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1.
以硅烷为锚固基团(A段),丙烯酸丁酯为溶剂化链(B段),合成了超分散剂YB系列,研究了它对微细CaSO4粉体在液体石蜡中的沉降体积和粘度的影响。结果表明:YB系列超分散剂对CaSO4粉体有很好的分散和降粘作用,当锚固基团与溶剂化链摩尔比为1:10时,超分散剂用量为粉体质量的1%的情况下分散和降粘效果最佳,YB-2超分散剂的改性效果要优于F-2钛酸酯偶联剂和硬脂酸。同时通过对改性前后粉体做了扫描电镜(SEM)和红外光谱(FT-IR)检测,对比显示改性后的CaSO4粉体表面连接了有机基团。 相似文献
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通过在水基钻井液中添加纳米氧化物颗粒,来改善其润滑性能。选用了Al2O3、TiO2及SiO2三种纳米氧化物颗粒作为钻井液改性添加剂,利用极压润滑仪及销盘摩擦磨损实验仪研究了添加不同种类和浓度纳米颗粒氧化物对水基钻井液的润滑性能及减摩效果的影响。结果表明,所添加的3种球形纳米颗粒均有润滑减阻减摩的效果,其中SiO2颗粒的钻井液的润滑性能、滤失性能以及减摩效果都是最好的。当纳米SiO2颗粒加量为0.4%时,滤失量最小,润滑系数降低率达到15.6%,摩擦系数降低率为32.0%,磨痕轨迹平滑,减摩效果最为明显。当纳米颗粒浓度超过0.5%时,减摩效果降低,磨盘脱层磨损明显。 相似文献
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利用水泥、石灰等材料作为固化剂，通过特制的深层搅拌机械，在地基深部将软土粉体强制拌和，使软土凝结加固的粉体喷射搅拌法在郑州一工地应用中效果良好，施工过程中建立质量控制体系，确保了工程质量。 相似文献
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为了满足彩色等离子体平板显示(PDP)用荧光粉的要求,采用化学共沉淀法并结合超声波分散技术制备PDP用(Y,Gd)BO3∶Eu3 红色荧光粉.在稀土离子浓度、烧结温度等实验的基础上,得到分子式为(Y0.85Gd0.1)BO3∶Eu0.05、烧结温度为1 000℃的最佳实验方案.同时选择了不同的分散试剂并结合超声波分散技术对样品进行了后处理实验.结果表明:当分散试剂为乙醇时,样品的相对发光强度最高;同时,采用后处理试剂并结合超声波分散技术对样品进行后处理大大降低了粉体的团聚现象并增强了粉体的分散性,提高了粉体的质量.与传统的固相法相比,此法不仅大大降低了合成温度,同时,粉体的质量比固相法合成的要好,粉体的亮度高(以国外红粉为参考),样品经后处理后,颗粒细小、均匀,粒径分布约为300 nm. 相似文献
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硅灰石与盐酸快速反应规律及应用研究 总被引：5，自引：0，他引：5
反应体系pH≤1．5时，硅灰石与盐酸快速反应，反应后体系中Si,Ca,Fe,Mg等元素在固液两相中化学状态及分布不同，当pH值为0．3－0．6时，液相中SiO2(硅溶胶）比例最大，Ca主要存在于液相中，但固相中总有少量Ca存在。快速反应固相比表面积较大，若反应前添加PEG，反应后中和到pH=4，可制备高比表面多孔SiO2，其比表面积＞430m^2/g，孔径1－2nm，该产物在合成以二氧化硅为基质的纳米复合材料及用作催化剂载体等方面有较好的应用前景。 相似文献
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新型混凝剂处理印染废水的实验研究 总被引：5，自引：0，他引：5
采用自行制各的具有不同SiO2:Al:Fe(摩尔比值)和碱化度的两类新型无机高分子混凝剂聚硅酸氯化铝铁(PSAFC)和聚硅酸硫酸铝铁(PSAFS）各7种，直接对印染废水进行处理。从中选出2种温凝剂，考察了pH值、混凝剂投量等对混凝效果的影响，并对混凝处理后，印染废水出水中残留温凝剂主要成分Al、Fe、SiO2的含量进行分析。实验结果表明，氯化物型(PSAFC)和硫酸盐型(PSAFS)混凝剂对印染废水的色度、浊度、COD Cr均有良好的去除效果；总体而言，PSAFS的混凝效果略优于PSAFC；混凝处理后印染废水出水中残留铝、铁、硅的含量均比较低；pH值和碱化度对温凝剂在水体中残留铝含量有影响。 相似文献
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硅钨酸是一种杂多酸。在600～650℃失水分解成SiO2和WO3。其SiO2含量为1．80～2．35％，WO3含量达85％。 相似文献
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Sol-gel法制备SiO2-TiO2复合薄膜，进行甲醛的光催化降解实验，研究了SiO2掺杂量、薄膜焙烧温度、甲醛溶液pH值及初始浓度对光催化性能的影响。结果表明，500℃焙烧1h，掺杂质量SiO2：TiO2=12：100时，SiO2-TiO2薄膜的光催化活性最高，150min后甲醛降解率达76％，是单纯TiO2薄膜的1．3倍，该薄膜稳定性较好，经重复8次使用，最大降解率只下降4％。 相似文献
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利用粉煤灰制备多孔氧化硅的实验 总被引：3，自引：2，他引：1
利用相分离原理,以粉煤灰经硅铝分离后所得的硅酸凝胶为原料,选用聚乙烯醇为造孔剂,硝酸为催化剂,成功地制备了多孔氧化硅。实验结果表明:制备的多孔氧化硅的孔道发育良好,含有三级孔道。扫描电镜分析显示:大孔孔径为1～2 μm,比表面积为12.03 m2/g,这与实际应用的硅藻土助滤剂制品大致相当。对实验制品在啤酒液中的稳定性实验结果显示:多孔氧化硅制品在浸泡于啤酒过程中几乎没有Ca2+、Fe3+离子溶出,浸泡后的啤酒液的pH值基本不变。上述结果表明:实验制备的多孔氧化硅制品作为硅藻土助滤剂的替代品具有良好的实际应用前景。 相似文献
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为了研究孔隙结构和水动力对悬浮颗粒在饱和多孔介质中沉积和迁移特性的影响,对天然硅粉（悬浮颗粒）和荧光素钠（示踪剂）在饱和多孔介质中的渗流迁移特性进行土柱试验,分别得到了5种不同渗流速度（0.033、0.066、0.132、0.199、0.265 cm/s）、两种不同多孔介质（石英砂和玻璃球）的悬浮颗粒和示踪剂全组合下的20条穿透曲线。根据试验结果,研究孔隙结构、渗流速度对饱和多孔介质中颗粒迁移和沉积过程中水动力作用机制、弥散效应、加速效应的影响。研究表明,悬浮颗粒的穿透曲线可以用一阶沉积动力学对流弥散方程的解析解来描述。随着渗流速度的增大,水动力学作用对颗粒出流浓度的影响越来越大,而孔隙结构的影响则相对减弱。同时,存在一个临界渗流速度值。当渗流速度超出该值时,悬浮颗粒迁移要快于示踪剂,而且临界渗流速度对于玻璃球和石英砂两种多孔介质是不同的;其次,在两种介质中,随渗流速度增大,弥散度增加,回收率和回收悬浮颗粒粒径增大,沉积系数先增大后减小。此外,在孔隙比相近的情况下,悬浮颗粒在玻璃球介质中的回收率要大于其在石英砂中的。可见,孔隙结构和渗流速度是影响饱和多孔介质中颗粒输运的重要因素,渗流速度越大,孔隙结构的作用越明显。 相似文献
