Ca(OH)2解耦法对混合水泥中C-S-H凝胶的半定量研究

基于掺合料反应程度与Ca(OH)2消耗量之间关系的建立,结合水泥水化平衡计算理论,提出混合水泥水化产物中Ca(OH)2量的解耦方法并将其用于混合水泥水化产物C-S-H凝胶半定量计算.采用该法对掺粉煤灰的混合水泥不同龄期水化产物C-S-H凝胶进行了半定量分析研究.     

用于地聚合物的粉煤灰活性评价研究

由于粉煤灰的非均质性,很难直接预测粉煤灰的活性.本实验研究了不同粉煤灰在不同时间、温度和碱浓度条件下的浸出过程(先将粉煤灰在碱液中溶解,再将其残留物在酸溶液中解离).通过电感耦合等离子体发射光谱仪(ICP)和化学分析表明,温度、反应时间和碱浓度都会影响粉煤灰的溶解速率和浸出含量.粉煤灰中浸出的反应性n(Si)/n(Al)为2.3～2.7,粉煤灰中硅和铝的总浸出量与成型用其制备的地聚合物强度呈正相关.另外,可发现建立在硅酸盐水泥体系上的粉煤灰活性评价体系并不完全适用于地聚合物体系.通过XRD、FTIR和SEM分析可发现,粉煤灰由反应性材料和惰性材料组成,而活性物质在地聚合过程中迅速溶解,酸完全解离在地聚合过程中生成的凝胶,浸出过程更能准确表征粉煤灰中反应性物质的含量.碱溶解?酸解离法可定量估算粉煤灰的反应物含量和反应性n(Si)/n(Al),并简单预测用于地聚合物体系的粉煤灰的潜在反应活性,还可指导粉煤灰地聚合物的配比设计.     

石灰基材料对生土改性效果及机制研究

针对当前石灰、矿渣、粉煤灰等作为生土改性剂的研究主要是在力学性能及耐久性等宏观性能方面,尝试从上述改性材料对生土改性前后的矿物组成、官能团特征峰、微观结构等微观角度来阐述生土改性的内在作用机制。试验结果表明,(1)单掺石灰时,生土改性效果随石灰掺量增加而提高,最佳掺量为10%,其28 d抗压强度和软化系数分别达到3.69 MPa和0.80,原因是其板状的Ca(OH)_2水化产物填充生土颗粒间的空隙,达到饱和后的Ca(OH)_2仅其骨架作用;(2)当10%石灰分别复掺5%矿渣和5%粉煤灰时,28 d抗压强度分别增长了8.1%和2.4%,软化系数分别达到了0.92和0.90,原因是粉煤灰和矿渣发生二次水化反应,其中Mg—O、Al—O等键断裂,Al~(3+)、Mg~(2+)等阳离子与Ca(OH)_2发生置换反应,致使1 436.47 cm~(-1)处的峰位偏移至1 400 cm~(-1)附近,同时出现了1 030 cm~(-1)附近的C-S-H凝胶特征峰以及3 120 cm~(-1)处左右的火山灰反应特征峰;(3)掺矿渣改性效果优于单掺石灰,而复掺粉煤灰的改性效果不佳。     

LiNO_3对碱硅酸反应及其膨胀的影响

本文研究了38℃下LiNO_3对石英玻璃在NaOH溶液中碱硅酸反应(ASR)的影响,采用等离子发射光谱仪(ICP)、酸化处理、X射线衍射仪(XRD)和扫描电镜(SEM)对溶液中的离子浓度、SiO_2分布、固相产物的组成和微观形貌进行分析和表征。测定了长龄期在38℃湿气养护下LiNO_3对沸石化珍珠岩和防城港砂岩混凝土微柱中ASR膨胀的作用效果。结果表明:掺LiNO_3的碱溶液中,Li~+先于Na~+与溶出的SiO_4~(4-)反应,生成低溶解性的含锂产物,并附着在石英玻璃表面,降低了溶液中OH~-对石英玻璃的溶蚀,进而减缓了ASR的反应速率。混凝土试件中[Li]/[Na+K]摩尔比越高,LiNO_3抑制ASR膨胀效果越好;随着龄期的延长,后期掺锂试件仍存在ASR膨胀。短龄期下LiNO_3抑制活性集料的ASR膨胀效果良好,长龄期作用效果减弱。     

