RESUMO
At present, in the process of weld induction heat treatment, the common method is to carry out centralized induction heating in the weld area, which will lead to large radial temperature difference of the weld, poor controllability of temperature distribution and easy to cause the defects of residual stress concentration in the weld area. To solve the above problems, this paper adopts the two-sided method to conduct induction heating on both sides of the weld, and at the same time, the auxiliary pulse current is passed into the weld to improve the quality of the weld. ANSYS finite element software is used to establish a multi-field coupling prediction model of electric-magnetic-thermal structure, and explore the distribution law of the auxiliary pulse current and the temperature field of the weld. Finally, an experimental study of pulsed current assisted two-sided induction heating is carried out. Temperature test and metallographic test were carried out respectively to verify the effectiveness of pulsed current assisted induction heating technology.
RESUMO
Rhodium(II) catalyzes carbene transfer from trimethylsilyldiazomethane to arylmethyl thioethers, generating sulfonium ylides that undergo [2,3]-sigmatropic rearrangement, punching quaternary centers into aromatic rings. The reaction works well with naphthalene, indole, and benzofuran ring systems, but the reaction is unsuccessful with the monocyclic benzene homologue. For aryl thioethers, Rh2(OAc)4 gives good results. For alkyl thioethers, the yields improve with Rh2(cap)4. Surprisingly, thioesters and thiocarbamates are also competent substrates for the reaction.