Fabrication of In Situ rGO Reinforced Ni–Al Intermetallic Composite Coatings by Low Pressure Cold Spraying with Desired High Temperature Wear Characteristics

Abstract

In this study, the surface of aluminum powder was uniformly coated with in situ reduced graphene oxide (r-GO) sheets (Al/r-GO). The Ni powder, Al2O3 powder, and Al/r-GO powders were mixed uniformly in a mass ratio of 20:6:4. In situ rGO-reinforced Ni–Al intermetallic composite coatings were successfully prepared using low-pressure cold spraying and subsequent heat treatment. The microstructure and phase of the composite coatings were characterized using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The high-temperature wear test was conducted at 200 °C, 400 °C, and 600 °C to understand the mechanism. The results indicate that the in situ rGO-reinforced Ni–Al intermetallic composite coatings exhibit a 33.3% lower friction coefficient and 26% lower wear rate in comparison to pure Ni–Al intermetallic coatings, which could be attributed to the generation of an easy-shearing transferred film between the coating and grinding ball.

The Preparation and Properties of Ni2Al3 Intermetallic Compound Coating

“…As shown in Figure 2b, it can be seen that the coating is mainly composed of Ni2Al3 (JCPDS: 14-0648) and also contains a small amount of NiAl (JCPDS: 44-1188), Ni3Al (JCPDS: 09-0097), Ni (JCPDS: 04-0850), and Al2O3 (JCPDS: 82-1399) phases, while a small amount of elemental Ni phase is left by an incomplete solid-state reaction. Cold-sprayed Ni-Al alloy coatings can obtain coatings with Ni2Al3 as the main phase under high-temperature conditions for insulation [25]. It found that the order of the solid-state reaction products of Ni-Al metal is NiAl3, Ni2Al3, NiAl, and Ni3Al [26].…”