Surface Protection Methods against Fretting Fatigue for TC11 Titanium Alloy

The influence of various surface coatings, including flame sprayed Cu、 plasma sprayed Cu Ni In、 exploding sprayed WC/Co Ⅰ and plasma sprayed WC/Co Ⅱ, on fretting fatigue resistance for TC11 titanium alloy at 20℃ and 500℃ is studied. The results show that the plasma sprayed WC/Co Ⅱ coating has good protection performance and makes the fretting fatigue strength of TC11 titanium alloy raise 40% at both 20℃ and 500℃. The fretting fatigue strength of TC11 alloy with Cu coating is increased about 62% at 20℃, but the protection performance at 500℃ is not so good as that at 20℃.

Carbonation Resistance of Hybrid NanoSiO_(2) Modified Cementitious Surface Protection Materials

Hybrid nanoSiO_(2) (HNS) modified cement pastes were explored as a kind of surface protection material (SPM).The carbonation resistance and mechanical properties of SPMs coated samples were tested.Thermogravimetric analysis (TGA),X-ray diffraction (XRD),scanning electron microscope (SEM),and mercury intrusion porosimetry (MIP) were further employed to evaluate the chemical composition and microstructure characteristics of SPM.Besides,thermodynamic modeling was adopted to simulate the changes in the phase assemblages of SPM under the carbonation process.The results showed that SPM with 1 wt% HNS could effectively enhance the carbonation resistance.The incorporation of HNS could densify the microstructure and refine the pore structure.Moreover,the thaumasite can be stable at ambient temperature with the addition of HNS,which is beneficial to maintain alkalinity under the carbonation process.

Lithium metal anodes: Present and future

Commercial lithium-ion(Li-ion)batteries based on graphite anodes are meeting their bottlenecks that are limited energy densities.In order to satisfy the large market demands of smaller and lighter rechargeable batteries,high-capacity metallic Li replacing low-specific-capacity graphite enables the higher energy density in next-generation rechargeable Li metal batteries(LMBs).However,Li metal anode has been suffering from dendritic problems,interfacial side reactions,volume change and low Coulombic efficiency.Therefore,performance enhancements of Li metal anodes are rather important to realize the high energy density characteristic of metallic Li.In this review,the annoying Li dendrite growth,unstable reaction interface and practical application issues of Li metal anodes are summarized and detailedly discussed to understand the current challenges concerning Li metal anodes.For overcoming such remaining challenges,the corresponding strategies and recent advances are covered and categorized.Finally,we discuss future opportunities and perspectives for developing high-performance Li metal anodes.

The ancient Chinese casting techniques

In the course of Chinese civilization,which lasted more than 5,000 years,casting production has made a huge contribution.In this paper,some representative metal castings were presented.According to their forming techniques,they can be grouped into stone mould casting,clay mould casting,ablation casting,lost wax casting,stack casting,permanent mould casting,sand casting,etc.According to their materials,they can be categorized into tin bronze,bimetallic bronze,malleable cast iron,ductile cast iron,brass,cupronickel alloy (Packtong),etc.According to their surface decorative techniques they can be devided into gem inlay,gilding,gold and silver inlay,copper inlay,engraved decoration,surface tin-enrichment,mother-of-pearl inlay,burnished works with gold or silver inlay,surface coloring and cloisonné enamel,etc.

The Tribological Properties of the Hot-extrusion Nylon Coating in the Oil Well Environment

The friction and wear properties of the nylon coating,prepared by hot-extrusion, used to protect the surface of the flexible continuous sucker rod were studied by using a pin-on-disc wear tester in the simulated oil well environment.The effects of sliding speed and load were considered.The wear mechanism was also studied by using a scanning electron microscope (SEM).The result shows that the friction coefficients of both kinds of materials,JKPA and ZZ7024B,used to protect the surface of the flexible continuous sucker rod decrease with sliding speed increase,but change little with load increase in the simulated oil well environment.The value of friction coefficient of ZZ7024B is smaller than that of JKPA.The minimum value of friction coefficient of ZZ7024B is about 0.05.The wear volume of ZZ7024B is smaller than that of JKPA under the same conditions of experimentation.

