to 800 °C. By means of high temperature Vickers hardness tester and high temperature X-ray diffractometer, the mechanical properties and microstructures of NiCrWMoCuCBFe coating were measured. And the effect of the mechanical properties and microstructures of the coating on tribological performance was discussed in detail. The results showed both its friction coefficient (0.37) and wear rate (5.067 × 10−6 mm3·N−1·m−1) at 800 °C were the lowest, which was mainly related to the formation of “glaze” layer on the coating surface at high temperature. The glaze layer consisted of two parts, which were NiCr2O4 oxide film with the ability of interlaminar slip formed in the outer layer and nano-grains existed in the inner layer. Worth mentioning, these nano-grains provided bearing capability while the oxide film was vital to reduce wear rate and friction coefficient. As the ambient temperature increased, many hard oxides were produced on the wear scars, including NiO, Cr2O3, MoO3, and Mo2C. They can improve tribological and mechanical properties of NiCrWMoCuCBFe coating at a wide temperature range.

Mechanical, morphological, and corrosion features of Ni–Cr oxide nanocomposite coating deposited on SS304 by EPD

“…The wear resistance improved dramatically for 50–50 sample. The cubic spinel of NiCr 2 O 4 , with the maximum value in the 50–50 composition, can be the main reason for improving wear resistance 7 . It should be noted that NiCr 2 O 4 is a hard and also malleable material 69,70 .…”

“…The cubic spinel of NiCr 2 O 4 , with the maximum value in the 50-50 composition, can be the main reason for improving wear resistance. 7 It should be noted that NiCr 2 O 4 is a hard and also malleable material. 69,70 The tough oxide layer of NiCr 2 O 4 , which is expected to be mainly formed on the coating surface, preserves coating integrity against the applied stresses.…”

“…In the 60-40 and 70-30 coatings, the toughness declines by decreasing the NiCr 2 O 4 value, which decreases the plastic deformability against external stresses and causes premature destruction of coatings. 7 The wear performance does not only depend on the hardness, because the mechanical properties can be governed by other factors, such as adhesion strength, residual stress, and thickness of the coating. 71,72 Lin et al concluded that the plastic deformation in ceramic-based coatings reduces wear rate, which is in line with the findings of the present study.…”

“…6 NiO nanoparticles with favorable magnetic, optical, photochemical, photocatalytic, and dielectric properties have various applications, such as making gas sensors, supercapacitors, solar cells, and drug delivery materials. [7][8][9][10][11] Moreover, the chemical stability of NiO particles has caused it to be a suitable inhibitor to prevent the substrate reaction with the surrounding environment in coating applications. 2,12,13 Green particles of Cr 2 O 3 with antibacterial features, chemical stability, thermal stability, and high hardness are used in medical fields, improving the corrosion properties of metals at high temperatures and forming wear-resistant coatings in dry and wet environments.…”

“…In the meantime, metal oxides produced at the nanoscale are an essential member of widely used materials in surface engineering 6 . NiO nanoparticles with favorable magnetic, optical, photochemical, photocatalytic, and dielectric properties have various applications, such as making gas sensors, supercapacitors, solar cells, and drug delivery materials 7–11 . Moreover, the chemical stability of NiO particles has caused it to be a suitable inhibitor to prevent the substrate reaction with the surrounding environment in coating applications 2,12,13 .…”