共查询到19条相似文献,搜索用时 125 毫秒
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针对混凝土用人造骨料表面疏松多孔和水泥浆体结合能力不足的问题,提出包覆和表面疏水特性修饰的新方法处理人造骨料。试验将不同质量分数的硅烷偶联剂溶液与有机硅树脂联合改性应用于碳化养护的人造骨料,研究改性方法对人造骨料吸水率、颗粒强度、骨料-水泥砂浆黏结强度等性能的影响规律,利用细观/微观测试分析方法表征改性前后人造骨料的微观结构以及人造骨料与水泥砂浆的界面形貌。结果表明,较单一使用化学溶液改性人造骨料,联合改性方法可显著优化人造骨料的表面微观结构,提升骨料性能,骨料吸水率可降低至1.74%。当硅烷偶联剂质量分数为5%时,人造骨料表面形成厚度合适的改性层,人造骨料与水泥砂浆的结合程度显著提升。 相似文献
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金属垫片密封表面形貌的分形表征 总被引:2,自引:1,他引:2
引言 金属垫片密封结构常见于石油、化工、核能等装置中,广泛应用于高温、高压及强腐蚀介质等操作条件恶劣、密封要求高、一般的垫片无法满足要求的场合. 相似文献
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基于显微边界形貌分形特征的耐火材料侵蚀维数研究 总被引:2,自引:0,他引:2
通过对侵蚀残砖的显微边界形貌研究发现 :耐火材料的抗侵蚀性能和基于显微边界形貌分形特征的分形维数存在良好的线性关系。根据分形维数的定义和含义 ,作者提出了一种基于分形理论的耐火材料侵蚀维数Rf (Refractoryfractal)的概念和抗侵蚀分类建议。根据耐火材料的使用经验和实绩而定义的Rf =[1.0 ,1.0~ 1.15 ,1.15~ 1.2 0 ,≥ 1.2 ]数值范围 ,可以用于耐火材料抗侵蚀性能的评判、分类 ,并且可用于设计选型和编制相对应的耐火材料的残余安全厚度的日常维护规程等 相似文献
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开发了一种基于分形维数来表征纳米颗粒团聚行为的方法,通过对纳米SiO2颗粒的透射电子显微镜的图片进行分析,并借助冷冻切片技术对硅橡胶中的SiO2分布状态进行观测和分形维数的计算,探究了分形维数与吸油值、表面羟基数、力学性能等的关系。结果表明:纳米颗粒的团聚程度越大其分形维数越大;通过对纳米SiO2补强硅橡胶的超薄切片的分形维数的计算可知,在聚合物中的纳米颗粒的团聚也呈现相同的规律,即分形维数越大团聚程度越大;此外,分形维数越大,纳米SiO2的吸油值越小,表面羟基数越少,硅橡胶片的拉伸强度、撕裂强度及邵尔A硬度则越大。 相似文献
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采用电刷镀技术,在45钢上获得了n-Al2O3/Ni-Co纳米复合电刷镀层.研究了镀液中纳米颗粒加入量对镀层的表面形貌和显微硬度的影响,并利用盒维数的计算方法,计算了表面形貌的分形维数,初步建立了表面形貌的分形维数与镀层显微硬度之间的关系.对比分析表明:随着镀液中纳米颗粒含量的增加,镀层表面形貌的分形维数先减小后增大,镀层的显微硬度则先增大后减小,但都在镀液中纳米颗粒加入量为20g/L时达到最值,即镀层表面形貌的分形维数与其显微硬度有负相关的对应关系. 相似文献
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采用电刷镀技术,在45钢上获得了n-Al2O3/Ni–Co纳米复合电刷镀层。研究了镀液中纳米颗粒加入量对镀层的表面形貌和显微硬度的影响,并利用盒维数的计算方法,计算了表面形貌的分形维数,初步建立了表面形貌的分形维数与镀层显微硬度之间的关系。对比分析表明:随着镀液中纳米颗粒含量的增加,镀层表面形貌的分形维数先减小后增大,镀层的显微硬度则先增大后减小,但都在镀液中纳米颗粒加入量为20g/L时达到最值,即镀层表面形貌的分形维数与其显微硬度有负相关的对应关系。 相似文献
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为了研究模板材料对沸石分子筛表面形貌和孔结构性质的影响以及在焙烧除模板材料过程中分子筛表面复杂程度和孔道分布的变化,分别采用X射线衍射和氮气物理吸附-脱附对沸石分子筛进行表征,基于分形学理论引入分形维数及其计算,并将计算结果与分析结果进行对比讨论。结果表明,分形维数与分子筛表面的复杂程度密切相关,分子筛表面越复杂、沟壑越多,分形维数越大,反之则越小;模板材料影响分子筛不同指数晶面的生长速率和生长取向,进而影响分子筛的外观形貌和孔道结构性质,在焙烧除模板材料后,分子筛表面部分较大孔道发生塌陷,致使整体结构趋于平整化,分形维数减小。 相似文献
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利用橡胶高温磨耗试验机,进行不同温度、角度、负荷及路面条件下的高温磨耗试验,获得具有不同形貌的橡胶磨耗试样。借助3D测量显微镜采集橡胶试样表面形貌图像并进行表征,对橡胶表面磨耗形貌图像进行黑白二值化处理,利用分形理论建立多重分形谱分析模型,定量分析不同试验条件下橡胶试样表面磨耗形貌,定性描述表面磨耗形貌分布特点。研究结果表明,橡胶复合材料磨耗表面形貌具有明显的分形特征,橡胶磨耗性能(磨耗量)随着温度、角度、负荷和路面粗糙度增大而增大。 相似文献
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《分离科学与技术》2012,47(18):2713-2723
2D fractal dimension analysis of inline-coagulation (IC) flocs in microfiltration of NOM using power-law relationship and box-counting was done. Different process conditions represented by two types of coagulants (PIX and PAX) at four different hydraulic gradients (G-values of 4, 31, 98, and 300 s?1) were tested. Fractal dimensions of the flocs formed under the varying process conditions were found to be different. Overall NOM removal was found to be similar for all cases; however, the membrane filtration and fouling phenomenon observed were affected by the process conditions. This study has investigated the relationships between fractal dimensions, aggregate properties, and membrane fouling behavior observed. In general, PIX resulted in higher particle concentrations and the more irregular floc shapes resulted in high irreversible fouling, lower specific cake resistance, and a more compressible cake layer. In contrast, PAX resulted in lower particle concentrations and the more regular floc shapes resulted in a more reversible fouling, higher specific cake resistance and a less compressible cake layer. The fractal dimensions properties were found to be complementary for the analysis of membrane and cake resistances and can be useful tools in membrane fouling elucidation and minimization. 相似文献
