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。     

超声波辅助氧化改性钙基吸收剂的制备及性能研究

通过超声波辅助溶液浸渍的方法,将K2 S2 O8、Ca(ClO)2、(NH4)4 Ce(SO4)4及K2 Cr2 O7等氧化剂分别浸渍在钙基吸收剂表面,形成具有氧化性的活性位点,即氧化位点,改善钙基吸收剂脱除NOx的效果.通过正交实验,在不同超声波功率、浸渍时间和浸渍温度下,按照一定掺杂比例,利用氧化剂对钙基吸收剂进行化学调质.将改性后钙基吸收剂在固定床反应器上进行了同时脱硫脱硝实验,选择污染物的平均脱除率作为评价指标.正交实验结果表明:以Ca(ClO)2作为氧化剂进行超声波浸渍改性效果最好,最优改性工艺参数为氧化剂掺杂比例20％(质量分数,下同)、超声波功率100％、浸渍时间1.5 h、浸渍温度70℃.同时,基于晶相结构(XRD)分析和扫描电镜(SEM)显微形貌观测,可知超声波辅助氧化改性的方法能有效改善钙基吸收剂表面形貌,表面上形成了氧化位点,该氧化位点不仅能够增大吸收剂与SO2和NOx的接触,还能促进NO氧化为NO2,进一步提高SO2和NOx的脱除率.     

膨润土的超声自然沉降提纯方法研究

以焦磷酸钠为分散剂,采用基于超声波辅助处理的自然沉降湿法提纯工艺,对低品位钙基膨润土进行提纯;探索分散剂浓度、超声作用时间、超声功率、搅拌时间、搅拌温度、搅拌转速对提纯纯度的影响,并利用X射线衍射分析对膨润土原矿及提纯膨润土进行表征。结果表明:超声功率和超声时间对膨润土提纯影响显著,分散剂浓度和搅拌时间对膨润土提纯影响较小;在最佳工艺条件下,提纯后的膨润土中蒙脱石质量分数从59.71%增大为99%,回收率达到81.33%,吸蓝量从0.263 9 g/g增大为0.441 9 g/g,膨胀容从5 mL/g增大为14 mL/g。     

多孔羟基磷灰石微球的原位转化制备研究

利用锂钙硼(LCB)玻璃在磷酸盐溶液中的原位转化反应制备多孔的羟基磷灰石(HAP)微球,通过XRD、SEM和FTIR对微球的物相组成、形貌等进行了表征。结果表明,微球具有良好的多孔结构,表现为非晶态特性,600℃热处理后,转变成HAP晶体,同时HAP部分分解转变为Ca3(PO4)2。此外,对多孔HAP微球的形成机理进行了分析。在磷酸盐溶液中,玻璃表面原位生成Ca-P-OH水化物,并在玻璃表面原来Ca2+的位置沉积下来,形成微球壳,而由Li+和B3+占据的位置,因其溶出形成孔隙。这样的结构将使之成为良好的药物载体。     

常温常压下文石球形超结构的仿生合成

本文利用生物矿化原理,首次在常温常压下以竹蛏韧带纤维状蛋白质层为基底,采用气体扩散法,通过氯化钙溶液和二氧化碳反应制备了纳米文石晶体且具有捆状和球状超结构。并通过红外光谱、扫描电镜、X射线衍射对产物的晶型、形貌及物相进行了详细表征,并初步探讨了文石晶体形成及生长机理。结果表明,采用该反应体系可以在较大的条件范围内合成出纯文石。文石晶体生长为分裂式生长,其形成机理为竹蛏韧带纤维状蛋白质中天冬氨酸的β-羧基所带负电荷之间的距离与文石晶格中Ca2+之间的距离匹配。本文不但对深入探讨碳酸钙的生物矿化机理具有重要意义,同时提供了一种简单高效节能的合成球状纯文石材料的新方法。     

无水钾明矾熔盐法合成α-Al_2O_3片晶实验研究

以无水钾明矾为原料,K2SO4为熔盐介质,成功制备出片状α-Al2O3晶体。通过改变反应温度、恒温反应时间、熔盐用量及外加剂TiO2的掺入量,考察实验条件对α-Al2O3晶体生长及微观形貌的影响。结果表明,当反应体系中KAl(SO4)2与K2SO4物质的量比为1∶2,在1200℃反应6h后,可制得直径约为20μm、厚度为200nm的六方片状α-Al2O3单晶;外加剂TiO2的加入提高了晶体的各向异性,对六方片状α-Al2O3晶体的均匀形成具有促进作用。     

