No abstract

Constructing a heterojunction and designing a band gap are effective methods to promote the efficiency of a photocatalyst and solar energy utilization. In this work, g-C 3 N 4 /Yb 3+ -Bi 5 O 7 I nanostructured photocatalysts were successfully prepared using a hydrothermal method with glycol as a solvent and a calcination method, and the performance of the photocatalysts containing different amounts of g-C 3 N 4 was studied. A series of characterizations confirmed the successful complexation of g-C 3 N 4 nanosheets with Bi 5 O 7 I, and Yb 3+ was successfully doped into the lattice of Bi 5 O 7 I. g-C 3 N 4 and Yb 3+ have a synergistic effect on expanding the photoresponse range of CYB(g-C 3 N 4 /Yb 3+ -Bi 5 O 7 I) composite photocatalysts. As expected, CYB samples have wonderful photocatalytic performance and stability in the removal of Hg 0 , among which CYB-20 has the highest removal efficiency, reaching 79%. Yb 3+ with upconversion characteristics can convert infrared light into visible light and form new energy levels in Bi 5 O 7 I. g-C 3 N 4 and Bi 5 O 7 I form a Z-scheme heterojunction to improve the photocatalytic performance of Bi 5 O 7 I. Besides, the electron and hole transmission paths and the catalytic mechanism of the photocatalysts are also proposed. This work offers a new approach to construct a photocatalyst system for pollutant emission control with a wide wavelength range of sunlight, which may be helpful to develop environmentally benign functional materials.

The precise estimation of the cutting force coefficients in milling is very important, which has great impact on the precise calculation of the milling forces and the stability lobes of the system. On the basis of the imprecise estimation of cutting force coefficients in milling of thin-walled part using cutter with different tooth radii, the calculation process of actual cutting force coefficients is proposed in this article. First, based on the different amplitudes of milling forces caused by the long and short teeth of cutter, the nominal milling forces and nominal cutting force coefficients are constructed, and the radii error of the long and short teeth of cutter is calculated. Then, actual cutting force coefficients are derived based on radii error of cutter teeth. Finally, an experiment is performed to verify the validity of the calculation process of actual cutting force coefficients proposed in this article, and the results show that the actual cutting force coefficients obtained by consideration of radii error are more effective than theoretical cutting force coefficients obtained without consideration of radii error in the calculation of milling forces.

No abstract

No abstract