**3.3. Effects of heat treatment on the tribological properties of electrodeposited Ni-P-SiC composites**

Over the last two decades, a variety of surface engineering processes have been developed to enhance the wear resistance, hardness, and corrosion performance of materials. Today, Ni-P alloys are widely used in the aerospace, automotive, and electronic industries because they possess a high degree of hardness, wear resistance, and corrosion resistance, as well as a low friction coefficient [25–28]. In this regard, Malfatti et al. [29] found that the transition from crystalline to amorphous structures occurs progressively over the range of several atomic percent of P and that as-deposited Ni-P coatings are amorphous when the P content exceeds 15 at.%. In contrast, the amorphous alloys can be crystallized via heat treatment, followed by decomposition to nickel phosphide (Ni3P) and face-centered cubic (fcc) Ni crystals at temper‐ atures above 350 °C [30]. The tribological characteristics of the Ni-P coatings can generally be improved via an appropriate heat treatment [31–33], which can be attributed to precipitation of fine Ni crystallites and hard intermetallic Ni3P particles during the crystallization of the amorphous phase [34]. In this respect, the wear resistance of the Ni-P alloys increases after heat treatment [35]. Moreover, Wang et al. [8] recently showed that Ni-P electroless coatings heat treated at 400 °C exhibited corrosion resistances of over two orders of magnitude better than hard Cr deposits.

The aim of this section was to study the effects of heat treatment on the physical properties of electrodeposited Ni-P-SiC coatings, including their crystalline structure, hardness, and resistance to wear.
