Microstructure and phase transformation behavior of Al2O3–ZrO2 under microwave sintering

Zirconia is an inorganic, nonmetallic material with excellent properties. However, the brittleness of the zirconia, resulting from the thermal performance during the heating and cooling process, seriously limits the application of zirconia in the metallurgical, military, and aerospace industries. Al₂O₃ doped ZrO₂ was developed to improve the potential material's toughness. This paper studied the evolution of the surface functional groups, phase composition, toughening mechanism, and particle morphology of Al₂O₃ doped ZrO₂ during the heating process. Especially microwave heating was selected as the heating method during the experiments to save energy consumption. The results showed that the phase transition temperature was reduced by the microwave sintering technique, which also promoted the transformation between the m-ZrO₂ and t-ZrO₂, advancing the crystallinity and structural properties of the samples. The specific surface area shows a positive relationship with the microwave heating temperature, while the particle size of the powder decreased with the temperature increase. The optimized sintering effect appears at 1000 °C in the studied roasting temperature range (800 °C–1200 °C) for Al₂O₃–ZrO₂ powders. With the optimized sintering temperature, the void of the granular zirconia material was controlled, and the best micromorphology was obtained. In practical production, the application of microwave sintering and alumina doping is beneficial to saving costs and protecting the environment.     

焙烤对甜荞关键组分及风味物质的影响研究进展

甜荞是一种高营养价值的功能性杂粮，焙烤是改善甜荞粉风味的一种工艺，其对甜荞的淀粉、蛋白、抗氧化物活性物质及风味物质有显著影响。其中，经过焙烤后的甜荞粉，淀粉糊化程度增加，糊化温度升高，结晶程度降低，淀粉颗粒结构被破坏；蛋白质性质发生变化，氨基酸含量增加；抗氧化活性物质含量随焙烤程度呈先增加后降低的趋势。此外，焙烤使甜荞粉风味丰富，增加了吡嗪类物质，使甜荞粉的风味中添加坚果味以及焦香味，甜荞粉的风味得到改善。本文首先从甜荞的焙烤工艺入手，重点回顾了焙烤过程对甜荞籽粒及甜荞粉的关键组分及风味物质的影响，并对影响甜荞焙烤品质的关键因素进行了分析，最后，对焙烤甜荞的应用前景进行了展望。     

低品位铌矿硫酸焙烧——草酸浸出回收铌的研究

开展了对低品位铌精矿进行硫酸焙烧及草酸浸出研究，考察了不同因素对铌富集效果的影响。结果表明，在硫酸焙烧阶段，在矿物粒径为-150 200目、焙烧温度为200℃和硫酸浓度为80%的条件下，焙烧40min，可使铌精矿中97%以上的铌和90%以上的钙留在渣相，93%以上的铁、锰及钠进入液相；在草酸浸出阶段，在草酸浓度为85%及浸出温度为80℃的条件下，含铌滤渣浸出60min，可使铌浸出率达到98%以上，钙浸出率低于0.6%。     

Supercritical fluid extraction as a potential mitigation strategy for the reduction of acrylamide level in coffee

The removal of acrylamide from coffee through supercritical CO₂ extraction has been investigated for the first time. Two steps were performed: a pre-roasting treatment and a supercritical extraction process. The main aim of this first work was to investigate the feasibility of the process more than the impact of the treatment on the organoleptic properties of coffee. The efficiency of acrylamide removal was checked by measuring its content in the coffee beans before and after the supercritical treatment. The role of temperature, pressure, extraction time and the addition of a modifier (ethanol) was examined.