Microstructure-abrasive wear correlation of in situ ZA27/TiC composites

Abrasive wear is a complex surface degradation process driven by various factors such as microstructure, the mechanical properties of the target material, the abrasive, loading conditions, and the surrounding environment. In this study, in situ TiC reinforced Zinc Aluminum alloy composites were prepared through a liquid metallurgy route and the synergistic effect of applied load, sliding speed, abrasive grit size and TiC content on the high-stress abrasive wear response were investigated. The test materials' wear response was established by characterising wear surfaces, sub-surfaces, debris particles, and an abrasive medium. The study suggests that the wear resistance of the specimens decreases with an increase in the applied load, and the composite reinforced with 10 wt % of TiC shows superior wear behaviour among all the test materials. The study also points out that the ZA-27 alloy reinforced with in situ TiC can be a suitable replacement of the conventionally used materials for automotive applications.     

不同改良措施对排土场土壤微形态影响的试验研究

以铁矿排土场废石土为研究对象,自制模型试验装置,设计4种基质改良方法,开展SEM检测实验,并应用IPP软件对SEM照片进行定量化分析,研究在不同改良措施下对铁矿排土场土壤微结构的影响。结果表明：单施3%有机肥土壤孔隙度为16%,与对照组排土场原矿土相比增加了60%。复合施用3%有机肥、掺拌30%的黄土的处理孔隙度达到最大33%。单施3%有机肥、5%有机肥对土壤大团聚体含量皆有显著的促进作用,复合施有机肥、掺拌黄土的处理与单施有机肥的处理对比,土壤大团聚体含量增加并不显著。各改良措施的MWD与FMD均随着土壤中大团聚体的含量增加而增加。     

Effects of three types of modified atmospheric packaging on the physicochemical properties of selected glutinous rice

The effect of modified atmospheric packaging (MAP) on the physicochemical properties of selected glutinous (Thadokkham-8 and Thadokkham-11) rice was studied and compared with a non-glutinous rice (Doongara). The freshly harvested/milled grains were packed in four different MAP conditions viz. control, vacuum, CO₂ and N₂ for 12 months at room temperature (23 ± 1 °C). Gas (N₂ or CO₂) was flushed in aluminum bags at the pressure of 300 kPa for 3 s and subsequently hermetically sealed. Vacuum packaging was done at −100 kPa. Results showed that ageing induced changes in the starch granules were less prominent in vacuum and/or MAP samples using CO₂ or N₂. Surface analysis showed that control storage significantly reduced the percentage of lipids and increased the percentage of proteins on the surface in all selected varieties. N₂ and CO₂ storage of TDK8 and DG slowed down the shift of properties of macromolecules and maintained the surface starch/proteins/lipids ratios during 6 months of storage. Moreover, the grains stored in vacuum maintained the lipids with lower proportion of proteins exposed to the surface after cooking. N₂ and CO₂ induced increase in pasting temperature but significant reduction in final viscosity when compared to control. The findings correlated well with thermal analysis. The in situ Thermal Mechanical Compression Test (TMCT) device cooking and texture analysis revealed that modified storage slightly slowed the ageing induced changes in the cooking quality and stickiness of glutinous rice. Among all storage conditions used vacuum was relatively the best to maintain the quality of the grain.     

The control of paracetamol particle size and surface morphology through crystallisation in a spray dryer

The parameters governing the crystallisation of paracetamol using various conventional techniques has been extensively studied, however the factors influencing the drug crystallisation using spray drying is not as well understood. The aim of this work was to investigate the crystallisation of an active pharmaceutical ingredient through evaporative crystallisation using a spray dryer to study the physicochemical properties of the drug and to use semi-empirical equations to gain insight into the morphology and particle size of the dried powder. Paracetamol solutions were spray dried at various inlet temperatures ranging from 60 °C to 120 °C and also from a series of inlet feed solvent compositions ranging from 50/50% v/v ethanol/water to 100% ethanol and solid-state characterisation was done. The size and morphology of the dried materials were altered with a change in spray drying parameters, with an increase in inlet temperature leading to an increase in particle Sauter mean diameter (from 3.0 to 4.4 µm) and a decrease in the particle size with an increase in ethanol concentration in the feed (from 4.6 to 4.4 µm) as a result of changes in particle density and atomised droplet size. The morphology of the dried particles consisted of agglomerates of individual crystallites bound together into larger semi-spherical agglomerates with a higher tendency for particles having crystalline ridges to form at higher ethanol concentrations of the feed.     

选区激光熔化工艺参数对气雾化316L不锈钢粉末成形制品性能的影响

本研究系统考察了激光功率和扫描速度对316L不锈钢粉末选区激光熔化工艺成形熔道、制品微观组织及力学性能的影响,并分析了各类缺陷的形成原因。研究结果表明:在低激光功率和高扫描速度条件下,熔道中出现了大量球状颗粒,这些颗粒之间的空隙恶化了下一层粉末的熔化条件,这正是成形制品中熔道分布混乱以及孔洞、裂纹产生的根本原因,进而导致成形制品力学性能降低;在高激光功率和低扫描速度条件下,熔池快速升温/冷却的热应力作用增强,使得成形制品的熔道交界处也存在孔洞和裂纹等缺陷。在本研究实验条件下,激光功率为350 W,扫描速度为1750 mm/s时,SLM成形制品的力学性能最为优异,其中抗拉强度为731 MPa、屈服强度为638 MPa、断后伸长率为40.0%,致密度为96.27%。     

