Corrosion Resistance of Nanostructured Cemented Carbides with Alternative FeNi and FeNiCo Binders

Abstract

Nanostructured cemented carbides with Co binders have shown excellent mechanical properties in various applications. Nevertheless, their corrosion resistance has shown to be insufficient in different corrosive environments, leading to premature tool failure. In this study, WC-based cemented carbide samples with different binders were produced using 9 wt% of FeNi or FeNiCo with the addition of Cr3C2 and NbC as the grain growth inhibitors. The samples were investigated using electrochemical corrosion techniques: the open circuit potential Ecorr, the linear polarization resistance (LPR), the Tafel extrapolation method, and the electrochemical impedance spectroscopy (EIS) at room temperature in the solution of 3.5% NaCl. Microstructure characterization, surface texture analysis, and instrumented indentation were conducted to investigate the influence of corrosion on the micro-mechanical properties and the surface characteristics of the samples before and after corrosion. The obtained results indicate a strong binder chemical composition’s effect on the consolidated materials’ corrosive behavior. Compared to the conventional WC-Co systems, a significantly improved corrosion resistance was observed for both alternative binder systems. The study shows that the samples with the FeNi binder are superior to those with the FeNiCo binder since they were almost unaffected when exposed to the acidic medium.

Corrosion and Micro-Abrasion Properties of an AISI 316L Austenitic Stainless Steel after Low-Temperature Plasma Nitriding

“…It is also possible to notice that the slope of the curve is much milder in the case of the heat-untreated sample, and that all four curves were shifted in a negative direction, which indicates the corrosion instability of the working electrodes in the chloride medium. All samples showed the same trend and good repeatability of the results [45,46].…”

“…It is also possible to notice that the slope of the curve is much milder in the case of the heat-untreated sample, and that all four curves were shifted in a negative direction, which indicates the corrosion instability of the working electrodes in the chloride medium. All samples showed the same trend and good repeatability of the results [45,46]. From the numerical and graphical values of Ecorr (Table 5 and Figure 11), it can be concluded that nitriding time has no significant influence on the corrosion stability of the samples of nitrided AISI 316L steel in the test medium.…”

“…, x FOR PEER REVIEW 20 of 29 slope of the curve is much milder in the case of the heat-untreated sample, and that all four curves were shifted in a negative direction which indicates the corrosion instability of the working electrodes in the chloride medium. All samples showed the same trend and good repeatability of the results[45,46].To define susceptibility to pitting corrosion, the pitting potential (Epitt) was measured. The initial potential for cyclic polarisation was −0.1 V vs. Ecorr and the vertex potential was 1.2 V vs. Ecorr.…”

Influence of Catalytic Infrared Radiation on the Protective Properties of Industrial Epoxy Primers

“…To characterize the corrosion behavior and to determine coating protective properties, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) analyses were conducted [39] with a VersaSTAT 3 Potentiostat/Galvanostat (AMETEK Scientific 131 Instruments, Princeton applied research, Berwyn, PA, USA). The measurements were performed in 3.5% NaCl solution, and the results were obtained after 24, 250, and 500 h of immersion at room temperature (23 ± 2) • C. This is a standard test solution, used in many papers because it simulates the marine environments since it is the average concentration of salt in the oceans [40][41][42]. The frequency range of the EIS test was 10 5 -10 −1 Hz with 100 mV amplitude operating at ten points per decade.…”

“…In the beginning, Ching's primers' samples displayed an incomplete semicircle, indicating a robust coating. At this time, the electrolyte had not yet damaged the coating's substrate, so the coating provided high resistance which the current could not penetrate [41]. Hempel's primer displayed a full semicircle after 1 day in the electrolyte, meaning the current was able to pass through, due to lack of coating's resistance.…”