Analysis and Comparison of the Corrosive Behavior of Nickel-Based and Cobalt-Based Dental Alloys

Nickel-based and cobalt-based metal alloys are frequently used in dentistry. The introduction of various elements in the alloy changes its characteristics, and a thorough study of each alloy should be completed to determine its appropriate corrosion resistance and biocompatibility in contact with physiological fluids. There are scarce investigations on these widely used dental alloys in Ringer solution, and findings in this research bring new experimental data and information. The present study evaluated and compared the corrosion behavior of six NiCr- and two CoCr-based dental materials in Ringer solution, using the following techniques: potentiostatic polarization curves (chronoamperometry), microstructural analysis, and EIS (electrochemical impedance spectroscopy). The results obtained in this investigation showed that in the NiCr-based specimens Ni4, Ni5, and Ni6 the stability of the passive layer was destroyed after polarization and a development and growth of stable pits was found in the microstructural analysis after electrochemical treatment. In terms of susceptibility to corrosion, two different groups of specimens were derived from this investigation. A first group which included the two CoCr (Co1 and Co2) and three of the six NiCr alloys studied (Ni1, Ni2, and Ni3). A second group with the other NiCr alloys investigated Ni4, Ni5, and Ni6.

Characteristics of Passive Films Formed on As-Cast Ti–6Al-4V in Hank’s Solution Before and After Transpassivation

In this work, the characteristics of passive films formed on as-cast Ti-6Al-4V before and after transpassivation by electrochemical methods will be studied. A simulated body fluid of Hank’s solution was used as the electrolyte in this work. According to the potentiodynamic polarization test, the passivation range, transpassive range, and repassivation range of as-cast Ti-6Al-4V were obtained. Afterward, the potentiostatic polarization was employed to passivate the Ti-6Al-4V in both passivation and repassivation ranges. Electrochemical impedance spectroscopy (EIS) was used to analyze the characteristics of formed passive films. Different electrochemical behavior of as-cast Ti–6Al-4V is found in passivation and repassivation ranges. The passivation current density of the sample in the repassivation range is significantly larger than that in the passivation range. Meanwhile, the growth rate of passive film in the repassivation range is also greater than that in the passivation range. Although the sample shows a higher charge transfer impedance in the repassivation range, metastable pitting corrosion is also observed, indicating the formation of the unstable passive film. Such results advance the understanding of as-cast Ti-6Al-4V polarized under different potentials for potential biomedical applications.

Study of Corrosion Behavior of Carbon Fiber Reinforced Plastics (CFRPs)

This paper is intended to find the corrosion behavior of carbon fiber reinforced Plastics (CFRPs). Some of the corrosion parameters such as 3.5% of NaCl, current density and voltage were taken into consideration. They were examined by potentiostatic polarization and scanning electron microscopy to find the corrosion rate of the CFRPs. The experiments were done by applying different voltages to the CFRPs and the corresponding current obtained will denote the corrosion rate. Based on the corrosion rates observed, the better combination can be selected in order to eliminate corrosion.

Study of Corrosion Efficiency of Mild Steel Using Commercial Liquid Additives for Fish in Natural Water

This work is devoted to examine the effectiveness of the different commercial liquid additives for fish (sweet corn and molasses) on corrosion of mild steel in natural water by different methods (gravimetric and potentiostatic polarization) at room temperature. The corrosion tests were employed to evaluate corrosion rate (CR) and inhibition efficiency (IE %). The maximum inhibition efficiency was obtained for the inhibitor type molasses of 90.00% by gravimetric method for a period of 3 hours and over 31 % by potentiostatic polarization method. It was found that the commercial liquid additives acted as a good inhibitors for the tested environment. Furthermore, the corroded metal was observed by metallographic microscope.

Corrosion characterization of Sn-Zn solder: a review

PurposeThe purpose of this paper is to review and examine three of the most common corrosion characterization techniques specifically on Sn-Zn solders. The discussion will highlight the configurations and recent developments on each of the compiled characterization techniques of potentiodynamic polarization, potentiostatic polarization and electrochemical impedance spectroscopy (EIS).Design/methodology/approachThe approach will incorporate a literature review of previous works related to the experimental setups and common parameters.FindingsThe potentiostatic polarization, potentiodynamic polarization and EIS were found to provide crucial and vital information on the corrosion properties of Sn-Zn solders. Accordingly, this solder relies heavily on the amount of Zn available because of the inability to produce the intermetallic compound in between the elements. Further, the excellent mechanical properties and low melting temperature of the Sn-Zn solder is undeniable, however, the limitations regarding corrosion resistance present opportunities in furthering research in this field to identify improvements. This is to ensure that the corrosion performance can be aligned with the outstanding mechanical properties. The review also identified and summarized the advantages, recent trends and important findings in this field.Originality/valueThe unique challenges and future research directions regarding corrosion measurement in Sn-Zn solders were shown to highlight the rarely discussed risks and problems in the reliability of lead-free soldering. Many prior reviews have been undertaken of the Sn-Zn system, but limited studies have investigated the corrosive properties. Therefore, this review focuses on the corrosive characterizations of the Sn-Zn alloy system.

Preparation of cell adhesive micropores by one-step potentiostatic polarization on 304 stainless steel

Non-conventional electrochemical machining in micro-manufacturing has atomic-scale machining accuracy only in theory. By taking full advantage of the material heterogeneity, the micropores which most easily initiate at the surface stoichiometric inhomogeneities for stainless steel can be prospectively obtained with the size kept under control by adjusting the machining parameters. Taking the economy and efficiency into account, a one-step potentiostatic polarization method was established. Optimization of the machining parameters for achievement of microporous structure required by cell adhesive surface on 304 stainless steel in natural 15 wt% NaNO3 solution was confirmed. Based on the potentiodynamic polarization curve, a DC voltage of 5 V in the region of secondary passivation was selected due to the porous secondary passivation film which results in the initiation of large amounts of pores. The effects of the machining time on the pore size, coverage ratio, density, unevenness degree and adhesive cell density on the porous surface were investigated through statistical analysis. The results show that there is a maximum value of machining time, tm, when the surface has a maximum pore density, and minimum pore unevenness degree. Meanwhile, adhesive cell density increases to significant level at tm then levels off over time. Therefore, this approach has been testified possible through the novel use of material microdefects and electrochemical machining to obtain cell adhesive micropores.

Application of Carboxymethyl Chitosan-Benzaldehyde as Anticorrosion Agent on Steel

Corrosion is one of the problems that is often found in daily life especially in petroleum and gas industry. Carboxymethyl chitosan- (CMC-) benzaldehyde was synthesized as corrosion inhibitor for steel. Corrosion rate was determined by potentiostatic polarization method in HCl 1 M. Dripping and coating, two different treatment, were used to drop and coat steel by CMC-benzaldehyde. The results showed that CMC-benzaldehyde could inhibit the corrosion rate of steel with concentration of 1 g, 3 g, 5 g, and 7 g in 60 mL of solvent. Coating steel with CMC-benzaldehyde with concentration of 7 g/60 mL of solvent and starch of 0.1 g/mL showed the highest efficiency to inhibit corrosion rate of steel. These treatments give corrosion efficiency of 99.8%.