TMCP工艺下Ti-Mg氧化物冶金钢轧态组织性能

摘要：为研究轧制过程中氧化物粒子对母材组织性能的影响，提出了一种只在再结晶区进行轧制的新工艺路线，利用常规冶炼及氧化物冶炼的实验钢分析其轧态显微组织、力学性能及相变过程。结果表明：在新轧制工艺下，氧化物冶金钢母材显微组织由常规的贝氏体板条束变为针状铁素体，其基体具有良好的力学性能，-80℃冲击韧性达149J；热轧工艺下的组织转变分两阶段进行，初期是针状铁素体的形核和晶粒细化，之后贝氏体相变被限制在针状铁素体板条间构成的区域内。     

Advanced Friction–Wear Behavior of Organic Brake Pads Using a Newly Developed System

The objective of this study was to investigate the influence of an advanced performance system on the tribological behavior of brake pad material using a specially designed brake pad tester system following standard SAE J-661. The tribological behavior and friction and wear characteristics of the organic brake pad samples were evaluated. During braking tests, the samples, in contact with a cast iron disk, were studied at different disc speeds, temperatures, and braking cycles under a constant pressure. In order to understand the friction and wear behavior, the unworn surfaces, worn surfaces, and wear debris were characterized by means of scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). Furthermore, the surface characteristics and differences in the wear modes of the brake pad samples were examined. Wear debris was permitted to deform the brake pad surfaces, leading to friction layers and enabling the estimation of the friction behavior of the brake pads. The results showed that the best friction–wear behavior was obtained with lower braking cycles at low speeds and temperature. Thus, the newly developed brake pad tester system proved very effective in evaluating the performance of the brake pad samples.     

New insights into microstructural changes during transient liquid phase bonding of GTD-111 superalloy

The effects of joining temperature (T_J) and time (t_J) on microstructure of the transient liquid phase (TLP) bonding of GTD-111 superalloy were investigated. The bonding process was applied using BNi-3 filler at temperatures of 1080, 1120, and 1160 °C for isothermal solidification time of 195, 135, and 90 min, respectively. Homogenization heat treatment was also applied to all of the joints. The results show that intermetallic and eutectic compounds such as Ni-rich borides, Ni−B−Si ternary compound and eutectic-γ continuously are formed in the joint region during cooling. By increasing t_J, intermetallic phases are firstly reduced and eventually eliminated and isothermal solidification is completed as well. With the increase of the holding time at all of the three bonding temperatures, the thickness of the athermally solidified zone (ASZ) and the volume fraction of precipitates in the bonding area decrease and the width of the diffusion affected zone (DAZ) increases. Similar results are also obtained by increasing T_J from 1080 to 1160 °C at t_J=90 min. Furthermore, increasing the T_J from 1080 to 1160 °C leads to the faster elimination of intermetallic phases from the ASZ. However, these phases are again observed in the joint region at 1180 °C. It is observed that by increasing the bonding temperature, the bonding width and the rate of dissolution of the base metal increase. Based on these results, increasing the homogenization time from 180 to 300 min leads to the elimination of boride precipitates in the DAZ and a high uniformity of the concentration of alloying elements in the joint region and the base metal.     

机械活化对粉煤灰提铝影响研究

为提高粉煤灰中铝提取率, 采用机械活化对粉煤灰进行预处理, 探讨了机械活化对粉煤灰焙烧-酸浸效果的影响。结果表明: 机械活化能提高粉煤灰比表面积、增加反应活性点, 促进活化反应的进行; 通过机械活化, 在Na₂CO₃与Al₂O₃物质的量比1.6、850 ℃下焙烧50 min后酸浸, 铝浸出率达到91.58%。     

Effects of direct current magnetic field treatment time on the properties of pork myofibrillar protein

This study investigated the effects of direct current magnetic field (DC-MF) treatment time (1, 3, 5, 8 h) on properties of porcine myofibrillar protein (MP). Gel water-holding capacity increased from 83.40% to 87.20% when DC-MF-treatment time changed from 1-h to 8-h. The 3-h treatment time of DC-MF was found to promote MP unfolding, rearrangement and aggregation, leading to the loss of total sulfhydryl, the increase of reactive sulfhydryl, surface hydrophobicity, turbidity as well as the formation of MP clusters and the greater degree of crosslinking as compared with 0-h treatment, thus a firmer and more ordered MP gel network for trapping more water. However, excessive DC-MF treatment (8-h) weakened DC-MF effect on MP aggregation as well as gel network and texture. This study has shed light on the effects of DC-MF treatment time on MP properties and provides useful information for the application of DC-MF in the food industry.     

加工精度对方便米饭理化性质的影响

过度"精、细、白"的大米加工方式造成大量的粮食和营养浪费。为促进我国粮食适度加工政策的实施,研究大米加工精度(DOM)对方便米饭复水性质(水分含量和水分分布)、形态特征(长宽比、延长率和体积膨胀率)、颜色(L值、b值和ΔE值)、质构(硬度和黏度)和微观结构的影响及规律。结果表明,当DOM≥3%时,方便米饭的水分吸收速率、水分分布和形态特征与精白米方便米饭(DOM 12%)相近。当DOM升至6%时,方便米饭的形态特征、总体颜色ΔE值、硬度和微观结构也与精白米方便米饭相近。当DOM达到9%时,方便米饭的黏度已与精白米方便米饭无显著差异。由此可见,生产方便米饭的大米DOM范围宜为6%～9%。用此DOM范围的大米生产方便米饭,可以保留部分糠层营养物质,节约3%～6%的粮食。     

Predicting elastic modulus of porous La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes from microstructures via FEM and deep learning

In this work, a deep learning accelerated homogenization framework is developed for prediction of elastic modulus of porous materials directly from their inner microstructures. The finite element method (FEM) and the homogenization theory are used to obtain the macroscopic properties of materials based on their microstructures. Based on a large dataset consisting of various microstructures and corresponding elastic properties via FEM, a deep convolutional neural network (CNN) is trained to capture the nonlinear functional relationship between the microstructure features and their macroscopic elastic properties. The deep learning model is finally well validated against extra new samples with excellent predictive performances. This demonstrates that the CNN deep learning model can be trusted as a surrogate model for the FEM based homogenization method, with the computation time being reduced by several orders of magnitude. The proposed deep learning framework is highly extendable for prediction of various macroscopic properties from microstructures.