Characterization of Phosphate Coatings: Influence of the Acid Pickling Conditions

This research emphasizes the importance of the acid cleaning prior to the phosphate development on high-strength steel rods. It compares the phosphate properties achieved after different acid-pickling conditions. The most common inorganic acids were considered in this study. Additionally, taking into account the environmental and safety concerns of these acids, the assessment of a less harmful organic acid is presented. This study revealed significant differences in the coating morphology and chemical composition whereas no great changes were found in terms of the coating weight or porosity. Thus, hydrochloric and sulfuric acid promote the growth of a Fe-enriched phosphate layer with a less conductive character that is not developed after the pickling with phosphoric acid. The phosphate developed after the citric acid pickling is comparable to that developed after the inorganic acids although with a porosity slightly higher. The temperature of the citric acid bath is an important parameter that affects to the phosphate appearance, composition, and porosity.

Synergetic Effects of Temperature and Perpendicular Magnetic Field on Zn-Ni Alloy Electrodepositing Process

The zinc-nickel alloys were electrodeposited on stainless steel substrates during a chloride acid bath. The electroplating processes were investigated under a moderate perpendicular magnetic flux at uncommon temperatures. The coatings obtained were characterized by scanning microscopy (SEM) including EDX and X-ray diffraction (XRD). Chronopotentiometric curves were additionally implemented for electrochemical analysis. Structural analysis revealed that the obtained alloys consisted of a mix of the homogeneous phase γ-Ni3Zn22 and α-Zn-Ni at 70 ºC. The alloys variations observed within the chemical composition, crystallographic phases and morphology of the alloys. It is often explained particularly, by the progressive hydrogen reaction and therefore the evolution of the adsorbed intermediate species. The synergetic effect was significant at 70 ºC within the 1T field, including the appearance of normal co-deposition.

O PROCESSO DE ANODIZAÇÃO DO ALUMÍNIO E SUAS LIGAS: UMA ABORDAGEM HISTÓRICA E ELETROQUÍMICA

THE ANODIZING PROCESS OF ALUMINUM AND ITS ALLOYS: A HISTORICAL AND ELECTROCHEMICAL APPROACH. Al and its alloys are found in several industrial applications. However, like most metals, this material is not immune to corrosion, being necessary to be protected against corrosion. One of the methods most commonly employed to improve the corrosion resistance of Al alloys is the anodizing process, which consists of thickening of the natural oxide (Al2O3) presents in Al through anodic oxidation. The anodizing process is accomplished by immersion of the Al alloy into an acid bath and passing an electric current through it. This process produces two layers: a barrier layer thicker than the natural oxide and a layer with regular arrangement of nanopores (porous layer). This duplex structure forms the anodized layer with a large specific surface area. With the advent of nanotechnology, this layer has been applied in other areas due to its low cost, stability, absence of toxicity, and biocompatibility. In this context, this paper addresses a historical and electrochemical review of the anodizing process of Al and its alloys, presenting the main events that culminated in the development of the current processes and the understanding of the relationship between the chemical reactions and the mechanisms that occur during nucleation and development of the oxide layer

A Comparative Study of Carbon Emission of Wormwood Viscose Fiber and Flax Fiber for the Production of Antibacterial Nanofibers Based on GaBi Software

Because of its antibacterial properties, wormwood can be used in the production of nanobiomaterials. In this paper, each stage of the production process of wormwood viscose fiber and flax fiber was determined. The carbon emission of each stage of the production process of 1 ton wormwood viscose fiber and flax fiber was analyzed by GaBi software, and the environmental impact of the production process was evaluated by using the CML2001 method provided by the software. The results showed that a total of 1690.04 kg of carbon dioxide was emitted in the production of 1 ton of wormwood viscose fiber, 60% in the preparation stage, 36.36% in the acid bath stage and 3.64% in the treatment stage. A total of 1541.41 kg of carbon dioxide was emitted in the production of 1 ton of flax fiber, with the pretreatment stage accounting for 39.95% of the total amount, the alkali cooking stage accounting for 50.06% of the total amount, and the pickling stage accounting for 9.99% of the total amount. The results can provide support for the production of antibacterial nanofibers.

Study on Zn-Mn Alloy Plating on the Surface of Steel Sheet Prepared in Hydrochloric Acid Bath

Zinc plating using the principle of sacrificial anode is used to prevent steel corrosion. Pure zinc plating has some problems and Zn-Mn alloy plating has been studied as one of the measures to increase the corrosion resistance. Zn-Mn alloy plating can be applied to automotive parts requiring high corrosion resistance despite high plating cost. In this study, Zn-Mn alloy plating was electrodeposited in acidic chloride solution. The effects of electrolytic conditions on the composition of the alloy plating in the chloride bath were investigated. As the current density increased, the Zn content decreased and the Mn content increased. As the temperature of the electrolyte increased, the Zn content decreased and the Mn content increased.

Producing Platinum Resistant Nanolayer by Electrodeposition Method and Investigation of its Behavior in Acidic and Chloride Media

The purpose of this study is obtaining resistant platinum coating in acidic and chloride media. In this regard, gold coating as an interlayer coated on copper substrate was selected as the most beneficial substrate for platinum plating according to the study among different substrates. In this study, Chronoamprometry (constant potential) method was conducted as the electrodeposition process and scanning electron microscope (SEM) images were utilized to investigate the coating morphology. Cyclic voltammetry (CV) tests were performed in the hydrochloric acid bath to check the durability and stability of the resultant pt. coating. The results show that the resistant platinum coating has been obtained.