杨金瑞
,
余尚先
,
顾江楠
高分子材料科学与工程
通过对resol(羟甲基酚化合物和低分子量羟甲基酚树脂)DEPT135图谱的分析讨论,得到一系列计算resol微细结构参数的经验公式.根据DEPT135图谱可判断是否发生缩聚反应,根据经验公式可计算酚单体各个活性点参与反应百分率或酚羟基导入率、不同类型缩聚所占百分率及低分子量羟甲基酚树脂的平均核体数.
关键词:
羟甲基酚化合物
,
羟甲基酚树脂
,
DEPT135
,
结构参数
Acta Physico-Chimica Sinica
Adsorption of thiourea (TU) and ethylthiourea( ETU) on roughened silver electrode was investigated using in situ surf. enhanced Raman spectroscopy(SERS) Using quantum chemistry and HSAB theories, the influences of electrode potential and the different substituent groups on SERS were disc i. TU is chemisorbed perpendicularly by Ag-S bond on silver at E = -0.3 V and adsorption of TU turns into a parallel orientation at E = -0.9 V. ETU is always chemisorbed at an angle from Ag. The adsorption of ETU is through and C=C and C=O groups at E = -0.3 V, and mainly through C=C at E = -0.9V.
关键词:
Surface enhanced Raman spectroscopy;Adsorption;Quantum chemistry;Thiourea;Inhibitor
Shanthi Subramanian
,
David Muller
,
John Silcox and Stephen L.Sass (Department of Materials Science and Engineering and Department of Applied and Engineering Physics
,
Cornell University
,
Ithaca. NY 14853)
金属学报(英文版)
Local chemistry plays an important role in determining the cohesive strength of grain boundaries in Ni3Al. Doping with B increases the room temperature ductility and changes the fracture mode from intergranular to transgranular, while doping with Zr increases the ductility but leaves the fracture mode predominantly intergranular.Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive X-ray Spectroscopy (EDS) were used to probe the changes in local bonding (and hence the cohesive strength) produced by changes in local chemistry at large angle boundaries in Ni3Al.In addition , small angle tilt boundaries were studied to correlate structure with Nienrichment at the interface. B segregation to Ni-rich grain boundaries was shown to make the bonding similar to that of the bulk, thereby increasing their fracture resistance. Ni-enrichment does not occur in the presence of Zr segregation to grain boundaries. Ni-enrichment to antiphase boundaries (APB) in small angle tilt boundaries lowers the APB energy by reducing the number of high energy Al-Al interactions across the interface. Ni-enrichment to large angle boundaries is expected to produce a similar effect on energy.
关键词:
: grain boundary chemistry
,
null
,
null
,
null
X.M.Min
,
Y. Daiand C.W.Nan National Key Laboratory of Advanced Technology for Materials Synthesis and Processing
,
Wuhan University ofTechnology
,
Wuhan 430070
,
China
金属学报(英文版)
Al NMRand quantum chemistry calculation have been used to study thestructureof γ Al2O3 and AlON. The NMRspectra arecharacterized bythree distinctresonance peaksat114 , 66 and 12 , corresponding to 〔AlN4〕,〔AlO4〕and 〔AlO6〕respectively. The uantum chemistrycalculationsshowqd thatthe models with vacancieslocated at octahedralsitein B block are morestablethanthose with vacancieslocated attetrahedralsitein A blockforboth of γ Al2 O3 and AlON. In AlON, nitrogen atoms preferentially replace oxygen atoms in〔AlO4〕tetrahedrons, and the model with 〔AlN4〕is morestablethan that with 〔AlO4 xNx〕(x= 1 ,2 and 3) and 〔AlO6 - yNy〕(y= 1 ,2 ,3 and 4) , which isin agreement with theexperimental analysisby NMR.
关键词:
Al2 O3 and AlON
,
null
,
null
,
null
PAN Tao
,
YANG Cai-fu
钢铁研究学报(英文版)
Chemistry and process optimization of N80 seamless tube was studied by thermo-mechanical simulation tester Gleeble 1500D. Several heats of V-microalloyed steel with different N contents were firstly made at lab in order to simulate N80 seamless tube steel. The results showed that N addition increased strength under condition that toughness was kept at a high level compared with low-N steel. In this study N content with 120-200 ppm enhanced combination performance of strength and toughness whether in-line normalizing process was adopted or not. In-line normalizing process was helpful to improve the toughness though it lowered strength by some degree. However, direct final rolling after tandem rolling (without in-line normalizing) helped increase strength while the toughness remained somehow poor. The above phenomena concerning N80 seamless tube was closely associated with dissolution and precipitation behavior of V(CN). V(CN) precipitation was optimized when N content was increased. When in-line normalizing process was adopted, V(CN) precipitation in austenite increased due to low temperature history during intermediate (in-line) normalizing process. V(CN) particles existing in austenite contributed to grain refinement for VN induced intergranular ferrite, while they weakened precipitation strengthening effect since V precipitating in ferrite wais reduced.
关键词:
seamless tube;in-line normalizing;V-N microalloying;reheating;mechanical properties;Gleeble simulation
Journal of the American Ceramic Society
The surface chemistry and dispersion properties of aqueous Ti(3)AlC(2) suspension were studied in terms of hydrolysis, adsorption, electrokinetic, and rheological measurements. The Ti(3)AlC(2) particle had complex surface hydroxyl groups, such as equivalent to Ti-OH,=Al-OH, and -OTi-(OH)(2), etc. The surface charging of the Ti(3)AlC(2) particle and the ion environment of suspensions were governed by these surface groups, which thus strongly influenced the stability of Ti(3)AlC(2) suspensions. PAA dispersant was added into the Ti(3)AlC(2) suspension to depress the hydrolysis of the surface groups by the adsorption protection mechanism and to increase the stability of the suspension by the steric effect. Ti(3)AlC(2) suspensions with 2.0 dwb% PAA had an excellent stability at pH=similar to 5 and presented the characteristics of Newtonian fluid. Based on the well-dispersed suspension, dense Ti(3)AlC(2) materials were obtained by slip casting and after pressureless sintering. This work provides a feasible forming method for the engineering applications of MAX-phase ceramics, wherein complex shapes, large dimensions, or controlled microstructures are needed.
关键词:
liquid reaction synthesis;poly(acrylic acid);nitride;hydrolysis;stability;silica;carbide;powders;ftir
Corrosion Science
Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-low alloy steel (LAS) dissimilar weld joint in 288 C water was investigated by experiments and finite element simulation. Creviced bent beam and crack growth rate (CGR) experiments showed that, while the FB was a barrier to SCC growth, further crack growth into LAS was activated by a combined effect of sulfate and dissolved oxygen in water. Finite element simulation suggested that a positive gradient of hardness as the crack approached to the FB in dilution zone caused decreased CGR. Role of microstructure and water chemistry in SCC was discussed. (C) 2011 Elsevier Ltd. All rights reserved.
关键词:
Low alloy steel;Alloy;SEM;TEM;Stress corrosion;Welding;environmentally-assisted cracking;nickel-base alloys;stainless-steels;susceptibility;property
