Electrodeposition of Nanocrystalline Fe-P Coatings: Influence of Bath Temperature and Glycine Concentration on Structure, Mechanical and Corrosion Behavior

Abstract

A detailed electrochemical study and investigation of a Fe-P glycine bath as a function of the temperature and glycine concentrations and current density, and their resulting corrosion and mechanical behavior is presented. A low addition of glycine to the electrolyte led to a drastic increase of the P content. At low Fe-P deposition rates, heterogeneous rough deposits with morphological bumps and pores were observed. By increasing the Fe-P deposition rate, the number of pores were reduced drastically, resulting in smooth coatings. Increasing the P content led to the formation of nanocrystalline grains from an “amorphous-like” state. Coatings with higher P contents exhibited better corrosion resistance and hardening, most likely attributed to grain boundary strengthening.

Mass transport-enhanced electrodeposition of Ni–S–P–O films on nickel foam for electrochemical water splitting

“…According to the literature, co-deposition of Ni and P is assumed to occur in a way analogous to the formation of CoP, where elemental Co and P produced during electrodeposition react to yield CoP. 45,46 Elemental P is produced from reduction of H 2 PO 2 − in acidic conditions as follows: 47 H 2 PO 2 − + 2H + + e − → P + 2H 2 O…”

The role of glycine in the iron-phosphorous alloy electrodeposition

“…In the absence of glycine, the Nyquist result shows inductive loops (Fig. 7) at potentials where Fe-P deposition took place (U À0.67 V [35]in publication). These results can successfully be interpreted by an equivalent electric circuit (EEC) shown at the Nyquist plot in Fig.…”

“…10a) to nanocrystalline (Fig. 10b) upon addition of glycine [35,39]. XRD studies of Fe-P coatings showed the appearance of the broad bands at P concentrations higher than 13 at.% indicating amorphous morphologies [15,40].…”

Effect of P Content on the Corrosion Behavior of Electrodeposited Fe-P Coatings

“…13 These coatings can be obtained from acidic and alkaline chloride and sulfate baths. 12,14,15 Chloride and sulfate baths (pH 2-3) containing sodium hypophosphite and different additives such as glycine as a complexing agent and oxalic acid as a stabilizer are common electrolytes used for electrodeposition of Fe-P film onto different substrates such as Cu, Pt, brass, and stainless steel. [12][13][14][15][16][17] Soares used an acidic bath containing FeSO 4 .7H 2 O and H 3 PO 4 to deposit Fe-P coatings containing less than 5 wt% P content.…”

“…12,14,15 Chloride and sulfate baths (pH 2-3) containing sodium hypophosphite and different additives such as glycine as a complexing agent and oxalic acid as a stabilizer are common electrolytes used for electrodeposition of Fe-P film onto different substrates such as Cu, Pt, brass, and stainless steel. [12][13][14][15][16][17] Soares used an acidic bath containing FeSO 4 .7H 2 O and H 3 PO 4 to deposit Fe-P coatings containing less than 5 wt% P content. 13 The P content of electrodeposited Fe-P film depends on different parameters, including bath temperature, bath P content and pH value, and electrodeposition current density.…”