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The precision and efficiency of machining of aerospace thin-walled components (ATWCs) directly affect aircraft performance and reliability. This paper systematically reviews the cutting technology for ATWCs, covering advanced fixture technology, the prediction and control (or suppression) of machined surface integrity, deformation, and cutting chatter, as well as the application of digital twin (DT) technology. The section on advanced fixture technology provides a detailed analysis of the operational mode, structural features, functionality and applications of various advanced fixtures suitable for the machining of ATWCs. The surface integrity section discusses the mechanisms of surface state formation during machining of aerospace metal material parts, alongside predictions and control methods for surface integrity. The deformation section analyzes causes of machining-induced deformation in machining ATWCs and introduces relevant prediction and control methods. The cutting chatter section discussed the stability analysis techniques of cutting process and chatter suppression technology, including online monitoring and recognition, active and passive suppression technologies, and methods. The DT technology section showcases the specific application of this technology in the machining of ATWCs. The paper summarizes different aspects of these technologies, offering a comprehensive understanding and facilitating in-depth research into the machining technology of ATWCs. It can serve as a reference and guide for scholars conducting research in this field.

A novel CrII-dimeric complex, [CrIIN(SiiPr3)2(μ-Cl)(THF)]2(1), has been successfully constructed using a bulky silyl-amide ligand. Single-crystal structure analysis reveals that complex 1exhibits a binuclear motif, with a Cr2Cl2rhombus core, where two equivalent tetra-coordinate CrIIcenters in the centrosymmetric unit display quasi-square planar geometry. The crystal structure has been well simulated and explored by density functional theory calculations. The axial zero-field splitting parameter (D< 0) with a small rhombic (E) value is unambiguously determined by systematic investigations of magnetic measurements, high-frequency electron paramagnetic resonance spectroscopy, and ab initio calculations. Remarkably, ac magnetic susceptibility data unveil that 1features slow dynamic magnetic relaxation typical of single-molecule magnet behavior with Ueff= 22 K in the absence of a dc field. This increases up to 35 K under a corresponding static field. Moreover, magnetic studies and theoretical calculations point out that a non-negligible ferromagnetic coupling (FMC) exists in the dimeric Cr–Cr units of 1. The coexistence of magnetic anisotropy and FMC contributes to the first case of CrII-based single-molecule magnets (SMMs) under zero dc field.

The hydrolysis of CH2OO is not only a dominant sink for the CH2OO intermediate in the atmosphere but also a key process in the formation of aerosols. Herein, the reaction mechanism and kinetics for the hydrolysis of CH2OO catalyzed by the precursors of atmospheric aerosols, including H2SO4, H2SO4···H2O, and (H2SO4)2, have been studied theoretically at the CCSD(T)-F12a/cc-pVDZ-F12//B3LYP/6-311+G(2df,2pd) level. The calculated results show that the three catalysts decrease the energy barrier by over 10.3 kcal·mol–1; at the same time, the product formation of HOCH2OOH is more strongly bonded to the three catalysts than to the reactants CH2OO and H2O, revealing that small clusters of sulfuric acid promote the hydrolysis of CH2OO both kinetically and thermodynamically. Kinetic simulations show that the H2SO4-assisted reaction is more favorable than the H2SO4···H2O- (the pseudo-first-order rate constant being 27.9–11.5 times larger) and (H2SO4)2- (between 2.8 × 104and 3.4 × 105times larger) catalyzed reactions. Additionally, due to relatively lower concentration of H2SO4, the hydrolysis of CH2OO with H2SO4cannot compete with the CH2OO + H2O or (H2O)2reaction within the temperature range of 280–320 K, since its pseudo-first-order rate ratio is smaller by 4–7 or 6–8 orders of magnitude, respectively. However, the present results provide a good example of how small clusters of sulfuric acid catalyze the hydrolysis of an important atmospheric species.