Materials and Corrosion-werkstoffe Und Korrosion最新文献

This study investigates the corrosion resistance of 3003 aluminum alloys from different sources used in the semiconductor industry, exploring their behavior in both liquid and gas environments. The corrosion mechanisms were analyzed through microscopic characterization and calculations. The results reveal significant variations in the distribution of particles, with notable differences in the number and area of Al₆(Mn,Fe) phase. The slightly higher electrochemical potential of the Al₆(Mn,Fe) phase compared to the matrix was identified as a key factor accelerating corrosion in liquid environments. Additionally, the lower saturation vapor pressure of silicon chloride led to the accumulation of minimal corrosion products on the surface of α-Al₁₂(Mn,Fe)₃Si phase.

A novel Al-alloyed 3Ni steel was developed to enhance the corrosion performance of marine weathering steel. Its corrosion resistance was evaluated in simulated tropical marine environment with different chloride concentrations. Results show that the formed corrosion film exhibits a dual-layer structure: porous outer layer and compact inner layer. The corrosion resistance is closely associated with the content of NiFe₂O₄ and FeAl₂O₄ phases in the corrosion film. As chloride concentration increases, the FeAl₂O₄ content steadily rises, while the NiFe₂O₄ content initially increases and then decreases. The exceptional corrosion resistance of this steel is primarily attributed to the compactness and electronegativity of the protective inner layer.

Single-layer multipass Fe–0.3C–15Cr–1Ni alloy cladding layers were prepared on the surface of 3Cr13 martensitic stainless steel using different laser powers. The effects of laser power on the size of dendrite morphology, carbide size and distribution, and wear and corrosion resistance of Fe–0.3C–15Cr–1Ni alloy cladding were investigated. With the increase of laser power, the number of carbides gradually decreases, and the microhardness, wear resistance, and corrosion resistance of the cladding layer show a pattern of increasing and then decreasing. When the laser power is 1400 W, the hardness, wear resistance, and corrosion resistance of the cladding layer are the best, and the stability of the coefficient of friction is the best. It has the largest pitting potential, the widest width of the passivation zone, the lowest reactivation rate, a significant increase in matrix impedance, smaller pits after immersion corrosion, and the best corrosion resistance. This is due to 1400-W microstructure uniformity being better, the alloying elements in the matrix, and carbide reasonable distribution, thus improving the matrix wear and corrosion resistance.

This paper enhances the corrosion resistance of Q235A steel in a seawater environment by employing laser cladding technology to prepare Ni-Cr-Mo-Si/x Cr₃C₂ (x = 0, 5, 15 wt%) hydrophobic coatings on its surface. The results indicate that the introduction of Cr₃C₂ substantially refines the microstructure of the coating and forms additional reinforcing phases, primarily including Cr₂₃C₆, Ni₃C, and Cr_1.12Ni_2.88. The addition of an appropriate amount of Cr₃C₂ significantly contributed to the enhanced formation of hard phases. Specifically, when the Cr₃C₂ content is 15%, the average hardness reached a maximum of 395.2 HV_0.5. Combining wettability tests with electrochemical results, the Ni-Cr-Mo-Si/Cr₃C₂ coatings show lower surface energy, improved hydrophobicity, and reduced corrosion rates. When the Cr₃C₂ content reaches 15%, the synergistic effect of hydrophobicity and carbides optimized the corrosion resistance of the coating. Therefore, this paper reveals the multifaceted roles of Cr₃C₂ in refining the microstructure and improving corrosion resistance.

Oxidation of titanium during hot working processes is an important performance factor. This study investigated the oxidation behavior of the Ti-0.3Mo-0.8Ni alloy in air at various temperatures ranging from 850°C to 950°C for different times. The oxidation kinetics were determined by isothermal oxidation weight gain experiments. Results showed that the oxidation kinetics of the Ti-0.3Mo-0.8Ni alloy approximately followed a parabolic law. The oxidation activation energy was 238.73 kJ/mol. The oxide scales were formed on the surface of the alloy at all experimental temperatures, and the oxide scales mainly consisted of Ti₆O, Ti₃O, Ti₂O₃, and TiO₂. TiO₂ dominates at each oxidation temperature. Below T_β, the presence of the Mo element effectively improved the oxidation resistance of the alloy. Above T_β, the oxidation resistance decreased with increasing temperature, which was mainly due to the enrichment of the Mo element in the β phase with increasing temperature, resulting in the decrease in Mo content in the substrate.

In this study, the spatial distribution characteristics and mechanisms of microbiologically influenced corrosion (MIC) in the accumulation liquid environment of shale gas-gathering pipelines were systematically investigated. A simulation device was utilized, and electrochemical tests, gas-liquid analysis, and X-ray diffraction (XRD) were conducted to explore the relationship between biofilm formation and corrosion behavior in different spatial directions. The results indicate that biofilm formation at the 6 o'clock direction occurs earlier, which triggers a high risk of pitting, with an average rate of 0.1922 mm/a. In contrast, biofilm development at the 4 and 8 o'clock directions lags initially, but due to metabolite accumulation, the corrosion rate increases to 0.2608–0.2625 mm/a, with a risk of hydrogen-induced cracking (HIC). Notably, no significant biofilm was observed at 0.5 cm below the liquid level, but H₂S and CH₄ produced by microbial metabolism contributed to the risk of HIC, with a late-stage corrosion rate of 0.3443 mm/a.

AC-impedance measurements were performed in the alloy AA6061 in a mixture of sulfuric acid and sodium sulfate 0.05 M at pH of 1.45, 2 and 3, in the potential range of –0.8 V and 1.8 V_SSE. For all the ranges of potential and pH, the impedance of the system is characterized by three time constants, i.e., a capacitive behavior at high frequencies, an inductive loop at intermediate frequencies and a capacitive behavior at low frequencies. All impedance diagrams obtained were fitted with a single equivalent circuit. A theoretical impedance expression is presented based on a four-reactions physical model. Based on certain assumptions, this model allows evaluating the thickness of the film, the concentration and the velocity of charge carriers, as well as the potential distribution between the film and the interfaces and the electrical field on the oxide.