Volume 43, Issue 2

The requirement for sustainable and environmentally friendly materials has led to the exploration of lignin as a potential candidate for protective coatings in various industrial applications. Recent researches demonstrate the feasibility of lignin-based coatings for enhancing wear and corrosion resistance. The lignin improved the coating’s barrier properties and prevented corrosive electrolytes from contacting the metal. The lignin additives also functionalised wear resistance coating. This review points out the improvements in using lignin extraction to produce high-quality materials suitable for corrosion and wear resistance coating purposes. However, the application of lignin in coatings faces significant challenges, primarily due to its heterogeneous and complex nature, which complicates the attainment of uniform and reliable coating qualities. Moreover, it emphasises the need for further studies on lignin to harness lignin’s potential. Future research needs include the development of standardised methods for lignin characterisation and modification, the exploration of novel lignin-based composites and the evaluation of lignin coatings in real-world applications. This review probes into the burgeoning field of lignin-based coatings, evaluating their potential for wear and corrosion resistance, and discusses the current state of research, challenges and future directions in this promising area.

Magnesium, titanium, and their alloys are considered very promising in bio-materials. However, their poor antimicrobial and corrosion resistance in physiological environments dramatically limits their application in practical situations. Micro-arc oxidation (MAO) technology has attracted much attention due to its low cost and convenient operation. Based on this, this paper summarizes and rationalizes key findings from the last 15 years of the current research status of MAO surface technology of magnesium and titanium alloys in the biomedical field. It analyzes the research work of doping functional elements into micro-arc oxidized ceramic membranes, preparing composite coatings by deposition and sol-gel technology, and changing the time of MAO, electrolyte, and electrical parameters to improve the antimicrobial and corrosion–resistant performance of the membrane layer. Moreover, this paper reveals the characteristics and principles of antimicrobial and corrosion resistance of MAO ceramic layers and expands the application of MAO magnesium and titanium alloys in bio-medicine. Finally, this paper summarizes the problems and shortcomings of the MAO technology that still need to be solved. It also looks forward to future research on the direction of MAO technology, which provides a theoretical basis for further application bio-medicine.

This review paper explores the ongoing challenge of internal corrosion in oil and gas pipelines, specifically focusing on the damage caused by hydrogen sulfide (H 2 S). It highlights the superior performance of coating technologies such as chemical resistance, long-term durability, and resistance to high temperatures, including epoxy and other nonmetallic coatings, which effectively protect pipelines against H 2 S-induced corrosion. The review covers the practical application of coating technologies to improve pipeline durability and operational efficiency, beginning with an examination of the corrosive impact of H 2 S on pipelines. It reviews existing mitigation strategies, highlighting their advantages and limitations, and then analyzes nonmetallic coatings as a promising solution to H 2 S-induced corrosion. The paper demonstrates the benefits of these advanced coatings. It concludes with a summary of key findings and provides industry recommendations for selecting and implementing effective coating technologies, alongside suggestions for future research in this field.

Microbiologically influenced corrosion (MIC) caused by sulphate-reducing bacteria (SRB) is an important issue, particularly in the offshore industry where cathodic protection (CP) is commonly used to prevent the corrosion of steel structures. However, its relation with MIC remains unclarified, as the interaction between CP and microbial activity is still far from understood. Under overprotection conditions, the water reduction reaction can lead to atomic hydrogen uptake, which may result in hydrogen embrittlement (HE). This uptake is influenced by calcareous deposits, i.e. inorganic compounds formed during CP. Additionally, SRB are argued in literature to enhance hydrogen uptake. This review explores various perspectives on the interaction between microbial activity, particularly SRB, and CP, as well as their individual and combined impact on hydrogen uptake in an offshore context.

AA2024 is widely employed within the aerospace sector; nevertheless, its susceptibility to pitting upon exposure to chloride ions presents a notable challenge. This investigation proposes an in-situ co-precipitation technique for effectively sealing the anodic oxide layer on the AA2024 substrate by nickel–aluminum layered double hydroxides (LDH) conversion coating. Given the lack of reported data concerning the correlation between the nucleation/growth behavior and the anti-corrosion performance of NiAl-LDH coatings, the current research aimed to investigate the effect of synthesis conditions including temperature and pH on the morphology and nucleation of LDH nanoplatelets, as well as the corrosion resistance of prepared coatings. Field-emission SEM, atomic force microscopy, X-ray diffraction analysis, electrochemical measurements, Raman, FT-IR, and X-ray photoelectron spectroscopy were utilized to study the behavior of coatings. The results indicated that the prolonged nucleation/growth stage of synthesized NiAl-LDH nanoplatelets at pH 7.5 improves the electrochemical performance through providing a compact LDH coating.

This study investigated the impact of different deformations on the corrosion resistance of duplex stainless steel in an industrial environment simulation solution using various electrochemical, electron backscatter diffraction analysis, and surface analysis methods. Electrochemical results show that under small deformation conditions (10 %), the corrosion current of S32304 duplex stainless steel decreases due to the coupling effect of the austenite phase with increased potential and the ferrite phase with decreased potential. However, due to the increased potential difference between the austenite and ferrite phases, the pitting corrosion resistance of the material decreases. Under large deformation conditions, the corrosion current of S32304 duplex stainless steel continuously increases but still remains lower than the corrosion current under undeformed conditions. The pitting potential of duplex stainless steel first decreases and then increases. When the deformation reaches 70 %, high-angle grain boundaries are formed in the austenite phase, leading to a sharp decrease in potential. The potential of austenite begins to be lower than that of ferrite, and the preferentially corroded phase changes from ferrite to austenite. The experimental results found that deformation does not affect the semiconductor properties of the passivation film of S32304 duplex stainless steel. The main components of its passivation film include iron oxides (FeO and Fe 2 O 3 ) and chromium oxides (Cr 2 O 3 and Cr(OH) 3 ).