Papers by Keyword: Zinc Coating

Abstract: This study evaluates and compares the corrosion resistance of zinc coatings deposited on mild steel using three different techniques: electroplating, TREFISSOUD Company hot-dip galvanization, and conventional hot-dip galvanization. Coated and uncoated samples were characterized by electrochemical polarization, microscopic analyses (optical microscopy and SEM), and X-ray diffraction (XRD). Electrochemical results demonstrated a significant decrease in corrosion current density (Icorr) for all zinc-coated specimens compared to bare steel, confirming the protective effect of the coatings. Among the coatings, hot-dip galvanization exhibited superior performance, with the TREFISSOUD Company method achieving the lowest corrosion current and the highest polarization resistance, indicating enhanced corrosion protection. Electroplated zinc, although thinner, provided adequate resistance in moderately aggressive environments. XRD analysis revealed zinc oxide (ZnO) and iron oxide (Fe₂O₃) as the main corrosion products. Their intensity was more pronounced in galvanized coatings than in electroplated zinc. Microscopic observations confirmed uniform and adherent coatings, with hot-dip galvanization producing thicker layers and stronger adhesion than electroplating. Overall, the findings demonstrate that hot-dip galvanization, particularly the TREFISSOUD Company method, provides the best long-term protection for mild steel exposed to harsh conditions. Electroplated zinc, while less durable, remains suitable for applications where a thinner, uniform coating is required. These results highlight the importance of selecting the coating method according to specific service conditions in industrial applications such as construction, pipelines, and marine environments. This study provides a new comparative analysis between conventional and TREFISSOUD company hot-dip galvanization methods, which has not been reported previously in the literature. The results highlight the distinctive performance of the TREFISSOUD Company process in improving coating uniformity, adhesion, and corrosion resistance. This novelty contributes to a better understanding of industrial zinc coating optimization for mild steel.

Abstract: A 7 wt.% Mn steel was designed and was cast and processed to 1.5 mm sheets. The sheets were continuous annealed and coated with a Zn alloy by hot dip galvanizing before subjecting them to hot press forming cycles. The final microstructure was characterized by ultrafine ferrite grains and a high fraction of retained austenite. Excellent combinations of in-service strength-ductility-bendability were achieved for hot forming in the temperature range of 530-675 °C. The use of the low temperature hot forming minimized the liquid metal embrittlement induced cracking with Zn coating during hot forming and spot welding. Various application properties such as oxidation resistance, corrosion resistance, and springback were found at optimum levels for hot forming at 675 °C.

Abstract: One of the most effective means of protecting metalwork equipment premises from corrosion is currently zinc-plating. Zinc-plating increases the service life of the equipment by 2-3 times, i.e. up to 20 years, which makes this method economically justified.We measured the electrode potentials and corrosion current between two plates – steel and zinc, depending on the size of the zinc plate. Modeling of the corrosion process with a decrease in the zinc coating was carried out by reducing the area of the zinc plate. At the same time, the area of the steel plate was constant. The protective ability of the zinc coating is maintained as long as it occupies at least 10% of the surface area of the steel product. Reducing the area of the zinc coating leads to catastrophic corrosion failure of the coating.

Abstract: Alloying zinc melt with nickel is used to control the thickness of the zinc coating on steels with different contents of silicon and phosphorus. Nickel is involved in the formation of iron-zinc phases in the coating and inhibits their growth. The use of zinc-nickel master alloys is well studied and has a significant disadvantage - the significant wastage of nickel in the bottom dross. The application of nickel tablets avoids wastage, because it allows us to distribute nickel evenly throughout the bath volume. The aim of this work was to determine the working concentration of nickel introduced into the melt from nickel tablets for a wide range of silicon-containing steels and for a galvanizing time of 2-5 minutes. It was found that the nickel concentration of 0.04% leads to the coating thickness decrease and normalization of the variation in coating thickness on steels with a silicon equivalent SiEV 0.12-0.28% at the galvanizing time of 2-5 minutes, and on high-silicon steel (SiEV 0.75%) at the holding time of 3 minutes. A nickel concentration of 0.03% is effective for SiEV steels 0.12-0.18% with a galvanizing time of 2-3 minutes. "Sandeline Peak" is completely smoothed out with a holding time of 3-5 minutes in the melt with a Ni content of 0.05%. The nickel presence in the zinc melt modifies the ζ-phase structure in the coating, making it more dense and uniform in thickness.

