The Improvement of Hardness and Corrosion Resistance of Electroplated Pd-Ni Film on 316L Stainless Steel by CeCl3

Abstract

By using the methods of XRD, SEM/EDS, electrochemical polarization, and a weight loss test, the effects of the rare earth salt CeCl 3 on the adherence, hardness, porosity and corrosion resistance of an electroplated Pd-Ni film on 316L stainless steel were studied. The results showed that by adding 1.0 g L −1 CeCl 3 in the plating bath, the obtained Pd-Ni film was obviously improved. The grain size was refined, and the microstructure was more compact and uniform. The film hardness and the adherence to the substrate increased, and the corrosion resistance in a 20 wt % H 2 SO 4 solution (80 • C) obviously increased. Ce 3+ increased the throwing power of the bath, which resulted in more uniform current distribution and strengthened the cathodic polarization degree during the electroplating process.The rare earths have been used in many fields such as electroplating, surface conversion coating, heat treatment, metal corrosion protection, and friction resistance, which makes them good prospects for applications [1-6] due to their unique electronic structures and chemical activity. Electroplating is a traditional surface protection technology. In the electroplating process, adding a small amount of soluble rare earth salt in the plating bath can improve the properties of the coatings, such as some physical properties and corrosion resistance [1,3,4] In addition, a rare earth salt can improve the throwing power (T.P.) of the plating solution, reduce the grain size of the plating alloy, and make the microstructure of the coating more uniform [7-9]. The T.P. is a measure of an electroplating solution's ability to plate a uniform film over an irregularly shaped cathode, which can be evaluated by using a Haring-Blum rectangular cell. Under the same plating conditions, the larger the T.P. value, the stronger throwing power of the electroplating solution and the more uniform the film formed on the surface of the substrate [9].The palladium film has excellent corrosion resistance, abrasive resistance, electrical conductivity, catalytic properties, hydrogen evolution performance, and a white appearance, all of which have led to its use as good hydrogen storage and catalytic materials. It has also been widely used in the electronics industry, in applications such as semiconductors and printed circuit boards, and the decorative industry [10,11]. In our previous study, Pd film plating on stainless steel was shown to greatly improve corrosion resistance in strong reductive corrosive environments, such as a hot, diluted sulfuric solution, by effectively improving the passive ability of the steel [12]. Pd-Ni and Pd-Cu alloy coatings with good surface micro-hardness and adhesive strength were deposited on 316L stainless steel by electroplating, and these coatings showed very good corrosion resistance in a hot sulfuric acid solution and an acetic

Application of noble cerium-based anti-corrosion sealing coating approach applied on electrical insulators installed in industrial regions

“…Meanwhile, Wang et al reported that the addition of Ce salt refines the grain size, enhances the crack resistance, reduces the pin holes and develops a compact and uniform protective film. This enhances the bonding strength between the substrate and the sealing coating film [26][27][28][29][30]. Furthermore, simulations were performed to evaluate the interface strength of the coating-substrate system.…”

“…Ce compounds are widely investigated for future thermal barrier coatings and hydrophobic coatings owing to their high melting point (1060 K), low thermal conductivity (2 W mK −1 ) and easily tailored structures [28][29][30][31][32]. Interest in Ce-based anti-corrosion approach has increased in recent decades owing to their various positive characteristics.…”

The effect of lanthanum chloride on the electrocrystallization behavior of cobalt and grain refinement in deposition layers

“…However, when rare earth ions are abnormally co-deposited with other metal ions, they can effectively improve the surface smoothness of the deposition layers. During electrodeposition, the addition of rare earth elements can increase the deposition rate, increase the cathode polarization degree, refine the grain size of the deposition layers and improve their hardness, corrosion resistance [12,13], and other properties [14].…”

Electrodeposition of Pd–Ag alloy for electrical contacts

“…Furthermore, the structural characteristics of the coating can be altered by changing electroplating parameters such as temperature, pH, agitation speed, compositional concentration, and current density. Previous studies have focused on the electrodeposition of Pd alloys such as Pd–Ni [9-18], Pd–Ag [19-21], and Pd–Sn [22]. However, only a few studies have been conducted on Pd and Pd-based alloy electrodeposits used as electrical contacts.…”