钼酸铵复合缓蚀剂对LY12铝合金的缓蚀作用

采用电化学方法研究了钼酸盐、锌盐和苯并三氮唑 (BTA)对LY12铝合金在 3 5 %NaC1溶液中的缓蚀作用。结果表明 ,随着钼酸盐浓度的增大 ,缓蚀效率增大 ,达到一个最大的值后基本保持不变。钼酸盐通过抑制铝合金的阴极反应和阳极溶解实现缓蚀作用。钼酸盐与锌盐和BTA复合后 ,明显提高了对铝合金的缓蚀作用 ,表现出良好的协同效应     

Application of an analytical phase transformation model

Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic.     

热型连铸过程的一维稳态传热模型

根据热型连铸技术原理，建立了热型连铸凝固过程一维稳态温度场的物理、数学模型。通过数值计算，得出了铸型出口温度、冷却距离、拉铸速度和喷水冷却强度等工艺参数对铸坯固液界面位置的影响。计算结果与试验结果吻合。     

汽车后市场准入门槛亟需设防

任何市场都是有规则的,没有标准的市场是短暂的.经销商要有一个好的经营环境,必须把这个门槛设好. 汽车后市场还需要准入门槛? 李庆云现任天津环渤海汽车城董事长并身兼天津市交易市场协会会长,在没有跨进汽车行业之前,一直觉得这样的问题多余:哪个行业没有准入门槛?等自己在天津建立环渤海汽车城之后,才意识到,中国的汽车后市场是多么需要"设防".     

环保型木器涂料

介绍水性和紫外光固化两类环保型木器涂料及其研究进展。水性木器涂料主要为丙烯酸酯与聚氨酯两大类，其研究进展集中表现为乳液改性，包括自交联、共混共聚、微乳液等；紫外光固化木器涂料包括其光固化树脂、活性稀释剂和光引发剂的功能及进展；指出研究新型乳液以提高水性木器涂料涂膜的表面性能，开发新型原材料以降低紫外光固化木器涂料的成本、扩大适应范围将成为今后环保型木器涂料的研究重点。     

Thermal analysis of polymer–water interactions and their relation to gas hydrate inhibition

Gas hydrates formed in oil production pipelines are crystalline solids where hydrocarbon gas molecules such as methane, propane, and their mixtures are trapped in a cagelike structure by hydrogen‐bonded water molecules to form undesirable plugs. Methanol and glycol are currently used to prevent these plugs via thermodynamic inhibition. Small amounts of water‐soluble polymers may provide an alternate approach for preventing gas hydrates. In this study, we expand the fundamental understanding of water–polymer systems with differential scanning calorimetry. Nonfreezable bound water was used to quantify polymer–water interactions and relate them to the chemical structure for a series of polymers, including acrylamides, cyclic lactams, and n‐vinyl amides. For good interactions, the water structure needs to be stabilized through hydrophobic interactions. An increased hydrophobicity of the pendant group also appears to favor polymer performance as a gas hydrate inhibitor. Good inhibitors, such as poly(diethyl acrylamide) and poly(N‐vinyl caprolactam), also show higher heat capacities, which indicate higher hydrophobicity, than poor performers such as polyzwitterions, in which hydrophilicity dominated. The phase behavior and thermodynamic properties of dilute polymer solutions were also evaluated through measurements of the heat of demixing and lower critical solution temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2642–2653, 2007     

Properties of poly(n‐butyl methacrylate) prepared by reverse atom transfer radical polymerization in an aqueous dispersed system

Reverse atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) in waterborne media using Cu(II) complexes with azo initiators (i.e., reverse ATRP) was conducted. The influence of several factors, such as surfactant, catalyst, and reaction time, on the stability of the emulsion, the particle size, the morphology of the emulsion particles, and the control of the polymerization was investigated. The results showed great differences between ATRP and conventional emulsion polymerization, especially the nucleation mechanism and the kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1542–1547, 2003     

Tensile mechanical properties of sulfonated poly(ether ether ketone) (SPEEK) and BPO4/SPEEK membranes

A study to evaluate the tensile mechanical properties of sulfonated poly(ether ether ketone) (SPEEK) and BPO₄/SPEEK composite membranes has been carried out. It is aimed to give an assessment of these materials for applications in proton exchange membrane fuel cells. The stress–strain response of the membranes was measured as a function of the degree of sulfonation (DS) and the filler–matrix ratio. In addition, the effects of immersion in water at various temperatures were explored in situ by means of a homemade testing chamber fitted to the tensile analyzer. The results indicate that the DS has an important influence on the final mechanical behavior of the membranes. The introduction of the BPO₄ solid filler leads to deterioration in mechanical performance compared to unfilled SPEEK. A general picture of the microstructural features influencing the mechanical properties of SPEEK and BPO₄/SPEEK membranes is proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2380–2393, 2005     

激光诱导二甲基二乙氧基硅烷气相合成碳化硅超细粉

本工作首次采用有机硅试剂二甲基二乙氧基硅烷为反应物，进行了激光导气相反应，制备出平均粒径为４０ｎｍ的非晶ＳｉＣ粉末，粉末中Ｃ／Ｓｉ比随反应气流量的变化而变化。非晶ＳｉＣ粉末在１８７３Ｋ，氮气中退火１ｈ后转变为β－ＳｉＣ及α－ＳｉＣ，同时，粉末中部分氧杂质及自由碳脱出粉末。     

Perylene derivative sensitized multi-walled carbon nanotube thin film

Perylene-sensitized multi-walled carbon nanotubes (PV-MWNT) have been prepared by a π-stacking between nanotubes and perylene derivatives, N,N′-diphenyl glyoxaline-3,4,9,10-perylene tetracarboxylic acid diacidamide (PV). The resultant nanocomposites have been characterized by transmission electron microscope (TEM), UV-vis absorption, photoluminescence (PL) and photocurrent spectra. Long range ordering can be observed in the form of PV-MWNT via π-stacking by TEM. Red-shift in the optical spectra consisting of the UV-vis absorption and PL spectra with the attraction of PV on the surface of the MWNTs were observed. The evident quenching in PL spectra of PV-MWNT was ascribed to the absorption and transfer of recombination energy by MWNT. Photosensitivity spectra demonstrated an increasing photocurrent in the ultraviolet region and a broadening photosensitivity in the red spectral region for solar cells based on PV-MWNT.