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In view of the technology bottleneck of the adhesion failure of traditional functional protective coatings on the smoother surface of precise parts served in the marine atmosphere, a room-temperature-curable fluoropolymer/polyurethane (denoted as RFP) polymer composite coating of 20–30 μm is prepared on the metal substrates. Static pull-off and dynamic friction test methods are used to evaluate the interface adhesion of the coating. The coating shows superior adhesive strength of 18–24 MPa on a variety of metal substrates with a wide range of surface roughness (Ra = 0.1–1.6 μm). The friction coefficient of the coating surface is about 0.05–0.08, and the wear life is up to 9–12 km/μm. Furthermore, the adhesion strength of the coating remains 12–14 MPa after 1600 h of salt spray while the wear life of the coating keeps 3–9 km/μm after 720 h of salt spray. The influences of surface roughness (R a) , surface free energy (γ O x i d e ), surface potential (φ O x i d e) of the metal substrates and the bonding force at substrate-coating interface on the adhesive energy (E a d h.) are discussed, and the mechanism of "physical-chemical-surface" synergetic enhanced interface adhesion is proposed. The RFP coating is used as the intermediate layer for traditional PU and EP coatings to improve their adhesion on smooth aluminum substrate from 1.39 MPa to 17.5 MPa (increased by 1260 %). Thus, the polymer coating has the potential to provide technical support for the development of long-term anticorrosive coating technology for precision components of marine high-tech equipment. • The RFP polymer coating showed adhesive strength of 18-24 MPa on metals with surface roughness (Ra) about 0.1-1.6 μm. • Static pull-off and dynamic friction tests were integrated to evaluate the interface adhesion and reveal its mechanism. • The adhesion remained 12-14 MPa after 1600 h of salt spray and the wear life reached 3-9 km/μm after 720 h of salt spray. • Ra , γ O x i d e , φ O x i d e E a d h. .A mechanism of "physical-chemical-surface" synergetic enhanced interface adhesion has been innovatively proposed. • The RFP coating shows promise in addressing adhesion for functional coatings on smoother substrates or primers. [ABSTRACT FROM AUTHOR]

At present, mechanical de-rust technologies (grinding and sandblasting) are forbidden in some specific engineering fields such as oil drilling platforms equipped with storage tanks, chemical pipelines and power transmission system. It is passivated rust with cracks and holes that is known to hinder adhesion between anticorrosive coating and metallic substrate. This paper reported an organic-organic fluoropolymer/polyurethane (PF/PU) polymer coating, showing strong adhesion strength of 18.2 MPa with rust and 16.5 MPa after 240 h salt spray test, which is 2–3 times higher than conventional inorganic-organic epoxy (EP) coating (6–9 MPa). The PF/PU coating have protected rusted chemical pipelines from marine atmosphere corrosion for 3 years. Due to the micro/nano-channels in the rust layer, PF/PU precursor of appropriate surface tension and viscosity spontaneously adsorb/adhesive, wet, spread and fill with the channel by capillary force. A composite polymer-rust‑iron substrate with three-dimensional interpenetrating network is fabricated via mechanical interlocking/chemical bonding and PU cross-linking. The physical model of "capillary filling of polymer coating in micro/nano-rust-channels (μ/nRCs)" is proposed and demonstrated by "spinning by air cushion escaping" phenomenon as one end of the channel sealed. Based on researches and practical engineering applications on chemical pipelines and subway/railway tracks, a new polymer coating technology with rust towards on-site maintenance has been developed, aiming to realize the surface function remanufacturing of high-tech equipment served in severe corrosive medium and improve reliability of the equipment. [Display omitted] • A PF/PU polymer coating was designed to fabricate a polymer-rust‑iron with three-dimensional interpenetrating network. • The PF/PU coating with rust showed strong adhesion strength of 18.2 MPa, even 16.5 MPa after exposed to salt spray for 240 h. • A physical model of "capillary filling of polymer coating in micro/nano-rust-channels (μ/nRCs)" is proposed. • "Spinning by air cushion escaping" phenomenon is found at the rust-coating interface with the channel outlets sealed. • Based on engineering applications, a new polymer-coating-technology with rust towards on-site maintenance has been developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • An MP@PDA- E. coli -based colorimetric method was developed to detect L-Trp. • The method exhibited excellent chiral selectivity for L-Trp. • The method was successfully applied to detect L-Trp in millets. • The detection of percentage of L-Trp in the enantiomeric mixture can be realized. • A potable device was fabricated to make detecting L-Trp more convenient. Chiral recognition of enantiomers has always been a thorny issue since they exhibit the same properties under an achiral environment. Herein, polydopamine-functionalized magnetic particles (MP@PDA) were synthesized to immobilize the genetically engineered bacterium Escherichia coli DH5α (MP@PDA- E. coli). L-tryptophan (Trp) instead of D-Trp can be stereo-specifically degraded by tryptophanase in E. coli. The degradation product indole reacts with 4-dimethylaminobenzaldehyde to generate a rose-red adduct. Thus, MP@PDA- E. coli was employed to fabricate a chiral colorimetric method for chiral recognition and determination of L-Trp. The method averts the purification of tryptophanase. More importantly, tryptophanase demonstrates excellent enantioselective ability for L-Trp. The method can not only quantitatively detect L-Trp but also realize the measurement of the enantiomer percentage in the enantiomeric mixture. The feasibility was verified by detecting L-Trp in millet samples from different origins. Furthermore, a portable device was fabricated to make the method more convenient. [ABSTRACT FROM AUTHOR]

