The hardness, X-ray diffraction peak broadening parameter, R, and microstructures have been investigated for pure iron and iron alloys containing 3 mass%Cr, Mo or Si when subjected to 10-30% tensile ...deformation and then isochronal annealing for 3.6 ks. The annealing temperature-hardness curve consists of the slow and rapid softening parts due to recovery and recrystallization, respectively, with increasing annealing temperature. In alloys containing Si or Mo, strain age hardening takes place after annealing at temperature below the recovery stage. In the recovery stage, elongated cells change to several elongated subgrains, which grow and coalesce to a large equiaxis subgrain. The structure changes mentioned above correspond to the stepwise decrease in R value with increasing annealing temperature. The addition of Mo leads to the increase in temperatures required for recovery and recrystallization. The result suggests that Mo atoms with larger atomic size than Fe have strong interaction with vacancies which contribute to recovery and recrystallization. Recrystallization temperature for fine-grained specimens is lower than that for coarsegrained ones, because of the difference in stored energy after the deformation.
Repayment of oxygen debt incurred during physical effort is determined by measuring the extra oxygen used above the resting value during a recovery period of 0.5 to 1 h. Since this imposes an ...additional stress on the experimental subject, an attempt has been made to develop a simple, quick, and accurate method for determining oxygen debt. The method described here is based on the fact that the curve describing recovery is the resultant of two exponential curves, one fast and one slow, the former being complete in less than 3 min. We have derived a mathematical equation by means of which the total oxygen debt measurable over a 60 min period can be extrapolated from the measurements of excess oxygen consumption over the resting value at the end of 3, 6, and 9 min of the recovery period. The equation has been validated by observations on 10 young healthy subjects at sea level and at high altitude. The results show that the equation has good predictive value.
Sulfide SSEs (solid-state electrolytes) with high ionic conductivity are attractive for developing high-safety all-solid-state batteries (ASSBs). However, the poor chemical stability of sulfide SSEs ...toward moisture is a significant problem. Though the decomposition products when exposed to moisture and a possible property recovery by heat treatment are reported, the evolution of surface species in related to moisture exposure and to heat treatment is not clearly identified. This study applies in situ DRIFTS (diffuse reflectance infrared Fourier-transformed spectroscopy) analysis to examine the evolution of the surface species over pristine Li6PS5Cl (LPSC), during moisture exposure, and during heat treatment, complementary with tools like XRD, Raman, etc. The observed surface impurities over pristine LPSC include LiCl·H2O, LiOH·H2O, S3P-SH, PS4-xOx, SOx and carbonate species. Moisture exposure leads to increasing accumulation of these species over LPSC and evolving hydrogen sulfide. A stepwise heat treatment up to 480 °C illustrates the sequential removal of hydrated water, the decomposition of carbonate, LiOH, and PS4-xOx, leaving species like LiCl, Li2O, and PO4 on the surface. The EIS results shows a gradual increase in the ionic conductivity of LPSC with increasing heating temperature, mainly owing to the decreasing surface layer impedance. This strongly suggests that the surface species govern the properties of LPSC. When using the pristine LPSC after heat treatment at 480 °C, the Li||pristine LPSCHT||Li symmetric cell demonstrates a decreased polarization and a much-enhanced cycle stability comparing to the Li||pristine LPSC||Li symmetric cell.
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Aluminum is an important lightweight and high-value metal that is widely used in the transportation, construction, and military industries. China is the largest producer of Al in the world, and vast ...quantities of Al dross (ash) are generated and stored every year. Aluminum dross contains fluoride and heavy metals, and easily reacts with water and acid to produce stimulating, toxic, and explosive gases. Owing to a lack of developed technologies, most of this dross cannot be safely treated, resulting in a waste of resources and serious environmental and ecological risks. This review briefly describes the distribution and proportions of bauxite deposits in China, the Al extraction process, and the hazardous solid waste that is generated. It also discusses the comprehensive treatments for Al dross, including the hydrometallurgy and pyrometallurgy recovery processes, and reuse of Al, Al2O3, SiO2, and chloride salts as a summarized comparison of their advantages and disadvantages. In particular, this review focuses on the efforts to analyze the relationship between existing processes and the attempts to establish a comprehensive technology to treat Al dross. Additionally, areas for future research are suggested, which may provide new ideas for the closed-loop treatment of Al dross.
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•Describe the Al extraction process and the properties of Al dross in China.•Comprehensive treatments for recovery of valuable substances and the removal of impurity elements from the Al dross.•Establish a comprehensive technology to treat Al dross and also suggest areas for future research.
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