Herein, the curing kinetics and the glass transition temperature (T_g) of MXene/phenolic epoxy composites with two curing agents, i.e., 4,4-diaminodiphenyl sulfone (DDS) and dicyandiamine (DICY), are systematically investigated using experimental characterization, mathematical modeling and molecular dynamics simulations. The effect of MXene content on an epoxy resin/amine curing agent system is also studied. These results reveal that the MXene/epoxy composites with both curing agent systems conform to the SB(m,n) two-parameter autocatalytic model. The addition of MXene accelerated the curing of the epoxy composite and increased the T_g by about 20 K. In addition, molecular dynamics were used to simulate the T_g of the cross-linked MXene/epoxy composites and to analyze microstructural features such as the free volume fraction (FFV). The simulation results show that the introduction of MXene improves the T_g and FFV of the simulated system. This is because the introduction of MXene restricts the movement of the epoxy/curing agent system. The conclusions are in good agreement with the experimental results.

Natural gas as a clean energy, its extensive use can alleviate energy crisis and environmental pollution and other problems. The storage and transportation of natural gas are of great significance to the standard use of natural gas. Suqiao gas storage reservoir is responsible for seasonal peak adjustment and emergency gas supply in the Beijing-Tianjin-Hebei region, and the corrosion of tubular goods is the most important issue. In this paper, the tubing composition analysis, metallographic structure analysis, mechanical property analysis, simulated corrosion test, corrosion morphology, and product analysis were carried out to analyze and study the corrosion behavior under the conditions, and suggestions were put forward to control the corrosion of the outer surface of the tubing.

Al₂O₃-Y₂O₃ laminated coating can be applied in fusion reactors to prevent fuel leakage and radiological hazard. However, the residual stress induced by the thermal cycles during the operation of the reactor can cause the failure of the coating. In order to analyze the problem, finite element models of Al₂O₃-Y₂O₃ laminated coatings with 600 nm of total thickness and different layout were analyzed. The max principal stress site in the coatings is located at the sub-top layer. The max principal stress in laminated coating with the Y₂O₃ sub-top decreases from 657 MPa for a two-layer coating (300 nm) to 598 MPa for a four-layer coating (150 nm). On the contrary, if Al₂O₃ is the sub-top layer, the max principal stress increases from 463 MPa for a two-layer coating (300 nm) to 495 MPa for a four-layer coating (150 nm). The result shows that the more deformable amorphous Al₂O₃ layer in the laminated coating system is more influential to the thermal stress.

Hydrogen sulfide and other corrosive gases can dissociate and generate hydrogen atoms on metal surfaces, which can diffuse into the metal lattice, cause damages to the metal materials, and lead to a degradation in the mechanical properties, such as hydrogen embrittlement. Although much attention has been paid to the hydrogen atoms in Fe bulk and surface phases, the computational research on diffusion of hydrogen atoms across the Fe phase interface has been rarely reported to date. In this work, density functional theory based ab-initio calculations are used to investigate the hydrogen dissolution and diffusion across the γ -Fe/ α -Fe interface which is common in duplex stainless steels. The results show that the dissolution energies of hydrogen atoms in the γ -Fe(111)/ α -Fe(110) interfacial layers are smaller than that in bulk α -Fe, but larger than that in bulk γ -Fe. The forward and backward H diffusion paths across the interface are asymmetric, with the highest energy barrier across the interface from γ -Fe to α -Fe occurring in the interfacial layer close to bulk α -Fe but from α -Fe to γ -Fe in the interfacial layer close to bulk γ -Fe. The energy barriers for hydrogen diffusion across the interface are about 2 times higher than that in bulk α -Fe, but about 2 times lower than that in bulk γ -Fe, giving an moderate diffusion coefficients across the interface. The calculations support the experimental observation of the H-induced cracks in duplex stainless steels.