Sol-Gel Coating with 3-Mercaptopropyltrimethoxysilane as Precursor for Corrosion Protection of Aluminium Metal

Sol—gel coatings offer a number of advantages over other methods of protection for metallic materials.In the present work,3-mercaptopropyltrimethoxysilane（MPTS） was used as the precursor for sol—gel coating on aluminium metal.The gelation of MPTS sol—gel was characterized by Fourier transform infrared spectroscopy（FT-IR） studies.The formed film was found to be stable up to 350 ℃ as evident from thermogravimetric analysis.X-ray diffraction study and scanning electron microscopy supported the formation of MPTS coating on aluminium surface while the characterization of the coating was done by FT-IR studies.The corrosion inhibition potential of the sol—gel coatings on metal in 3.5%（w/v） of NaCI solution was assessed as a function of different concentrations of MPTS using electrochemical polarization and impedance measurements.The corrosion inhibition efficiency was found to increase with increasing MPTS concentration.The results of the study unravel the use of MPTS as a precursor in the formation of sol—gel coating over aluminium surface so as to protect the metallic surface from corrosion in neutral environment.

Anti-corrosive, weatherproof and self-healing polyurethane developed from hydrogenated hydroxyl-terminated polybutadiene toward surface-protective applications

Self-healing polyurethane(PU)faces aging deterioration due to active dynamic bonds,which remain a challenging predicament for practical use.In this work,a novel strategy is developed to address this predicament by leveraging the hydrophobicity and gas barrier of hydrogenated hydroxyl-terminated polybutadiene(HHPB).The dynamic oxime-carbamate bonds derived from 2,4-pentanedione dioxime(PDO)enable the elastomer to exhibit surface self-repairability upon applied mild heat and achieve~99.5%mechanical self-healing efficiency.The mechanical properties remained nearly intact after 30-d exposure to thermal oxidation,xenon lamp,acids,bases,and salts.Gas permeability,positron annihilation lifetime spectroscopy(PALS),and contact angle measurements reveal the pivotal role of gas barrier,free volume,and hydrophobicity in blocking undesirable molecules and ions which effectively protects the elastomer from deterioration.HHPB-PU also exhibits excellent adhesion to steel substrate.The shear strength achieves(3.02±0.42)MPa after heating at 80°C for 4 h,and(3.06±0.2)MPa after heating at 130°C for 0.5 h.Regarding its outstanding anti-corrosive and weatherproof performances,this self-healable elastomer is a promising candidate in surface-protective applications.

Anode corrosion in aqueous Zn metal batteries

Given their low cost and intrinsic safety,aqueous Zn metal batteries(AZMBs)are drawing increasing attention in the field of smart grids and large-scale energy storage.However,the Zn metal anode in aqueous electrolyte suffers from a critical issue,corrosion,which must be fully addressed before the practical implementation of AZMBs.In this perspective,the mechanisms of aqueous Zn metal anode corrosion in both alkaline and neutral electrolytes are compared and discussed.The methods for studying the corrosion processes and the strategies for Zn corrosion protection in AZMBs are also summarized.Finally,some expectations about potential research directions for making corrosion-resistant AZMBs a commercial reality are provided.

Tailoring the LiNbO_(3)coating of Ni-rich cathode materials for stable and high-performance all-solid-state batteries

The research and development of advanced nanocoatings for high-capacity cathode materials is currently a hot topic in the field of solid-state batteries(SSBs).Protective surface coatings prevent direct contact between the cathode material and solid electrolyte,thereby inhibiting detrimental interfacial decomposition reactions.This is particularly important when using lithium thiophosphate superionic solid electrolytes,as these materials exhibit a narrow electrochemical stability window,and therefore,are prone to degradation during battery operation.Herein we show that the cycling performance of LiNbO_(3)-coated Ni-rich LiNi_(x)Co_(y)Mn_(z)O_(2)cathode materials is strongly dependent on the sample history and(coating)synthesis conditions.We demonstrate that post-treatment in a pure oxygen atmosphere at 350℃results in the formation of a surface layer with a unique microstructure,consisting of LiNbO_(3)nanoparticles distributed in a carbonate matrix.If tested at 45℃and C/5 rate in pellet-stack SSB full cells with Li_(4)Ti_(5)O_(12)and Li_(6)PS_(5)Cl as anode material and solid electrolyte,respectively,around 80%of the initial specific discharge capacity is retained after 200 cycles(~160 mAh·g^(−1),~1.7 mAh·cm^(−2)).Our results highlight the importance of tailoring the coating chemistry to the electrode material(s)for practical SSB applications.