Low-temperature oxidation-induced crack healing in Ti2Al0.5Sn0.5C–Al2O3 composites

The oxidation-induced crack healing of an Al₂O₃ composite loaded with various volume fractions of Ti₂Al_0.5Sn_0.5C repair filler particles was investigated by annealing in air at a relatively low temperature of 700°C. After annealing a composite with 20 vol.% repair fillers (with a particle size of ~5.6 µm) for 48 hours, artificial indentation cracks prepared on the surface, as well as pores near the surface, were completely healed by filling with condensed oxidation products. Additionally, minor fraction of metallic Sn was detected. A complementary study by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy revealed that nano-sized oxidation products (SnO₂, TiO₂, and α-Al₂O₃ phase) were formed as major crack-filling species. After healing, the strength recovery of the Al₂O₃ composites was significantly improved in the composites loaded with more than 10 vol.% repair fillers and achieved 107% at 700 for 48 hours.     

Discoloration of Hydrotreated Naphthenic Rubber Base Oil at High Temperature

In this article, the reasons for discoloration of hydrotreated naphthenic rubber base oil under high temperature were studied in detail. In order to define compositional factors associated with the color deterioration, firstly liquid-solid chromatography was used to separate hydrotreated naphthenic rubber base oil into five different fractions, i.e., saturates, monoaromatics, diaromatics, polyaromatics, and polars. Then color change of each fraction was evaluated under high temperature. The results of the test indicate that polyaromatics and polars are the main precursor of color and deposits, respectively, and the composition of polyaromatics was characterized by elemental analysis, gas chromatography mass spectrometry (GC-MS) and atmospheric pressure chemical ionization mass spectrometer (APCI/MS).     

Mechanism of Surface White Discoloration of Peeled (Minimally Processed) Carrots During Storage

A proposed mechanism of white discoloration development on peeled carrots included both physical and physiological responses to wounding. The physical response is a color change due to reversible surface dehydration. This study was performed at 2.5 and 10°C using a mode1 system controlling relative humidity, at 33, 75 or 98%, and a commercial system with low-density polyethylene (LDPE) plastic film bags. The rate of surface discoloration increased with decreasing RH. When excess surface moisture was left on peeled carrots, rates of white development decreased sharply at all RH compared with a dewetted control. The same effects were observed on peeled carrots stored in LDPE bags. Carrots partially regained their original color when water-dipped, due to reversal of the physical response component.     

铜包铝紫铜带端面氧化原因分析及预防

铜包铝紫铜带因端面未进行钝化处理,在生产或贮存时端面易发生氧化,影响后续包覆焊接质量。由此衍生的质量问题,不仅导致所生产的铜包铝线其铜层与铝芯不能牢固结合,后续拉拔极易剥离或断裂,使用中极易造成安全事故。本研究从生产工艺的角度,分析了铜包铝紫铜带端面氧化变色的原因,并提出了相应的防氧化措施。     

催化褪色动力学光度法测定食品中微量碘的研究

研究了在3.0mol/L的硫酸介质中,溴化钾催化碘酸钠氧化偶氮胂M褪色反应的适宜条件与影响因素,建立了催化动力学褪色光度法测定痕量碘的新方法。I-浓度在0.010～2.00μg/25ml范围内与lg(Ao/A) 呈线性关系。其λmax=540nm,Sandell灵敏度为3.20μg/cm2,RSD%为1.70%～4.40%,CV%为98.20%～108.20%。该法用于环境样品、生物材料、食品等实际样品中I-的测定,多数常见离子无干扰,方法简快,选择性好,结果满意可靠。     

PVC型材表面硫污染变色研究

详细研究了PVC型材表面发生硫污染变色的物质来源,影响硫污染变色的各种条件,并提出了解决方案。     

浅析变色服装的研究与发展现状

从变色服装的变色原理出发,介绍了不同类型的变色服装,分析其在不同领域的应用,从中折射出国内外有关变色服装的研究差距,旨在全方位展现变色服装的研究和运用现状,以期对中国变色服装行业有所启发,且简要分析了变色服装趣味化、安全化、服务化、智能化的发展方向。     

2,2,6,6-四甲基-4-哌啶醇异常变色问题的研究

2,2,6,6-四甲基-4-哌啶醇久置易变色,通过GC-MS联用技术对产品变色问题产生的根本原因进行分析,并以硼氢化钠为还原剂,通过二次还原的方法处理变色哌啶醇以达到更好效果。     

十八硫醇/乙醇体系自组装膜对银的防变色作用

十八硫醇(ODT)是一种环境友好型金属处理剂。在乙醇体系中用十八硫醇在银表面制备自组装膜(SAMs)。采用加速变色、极化曲线、电化学阻抗、循环伏安等方法研究了乙醇溶液中十八硫醇自装膜对银表面的防变色作用。结果表明,在浓度为0.05mol/dm3,温度为50℃时,自组装最佳时间为1h,十八硫醇在银表面形成了一层致密的自组装膜,该膜具有良好的防变色效果。