Search

The shell mold-HIP forming process of TC4 pre-alloyed powder was investigated. The shrinkage of the molding part was revealed, and the microstructure and tensile property of the alloy as well as the interface between the alloy and mold were analyzed. Results show that the molding part with complete shape and a relative density of 98% is achieved by mold-HIP forming process. During densification, there is a small amount of shrinkage along the length and width of the molding part, while it is much larger along the depth, which reaches 30% in the centre; the process results in fine uniform basketweave microstructure, with a minority of equiaxed α grains surrounding the lamellar; the plasticity of the shell mold-HIP alloy is more than 1.5 times as much the casting alloy; the ultimate tensile strength of the shell mold-HIP alloy is up to and even higher than the level of the forged alloy. There is no obvious interface reaction between the TC4 alloy and shell mold during the HIP process, while a loose layer of about 10μm is formed on the alloy surface of the part.

Mineralogy and separation experiments were carried out for a low-grade linnaeite ore (0.052%), which belonged to limonite-hematite-pyrite type complex mineral. Under the grinding fineness of 80% -0.074 mm, linnaeite concentrate which contained cobalt grade of 0.51%, recovery rate of 80.99%, sulfur grade of 23.79%, recovery of 88.03% was obtained by closed-circuit processes of one roughing, two scaenging and one cleaning, which used sulfate acid (4500 g/t) and copper sulfate (300 g/t) as activator, so-dium silicate (1000 g/t) and CMC (30 g/t) as inhibitor, ethyl xanthate（100 g/t）and butyl xanthate (100 g/t) as collector, 2# oil (40 g/t) as forther in roughing, no agent in cleaing and first scavenging, used ethyl xan-thate（50 g/t）and butyl xanthate (50 g/t) as collector, 2# oil (20 g/t) as forther in second scavenging.

TMDs based heterostructure have drawn much attention for its potential application in photoelectric devices benefiting from the rapid and effective carrier separation and ultra-long interlayer exciton lifetime. Recent studies on carrier dynamics of TMDs based heterostructures are mainly focused on the transfer process of photo-generated carriers across the interface and lifetime of interlayer exciton but little attention is paid on the dynamics of hot carriers. Here, the carrier dynamics of hot carriers in MoS2/WS2 heterostructure is investigated by transient absorption spectra. Rapid separation of electron and hole is observed. More importantly, hot carriers of C exciton, which contribute to the absorption of most of the visible light, could compensate for the carrier loss in the band edge exciton energy band through the intervalley transfer process. This re-injection process of hot carriers of C exciton could compensate for carrier depletion in photoelectric devices, thus may greatly improve the light utilization in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Real-time and effective detection of atmospheric profiles is of great significance in understanding the evolution of climate system. Ground-based microwave radiometers can provide atmospheric temperature and humidity profiles with extremely high temporal and spatial resolution. Domestic MWP967KV microwave radiometer has effectively made up for problems of imported microwave radiometers, but there are relatively few studies on the performance evaluation and application of this microwave radiometer. In order to better apply data and products of MWP967KV microwave radiometer, inversion data from June 2018 to July 2021 at Jinghe Station of Xi'an are compared with L-band radiosonde observation. The accuracy of atmospheric temperature, relative humidity and vapor density retrieved from microwave radiometer under clear skies and different cloudy skies (classified as low cloud, middle cloud and high cloud, respectively) are analyzed, and the applicability of the related products in precipitation is further explored. Results show that correlation coefficients of temperature between microwave radiometer and radiosonde are 0.99, correlation coefficients of vapor density are 0.97, and correlation coefficients of relative humidity are less than 0.50 under clear skies and cloudy skies, all passing 0.01 significant test. The difference of temperature between clear and cloudy skies is small, but root mean square error of relative humidity in cloudy skies is more than 25%, which is significantly larger than that in clear skies. It indicates that the presence of clouds reduces the accuracy of the humidity inversion, causing large errors, and the inversion accuracy is higher near the ground. Under different cloud types, the temperature difference is small, while root mean square error and bias of relative humidity in low cloud are the largest, which are 26.85% and 9.51%, respectively. In addition, a case analysis shows that relative humidity, liquid water content, atmospheric precipitable water vapor and liquid water path increase significantly before the occurrence of precipitation, which can be used as indicators of the possible occurrence of precipitation. Statistic results show that the atmospheric precipitable water vapor reaches 4 cm and liquid water path reaches 0.2 mm during several precipitation cases, and these indexes can be used as the reference threshold for judging the precipitation of Xi'an.

Pinched P–E hysteresis loops have been observed in filled tungsten bronze Ba4Eu2Ti4Nb6O30, indicating the presence of novel polarization mechanisms. We investigate the evolution of polar order in filled tungsten bronze Ba4Eu2Ti4Nb6O30, together with its dielectric properties over a wide temperature range, from 50 K to 773 K. The temperature dependences of the dielectric properties exhibit two low-temperature dielectric relaxations, at around 300 K (P1), and 100 K (P2), and a high temperature peak at 588 K with no frequency dispersion, indicating the ferroelectric transition temperature Tc. Pinched P–E loops are observed in the temperature range between the low temperature relaxation at P1, and the ferroelectric transition. On cooling, the pinched P–E hysteresis loops open gradually, with increasing remnant polarization (Pr). Two pairs of reversal electric fields indicate two types of polar reversal mechanisms, with an activated energy of 1.41 eV (E1), and 0.94 eV (E2), respectively. One corresponds to the field-induced transition from a nonpolar to a polar state, which dominates at a high temperature close to Tc, while the other relates to the reversal of ferroelectric domains which stabilize gradually on cooling. At temperatures below 300 K, the polarization exhibits an evident decrease, probably related to the disruption of the polar order due to the dielectric relaxation at P1. [ABSTRACT FROM AUTHOR]