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The effect of microfabric on the mechanical behaviour of clays has been explored previously based on the response of dispersed and flocculated microfabrics only. However, the natural clays often have the geometric arrangement of particles between these two extreme cases which can be termed as intermediate microfabric. This paper explores the formation of intermediate microfabric of kaolin clay and its impact on soil’s consolidation behaviour by performing self-weight consolidation, slurry consolidation and 1-D consolidation tests. The effect of calgon content (dispersing agent) on geometric arrangement of the particles has been evaluated through cluster size distribution by performing double hydrometer tests. Then these clay slurries have been used to perform the AFM (Atomic Force Microscopy) test to obtain the variation in average angle of particle orientation with respect to the calgon content present in the slurry. AFM technique provides 3D image of the clay sample and 2D image with Z-information with the potential of measuring intermediate microfabric of clayey soil quantitatively including dispersed and flocculated microfabrics. Other traditional techniques such as SEM, TEM & XRD are limited to only qualitative analysis of soil’s microfabric, thus, having no capability to measure intermediate microfabric of clay. A methodology of preparing bulk specimens of clay with intermediate microfabric has been developed using slurry consolidation technique; and then these specimens have been consolidated under 1-D loading to evaluate the effect of intermediate microfabric on compressibility and permeability of clay. In this study, all the experiments reports that the dispersed type geometric arrangement increases with the increase in calgon content in soil up to 2 % and then the reverse behaviour is observed at 3 %; which may depend on the required amount of sodium cations to neutralize the negatively charged faces of the clay platelets present in the slurry. 相似文献
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钙质砂为海相沉积的多孔介质,是防护工程分配层的理想填充材料。利用改进的铝制分离式霍普金森压杆（split Hopkinson pressure bar,简称SHPB）,分别对颗粒级配以及相对密实度相同的南海钙质砂和福建石英砂进行了83组一维冲击试验,得到了应力波透射率、冲击响应和吸能效率曲线,分析了应变率、相对密实度和含水率对两种砂冲击特性的影响。结果表明,相同的荷载和边界条件下,钙质砂的刚度仅为石英砂的1/10。由于内孔隙的存在,钙质砂对冲击波的衰减作用大于石英砂,在承载性能允许的情况下,适当减小相对密实度、增加含水率可有效提高分配层消能效果。 相似文献
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WANG Lijuan LU Anhuai WANG Changqiu LI Xuejun ZHENG Xishen ZHAO Dongjun LIU Rui 《《地质学报》英文版》2006,80(2):180-184
With the TEM and physical gas adsorption techniques, porous properties of nano-ribriform silica （MLD： 92.73%） from natural chrysotile are studied in this paper. The results indicate that porous nano-fibriform silica results from brucite octahedral sheets of nature chrysotile dissolved completely and Si-O tetrahedral sheets collapsed by acid leaching. Its length is at a micron or nanometer scale. There are two types of pores： pores among neighboring fibers and pores in nanoriber. These pores （less than 6.5 nm in diameter, mostly 2.1 nm and 3.8 nm） all belong to mesopores. The pores in fibers consist of those among SiO2 particles, those among aggregates, remnant nanotubes and capillary tubes. Nanoribriform silica proves better than the traditional silica as a carrier of catalyzer and a filler for reinforce rubber and plastics. 相似文献