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A series of cross-linked polyether-polyester polyurethane dispersions modified with organosiloxane were prepared based on hydroxyl-terminated polydimethylsiloxane (HTPS) as hydrophobic component and 3-aminopropyl-triethoxysilane (APTS) as cross-linker as well as a bridge between polyurethane (PU) and polysiloxane (PSIL). It was discovered that polydimethylsiloxane segments were incorporated into PU chains chemically and organosiloxane was preferentially oriented toward the surface layer of the film by making a comparison of attenuated total reflection (ATR) spectra between the copolymer and the blend of PU and PSIL, which was further confirmed by investigation of electron spectroscopy for chemical analysis (ESCA). The relationships between surface properties of the film formed from polyurethane dispersion and organosiloxane content were also studied. The results showed that water contact angle of the film increased with the increase of organosiloxane content. Interestingly, it was also found that water contact angle of PUS film increased firstly and then decreased when film-forming temperature varied from 25℃ to 55℃. 相似文献
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The surface tension of atactic polystyrene (PS), isotactic poly(propylene) (PP) and PS/PP‐blends, and additionally the interfacial tension between PP/PS have been measured in the temperature range between 200 and 280°C using the pendant drop method. Within the temperature range studied, the surface tension decreased linearly with increasing temperature for all systems whereas the surface tension of neat PP is approximately 7 mN/m smaller than the value of PS. The interfacial tension between PS and PP is in the range of approximately 4 mN/m and this indicates a strong incompatibility. It results a heterogeneous PP/PS blend morphology. A significant increase of the surface tension of the blends as a function of composition is observed only when the PS content exceeds 60 wt.‐%. Furthermore, microscopic observations indicate that even if the bulk matrix material is PS, a thin layer of PP can be detected by atomic force microscopy on the droplet surface used for surface tension measurements. 相似文献
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钠-萘络合物对聚氯代对二甲苯薄膜的表面改性机理研究 总被引:1,自引:0,他引:1
采用钠-萘络合物对聚氯代对二甲苯薄膜进行表面改性,通过测试接触角研究了薄膜的润湿性能,用红外光谱、X射线衍射表征了膜表面的基团变化及物相变化,用热重分析仪考察了改性后薄膜的热稳定性,并测试了改性后薄膜的黏附性能。结果表明,改性后薄膜的表面能由28.64 mJ/m2提高到41.48 mJ/m2,剪切强度由150.5 kPa提高到219.5 kPa,表面能的提高主要是由于聚合物链的氯苯发生还原反应引起。 相似文献
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Biseeds emulsion polymerization was investigated with poly(methyl methacrylate) (PMMA) and polystyrene (PSt) as biseeds and styrene (St) as second‐stage monomer, as well as with thermodynamic analysis; namely, the principle of minimum interfacial free‐energy change was utilized to explain the competitiveness of different seeds for second‐stage monomer and the final equilibrium morphology of composite polymer particles. The experimental results indicated the polymeric particles prepared had bimodal size distribution and the PMMA seed particles showed a higher chance of obtaining St than that of the PSt seed particles, which was in agreement with the computational outcome by the principle of minimum interfacial free‐energy change. Owing to the kinetic factors, the equilibrium morphology could not be reached in the experiments. However, the results demonstrated that double or multiple seeds emulsion polymerization could be used as a model experiment to study the morphology of polymer particle and the morphological prediction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2675–2680, 2004 相似文献
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Polymeric supports based on divinylbenzene (DVB) were prepared by aqueous suspension polymerization in presence or absence of styrene (S), using toluene and n‐heptane as diluents of the monomers. Poly(S–DVB) and poly(DVB) were sulfonated with sulfuric acid in presence of 1,2‐dichloroethane. The influence of the morphological structure of the supports and as a consequence of the catalyst on the esterification reaction of acetic acid with n‐butanol was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3616–3627, 2006 相似文献
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通过钠-萘络合物的处理,在聚氯代对二甲苯膜表面形成自由基,通过表面自由基原位引发甲基丙烯酸甲酯聚合,在薄膜表面引入极性基团以提高膜表面黏结性能。利用红外光谱、X射线衍射和显微镜对接枝改性后薄膜的化学组成和表面形貌进行了表征,运用聚合物膜表面接触角的变化表征了其改性效果。结果表明,甲基丙烯酸甲酯单体由聚氯代对二甲苯膜表面自由基引发,从Cl位置接入,接枝链以共价键的形式与聚氯代对二甲苯膜连接;接枝改性后聚氯代对二甲苯膜表面出现-C=O的特征吸收峰,-CH2的吸收峰随接枝时间的延长而逐渐增大;接枝后薄膜的表面能由28.6 mJ/m2提高到54.1 mJ/m2,拉伸强度由150.5 kPa提高到222.5 kPa。 相似文献