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Corrosion inhibitors are widely used because they have the characteristics of trace and high efficiency， can prevent metal corrosion，while maintaining the physical and mechanical properties of the metal unchanged， and easy to use.Traditional metal corrosion inhibitors have poor biodegradability， toxicity and are easy to cause environmental pollution.Based on the concepts of environmental protection， sustainable development and green chemistry， the use of traditional metal corrosion inhibitors has been severely restricted， and the research on corrosion inhibitors is gradually shifting to environmentally friendly substances.In this paper， green environmental protection corrosion inhibitors were divided into single system corrosion inhibitors and compound system corrosion inhibitors， and the research progress in recent years were reviewed.Furthermore， the advantages and disadvantages of various types of corrosion inhibitors were classified and summarized， and the current status and research direction of environmentally friendly corrosion inhibitors were prospected.

Deposition pressure is an important process parameter for coating preparation. To study its influence on the microstructure, mechanical properties and high-temperature oxidation resistance of AlCrTiSiN nanocomposite coatings, two types of AlCrTiSiN nanocomposite coatings were prepared using RF magnetron sputtering and pulse DC magnetron sputtering composite technologies at different deposition pressures(0.6, 0.8 Pa). Comparative analyses of the structure and properties of two types of coatings were performed using X-ray diffractometer(XRD), scanning electron microscope(SEM) equipped with an energy dispersive spectrometer(EDS) and nanoindenter. Results showed that the phase structure of the coatings prepared under two kinds of deposition pressures was fcc-(Al, Cr, Ti) N, which grew preferentially along the(111) crystal plane. However, the larger(111) texture coefficient of the coating prepared at 0.8 Pa indicated that the preferred orientation was more pronounced. Compared to the coating prepared at the deposition pressure of 0.8 Pa, the coating prepared at 0.6 Pa was characterized by finer surface particles, a denser coating and better mechanical properties, including better resistance to elastic and plastic deformation, as well as better adhesion between film and substrate. This was partly because the deposited particles reached the substrate with greater energy at the lower deposition pressure. On the other hand, a thicker and softer Si3N4 phase might have been present in the coating prepared at 0.8 Pa. After oxidation at 900 ℃ for 6 h, a continuous and dense Al2O3 mixed oxide film had formed on the surface of the coating, effectively preventing the diffusion of oxygen into the coating and protecting the coating under the oxide film. With the increase in deposition pressure from 0.6 to 0.8 Pa, the oxide particles increased, the thickness of the oxide film increased, and the high-temperature oxidation resistance decreased.

With the increasing improvement of industrial requirements for cutting accuracy and efficiency and the emergence of difficult-to-machine materials such as titanium alloys, the development and modification of new hard coating materials with excellent comprehensive properties has become a research hotspot. The CrAlSiN coating has attracted widespread attention from researchers due to its ultra-high hardness exhibited by its nanocomposite structure, along with its excellent resistance to high-temperature oxidation and wear. In this paper, the characteristics and related mechanisms of the microstructure, mechanical properties, wear resistance, high-temperature oxidation resistance, high-temperature thermal stability, corrosion resistance and cutting performance of CrAlSiN coatings were summarized. The influencing law and mechanism of Al and Si content in the coatings on microstructure and performance was described. The effects and mechanism of element doping (doping with Ti, V, O, Mo, etc.) and microstructure design (adding transition layer, multi-layer, and gradient structure) on the microstructure and properties of CrAlSiN coatings were reviewed. Finally, the development and research direction of CrAlSiN coatings were prospected.

Laminated composite bolted joints are increasingly used in the aerospace field, and their damage and failure behavior has been studied in depth. In view of the complexity and stability requirements of laminated composite bolted structures, accurate prediction of damage evolution and failure behavior is significant to ensure the safety and reliability of the structures. In this paper, a novel asymptotic damage model is developed to predict the damage process and failure behavior of laminated composite bolted joints. In this model, the modified Puck criterion and the maximum shear stress criterion are used for fiber yarns. The parabolic yield criterion is adopted for the matrix, and the fiber fracture, inter-fiber fracture and matrix fracture are considered at the microscopic level. The pull-out strength and progressive failure behavior of countersunk and convex bolted joints structures are predicted by using the proposed model, and the corresponding experimental studies are carried out. The results show that the prediction results are in good agreement with the experimental data, which verifies the reliability of the model. Additionally, the effects of different structural parameters (thickness and aperture) on the progressive damage and failure behavior during pull-out is analyzed by the proposed model, and correction factors of pull-out strength are obtained, which provides a powerful tool for the design, analysis and progression of laminated composite bolted joint structures. [ABSTRACT FROM AUTHOR]

The synergistic inhibition effect of sodium phytate (PA) and benzotriazole (BTA) on 20SiMn steel in 3.5 wt-% NaCl solutions was studied using electrochemical methods, SEM, FTIR, XPS and quantum chemical calculations based on density functional theory (DFT). Results indicate that a protective bi-layer film is formed with the presence of the mixture of PA and BTA: the inner layer consists of iron oxides, while the outer one is an adsorption layer of BTA and PA. Based on the analysis of XPS and DFT, the function of BTA belongs to chemisorption, while that of PA obeys Langmuir adsorption isotherm and could be mainly assigned to physisorption. The inhibition efficiency of the mixture inhibitor is 99.12%, with a synergism parameter of 3.62, which could be ascribed to a cross-linking structure containing more BTA promoted by PA through hydrogen bonds. [ABSTRACT FROM AUTHOR]