استكشف المجموعة الواسعة من العناوين المتاحة.

In this study, we optimized the traditional composition of AISI 8630 steel and evaluated its corrosion resistance through a series of tests. We conducted corrosion tests in a 3.5% NaCl solution and performed a 720 h fixed-load tensile test in accordance with the NACE TM-0177-2016 standard to assess sulfide stress corrosion cracking (SSCC). To analyze the corrosion products and the structure of the corrosion film, we employed X-ray diffraction and transmission electron microscopy. The corrosion rate, characteristics of the corrosion products, structure of the corrosion film, and corrosion resistance mechanism of the material were investigated. The results indicate that the optimized AISI 8630 material demonstrates excellent corrosion resistance. After 720 h of exposure, the primary corrosion products were identified as chromium oxide, copper sulfide, iron oxide, and iron–nickel sulfide. The corrosion film exhibited a three-layer structure: the innermost layer with a thickness of 200–300 nm contained higher concentrations of alloying elements and formed a dense, cohesive rust layer that hindered the diffusion of oxygen and chloride ions, thus enhancing corrosion resistance. The middle layer was thicker and less rich in alloying elements, while the outer layer, approximately 300–400 nm thick, was relatively loose.

Plain carbon steel is the most widely applied steel in current engineering construction. With the increased application property needs, the service life of plain carbon steel has been severely tested. As one of the most destructive failure modes, corrosion resistance of carbon steel has attracted wide attention. Rare earth La, as the microalloying element, was employed in plain carbon steel, Q355, to improve its corrosion resistance. As the content of La increased, the microstructure was refined. The fraction of pearlite decreased, while the content of acicular increased. Within the La addition of 230 ppm, the tensile strength and impact energy were jointly improved. Furthermore, the microalloying element of La modified the inclusion types and refined the inclusion size. The modified microstructure and inclusions by La co-improved the corrosion resistance. The formula of effective La content was proposed to estimate the effect of La on corrosion. As the effective content of La increased, the relative corrosion rate decreased. La3+ promoted the protective rust layer to increase corrosion resistance.

This study investigates the application of bypass coupling twin-wire indirect arc welding (BC-TWIAW) in arc additive manufacturing of 18–8 stainless steel. It is found that the droplet transfer changed from short circuit mode to stable spray mode with the welding current rising. Droplet transfer was the most stable when welding current was 200 A. Compared with the conventional MIG welding arc additive manufacturing, the efficiency of BC-TWIAW additive manufacturing can be increased by more than 30%. Electrochemical tests show that the BC-TWIAW overlay has a lower reactivation rate, higher charge transfer resistance, and lower carrier concentration, indicating that the overlay has better resistance to intergranular corrosion and pitting corrosion.

Magnesium (Mg) alloys have received increasing interest in the past two decades as biomaterials due to their excellent biological compatibility. However, the corrosion resistance of Mg alloys is relativity low which limits their usage in degradable implant applications, and controlling the corrosion resistance is the key to solving this problem. This review discusses the relative corrosion mechanisms, including pitting, filiform, high temperature, stress corrosion, etc., of Mg alloys. Various approaches like purification (Fe, Ni, Cu, etc.), micro-alloying (adding Zn, Mn, Ca, RE elements, and so on), grain refinement (severe plastic deformation, SPD, etc.), and surface modifications (various coating methods) to control corrosion and biological performance are summarized. Moreover, the in vivo implantations of Mg alloy vascular stents and the issues that have emerged based on the reports in recent years are introduced. It is recommended that corrosion mechanisms should be further investigated as there is no method that can remove all the impurities and a new purification approach needs to be developed. The concentration of micro-alloy elements should be carefully controlled to avoid superfluous compounds. Developing new continuous SPD methods to achieve fine-grained Mg alloys with a large size scale is necessary. The development of a multifunctional coating could also be considered in controlling the Mg degradation rate. Moreover, the research trends and challenges in the future of Mg biomaterials are proposed.

Environmentally-friendly magnetic metallic absorbers with high-performing antioxidant property, thermal stability, and anti-corrosion capability have attracted great attention in real-world applications. A surface modification technology of magnetic metallic absorbers with dense and inert materials has been an effective strategy to solve the aforesaid problem. Herein, fluorine-free core—shell carbonyl iron-organic silicon absorbers (CI@SiO 2 /1,1,1,3,3,3-hexamethyl disilazane (HMDS)) were fabricated via a facile one-pot synthesis using tetraethyl orthosilicate (TEOS) and HMDS as the precursor of protective layer (SiO 2 /HMDS), and CI@SiO 2 /HMDS hybrid reveals its long-term corrosion resistance and excellent microwave absorption performance with a minimum reflection loss value of −44.3 dB and an effective absorption bandwidth of 5.3 GHz at a thin thickness of 2.0 mm after immersion in 5.0 wt.% NaCl acidic solutions for 2,160 h. Meanwhile, CI@SiO 2 /HMDS hybrid can still achieve the maximum radar cross-sectional (RCS) reduction values about 16.5 dB·m 2 at the detection θ of 0°. The exceptional microwave absorption performance and structural stability are largely due to the extraordinary wave-transparent property and shielding ability against corrosive medium of SiO 2 /HMDS hydrophobic protective layer with a contact angle of 132.5°. The research paves the way for the large-scale and batch production of high-performance magnetic metallic absorbers and increases their survivability and reliability in the harsh environments.