纳米Cu／HAP制备中四氨合铜（Ⅱ）的作用

将[Cu（NH3）4]^2＋用于以（NH4）2HPO4和Ca（NO3）2为前体的HAP合成体系中，制备出了纳米级Cu／HAP晶体，合成反应中，[Cu（NH3）4]^2＋是铜离子的供体，又是粒子尺寸控制剂。研究了不同浓度、不同反应温度下[Cu（NH3）4]^2＋对Cu／HAP合成和晶粒尺寸的影响。结果表明：在试验浓度范围内[Cu（NH3）4]^2＋浓度越大，所得晶粒尺寸越小；Cu^2＋取代HAP晶格中的构晶离子Ca^2＋可引起HAP晶体生长习性的改变，抑制晶体沿C轴生长。[Cu（NH3）4]^2＋存在的条件下，温度升高仍然可以形成大颗粒的Cu／HAP。     

酒石酸还原Cu(Ⅱ)制备多种形貌Cu_2O晶体及形成机理

以CuSO_4·5H_2O为原料,KOH为添加剂,酒石酸为还原剂,在水热条件下通过调整相关的实验参数,制备了一系列不同形态的Cu_2O微-纳米晶体及三维十字形枝晶。采用XRD、SEM等手段对不同形态的Cu_2O晶体进行了表征,探讨了不同因素变化对Cu_2O晶体形态的影响。分析认为,晶体生长过程控制了晶体的具体形貌和大小,Cu_2O晶体显露的单形晶面随晶体生长条件的变化而不同。在低温、弱碱性、高浓度溶液中有利于形成八面体形态的Cu_2O晶体,而菱形十二面体单形晶面在高温、强碱性、低浓度溶液中形成的晶体中显露的面积有所增大。     

多晶片超声聚焦探头

一、引言 超声聚焦探头作为超声断面图象系统中不可缺少的部份,愈来愈显示出它的重要性。自六十年代后半期开始,国外对单晶片聚焦探头进行了广泛的研究,而对于多晶片探头到七十年代才开始受到人们的重视。性能良好的多晶片聚焦探头1976年左右才被研制出来[1][2],而带有阻抗匹配层的多晶片聚焦探头1980年后才有产品出现。随着基础研究的深入,人们能容许接受超声功率的剂量愈来愈低,所显示的人体断面图象要求愈来愈清晰。所有这些,都对超声探头的性能提出更高的要求。 对于超声探头来说,具有宽阔的频带或低的Q值、短的脉冲响应、低的损耗和高…     

硫酸盐类晶体中[SO_4]~(2-)四面体的结晶方位与晶体的形貌

本文从硫酸盐类晶体中负离子配位多面体的结晶方位和相互联结的稳定性出发，探讨了硫酸盐类晶体中[SO4]2-结晶方位与晶体结晶形貌之间的关系;认为[SO4]2-四面体与金属阳离子（Ba2 、Ca2 、Mg2 …）结合时，由于晶体结构和生长条件（如温度、过饱和度等）的不同，在晶体各族晶面上的叠合速率和取向不同;晶体的结晶形貌迥然有别.晶体的结晶形貌与[SO4]2-四面体在晶体中的结晶方位密切相关，四面体的面和棱的法线（L2）所对向的晶面，生长速率慢，顽强显露，均属晶体的板面;四面体的顶角所指向的晶面，生长速率快，显露面积小，经常消失.     

超声外场对SiCp/7085复合材料界面及拉伸性能的影响

为研究超声辅助制备工艺对SiC_p/7085复合材料界面结合及拉伸性能的影响,用机械搅拌、机械搅拌+超声施振、超声施振3种工艺制备体积分数为10%的SiC_p/7085复合材料.采用扫描电子显微镜(SEM)、能谱(EDS)研究各工艺对SiC_p/7085复合材料的界面微观组织和拉伸性能的影响.实验结果表明:机械搅拌工艺促进大颗粒(80μm)与熔体结合,但产生了粗大Al4C3界面产物包裹层,且难改善小颗粒(37μm)与熔体界面结合差的问题;超声施振能促进界面反应,生成尺寸细小、排列规整、紧密的Mg O、Mg Al2O4界面强化相覆盖层,有效改善小颗粒与熔体界面结合;相比于7085铝合金,机械搅拌不能改善SiC_p/7085复合材料拉伸性能,而超声施振的加入能显著提升材料拉伸性能.     

