Abstract
The addition of superelastic NiTi to electroless Ni-P coating has been found to toughen the otherwise brittle coatings in static loading conditions, though its effect on erosion behaviour has not yet been explored. In the present study, spherical WC-Co erodent particles were used in single particle impact testing of Ni-P-nano-NiTi composite coatings on API X100 steel substrates at two average velocities—35 m/s and 52 m/s. Erosion tests were performed at impact angles of 30°, 45°, 60°, and 90°. The effect of NiTi concentration in the coating was also examined. Through examination of the impact craters and material response at various impact conditions, it was found that the presence of superelastic NiTi in the brittle Ni-P matrix hindered the propagation of cracks and provided a barrier to crack growth. The following toughening mechanisms were identified: crack bridging and deflection, micro-cracking, and transformation toughening.
Highlights
Impacting of surfaces with hard particles, typically known as solid particle erosion, can result in material removal, or even fracture of the surface [1] [2]
For spherical shaped impact particles, like the ones used in this study, it has been found in the literature that ductile materials exhibit lower material removal rates in comparison to those found for brittle materials under impact of the same spherical particles [6]
Samples tested at 35 m/s had smaller impact craters relative to the samples tested at 52 m/s, which is similar to results found in the literature [7] [32]
Summary
Impacting of surfaces with hard particles, typically known as solid particle erosion, can result in material removal, or even fracture of the surface [1] [2]. This is a common issue in aerospace and oil and gas applications where components such as jet engine compressor blades or pipeline walls are subject to impacting. Plain carbon steels are commonly used in oil and gas applications, as the pipeline material. These pipe materials are subject to wear from particulates or contaminants contained in the oil or gas being transported. For brittle materials, the maximum material removal rate occurs at an angle normal to the surface [7] [8] [9]
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