陶瓷原料中二氧化硅分析方法的对比与选择

本文综合各种文献 ,对陶瓷原料中SiO2 的各种分析方法的优缺点 ,使用条件 ,应用侧重点进行了比较与评述     

Investigation of Flow Patterns in Continuous‐flow Stirred Vessels by Laser Doppler Velocimetry

The flow structure of a continuous‐flow reactor stirred by a Rushton turbine was investigated by laser Doppler velocimetry for two different mean residence time‐mixing time ratios. Velocity measurements were obtained for two inlet locations, corresponding to the incoming liquid stream being fed co‐currently or counter‐currently to the flow discharged by the turbine. In all investigated configurations and for all operating conditions, it was found that the flow disruption caused by the incoming liquid stream was observable mainly in the first vessel quarter, which followed the feed‐tube plane. From comparison of the velocities encountered in the various planes in the continuous‐flow reactor to the velocities of the batch reactor, it was also concluded that it may be possible to intensify the usage of the turbine‐stirred vessel by decreasing the characteristic times ratio, without considerable flow by‐pass and/or short‐circuiting problems.     

Novel fluorescent polynorbornenes with multi-functional armed structure by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization and atom transfer radical polymerization

Novel organosoluble fluorescent polynorbornenes with multi-functional armed structure were designed and prepared by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). A bromo-containing functional norbornene (NBMBr) was prepared from the Diels-Alder reaction of cyclopentadiene and allyl bromide. The diblock copolymer of 5-(N-carbazolyl methyl)bicycle[2.2.1]hept-2-ene (CbzNB) and NBMBr was successfully prepared using living ROMP and used as a novel macroinitiator [poly(CbzNB-b-NBMBr)] for ATRP. Carbazoyl-containing multi-functional armed copolymer with poly(methyl methacrylate) (PMMA) was prepared by using poly(CbzNB-b-NBMBr) as a macroinitiator for ATRP. Strong fluorescence emissions (370-450 nm) were observed in the low excimer-forming multi-functional armed fluorescent polynorbornenes. The fact is that low excimer-forming carbazole-containing polymeric compound would apparently be favorable in photoconductive materials. The multi-functional armed structure make this compound an attractive candidate for applications as multi-modified hole transport materials in molecular electronic devices. Multi-modification could be further considered to be carried out by using such a functional bromo group at the end of multi-arms.     

Radical entry mechanisms in redox-initiated emulsion polymerizations

The mechanisms and kinetics of radical entry in emulsion polymerizations utilizing redox initiation are investigated using polymerization rate data obtained by reaction calorimetry and electrospray mass spectroscopy analysis of initiator-derived aqueous-phase products. These data have been used to evaluate an initiation scheme for redox-initiated emulsion polymerizations of common monomers such as styrene and methyl methacrylate based around the oxidant, tert-butyl hydroperoxide. Redox initiators are broadly classed by the solubility of their radical products: Hydrophilic radicals enter by propagating to a critical degree of polymerization to become surface-active whilst more hydrophobic radicals may enter particles directly. When direct entry is applicable (the hydrophobic case), initiation efficiency will always be very high.     

Synthesis of thermosetting poly(phenylene ether) containing allyl groups

New thermosetting poly(2-allyl-6-methylphenol-co-2,6-dimethylphenol)s (3) have been developed by oxidative coupling copolymerization of 2-allyl-6-methylphenol (1) with 2,6-dimethylphenol (2), followed by thermal curing. Copolymerization was conducted in nitrobenzene in the presence of copper(I) chloride and pyridine as the catalyst under a stream of oxygen, producing high molecular weight copolymers (M_n∼50,000) with broad molecular weight distributions (M_w/M_n∼35). The structure of resulting copolymers 3 was characterized by IR, ¹H, and ¹³C NMR spectroscopy. Cross-linking reactions of copolymers were carried out by thermal treatment in the absence or presence of a peroxide (3 wt%, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-butane). The 10% weight loss and glass transition temperatures of the cured copolymers were 436 °C in nitrogen and 235 °C, respectively after curing at 70 °C for 1 h and 300 °C for 1 h. The average refractive index of the cured copolymer (3b) film was 1.5407, from which the dielectric constant (ε) at 1 MHz was estimated as 2.6. The ε and dissipation factor of copolymer-films at 1 MHz were directly measured from their capacitances as 2.5-2.6 and 0.0015-0.0019, respectively.     

2-（4-氯苯氨基）甲基苯酚降解的动力学研究

采用高效液相色谱技术,开展了Fenton试剂对2-（4-氯苯氨基）甲基苯酚（CMP）的氧化降解动力学的研究。考察了初始双氧水摩尔浓度、亚铁离子摩尔浓度和温度等因素对CMP降解速率的影响,结果表明,当双氧水摩尔浓度、亚铁离子摩尔浓度增大和温度升高时,CMP的氧化速率明显加快。在30~45℃的温度范围内,其氧化降解符合假一级反应动力学模型,反应的表观活化能Ea为102.90kJ/mol。     

视觉检测系统中亮度不均匀背景的一种去除方法

刀具形状视觉检测系统中，照明不均匀对测量结果影响很大。针对这种情况，提出了基于二维二阶多项式拟合并去除不均匀背景的方法。遵循最小均方程差原理，给出了二维二阶拟合的矩阵表达式。在编制的程序中，拟合点以人机交互形式由鼠标点击选出，程序自动记录所选点的图象人材与亮度值信息，然后拟合出背景曲面，并以二值图象形式给出去除背景后的目标图象。对一幅光照模型未知的网络图象进行了背景去除，实验结果良好。     

非平稳时序循环平稳趋势提取与机械故障诊断

在简单介绍非平稳时序模型周期趋势项提取方法的基础上，提出了机械故障诊断和分析方法，该方法利用旋转机械出现故障以后所呈现的循环平稳特性，使用循环平稳分析方法剔除非平稳时间序列模型中的趋势项，然后建立平稳时序模型，用该模型进行机械故障诊断分析。并运用仿真和实例对方法的正确性进行了验证。     

Effects of coating thickness and residual stresses on the bond strength of ASTM C633-79 thermal spray coating test specimens

Wire-arc-sprayed nickel-aluminum is widely used in the aircraft industry for dimensional restoration of worn parts and as a bond coat for thermal barrier coatings and other top coats. Some repair applications require thick coatings, which often result in lower bond strength. A mechanism being investigated to ex-plain this decrease in bond strength is the free edge effect, which includes both coating residual stresses and coating thickness. The layer-removal method was used to determine experimentally the residual stresses in wire-arc-sprayed nickel-aluminum coatings of different thicknesses. Bond strength evalu-ations were performed using an improved ASTM C 633-79 test specimen. Finite-element analysis and fracture mechanics were used to investigate the effects of coating thickness and residual stress state on coating bond strength.     

棒线材连轧中的微张力闭环控制

介绍了棒线材连轧中微张力闭环控制的基本思想及方法，并分析了微张控制技术的应用条件。