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

The combined effect of high intensity ultrasound and melt stirring on the degassing of AlSi₉Cu₃ using simultaneously the novel MMM (Multi-frequency Multimode Modulated) ultrasonic technology to promote cavitation, and low frequency mechanical vibration to induce melt stirring, was studied. On a first stage single low frequency mechanical vibration experiments were carried out in water in order to visualize and characterize its individual effect on the liquid dynamics. On a second stage ultrasonic vibration combined with different mechanical vibration frequencies, melt temperatures and processing times were tested in liquid AlSi₉Cu₃ alloy and their influence on the degassing efficiency was evaluated and compared with the results of the single MMM ultrasonic degassing technique. Fixed ultrasonic parameters (frequency and electric power) were used, according to the best results obtained in former experimental works developed by the authors. For the experimental conditions used in this research, it was found that melt stirring significantly improves degassing efficiency, and such improvement depends on the metal temperature and the mechanical vibration frequency. The experimental results suggest that combining melt agitation and ultrasonic vibration it is possible to achieve almost the aluminum alloy theoretical density without increasing the processing time.     

Thermal properties of PMMA/montmorillonite clay nanocomposites

Polymer/Clay offer tremendous improvement in wide range of physical and engineering properties for polymers with low filler loading. In nanotechnology polymer/clay nanocomposites use smectitetype clays that have layered structures. In this work, Poly (methyl methacrylate) (PMMA) was synthesized by free radical addition polymerization in the presence of high power ultrasound. The Poly (methyl methacrylate) (PMMA)-Montmorillonite (MMT) clay nanocomposites were synthesized by two different techniques viz., ultrasonic mixing and magnetic stirring. An analysis of the XRD data confirms that the composites are in the nanometer scale. The FTIR spectra show that there is strong interaction between the clay and the polymer that enhances the thermal stability. The thermal stability of the experimental nanocomposite prepared by the two processes is compared. Further analysis of XRD data shows that intercalation as well as exfoliation has taken place in both the types of nanocomposites preparation. An analysis of the TG, DTG curves reveal that the thermal stability is found to increase by nearly 30% for ultrasonic mixing than that of magnetic stirring.     

Decolorization of methyl orange by ozonation in combination with ultrasonic irradiation

The combination of ultrasound and ozone for the decolorization of azo dye, methyl orange, was studied. The effect of ultrasonic power, ozone gas flow rate, gaseous ozone concentration, initial dye concentration, pH and hydroxyl radical scavenger on the decolorization of methyl orange was investigated. The results showed that the synergistic effect was achieved by combining ozone with ultrasonic irradiation for the decolorization of methyl orange. The synergistic effect was more significant when the system temperature was raised due to the heat effect of ultrasonic irradiation. The decolorization of methyl orange fits the pseudo first order kinetic model. The decolorization rate increased with the increase of ultrasonic power, ozone gas flow rate, gaseous ozone concentration. However, the decolorization rate decreased with the increasing initial dye concentration. Either pH or sodium carbonate has little effect on the decolorization rate, indicating that the low frequency ultrasound enhanced ozonation process for the decolorization of methyl orange is mainly a direct reaction rather than radical reaction.     

纳米碳管对泡沫炭的超临界发泡行为及其力学性能的影响机制

采用超声波?磁力搅拌的方法, 实现了纳米碳管(CNTs)在中间相沥青(MP)中的均匀分散, 并考察了CNTs对泡沫炭的超临界发泡行为及其压缩强度的影响. 研究结果表明: 在超临界发泡过程中, 处于过饱和状态的甲苯将优先在CNTs/MP固-液界面处成核, 进而不断扩散、聚集、膨胀和发泡, 导致泡沫炭孔结构的均一性得以提高; 当在中间相沥青中均匀分散3.5wt%的CNTs后, 所制泡沫炭的压缩强度由3.2MPa提高到4.7MPa, 升高了46.9%; CNTs良好的导热性能降低了基体碳在石墨化过程中的热应力差异, 使得微裂纹的数量减少, 并且其一维纳米结构使得石墨化泡沫炭的孔壁和韧带结构得以增强.     

Experimental Study on Distribution Characteristics of Condensate Droplets Under Ultrasonic Vibration

This paper studied the effect of ultrasound on distribution characteristics of condensate droplets on a vertical metal surface. The surface was made of aluminum and coated with PVC film to obtain durable condensate droplets. Visualization of the condensation process was carried out under the action of ultrasonic vibration with a constant frequency of 20 kHz. The effects of ultrasonic power on surface coverage of condensate droplets, first shedding time of condensate droplets, total number of shedding, heat flux and condensation heat transfer coefficient were analyzed. Furthermore, the mechanism of ultrasonic vibration on accelerating the shedding of condensate droplets was discussed. The results indicated that the shedding of condensate droplets was accelerated by ultrasound compared with those without ultrasound. In addition, the shedding period of condensate droplets was decreased with the increase of ultrasonic power. Contrarily, the heat flux and the condensation heat transfer coefficient were increased with the increase of ultrasonic power. The maximum enhancement ratio of heat transfer coefficient reached 2.67 compared with that without applying ultrasound. This study shows that ultrasound has a good application prospect in strengthening condensation heat transfer, particularly for space applications in microgravity environment.     