Due to the development of the petroleum industry, more severe mining conditions put forward higher corrosion resistance requirements for materials. In this paper, the corrosion resistance and corrosion behavior of four TC4-xNi-yNb (x, y = 0, 0.5) alloys were investigated in a 1 mol/L HCl solution through microscopic characterization, electrochemical tests and corrosion weight loss testing. The results demonstrated that the addition of Ni and Nb elements could improve the corrosion resistance of TC4 alloy to varying degrees. The addition of niobium formed niobium oxide in the passive film, while the addition of nickel thickened the passive film without formation of nickel oxides. The improvement of corrosion resistance of TC4 by nickel is more significant. Finally, a new highly corrosion resistant alloy TC4-0.5Ni-0.5Nb is preferred.

In this investigation, the aqueous corrosion resistance of 9Cr series heat-resistant steel during tempering was investigated. Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometer (EDS) were used to analyze the effect of tempering temperature on the microstructure and precipitation behavior of precipitates. The heat-resisting steel was heated to 1150 °C for 1 h, and then tempered at different temperatures between 680 °C and 760 °C for 2 h. The microstructure of the heat-resistant steel after tempering was composed of lath-tempered martensite and fine precipitates. The hardness decreased with increasing tempering temperature, ranging from HBW 261 to HBW 193. The aqueous corrosion resistance improved as the tempering temperatures increased from 680 °C to 720 °C but deteriorated at higher temperatures, such as 760 °C, which was obtained by an electrochemical corrosion performance test. The aqueous corrosion resistance was affected by the decrease in dislocation density and the decrease in Cr solution in the tempered martensite. With the increase in the tempering temperature, the aqueous corrosion potential first increases and then decreases, the self-corrosion current density first decreases and then increases, and the polarization resistance first increases and then decreases. Furthermore, the increase in corrosion resistance is attributed to the reduction in dislocation density and chromium depletion in the martensitic structure as the tempering temperature approaches 720 °C. This paper reveals the effect of tempering temperature on the corrosion resistance of 9Cr series heat-resistant steel, which is a further exploration of a known phenomenon.

This paper provides a review of models commonly used over the years in the study of microscopic models of material corrosion mechanisms, data mining methods and the corrosion-resistant performance control of structural steels. The virtual process of material corrosion is combined with experimental data to reflect the microscopic mechanism of material corrosion from a nano-scale to macro-scale, respectively. Data mining methods focus on predicting and modeling the corrosion rate and corrosion life of materials. Data-driven control of the corrosion resistance of structural steels is achieved through micro-alloying and organization structure control technology. Corrosion modeling has been used to assess the effects of alloying elements, grain size and organization purity on corrosion resistance, and to determine the contents of alloying elements.

Reciprocating pumps are widely used in the current oil extraction process, and the plunger is a vulnerable part of these pumps that directly determines the service life of the reciprocating pump. To improve the service life of plungers, Ni60/WC coatings were applied to the surface of 45-steel plungers via laser cladding technology to improve wear and corrosion resistance. Defect-free and dense Ni60/WC coatings were successfully applied to the plunger surface with strong metallurgical bonding between the coating and the substrate. The coating consists mainly of a γ-(Ni, Fe) phase, which contains isotropic and isotropic-like crystals, dendritic crystals, and columnar crystals in the top, middle, and bottom regions of the coating, respectively. The service performance of the laser cladding coating was compared to the flame-sprayed plunger, which is widely used, and the laser cladding coating has a microhardness of up to 821.8 HV0.5, which is higher than that of the flame-sprayed coating (545.5 HV0.5) and the 45-steel substrate (200 HV0.5). The laser cladding coating has a lower friction coefficient and a smaller volumetric wear rate, and the corrosion current density and corrosion rate in the NaCl solution are 2.52 × 10−7 A/cm2 and 2.96 × 10−3 mmPY, respectively, which indicates superior corrosion resistance to the flame-sprayed coating and the substrate. The laser cladding of reciprocating pump plunger surfaces has a significantly improved comprehensive performance and is a promising way to increase the service life of reciprocating pumps.

Hydrogen generation from water splitting is of great prospect for the sustainable energy conversion. However, it is still challenging to explore stable and high-performance electrocatalysts toward hydrogen evolution reaction (HER) from saline water such as seawater due to the chloride corrosion. Herein, we developed a self-supported heterogeneous bimetallic phosphide (Ni 2 P-FeP) array electrode that possesses excellent HER performance in alkaline saline water with an overpotential of 89 mV at 10 mA·cm −2 and long-term stability over 90 h at 200 mA·cm −2 . The analysis showed that the heterostructure between the interfaces of Ni 2 P-FeP plays a pivotal role in promoting the activity of catalyst. Moreover, the bimetallic phosphide nanoarrays can be employed as a shield for chlorine-corrosion resistance in the saline water, ensuring the long-term durability of hydrogen generation. When employed for alkaline saline water electrolysis, a current density of 100 mA·cm −2 is achieved at cell voltage of 1.68 V. This work presents an effective approach for the fabrication of high-performance electrode for HER in alkaline saline environments.