AZ31 Mg alloy samples were processed by equal channel angular pressing (ECAP) at 220°C for four passes. An average grain size of ∼1·9 μm with reasonable homogeneity was obtained. The ECAP process imparted large plastic shear strains and strong deformation textures to the material. Subsequent annealing of the equal channel angular pressed samples produced interesting mechanical behaviours. While yield strength increased and ductility decreased immediately after undergoing ECAP, annealing at temperatures <250°C restored ductility significantly at a small decrease in of yield strength. Annealing at temperatures >250°C reduced yield strength without additional improvement in ductility. It is believed that the combination of stress relief via dislocation elimination, refined microstructure and the retention of a strong ECAP texture at low annealing temperatures enhance ductility. High temperature annealing breaks down the ECAP texture resulting in no further improvement in ductility. The results show that the mechanical properties of the alloy can be positively influenced by annealing after ECAP to achieve a combination of strength and ductility.
Work environments can affect job satisfaction and psychological well-being. Using the job demand-control model as a foundation, this study aimed to explore the relationships between physical and psychosocial work environments and psychological well-being and job satisfaction in the workplace. A multistage sampling method was used with the 2012 China Labor-force Dynamics Survey among 4442 employees. Our outcome measures included psychological well-being and job satisfaction. The final model showed migrants (odds ratio [OR] = 1.34, 95% confidence interval [CI] = 1.13-1.60) and nonmanagerial employees (OR = 1.49, 95% CI = 1.25-1.78) who worked in general enterprises (OR= 1.61, 95% CI = 1.34-1.92) or suffered longer weekly work hours (OR = 1.42, 95% CI = 1.24-1.63) had worse psychological well-being or lower job satisfaction. Following the job demand-control model, higher job demands and lower job autonomy were significantly and positively associated with worse psychological well-being and lower job satisfaction. This study highlights that improved work environments can protect employees’ well-being. Policymakers must provide better work environments. They must consider its physical environment (stable work contract and short work hours) and psychosocial environment (low job demands and high job autonomy) aspects, particularly for migrants and nonmanagerial employees.
The substitution of charcoal as an alternative fuel to coke breeze in a simulated Japanese Steel Mills (JSM) sinter blend was investigated. Compared with coke breeze, higher mix moisture contents were required for the sinter mixture containing charcoal to achieve optimum granulation. The green granules formed from the sinter mixture containing charcoal were clearly less dense and formed a less compacted green bed as evidenced by the packing density. To achieve return fines balance, fuel addition had to be increased from 3.62 to 4.17% (on a dry mixture basis) as the substitution of charcoal increased from 0 to 50%. However, at 100% subsitution, the sinter mixture failed to achieve balance even at a very high fuel addition level of 4.7%. Compared with the sinter fired with coke breeze, the sinter from the mixtures containing up to 50% charcoal was marginally weaker in terms of sinter yield, tumble strength (TI) and reduction disintegration (RDI). The reasons for weaker sinter are discussed. Fuel rate increased considerably with charcoal substitution due to increased fuel addition and decreased sinter yield. However, increasing fuel rate did not lead to a reduction of sintering productivity. In contrast, the sintering speed and productivity were maintained as the charcoal substitution rate increased from 0 to 25% and then increased considerably with further increase in charcoal substitution rate. The emission mechanisms of the CO, CO2, SO2 and NOX and H2O gases during sintering are clearly quite different. CO, CO2 and NOx emission was observed over the entire sintering process and varied slightly as the sintering process progressed. However, the SO2 and H2O emissions were observed only towards the completion of the sintering process. Both the CO and CO2 concentrations in the waste gas increased with the increasing substitution of charcoal for coke breeze; however the concentrations of SO2 and NOX in the waste gas decreased.
Abstract Comparing with the crystalline tungstate compounds, little work has been carried out and reported on the relation among the microstructure, W–O bond lengths, and characteristic Raman‐active vibration wavenumber of the molten tungstates, which allows us to diagnose and determine the structure of unknown clusters existing in and further predict the physicochemical properties of molten binary alkali tungstates. Raman spectra of an ensemble of eight model clusters were simulated in the present work by density functional theory (DFT) to establish the effect of the fine structures and W–O nb (non‐bridging oxygen) bond lengths of W–O complexes on the characteristic wavenumber of W–O nb Raman‐active vibration modes of the molten tungstates. Results show that the characteristic wavenumbers of the symmetric stretching vibration modes of W–O nb bonds increase almost linearly with the decreasing bond length. The characteristic wavenumbers of W–O nb symmetric stretching vibration modes generally follow [WO 4 ] 2− > [WO 5 ] 4− > [WO 6 ] 6− present in the melt simultaneously. The characteristic wavenumbers were also found to increase with the number of bridging oxygen for the same W–O complex. In situ Raman spectra of molten A 2 W n O 3n + 1 (A = Li, Na, K; n = 1, 2, 3) were then measured in order to verify the correlation observed among the microstructure, W–O bond lengths, and characteristic Raman‐active vibration mode wavenumbers. The correlation was successfully applied to deconvolute the in situ Raman spectrum of the molten Na 2 W 3 O 10 .
This paper studied room temperature and in-situ high temperature Raman spectra of coal samples of different carbon content with 355 nm laser Raman spectrometer.The deconvoluted parameters of D band and G band were analysed.The relationship between different carbon content and the Raman spectra characteristics of different kinds of coals and the carbon content was studied.In-situ high temperature (from 298 to 1473 K) Raman spectra of coals was tested.The change of internal structure during pyrolysis of coals was analysed and studied.Change of G band was discussed with the increase of temperature.
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