Relationship between corrosion and nanoscale friction on a metallic glass

Metallic glasses are promising materials for micro-devices, where corrosion and friction limit their effectiveness and durability. We investigated nanoscale friction on a metallic glass in corrosive solutions after different immersion times using atomic force microscopy to elucidate the influence of corrosion on nanoscale friction. The evolution of friction upon repeated scanning cycles on the corroded surfaces reveals a bilayer surface oxide film, where the outer layer is removed by the scanning tip. Friction and adhesion after different immersion times in different solutions allow to compare the physicochemical processes of surface dissolution at the interfaces of the two layers. The findings contribute to the understanding of mechanical contacts with metallic glasses in corrosive conditions by exploring the interrelation of microscopic corrosion mechanisms and nanoscale friction.

Research Progress on Corrosion of Equipment and Materials in Deep-Sea Environment

The deep sea is the frontier of materials research in the 21st century. Owing to the particularity of pressure (15–120 MPa), hydrothermal temperature (90–400°C), and explosive fluid (strong H2S) in the deep-sea hydrothermal field environment, the research on the corrosion mechanism of service materials in this environment under the coupling action of many harsh factors is almost blank. It has become the bottleneck of equipment and material research and development for China to explore the deep sea. This paper reviews the research progress of corrosion mechanisms of deep-sea environmental materials at home and abroad, and forecasts the research trend and difficulties in this field, especially in the deep-sea hydrothermal field. At the same time, it points out the urgency of the construction of harsh environment materials platform and its relevance to the discipline construction of marine college.

Driving electrochemical corrosion of implanted CoCrMo metal via oscillatory electric fields without mechanical wear

Decades of research have been dedicated to understanding the corrosion mechanisms of metal based implanted prosthetics utilized in modern surgical procedures. Focused primarily on mechanically driven wear, current fretting and crevice corrosion investigations have yet to precisely replicate the complex chemical composition of corrosion products recovered from patients’ periprosthetic tissue. This work specifically targets the creation of corrosion products at the metal on metal junction utilized in modular hip prosthetics. Moreover, this manuscript serves as an initial investigation into the potential interaction between implanted CoCrMo metal alloy and low amplitude electrical oscillation, similar in magnitude to those which may develop from ambient electromagnetic radiation. It is believed that introduction of such an electrical oscillation may be able to initiate electrochemical reactions between the metal and surrounding fluid, forming the precursor to secondary wear particles, without mechanically eroding the metal’s natural passivation layer. Here, we show that a low magnitude electrical oscillation (≤ 200 mV) in the megahertz frequency (106 Hz) range is capable of initiating corrosion on implanted CoCrMo without the addition of mechanical wear. Specifically, a 50 MHz, 200 mVpp sine wave generates corrosion products comprising of Cr, P, Ca, O, and C, which is consistent with previous literature on the analysis of failed hip prosthetics. These findings demonstrate that mechanical wear may not be required to initiate the production of chemically complex corrosion products.

Anaerobic corrosion of carbon steel in compacted bentonite exposed to natural Opalinus clay porewater: Bentonite alteration study

