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The hot deformation behavior of a typical nickel-based superalloy was investigated by isothermal compression tests in the temperature range of 1010∼1160 °C and strain rate range of 0.001∼1 s−1. The results indicate that the work hardening, dynamic recovery (DRV) and dynamic recrystallization (DRX) occurred in the alloy during hot deformation. Considering the coupled effects of deformation parameters on the flow behaviors of the alloy, the constitutive models were established to predict the flow stresses during the work hardening-DRV period and DRX periods. In the DRX period, the modified DRX kinetic equation was used to develop the constitutive models, and the strain for maximum softening rate was used in this equation. Additionally, the material constants in the constitutive models were expressed as the functions of Zener-Hollomon parameter by using a linear fitting method. Meanwhile, comparisons between the measured and the predicted flow stresses were carried out, while the correlation coefficient (R) and average absolute relative error (AARE) between the measured and predicted values were also calculated. The results confirm that the developed models could give an accurate estimation of the flow stresses.

Extracting value-added chemicals from renewable resources has attracted much attention in facing the crises arising from fossil resources. This study elucidates a promising strategy of producing valuable organic acids, including maleic acid, formic acid and succinic acid, via a new ozonation process. 5-hydroxymethylfurfural (HMF) and furfural, two platform chemicals obtained from biomass hydrolysis, are used as the raw materials. Under alkaline reaction condition (25 °C, 10 mg/L O3, and 90 min), improved yields of maleic acid, succinic acid and formic acid reached 25.3 wt%, 10.0 wt% and 41.1 wt% from HMF, as well as 17.6 wt%, 2.5 wt% and 79.5 wt% from furfural; respectively. This sustainable manufacturing technology exhibited significant advantages, including one simple process, room condition, avoiding of organic solvent and absence of metal catalysts. This work paves the ways from biomass to commercial organic acids via hydrolysis followed by ozonation.

The hydriding-dehydriding process was used to recycle AZ40 magnesium (Mg) alloy scraps, and the microstructure nanocrystallization was realized. X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy were carried out to characterize the microstructure. After mechanically milling in hydrogen for 72 h, matrix Mg was completely turned into nanocrystalline MgH2, with an average crystallite size of about 10 nm. And then, the MgH2 phase was completely transformed into Mg again through vacuum dehydriding treatment at 300 °C for 192 min, with an average crystallite size of about 20 nm. In addition, the nanocrystalline alloy powders were hot-pressed and extruded into bars. The average grain size of the bars was about 500 nm, which had reached the size of ultrafine-grain. Meanwhile, the yield strength and ultimate tensile strength of the as-extruded bars reached about 312 and 497 MPa, respectively. The results indicate that hydriding-dehydriding process is a feasible method for recycling of Mg alloy scraps, and it is expected to have a good application prospect in preparing ultrafine-grain Mg alloys.

In this paper, a virtual dynamic model using ADAMS, considering the effects of the mesh stiffness, mesh damping, load inertia, drive ratio and gear backlash is presented for a space manipulator joint. A kind of virtual sweep method is adopted to analyze the resonant frequency of the joint quantitatively and mesh stiffness and load inertia are proposed the key influence factors of frequency property of the joint. In order to design, validate and improve the performance of the joint mechatronic system, the ADAMS and SIMULINK co-simulation is used to build a servo-control model of the joint. The joint motor is derived and modeled, and the dynamic model of the space manipulator joint with sensors and actuator implemented in ADAMS is embedded into SIMULINK environment directly. The speed and position two-loop control system is modeled in SIMULINK, and the control parameters were obtained. A prototype joint and controller are manufactured, a virtual prototype model tuning is implemented through the experimental data. So the co-simulation joint model can be used for the design, simulation and testing of the space manipulator joint.