Controllable synthesis of hierarchical micro/nano structured FePO4 particles under synergistic effects of ultrasound irradiation and impinging stream

Hierarchical micro/nano-structured FePO₄ (FP) particles were environmental-friendly and controllable synthesized through synergistic intensification of ultrasound and impinging streams. Nano-scale FP seeds were firstly synthesized via ultrasound irradiation intensified impinging stream reaction (UISR), where the enhanced turbulent micromixing in the impinging streams benefits the nucleation process while the application of ultrasound to the impinging streams further intensifies such micromixing. The ultrasound frequency and power applied were 20 kHz and 600 W. The hierarchical micro/nano-structured FP particles are obtained when taking sufficient reaction time and stirring FP nano-seeds in a continuous stirring tank reactor (CSTR). Effects of the sonochemical pre-treatment, mean residence time and rotation speed on the physical-chemical properties of FP were investigated systematically. The characterization revealed that under the optimum operating condition, the FP particles presented near-spherical hierarchical micro/nano-structure, consisting of nanoscale primary grains. The mechano-chemical effects on the synthesized FP particles during different synthesis process were also studied.     

Study on the thermal and mechanical properties of epoxy–nanoclay composites: The effect of ultrasonic stirring time

Epoxy–clay nanocomposites were synthesized with organophilic montmorillonite and diglycidyl ether of bisphenol A by using the in-situ polymerization under ultrasonic treatment. The clay layers were found to be separated further with the increase in the duration of ultrasonic stirring as measured from the X-ray diffraction measurements. Thermogravimetric analysis provided the fact that the maximum thermal decomposition temperatures increased with the increase in the duration of ultrasonic stirring. However, both the glass transition temperature and the storage moduli of the composites decreased with the increase of ultrasonic stirring time as measured from the dynamic mechanical analysis.     

超声强化氨基化多壁碳纳米管改性环氧黏接接头性能研究

目的 探究超声处理对氨基化多壁碳纳米管(MWCNTs–NH2)改性环氧黏接接头黏接性能和热稳定性的影响,为强化MWCNTs–NH2改性环氧胶黏剂与铝合金的黏接提供参考。方法 通过机械搅拌与声波破碎的方法将质量分数为0.75%的MWCNTs–NH2添加到环氧胶黏剂基体中,使用MWCNTs–NH2改性环氧胶黏剂制备铝合金黏接接头,基于超声辅助黏接工艺在铝合金黏接过程中进行超声处理。通过傅里叶变换红外光谱仪(FTIR)分析MWCNTs–NH2改性环氧胶黏剂基体官能团的变化情况。采用单搭接剪切强度试验测定黏接接头的拉伸剪切强度。通过扫描电子显微镜(Scanning Electron Microscope,SEM)观察黏接接头拉伸失效断面以及铝合金与胶黏剂间的黏接界面。通过热失重分析仪(TGA)测试并记录胶黏剂试样质量随温度变化的曲线。结果 经超声处理后,MWCNTs–NH2与树脂基体间的化学反应增强。与纯环氧黏接接头相比,超声处理后的MWCNTs–NH2改性环氧黏接接头拉伸剪切强度提高了49.2%,黏接接头断面上的内聚失效部分显著增加。微观上,超声处理后的MWCNTs–NH2改性环氧黏接接头断面显示出更加复杂的塑性变形,胶黏剂与铝合金表面结合得更加紧密,MWCNTs–NH2随环氧胶黏剂流入铝合金表面凹槽内。经超声处理后,胶黏剂在失重率为5%、10%、50%以及热失重速率最大时的特征温度上升。结论 超声处理改善了MWCNTs–NH2与树脂基体的界面结合性能,促进了MWCNTs–NH2改性环氧胶黏剂在铝合金表面的渗透和填充情况,形成了MWCNTs–NH2对铝合金和胶黏剂的桥接。超声处理提高了改性环氧胶黏剂的交联密度,改善了胶黏剂的热稳定性。     

Study on Enhancement in Gibbsite Precipitation of Bayer Process under 33 kHz Ultrasound

The enhancement of gibbsite precipitation in Bayer process by 33 kHz ultrasound has been studied. From orthomethod experiment, the optimized operating parameters of treatment under 33 kHz ultrasonic cleaner have obtained.Compared with crystallization of Al(OH)3 without treatment of ultrasound, the precipitation time is reduced by 15 h when the precipitation ratio is 45%. From the results of grain size distribution and SEM photographs of gibbsite, it is found that secondary nucleation and agglomeration could be enhanced under 33 kHz ultrasound. The products are same from comparison of X-ray powder diffraction, but the Raman spectrum of sodium aluminate solution under 33 kHz ultrasound is different from that without ultrasound.