The effect of small amounts of chalcogen alloying elements (S, Se and Te) on the oxidation resistance (OR) of Cu has been investigated at 300–800 °C in 0.1 MPa oxygen atmospheres. Compared to pure copper, the addition of S, Se and Te could effectively improve the OR below 600 °C mainly owing to the chalcogen-element inclusions which hinder the diffusion of Cu. However, it becomes weak above 800 °C. In contrast, the failure at 800 °C is associated with the absence of those inclusions. The results are discussed in detail by the thermodynamic methods.
This study reports a facile method to prepare silica-coated graphene oxide nanoflakes (SiO2–GO). Results of X-ray diffraction analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy reveal that silica was successfully coated on the GO flakes. The effect of SiO2–GO nanosheets on the corrosion protection and barrier performance of the epoxy coating was investigated in this work. Results indicate that the mechanical properties of all coatings added with GO and SiO2–GO were significantly improved. Furthermore, electrochemical impedance and Tafer polarisation curves showed that added 0.5 wt% SiO2–GO nanoflakes into zinc-rich epoxy coating could greatly improve the anti-corrosion performance of the sample, and the corrosion protection efficiency increased from 67.01 to 99.58%.
The relatively limited data for the corrosion and pitting of high nickel alloys are reviewed herein and time-dependent trends developed for exposures in marine and atmospheric environments. Data sets for average or ‘uniform’ corrosion losses that are sufficiently extensive show topological consistency with the bimodal functional model previously observed for steels and various copper-nickel and aluminum alloys. Trends for localized corrosion (pit or crevice depth) plateau after earlier rapid growth over several years. The present observations add support to the concept that there is a change in corrosion behavior with extended temporal exposure and that this is generally consistent for many alloys. They also reinforce that shorter-term observations of maximum corrosion or pit depth usually is unsuited for extrapolation to, and prediction of, longer-term corrosion as typically important for practical infrastructure applications.
The state of art in alternating current (AC)-induced corrosion in pipelines is reviewed. Growing pipeline networks and their co-location with high-voltage (HV) transmission networks have brought into focus the issue of induced AC corrosion on the pipeline networks. Induced AC corrosion may quickly and severely affect the integrity of pipeline networks, especially considering that a number of such pipelines are transporting huge quantities of hazardous fluids. Any breach in pipeline integrity due to AC corrosion may result in disastrous consequences. In the last 30 years, it has been established that the induced AC corrosion can affect the buried pipeline integrity severely. During operations, the resistive as well as inductive coupling with transmission lines pose a significant risk of pipeline corrosion. The literature is reviewed to put together various issues and factors responsible for AC-induced corrosion in pipelines. The various publications on induced AC corrosion are reviewed to identify characteristics of AC-induced corrosion and major factors that determine the severity and impact of AC-induced corrosion. The areas have been identified wherein scope exists for additional studies on AC corrosion.
Biomaterials play a significant role in revolutionizing human life in terms of implants and medical devices. These materials essentially need to be highly biocompatible and inert to the human physiological conditions. This paper provides an in-depth, critical and analytical review on the previous research work and studies conducted in the field of metals and alloys used as implant materials including stainless steel, titanium and its alloys, cobalt chromium and others. Since the manufacturing of medical implants relies on selected grades of biomaterials, metals play a significant role in biomaterials market. This paper focuses on highlighting some basic principles of manufacturing implant materials underlying composition, structure and properties of these materials. Finally, attention is also given to the role of these implant materials on the betterment of human life in terms of their failures by critically analysing these materials.
The proposed work aims to improve the comprehensive properties of the composite coating by adding different content of graphene into the coating solution. Firstly, the formulation of the coating solution was determined by the L16(45) orthogonal test. Secondly, the conventional properties of the coating were tested using the optical microscope and micro-vickers hardness tester. Thirdly, the corrosion resistance of the coating was tested by the rapid ammonium nitrate corrosion test, immersion test, and neutral salt spray test. The changes of the microstructure and composition of the coating before and after corrosion were observed and analyzed using the scanning electron microscope, energy dispersive spectrometer, X-ray diffractometer, and Raman spectrometer, and the Tafel polarization curves and electrochemical impedance spectroscopy of the composite coatings with different graphene contents were tested by electrochemical experiments. The results show that the hardness of the coating increases with the increase in the content of graphene. Graphene intercalates between zinc and aluminum powders in a flaky structure, which reduces the appearance of voids and enhances the protection of chromium-free Dacromet coatings, slows down the penetration of electrolyte solutions and effectively slows down the penetration of corrosive media. The addition of a small amount of graphene can increase the corrosion potential and decrease the corrosion current density of the chromium-free Dacromet coating, the Nyquist low frequency of the coating is higher in the same period and the salt spray resistance of the coating is the best.
The work introduces a numerical external damage prediction method for buried pipelines. The external pitting initiation and corrosion rate of oil or gas pipelines are affected by pipeline age, physicochemical properties of soils and cathodic protection performance as well as coating conditions. Before developing the damage prediction model, the influencing factors were weighed by grey relational analysis, and then the relationship among the pitting depth and the influencing factors of external corrosion was established for corrosion damage prediction through artificial neural network (ANN). Subsequently, the established ANN was applied to predict corrosion damage and corrosion rate for some selected cases, and the neural network prediction model was analyzed and compared to another corrosion rate prediction models. Through the analysis and comparison, a few opinions were proposed on the external corrosion damage prediction and pipeline integrity management.
In this paper, the principle and application of atomic force microscopy (AFM) are reviewed and discussed in detail. Several scientific papers are used to find out data about AFM. The obtained scientific results are summarized to get a better understanding of the method and its application. The application of AFM for corrosion study is discussed in detail, and the possible conclusion is made based on the results of several articles. It is summarized that AFM is an important method to determine the surface phenomena of metal corrosion.
Biofilms cause huge economic loss to the industry through corrosion. A deeper understanding of how biofilms form, develop and interact will help to decipher their roles in promoting and inhibiting corrosion, thus in controlling it. The present review explores most mechanisms of biofilm development and maintenance with particular emphasis on the roles of the biomolecules characteristic of biofilms, including exopolysaccharides (EPSs), proteins/enzymes, lipids, DNA and other metabolites in the corrosion process. These biomolecules play a significant role in the electron transfer process resulting in corrosion induction and inhibition. Microbial attachment, biofilm formation, the EPS matrix and both positive and negative effects by specific biofilm-forming genes all play roles in the electron transfer process. The current review describes these roles in detail. Although challenging to understand and control, the potential of biomolecules in the corrosion process is huge, and the coming decades will witness significant progress in the field. As well as discussing the technologies available for investigating corrosion induction and its inhibition, we also point to gaps in this knowledge.