变温下SO_2~(-4)对水泥硬化浆体中Al~(3+)配位分布的影响

基于大体积混凝土内部的温度变化,利用27 Al魔角旋转核磁共振(27 Al MAS NMR)结合去卷积技术,研究变温下SO2-4对水泥硬化浆体中Al 3+配位分布的影响。结果表明,变温的高温阶段促进AFt、TAH(third aluminum hydrate)和掺杂在C-S-H结构中(C-S-A-H)的四配位铝(Al[4])向AFm转化;降温阶段促进TAH生成,利于AFm和C-S-A-H中Al[4]向AFt转化;而变温后20℃常温不仅利于AFt向AFm转化,TAH向Al[4]转变,而且利于Al[4]进入高钙硅比(Ca/Si)C-S-H结构。在5%Na2SO4溶液中,SO2-4在侵蚀3d时首先对AFm侵蚀,对TAH和C-S-A-H中Al[4]侵蚀作用较小;变温过程的高温加快SO2-4对AFm和TAH的侵蚀,并且对C-S-A-H凝胶有脱铝作用;变温后20℃常温有利于C-S-H凝胶与硫酸根竞争Al[4],低Ca/Si的C-S-A-H凝胶具有较强的抗SO2-4脱铝能力。     

粉煤灰在饱和Ca（OH）2溶液中的溶出行为

对在饱和Ca(OH)2溶液中养护至不同龄期的粉煤灰进行测试,对粉煤灰中氧化硅、氧化铝等成分的溶解速率、粉煤灰颗粒表面的微观形貌以及反应产物进行了分析,同时,对SO42-在钙矾石AFt晶体的形成过程中的影响也进行了探讨。结果表明:在饱和Ca(OH)2溶液体系中,粉煤灰中活性SiO2和Al2O3的溶出速率要比粉煤灰水泥浆体中的火山灰反应快;经饱和Ca(OH)2溶液处理后,粉煤灰颗粒表面主要有4种形貌———碱刻蚀现象、结构致密层、疏松的沉积层、颗粒表面形成钙矾石晶体;SO42-的浓度影响钙矾石的成核结晶。     

常温制备赤泥-低钙粉煤灰基地聚物的试验和微观研究

低钙粉煤灰在常温条件下合成地聚物存在反应度低、强度低的问题。本研究在低钙粉煤灰中掺入20%赤泥制备地聚物,研究其力学性质,并通过SEM、EDS和FT-IR分析地聚物的微观结构变化。进一步研究了化学配比n(Si)/n(Al)=1.8～2.5、n(Na)/n(Al)=0.8～1.1以及在100%相对湿度养护0～7 d对赤泥-粉煤灰基地聚物性质的影响。试验发现常温养护的赤泥-粉煤灰基地聚物的力学性质明显优于低钙粉煤灰基地聚物,且n(Si)/n(Al)=2.0～2.2、n(Na)/n(Al)=1.0为前者制备的最优配比,而较高的养护湿度可提高其早期强度。这证明赤泥对常温合成粉煤灰基地聚物有促进作用,并揭示了赤泥-粉煤灰基地聚物比粉煤灰基地聚物更密实的微观结构、更多的地聚物胶凝体形成和更高的反应度是前者力学性质优于后者的主要原因。     

碱对粉煤灰的活化和微观结构的影响

用X-射线、SEM研究了粉煤灰在不同碱度环境下的活化机制、水化产物和微观结构。研究表明:粉煤灰硅酸盐水泥在常温下养护,粉煤灰的反应能力较低,这是因为在Ca(OH)2存在条件下的活化很慢,只有提高养护温度或在复合碱和硫酸盐存在条件下才有利于结构的解体和水化产物的稳定。     

K~+和Na~+在C_3S-纳米SiO_2浆体上的存在形式

以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K~+和Na~+的影响以及浆体对K~+和Na~+的滞留能力;并采用29Si MAS NMR分析讨论了K~+和Na~+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随着液固比的增大,浆体释放的K~+和Na~+的百分数逐渐增大;经去离子水充分洗涤后仍有一部分K~+和Na~+存在于浆体中,且浆体对K~+和Na~+的滞留能力随着纳米SiO_2掺量的增加以及拌合液碱浓度的增大而增强。29Si MAS NMR分析证实了K~+和Na~+能够进入C-S-H凝胶层间形成不可逆的化学结合。K~+和Na~+通过取代C-S-H凝胶层间≡SiOCa+中的Ca2+,缩短了C-S-H凝胶中[SiO4]4-四面体链长,从而使凝胶中Q1和Q2峰向左移动。     

氯离子环境下钙矾石和水化硅酸钙体系铝配位分布

通过化学合成钙矾石和水化硅酸钙,利用XRD、27 Al核磁共振测试手段,研究了氯离子环境下钙矾石(AFt)和水化硅酸钙(C-S-H)凝胶体系中铝配位分布规律。结果表明,在C-S-H凝胶和氯离子共存环境中,第三类水化铝酸盐(TAH)凝胶中六配位铝(Al[6])首先转化为四配位铝(Al[4])进入C-S-H结构,且Al[4]总量不受C-S-H钙硅比限制;同时氯离子不影响Al[6]-TAH向Al[4]转化,当达到C-S-H凝胶容纳Al[4]的极限时,剩余的Al[6]-TAH才与氯离子反应形成Friedel盐(F盐)。TAH比AFt更容易与氯离子反应形成F盐;低钙硅比C-S-H环境不利于TAH与氯离子结合,但利于钙矾石分解并与氯离子反应生成F盐。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.