Mechanism of protective film formation during CO_2 corrosion of X65 pipeline steel

Electrochemical techniques, X-ray diffraction （XRD）, and scanning electron microscopy （SEM） were applied to study the corrosion behaviors of X65 steel in static solution with carbon dioxide （CO2） at 65℃. The results show that iron carbonate （FeCO3） deposits on the steel surface as a corrosion product scale. This iron carbonate scale acts as a barrier to CO2 corrosion, and can reduce the general corrosion rate. The protection ability of the scale is closely related to the scale morphological characteristics.

Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg-3Zn-xNd Alloys

The phosphate protective film and micro-galvanic corrosion of biological Mg-3Zn-xNd (x = 0, 0.6, 1.2) alloys were investigated by scanning and transmission electron microscopy, quasi-in-situ observation, scanning Kelvin probe force microscopy (SKPFM) and electrochemical tests. The results revealed the Mg-Zn-Nd phases formed in Mg-3Zn alloy contained with Nd. Adding Nd resulted in a significant decline in the cracks of the phosphate protective film and micro-galvanic corrosion of alloys, which were recorded by quasi-in-situ observation. In addition, the Volta potential difference of Mg-Zn-Nd/α-Mg (~ 188 mV) was lower than MgZn/α-Mg (~ 419 mV) and Zn-rich/α-Mg (~ 260 mV), and the corrosion rates of alloys markedly decreased after the addition of 0.6 wt% Nd. The improvement in corrosion resistance of Nd-containing alloys was mainly attributed to the following: (i) the addition of Nd reduced the Volta potential difference (second phases/α-Mg);(ii) the phosphate protective film containing Nd_(2)O_(3) deposited on the surface of the alloys, effectively preventing the penetration of harmful anions.

A Protective Film Produced by Whey Protein for Photonic Crystals： Inspired by the Epidermis Structure of Chameleon

Self-assembly technology of sub-micrometer-sized colloidal particles is the most promising approach for the preparation of large-area Photonic Crystals （PCs）. However, PCs obtained by this method are facile to be destroyed by external factors such as friction, impact, and pollutants. The highly keratinized epidermis of chameleon skin acts as a protective role for the dermis with photon ceils of the tunable band-gap structure. Inspired by the epidermis structure of chameleon, we use whey protein to develop a sort of protective film on the surface of artificially synthesized PCs. The film possesses positive mechanical properties that make the PCs friction and impact re- sistant. In addition, favorable resistance to water and C02 could prevent PCs from being destroyed by pollutants. Consequently, PCs with protective film are well preserved when subjected to external factors （such as friction） and the optical properties of the PCs are successfully maintained, that may significantly promote the utilization of PCs in optical devices.

Magnetic field enhanced radio frequency ion source and its application for Si-incorporation diamond-like carbon film preparation

Various ion sources are key components to prepare functional coatings,such as diamond-like carbon(DLC)films.In this article,we present our trying of surface modification on basis of Si-incorporation diamond-like carbon(Si-DLC)produced by a magnetic field enhanced radio frequency ion source,which is established to get high density plasma with the help of magnetic field.Under proper deposition process,a contact angle of 111°hydrophobic surface was achieved without any surface patterning,where nanostructure SiC grains appeared within the amorphous microstructure.The surface property was influenced by ion flow parameters as well as the resultant surface microstructure.The magnetic field enhanced radio frequency ion source developed in this paper was useful for protective film applications.

In situ formed cross-linked polymer networks as dual-functional layers for high-stable lithium metal batteries

Lithium-metal anodes(LMAs)have been recognized as the ultimate anodes for next-generation batteries with high energy density,but stringent assembly-environment conditions derived from the poor moisture stability dramatically hinder the transformation of LMAs from laboratory to industry.Herein,an in situ formed cross-linked polymer layer on LMAs is designed and constructed by a facile thiol-acrylate click chemistry reaction between poly(ethylene glycol)diacrylate(PEGDA)and the crosslinker containing multi thiol groups under UV irradiation.Owing to the hydrophobic nature of the layer,the treated LMAs demonstrate remarkable humid stability for more than 3 h in ambient air(70%relative humidity).The coating humid-resistant protective layer also possesses a dual-functional characterization as solid polymer electrolytes by introducing lithium bis(trifluoromethanesulfonyl)imide in the system in advance.The intimate contact between the polymer layer and LMAs reduces interfacial resistance in the assembled Li/LiFePO_(4)or Li/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)full cell effectively,and endows the cell with an outstanding cycle performance.

Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered in- termetallic particles were examined by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） after pretreatment. The anodic film was investigated by transmission electron microscopy （TEM）, and its corrosion resistance was analyzed by electrochemical impedance spectroscopy （EIS） and Tafel polarization in NaC1 solution. The results show that the size of A1-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the an- odic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

Suppressing by-product via stratified adsorption effect to assist highly reversible zinc anode in aqueous electrolyte

The development of promising zinc anodes mainly suffers from their low plating/stripping coulombic efficiencies when using aqueous electrolyte,which are mainly associated with the interfacial formation of irreversible by-products.It is urgent to develop technologies that can solve this issue fundamentally.Herein,we report an artificial Sc_(2)O_(3) protective film to construct a new class of interface for Zn anode.The density functional theory simulation and experimental results have proven that the interfacial side reaction was inhibited via a stratified adsorption effect between this artificial layer and Zn anode.Benefiting from this novel structure,the Sc_(2)O_(3)-coated Zn anode can run for more than 100 cycles without short circuit and exhibit low voltage hysteresis,and the coulombic efficiency increases by 1.2%.Importantly,it shows a good application prospect when matched with two of popular manganese-based and vanadium-based cathodes.The excellent electrochemical performance of the Sc_(2)O_(3)-coated Zn anode highlights the importance of rational design of anode materials and demonstrates a good way for developing high-performance Zn anodes with long lifespan and high efficiency.

Corrosion of candidate materials for supercritical water-cooled reactor

Supercritical water reactor(SCWR) was proposed as a GenerationⅣconcept for building large capacity nuclear power plants.Comparing with the present GenerationⅡandⅢlight water reactors,SCWR possesses great advantages of 10%higher efficiency,simpler system design,better sustainability,and so on. However,the selection of materials for fuel cladding and reactor internals of SCWR is facing a great challenge. Corrosion in supercritical steam is of the first important issue to be solved to meet the stringent requirement of the reactor internal components.Corrosion screening tests were conducted on candidate materials for nuclear fuel cladding and reactor internals of supercritical water reactor(SCWR) in static and re-circulating autoclave at the temperatures of 550,600 and 650℃,pressure of about 25 MPa,deaerated or saturated dissolved hydrogen(STP). Nickel base alloy type Hastelloy C276,austenitic stainless steels type 304NG,AL-6XN,HR3C.NF709 and SAVE 25,ferritic/martensitic(F/M) steel type P92,P122 and 410,and oxide dispersion strengthened steel MA 956,are tested.This paper presents corrosion rate,and focuses on the formation and breakdown of corrosion oxide film,and proposes the future trend for the development of SCWR internal structure materials.

Synergistic lubricating effect of graphene/ionic liquid composite material used as an additive

We prepared a graphene/ionic liquid(G/IL)composite material by the hybridization of G and an IL for use as a lubricating oil additive.The friction coefficient and wear volume of a base oil containing 0.04 wt%of the G/IL composite was reduced by 45%and 90%,respectively.Furthermore,the base oil containing the G/IL composite exhibited better lubricating properties than the base oil containing G,IL,or a mixture of IL and G at the same mass fraction.A synergistic lubrication mechanism was also revealed.The G/IL composite was adsorbed and deposited on the wear surface,forming a more ordered protective film and a unique tribochemical reaction film during rubbing.Therefore,the G/IL composite exhibited the synergistic lubricating effects of G and IL,which significantly improved the lubricating performance of the base oil.This study also suggested a way to limit the out-of-plane puckering of G at the macroscale.

Mitigating side reaction for high capacity retention in lithium-sulfur batteries

Li-S batteries have shown great potential as secondary energy batteries.However,the side reaction between Li anodes and polysulfides seriously limited their practical application.Herein,the artificial protective film,which is consisted of Li-Nafion and TiO_(2),was designed and successfully prepared to achieve a corrosion-resistant Li anode in Li-S battery.In the composite protective film,the Li-Nafion could efficiently prevent the contact between Li anodes and polysulfides,and the incorporation of TiO_(2)nanoparticles into the Nafion could significantly increase the ionic conductivity and mechanical strength of the protective film.Li-Li symmetric cells with an optimal artificial protective film exhibited an extended cycle-life of 750 h at a current density of 1 mA/cm^(2)in Li_(2)S_(8)electrolyte.Moreover,the Li-S full battery with an optimal protective Li anode exhibited higher capacity retention of 777.4 mAh/g after 100 cycles at 0.1 C as well as better rate performance than the cell with a pure Li anode.This work provides alternative insights to suppress the side reaction for Li-S batteries with high capacity retention.