With coupled mechanical-chemical field, the predominant role of fatigue crack evolution and tribo-chemistry on Si-DLC films were investigated under different relative humidity. Results show that incorporating Si stabilized friction interface and induced lubricating carbonaceous material transfer (0.053 under 20% RH), but the lubricating effect was deteriorated (0.12) by the iron oxide products on sliding shear stress. Furthermore, Si element aggravate overall wear rates than DLC film. Increasing relative humidity was beneficial to lowering wear rates of films with lower Si content, but aggravated the wear rates of films with higher Si content. The predominant role of tribo-chemistry on the friction coefficient (COF) was confirmed, meanwhile, critical impact of fatigue cracks evolution on surface wear is worse than that of tribo-chemistry. • Incorporating Si induced lubricating carbonaceous transfer, but the iron oxide products deteriorated lubricating effect. • Increasing relative humidity reduced wear rates of lower Si films, but aggravated the wear rates of higher Si films. • The fatigue cracks evolution of Si-DLC films was consistent with the increasing wear rates of Si-DLC films. [ABSTRACT FROM AUTHOR]

In order to study the influence of different guide vane angle variation on performance characteristics of reactor coolant pump (RCP) during idling process, the external characteristics of RCP model with five different guide vane angles at idling process state were analyzed. Radial force characteristics and blade load characteristics of RCP were analyzed. The results show that the head and torque changes of pump with different guide vane angles in different idle period are consistent. The head of DY1model (Guide vane angle increases sharply first and then decreases gently, which convexity is large) is the highest and torque is small. The head drop rate of DY5 model (Guide vane decreases first and then increases, and the concavity is large) is the highest and torque is the largest. With the idling, the radial force of impeller and guide vane decreases gradually. The radial force of DY5 model impeller is small and the fluctuation range is weak. The radial force of DY4 model (Guide vane shows concavity change with gentle increase) impeller before idling is the largest. In the nonlinear transition of idle period, the total radial force of DY4 model is 235 N when idling for 32 s, which is nearly 30 times lower than that before idling, and the radial force decreases the most. In different idling periods, the radial force amplitude of guide vane of DY5 model is the largest, and the radial force decrease amplitude of guide vane of DY4 model is the largest in the whole idling period. The impeller blade load of DY4 and DY5 model pumps with concavity guide vane angle change law is significantly higher than that of other model pumps after the relative position of streamline is 0.6. When the relative position of the guide vane along the streamline direction is less than 0.5, the load fluctuation of the guide vane of each model pump is large. When the relative position is greater than 0.5, the blade load fluctuation is relatively small. [ABSTRACT FROM AUTHOR]

Nitrogen ion implantation and AlN/MoS 2 –phenolic resin duplex coating are designed to improve wear and corrosion resistance of magnesium alloys. The microstructure and tribocorrosion behaviors of as-fabricated coatings are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), tribocorrosion and electrochemical tests. Studies show that Cl ions induce severe corrosion degradation of magnesium alloy during the tribocorrosion test. MoS 2 –phenolic resin coating has two phase composite structure consisting of MoS 2 crystalline and phenolic resin, but this coating shows poor tribocorrosion resistance because force–corrosion synergy interaction accelerates the degradation process. The introduction of nitrogen ion implantation and AlN interlayer remarkably retards the corrosion degradation process of magnesium alloy. AlN/MoS 2 –phenolic resin duplex coating exhibits better tribocorrosion resistance. These present results indicating that gradient duplex coating might be a good candidate as protective coating in engineering applications of magnesium alloys. [ABSTRACT FROM AUTHOR]

A novel ion implantation and Al/AlN/CrAlN/CrN/MoS2 gradient duplex coating was used to improve the wear-corrosion synergy performance of AM60 magnesium alloy. The wear and corrosion behaviors of the as-deposited gradient duplex coating were subsequently investigated. The results showed that the gradient duplex coating has excellent wear resistance with the wear rate of 2.31 × 10−6 mm3/Nm, which is far below compared to that of the uncoated magnesium alloy of about 3.15 × 10−4 mm3/Nm. The introduction of intermediate layers between the top MoS2 layer and magnesium alloy substrate remarkably improved the magnesium alloy's load bearing capacity. The hardness and modulus of the Al/AlN/CrAlN/CrN intermediate layer was 20 and 7 times larger than that of the uncoated magnesium alloy, respectively. In addition, the corrosion resistance of the magnesium alloy with the gradient duplex coating was also enhanced with the corrosion current density, which decreased from 1.25 × 10−5 A/cm2 to 6.19 × 10−7 A/cm2. The present work provided a feasible strategy to fabricate wear-corrosion resistant coating via component and structure gradient design. [ABSTRACT FROM AUTHOR]