Fiber laser spot welding of molybdenum alloy in a hyperbaric environment.

The effect of the growth of ambient pressures on the penetration of laser welded molybdenum (Mo) alloy was explored. It was found that when ambient pressure rose from 0.1 MPa to 1.8 MPa, the penetration of base metal (BM) was significantly reduced, which was only 17% of that obtained under ambient pressure of 0.1 MPa. Moreover, the mechanism underlying the significant reduction of the penetration of BM was analyzed. At first, by using a high-resolution scanning electron microscope (SEM), the size and the number of nano-sized metallic particles generated during laser welding under different ambient pressures were surveyed. Furthermore, the scattering and absorption of the nano-sized metallic particles for laser energy under different ambient pressures were investigated; afterwards, by applying a high-speed camera and a spectrometer, the transient behaviors and spectral signals of plasmas during fiber laser spot welding under different ambient pressures were monitored. On this basis, the inverse bremsstrahlung absorption of plasmas for laser energy under different ambient pressures was explored; finally, fiber laser spot welding test was carried out on glass/metal composite samples under different ambient pressures to survey the influence of the change of ambient pressure on dynamic behaviors of the molten pool during the welding.

Study on COD removal mechanism and reaction kinetics of oilfield wastewater.

The chemical oxygen demand (COD) removal mechanism and reaction kinetics were mainly studied in the treatment of oilfield oily sewage containing polymer by three-dimensional electrode reactor. The results proved that the residual active oxides O3, H2O2, •OH and active chlorine in the system of electrochemical reaction could be effectively detected, and the COD removal mechanism was co-oxidation of active oxides; Under these experimental conditions: the electrolysis current of 6 A, surface/volume ratio of 6/25(cm2·L-1), the reaction time of 50 min, the CODcr of treated sewage was no more than 50 mg·L-1; the removal reaction of COD conformed to apparent second-order reaction kinetic model, the correlation coefficient R2 was 0.9728, and the apparent reaction rate constant was k = 3.58 × 10-4 (L·min-1·mg-1·m-2). To reach the goal, the CODcr was no more than 50 mg·L-1 in treated sewage, and the theory minimum processing time was 45.73 min. The verification of experimental results was consistent with kinetic equations.

[Study on quantitative mechanism and the interference of the UV spectrum of HABS reduced by ß-Cyclodextrin].

A novel ultraviolet absorption spectrometry method was developed for the quantitative determination of HABS by adding ß-cyclodextrin with the molar ratio of 1:1 in strong interference aqueous solution. The results indicated that the effect of several common interfering flooding agents (SAS, OP-10, HPAM) on the determination of HABS could be greatly reduced in ß- cyclodextrin aqueous solution. Thus, the determination errors of the determined HABS were less than 2.0% under strong inter- ference, and the detection limit (S/N==3) of the method could be also as high was 8.3-9.1 x 10(-4) mg · L(-1). Various characterization results including 1H-NMR, TG-DSC and FTIR showed the interaction between ß-cyclodextrin and HABS. The results of H-NMR analysis showed that HABS molecule could enter into the interior of the cavity of ß-cyclodextrin molecule. TG-DSC analysis exhibited that the stable inclusion of ß-cyclodextrin and HABS could be automatically formed. The interactions between the functional groups of ß-cyclodextrin and HABS were showed by FTIR analysis, which also exhibited that the stable inclusion could be formed by HABS entering from the narrow or the broad mouth of the ß-cyclodextrin. The interference of the UV spectrum of HABS could be reduced by ß-cyclodextrin since the interaction between ß-cyclodextrin due to the interaction between ß-cyclodextrin and HABS in the inclusion complex.

[Study on the enhanced spectrum quantitative analysis of SDBS induced by beta-cyclodextrin].

A novel enhanced ultraviolet absorption spectrometry method was developed for the quantitative analysis of SDBS induced by beta-cyclodextrin(beta-CD) with strong interferences. The ultraviolet absorption spectra of SDBS indicated that the presence of beta-CD could result in the enhancement of absorption intensities of SDBS. A good linearity was obtained between the UV-absorption intensity of the system and the concentration of SDBS. The results indicated that the determination precision and the determination ranges of SDBS could be greatly improved by beta-CD. The effect of several common interfering substances (SDS, OP-10, HPAM) on the determination of SDBS could be significantly reduced in beta-CD aqueous solution. Therefore, the maximum errors of the determined SDBS were less than 2.0% under multifactor interferences, and the precision of the method was also as high as 10(-2) - 10(-3) mg x L(-1). The stable inclusion of beta-CD and SDBS could be automatically formed in water with molar ratio of 1 : 1. The stability constant of the inclusion, K(a), was 87 and the standard Gibbs function of molar reaction, delta(gamma)G(m)(see symbol) (298 K), was -11.064 kJ x mol(-1). FTIR analysis exhibited that SDBS could be induced by beta-CD since the phenyl group in SDBS molecule could exist stably in the cavity of beta-CD and form the inclusion.