Experimental studies and thermodynamic assessment of the Ba-Mo-O system by the CALPHAD method

Thermodynamic measurements on BaMoO₄, BaMoO₃ and BaMo₃O₁₀ are reported, that served as input for the development of a thermodynamic model of the Ba-Mo-O system using the CALPHAD methodology. The valence states of molybdenum in BaMoO₄ and BaMoO₃ were confirmed to be VI and IV, respectively, from X-ray Absorption Near Edge Structure Spectroscopy measurements at the Mo K-edge. The heat capacity at low temperatures of these compounds was obtained from thermal-relaxation calorimetry. Phase equilibrium data in the BaMoO₄-MoO₃ section were also measured, and the transition enthalpy associated with the peritectic decomposition of BaMo₃O₁₀ was determined using Differential Scanning Calorimetry. The developed thermodynamic model used the compound energy formalism for intermediate compounds, and an ionic two-sublattice model for the liquid phase. The optimized Gibbs energies were assessed with respect to the known thermodynamic and phase equilibrium data. A good agreement is generally obtained, but a number of ill-defined data were also identified.     

Charge Transportation and Chirality in Liquid Crystalline Helical Network Phases of Achiral BTBT-Derived Polycatenar Molecules

First examples of multichain (polycatenar) compounds, based on the π-conjugated [1]benzothieno[3,2-b]benzothiophene unit are designed, synthesized, and their soft self-assembly and charge carrier mobility are investigated. These compounds, terminated by the new fan-shaped 2-brominated 3,4,5-trialkoxybenzoate moiety, form bicontinuous cubic liquid crystalline (LC) phases with helical network structure over extremely wide temperature ranges (>200 K), including ambient temperature. Compounds with short chains show an achiral cubic phase with the double network, which upon increasing the chain length, is at first replaced by a tetragonal 3D phase and then by a mirror symmetry is broken triple network cubic phase. In the networks, the capability of bypassing defects provides enhanced charge carrier mobility compared to imperfectly aligned columnar phases, and the charge transportation is non-dispersive, as only rarely observed for LC materials. At the transition to a semicrystalline helical network phase, the conductivity is further enhanced by almost one order of magnitude. In addition, a mirror symmetry broken isotropic liquid phase is formed beside the 3D phases, which upon chain elongation is removed and replaced by a hexagonal columnar LC phase.     

Evaluation of particle recovery from microalgae

Coccoliths are micro-structured biomineral particles found in cell protective covering layers of coccolithophore species. They are mainly composed of CaCO₃ and their individual crystal entities are arranged in such a way that they construct complex and unique structures. This complexity is found down to the individual particle level and appears to have promising properties to offer. This study focuses on the essential step prior to any kind of implementation, which is the recovery of the material. It summarizes cleaning protocols found in literature, compares them for the first time for the same freshly cultivated material and addresses challenges that still need to be overcome. Further, it highlight the advantages and disadvantages of the best cleaning protocols, suggests optimizations with promising results and uses size distribution measurements to analyse the recovery efficiency. To that end, further characterization techniques, new for coccoliths, are introduced and used to improve our current knowledge of the particles behaviour.     

Evidence of nano-galvanic couple formation on in-situ formed nano-aluminum amalgam surfaces for passivation-bypassed water splitting

Reaction of Al metal with water is a well-known technique for large scale production of hydrogen. However, this method suffers from kinetic limitations due to formation of a passivation layer on Al, preventing optimal operations. Using high resolution Scanning Kelvin Probe Force Microscopy (SKPFM), we show the origin of formation of 'nano-galvanic couple' on in situ formed nano-aluminum amalgam surfaces in a water splitting system; passivation based limitations are completely bypassed in this approach. Furthermore, they offer an opportunity to beneficiate and recover mercury in contaminated water. The nano-galvanic corrosion due to substantial lateral variation in surface contact potential is responsible for the observed high throughput of hydrogen production (720 mL/min per 0.5 g Al salt). It may be noted that this process fares better than in situ prepared nano-Al based hydrogen production, wherein 600 mL/min of hydrogen is obtained for 0.5 g Al salt. Investigations using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) provide evidence for passivation-bypassed hydrolysis and favourable kinetics for in situ derived nano-AlHg hydrolytic agents (when compared to nano-Al). This study, to the best of our knowledge, reports the first direct proof of nano-galvanic couple formation on in-situ prepared nanoaluminum amalgam surface; paving a direct way to overcome the long standing passivation problem in Al hydrolysis. It is found that the hydrogen production rate and standard deviation (SD) of the contact potential of nanoaluminum amalgam are directly related to the rate of addition of the reducing agent, offering an opportunity for kinetic control for the in situ hydrolytic process.     

Principle of a two-output-difference interferometer for removing the most important interference distortions

This paper presents a two-output-difference interferometer for removing the most important interference distortions caused by nonlinear detectors. These distortions can be removed not only because the resulting interferogram is composed of the difference between the signals of the two detectors, but also because the modulated signals at each output have the same amplitude and opposite phases. Due to the use of two corner-cube mirrors fixed as a single moving element, the tilt and shearing problem will disappear. The effect of the corner-cube mirror deviation angle and the plane mirror tilt angle are investigated in detail, and the formulas of their tolerance are derived by means of modulation depth and phase error. The advantage of the interferometer enables it to be suitable for Fourier transform spectrometers.