Carbon steel is a potential canister material for the disposal of high-level radioactive waste in deep geological repositories in clays and clay rocks. Bentonite is considered as a potential backfill material for those multi-barrier systems. To predict the long-term performance and for safety assessment the knowledge of canister corrosion behavior is important. The corrosion products formed and mineralogically altered bentonite at the canister/bentonite interface can potentially provide an additional barrier against radionuclide migration. In-situ corrosion experiments were performed at the Mont Terri underground research laboratory. Coupons of carbon steel were embedded in Volclay MX-80 bentonite with controlled densities, installed in a borehole under simulated repository and anaerobic conditions and exposed to natural Opalinus clay porewater for a period up to 5.5 years (Smart et al., 2017). In the present study, the bentonite layer at the canister/bentonite interface was characterized by complementary microscopic and spectroscopic techniques (XPS, SEM-EDX, µXANES) under anoxic conditions. The interface revealed reddish-brown staining up to 2 mm depth into the bentonite in the zone adjacent to the steel in all three obtained samples. The XPS analysis revealed formation of sulfides at the interface consisting of iron and other trace metals present in the steel. The SEM-EDX analyses of the interface (embedded cross-cut with steel removed) showed different degrees of calcium enrichment in the bentonite adjacent to the metal for various samples. The µXRF analysis performed on the bentonite at the interface showed a scarce or distinct calcium-enriched rim up to 100 µm into the bentonite and iron-enriched rim depending on the sample (one sample in Fig. 1), while µXANES analysis revealed formation of iron silicate compounds in the reacted reddish-brown zone. The iron appears to displace calcium from the interlayer sites in montmorillonite. The calcium then precipitates at the interface as calcite. The extent of this process seems to be strongly related to the bentonite density. The steel coupon was removed prior to embedding, with the location marked as resin in Fig. 1. A line scan from the edge towards the bulk bentonite did not indicate any systematic gradient in the Fe2+/3+ ratio. The formation of mixed Fe2+/3+ silicate compounds appears to be heterogeneous. This work contributes to an increasing understanding of steel corrosion mechanisms in clay, which can improve the robustness of canister lifetime predictions.

2021 F.N. Speller Award Lecture: CORROSION MECHANISMS OF STEEL AND COPPER IN ENGINEERING APPLICATIONS

The main research lines of the scientific career of the author are herein, exemplified including corrosion and protection mechanisms of steel in different environments, and copper corrosion in climate systems. Stainless steel (SS) due to its high corrosion resistance is a material widely used for many engineering applications. Impedance measurements were performed on polarized at the pitting region AISI 304 SS in environment containing chloride at 25 and 60 ºC. The transfer function was analyzed indicating instability system, corroborating results obtained using the Kramers-Kronig transforms. Steel reinforcement has been studied for structural applications in civil engineering and architecture using cementitious materials, alkaline activated fly ash (AAFA), alternative to the ordinary Portland cement (OPC). The main compounds used as corrosion inhibitors in concrete were included. Carbon steel embedded in OPC mortar was tested in the presence of phosphates as corrosion inhibitors. An organic lacquer was applied to tinplate with titanium-passivation treatment and, in general, acceptable and comparable behavior was obtained to conventional chromium-passivated lacquered tinplate. Copper is also a material used in many engineering applications. Ant-nest corrosion of copper tubing in air-conditioning systems has been reported. The copper corrosion rate occasioned by carboxylic acids, formic, acetic, propionic and butyric, was included.

Untangling competition between epitaxial strain and growth stress through examination of variations in local oxidation

Understanding oxide formation during corrosion of high-performance alloys in harsh environments is of great fundamental and industrial interest and provides a potential route for reducing the significant annual cost of corrosion globally. However, corrosion mechanisms involve multiple length scales, requiring a multitude of advanced experimental procedures. Here, we use correlated high resolution electron microscopy techniques over a range of length scales, combined with crystallographic modelling to show that there is a clear competition between epitaxial strain and growth stress during oxidation. The degree to which these competing mechanisms operate is shown to depend on the orientation of the substrate grains leading to significant local variations in oxide microstructure and thus protectiveness, even across a single sample. This leads to the possibility of tailoring substrate crystallographic textures in order to promote gradual phase transformation and the development of stress driven, well-oriented protective oxides, and so to improving overall corrosion performance.

Corrosion processes in battery systems based on non-aqueous electrolytes (a review)

The article presents some new results of the studies of corrosion processes in lithium battery systems with non-aqueous electrolytes. The following processes are considered: electrochemical corrosion of positive and negative electrodes, corrosion of structural materials, and electrochemical and chemical decomposition of non-aqueous electrolytes, which occurs simultaneously with the main electrochemical process. The main attention is paid to the role of corrosion processes on current collectors of current sources. Corrosion processes on aluminum current collector and stainless steel current collector for positive electrodes of lithium batteries are particularly considered. An important role of corrosion in the degradation of the lithium battery is emphasized. Case studies on corrosion in positive electrodes and lithium electrode are mentioned. Considerable attention is paid to the contact corrosion in aircraft, with an emphasis on the need for further studies of this process. The proposed corrosion mechanisms are considered.