泡沫塑料分离富集微量银的研究

研究了用聚氨酯泡沫塑料分离富集微量银的方法,对银与邻二氮菲的配合物的吸附选择性和富集效果较佳,在EDTA存在下,其它金属离子不被吸附,银可用1m0l/L HNO_3定量洗脱。     

不锈钢基厚膜PTC热敏电阻浆料的制备与性能研究

以二氧化钌和氧化铜的混合物为功能相制备出不锈钢基厚膜PTC热敏电阻浆料.研究了功能相与玻璃相的配比、功能相的粒度对厚膜电阻方阻及电阻温度系数(TCR)的影响规律.结果表明:固定浆料中玻璃相的成分与含量(30wt%),控制功能相中RuO2的比例(45.4wt%～88.9wt%)或功能相的粒度(0.30～1.0μm),可制得具有不同方阻(1.5～12.8Ω/□)和TCR(2100～2900×10-6/℃)的厚膜PTC热敏电阻.     

完善立式电解槽电解精炼银的技术工艺

叙述立式银电解精炼的技术改进：①银电解中的残极处理方法，②电解银粉的出槽，③硝酸银的制备与废液的处理方法，④溶液循环系统的设计。     

热处理对Ag—15Al固溶体短程有序度的影响

研究了热处理对Ag-15Al(at％)固溶体合金电阻率和有序参数的影响,由X射线衍射分析表明,合金的短程序转变不是Ag_3Al化合物型的δ第二相的形成,而是α-Ag-Al固溶体原子的有序排列。     

湿法冶金制备的Ag—Pd合金粉末的固溶合金化研究

根据Ｘ射线衍射原理，建立湿法冶金固溶合金粉末的定量测定方法，可用于电子浆料合金粉末的检测，相对误差在±０．０１２５。     

离子轰击膏剂渗硼试验

通过增加辅助阴极,提高无附加热源的离子渗氮炉的升温速度和使用温度,以满足离子渗硼的需要,对以硼铁为供硼剂的渗硼膏剂进行试验,选出在本试验条件下的最佳渗硼膏剂。利用此膏剂,对45钢在850℃×3h条件下进行离子渗硼,得到180μm厚的渗硼层。     

A selective modified bentonite–porphyrin carbon paste electrode for determination of Mn(II) by using anodic stripping voltammetry

A novel voltammetric sensor based on chemically modified bentonite–porphyrin carbon paste electrode (MBPCE) has been introduced for the determination of trace amount of Mn(II) in wheat flour, wheat rice and vegetables. In this method Mn(II) gives well-defined voltammetric peak at the pH range of 3.5–7.5. For the preliminary screening purpose, the catalyst was prepared by modification of bentonite with porphyrin and characterized by thermogravimetric method (TG) and UV–vis spectroscopy. The detection limit (three times signal-to-noise) with 4 min accumulation is 1.07 × 10⁻⁷ mol L⁻¹ Mn(II). The peak currents increases linearly with Mn(II) concentration over the range of 6.0 × 10⁻⁷ to 5.0 × 10⁻⁴ mol L⁻¹ (r² = 0.9959). Statistical treatment of the results gave a relative standard deviation lower than 2.30%. The chemical and instrumental parameters have been optimized and the results showed that 1000-fold excess of the additive ions had not interferences on the determination of Mn(II).     

基于自适应方向模板搜索的 FPC 走线薄浆检测

本文薄浆是柔性印刷电路板(FPC)导电涂层的一种缺陷,为避免其对电路性能产生不良影响而造成经济损失,将薄浆 位置检测出来进行修补或直接剔除板材均是合理的处理方式。 然而由于薄浆缺陷尺寸不定、光照不均致使图像灰度分布不均 匀、走线区域与背景纵横交错等问题,使得走线上薄浆的检测具有一定难度。 针对该问题,在对薄浆纹理及 FPC 走线形态特征 进行详细分析的基础上,提出了一种基于自适应方向模板(ADT)和灰度差分法的检测方案。 首先,使用定义的 ADT 模板按照 骨架跟踪流程对预处理所得图像的走线区域进行遍历,分别搜索相对于该 ADT 模板尺寸而定义的大、小尺度薄浆纹理的端部 和全部候选像素,从而将预处理图像分割成若干小区域;然后,根据各小区域的能量倾向值与预设阈值的数值关系对其中的边 缘噪声区域加以排除;最后,采用灰度差分法对上述两个步骤处理所得结果中的非缺陷区域进行再次筛查,从中提取出大尺度 薄浆纹理的中间区域,至此实现全部薄浆纹理的检测。 在自建图库 SUT-F2 上进行了测试,结果显示本文方法对薄浆缺陷检测 的等误率仅为 3. 92%,相对于其他典型纹理特征提取和薄浆检测方法其等误率至少降低了 5. 28%,表明了本文方法的高效性, 具有实际应用价值。     

Electrochemical determination of hydrazine based on polydopamine-reduced graphene oxide nanocomposite

In this work, a simple and mild procedure was employed to synthesize polydopamine-reduced graphene oxide (PDA-RGO) nanocomposites, where the sheets of graphene oxide were functionalized firstly with PDA through self-polymerization. FTIR was used to confirm that the GO sheets had been functionalized successfully with PDA and reduced. Besides, UV-Vis and X-ray diffraction spectroscopy were employed to further demonstrate the formation of RGO. The electrochemical property of the PDA-RGO has been studied by the determination of hydrazine. The results indicated that the electrochemical oxidation of hydrazine was significantly improved by the obtained PDA-RGO nanocomposite due to the increased available surface area of electrode. A quick amperometric response was observed with the electrochemical sensor based on PDA-RGO nanocomposite for the hydrazine measurement in a wide linear range of 0.03–100 μM, where the limit of the detection was 0.01 μM.     

The rim zone of cement-based materials – Barrier or fast lane for chemical degradation?

Sophisticated evaluation models for the long-term stability of cement-based systems demand a precise knowledge of the mechanisms of deterioration reactions, particularly respecting a permanent exposure to aqueous environments. Commonly, insights into these mechanisms are deduced from long-term investigations. However, these chemical reactions start immediately after exposure to aggressive environments causing rapid changes of composition and structure. Consequently, properties of its rim zone change, which affects transport processes in aqueous solutions. In laboratory experiments, the influence of these surface processes on the stability of cement-based materials exposed to different chloride solutions was studied as a function of time and temperature. Analysis of compositional and structural changes beneath the surface reveal the role of crystalline covering layers for chemical resistance. Such layers are often described as protective barriers. However, these processes in the rim zone can accelerate chemical degradation and subsequently reduce the resilience of the cement-based materials to aggressive aqueous environments.