In this study, nano?TiO₂ was used as the additive phase, and B₂O₃ and H₃BO₃ were doped in a certain proportion, and then 4% nano?oxide particles reinforced Al matrix composites were prepared by high?energy ball milling and powder metallurgy. Finally, Al matrix composite rods were prepared with an extrusion ratio of 16∶1 at 723 K. The results show that the dispersion distribution of nano?oxides in Al matrix can be realized after 4 h ball milling. After vacuum hot pressing at 893 K, the addition phase reacts with the Al matrix in?situ and forms Al₂O₃ etc. When the molar ratio of Ti to B is 1.0∶1.5, the mechanical properties of the composites are the best. At the same time, when the chemical composition of the precursor of B element is different, the mechanical properties of the composites are significantly different; the tensile strength of TiO₂+H₃BO₃/Al at room temperature and 623 K is 507.7 MPa and 151.3 MPa, respectively, showing the highest room temperature mechanical properties; the tensile strength of TiO₂+B₂O₃/Al at room temperature and 623 K is 353.7 MPa and 167.1 MPa, respectively, manifesting the excellent high?temperature mechanical properties.

The catalytic oxidation of molecular oxygen based on nitroxide radical organocatalysts is one of the hot topics in the field of catalysis in recent years. The structures and catalytic activity of the nitrogenous six membered heterocyclic ring obtained by the pyridine ring and the pyrazine ring substituted for the benzene ring of N-Hydroxyphthalimide (NHPI) were studied by theoretical methods. The effect of protonic acid HCl on the catalytic activity of this kind of catalyst was investigated. The results show that the catalytic activity of nitrogenous six membered heterocyclic ring catalyst is higher than that of NHPI, even some of the catalyst is comparable to that of N,N′dihydroxypyromellitimide (NDHPI); pyrazine pyridine ring chain is helpful to improve the catalytic activity of the catalyst; HCl hydrogen bond interaction with the aromatic ring of these catalysts can improve the catalytic activity of the catalyst. This study is helpful to deepen the understanding of the intrinsic activity of this kind of catalyst and also to provide theoretical guidance for the catalytic mechanism and catalytic oxidation experiment of this kind of catalyst.