Abstract: The article contains the findings on impact of zinc coating specifications on corrosion resistance and service life of steels of various chemical composition used often in modern industries. Characteristics such as type, class, chemical compound and thickness of zinc-based coatings are also addressed. Experiments were performed in which corrosion rate and useful life of zinc coatings in probable operating-like conditions — i.e., in environments of varying degrees of corrosive power (humid and high-chloride environments) were determined. It has been established which one of the environments is the most corrosive for steels depending on the zinc-based coatings’ specifications. Qualitative (visual) and quantitative (gravimetric) assessment of corrosion resistance and service life of chosen steels is presented. Optimal hot dip galvanized coating specifications were determined using statistical analysis.

Abstract: Friction in sheet metal forming is a local phenomenon which depends on continuously evolving contact conditions during the forming process. This is mainly influenced by local contact pressure, surface textures of the sheet metal as well as the forming tool surface profile and material behavior. The first step for an accurate prediction of friction is to reliably estimate real area of contact at various normal loads. In this study, a multi-scale contact model for the normal load is presented to predict asperity deformation in coated steels and thus to estimate the real area of contact. Surface profiles of the zinc layer and steel substrate are modelled explicitly obtained from confocal measurements. Different mechanical properties are assigned to the zinc coating and the steel substrate. The model was calibrated and validated relative to lab-scale normal load tests using different samples of zinc coated steel with distinct surface textures. The results show that the model is able to predict the real area of contact in zinc-coated steels for various contact pressures and different surface textures. Current multi-scale model can be used to determine the local friction coefficient in sheet metal forming processes more accurately.

Abstract: Due to the restriction of passive layers containing Cr⁶⁺ [1], which were characterized by excellent corrosion protection due to their self-healing effect for scratches on metal surfaces, current corrosion protection systems consist of chromium (III) -containing thick layer passivation. Due to their lower hardness, current corrosion protection systems are susceptible to mechanical stress. This is particularly critical at barrel plating of screws, rivets etc. where the manufacturing process leads to damages of the corrosion protection layer and consequently to reduced corrosion resistance.To counter this problem, we point out one approach to install hard particles into the passivation layer. The entrapment of the hard particles into the passivation is detected by Glow Discharge Optical Emission Spectrometry. Comparative investigations in the corrosion chamber prove the improvement of the corrosion protection of steel parts with passivation layers containing hard particles.

Abstract: The purpose of the investigation carried out is the study of regularities in structural-phase changes and mechanical-chemical processes occurred in a surface layer under the influence of outer and inner technological factors. As experimental equipment there was used a vibration horizontal plant of UVG4x10 type. Working environment consisted of porcelain balls of 4mm diameter, PU-20 zinc powder and an aqueous solution of zinc chloride, and as abrasives – steel plates of 10x10 mm. As a result of the investigations there was determined a mechanism of coating formation, technological regulations for its application were established, surface morphology was investigated. The coating obtained exceeds the electrolytic one by a factor of 1.5 on corrosion resistance due to the absence of a hydrogenated layer.

Abstract: The features of the growth and the structure of diffusion zinc coatings in the process of galvanizing in powders with nanocrystallized surface area, alloyed with iron, are studied. It is established that the increase in the iron content in the powder substantially increases the area of the zinc solid solution in iron at a constant speed rate of the layer of zinc-iron phases. This effect is accompanied by the change in the morphology of powder particles as a result of iron saturation.

Abstract: Exploitation of ambulances in contaminated conditions causes that they are exposed to damaging the surfaces. Steel components are protected from corrosion by metallic and paint coatings, e.g. selected parts of medical equipment are protected by Ni, Cr, Cu coatings and additionally by hot-dip galvanizing or zinc galvanic. The appearance of corrosion cells has a significant impact on the products sustainability.In the study the results of the research, regarding the application of innovative solutions from the field of the material science and medicine in the interior of modern ambulances are described. The aim of investigations was the proper selection of anticorrosion coatings appropriate to ambulance considering the sterility keeping and the best anticorrosion properties.