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纳米纤维状白炭黑的孔隙特征 总被引：5，自引：0，他引：5
在与传统白炭黑对比研究基础上,利用TEM、XRD、FT_IR和氮吸附法对纳米纤维状白炭黑(MLD为92.73%)进行研究,主要讨论了纳米纤维状白炭黑多孔结构的成因、孔径大小、孔分布及孔类型等特征。分析表明纤蛇纹石中氢氧镁石八面体层被酸溶蚀和硅氧四面体层的塌陷是导致这种白炭黑具有多孔纳米纤维结构的直接原因;有两种孔隙类型,即纤维上的孔隙和纤维的堆积孔隙;纤维上的孔隙包括SiO_2微粒间的孔隙、其聚结体间的孔隙、残余纳米管的管道和毛细管道;孔径2.1和3.8nm处的孔隙数量多,并且在纳米纤维(或管)上存在大量小于5nm左右的微孔。研究证明了在用于橡胶、塑料填充补强剂和催化剂载体等方面,纳米纤维状白炭黑更优于传统白炭黑。 相似文献
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冰点下水合物在多孔介质的生成是一个复杂的多相转化过程,为了研究冰点下多孔介质中水合物生成过程的水相转化率、气体消耗量与稳定压力等生成特性,在定容条件下,进行不同孔径与粒径的多孔介质中甲烷水合物在冰点下的生成实验。所使用的多孔介质平均孔径为1295 nm、1796 nm和3320 nm。研究结果表明：水合物生成结束时水的转化率随着初始生成压力的增大而增大,随着温度的升高而降低,随着孔径的增大而增大;在相同的孔径下,多孔介质粒径的增大降低了水合物的生成速率但对最终气体消耗量没有影响;在相同的温度下,随着初始生成压力的增大,实验最终压力、气体消耗量与最终水的转化率均随之升高;温度越高,不同的生成初始生成压力下体系的最终稳定压力与水的转化率相差越大;在多孔介质的毛细管作用力与结合水的共同作用下,冰点下水合物生成的水的转化率会大大地降低。在本实验条件下,水相转化为水合物的比例最高为32.39%。 相似文献
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T.S. Peretyazhko J.M. Zachara D.W. Kennedy J.K. Fredrickson B.W. Arey J.P. McKinley C.M. Wang A.C. Dohnalkova Y. Xia 《Geochimica et cosmochimica acta》2010,74(13):3751-60
The reductive biotransformation of 6-line ferrihydrite located within porous silica (intragrain ferrihydrite) by Shewanella oneidensis MR-1 was investigated and compared to the behavior of 6-line ferrihydrite in suspension (free ferrihydrite). The effect of buffer type (PIPES and NaHCO3), phosphate (P), and an electron shuttle (AQDS) on the extent of reduction and formation of Fe(II) secondary phases was investigated under anoxic conditions. Electron microscopy and micro X-ray diffraction were applied to evaluate the morphology and mineralogy of the biogenic precipitates and to study the distribution of microorganisms on the surface of porous silica after bioreduction. Kinetic reduction experiments with free and intragrain ferrihydrite revealed contrasting behavior with respect to the buffer and presence of P. The overall amount of intragrain ferrihydrite reduction was less than that of free ferrihydrite [at 5 mmol L−1 Fe(III)T]. Reductive mineralization was not observed in the intragrain ferrihydrite incubations without P, and all biogenic Fe(II) concentrated in the aqueous phase. Irrespective of buffer and AQDS addition, rosettes of Fe(II) phosphate of approximate 20-30 μm size were observed on porous silica when P was present. The rosettes grew not only on the silica surface but also within it, forming a coherent spherical structure. These precipitates were well colonized by microorganisms and contained extracellular materials at the end of incubation. Microbial extracellular polymeric substances may have adsorbed Fe(II) promoting Fe(II) phosphate nucleation with subsequent crystal growth proceeding in different directions from a common center. 相似文献
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Porcellanite is a siliceous duricrust which has developed within altered Cretaceous mudrocks in the Darwin city area and is well exposed in coastal cliffs to the north. Its distinctive geotechnical properties include low bulk density, variable strength that is highly dependent on moisture content, and relatively high (but inconsistent) durability. The porcellanite rock mass is inhomogeneous and anisotropic; it is unrippable at the surface, but becomes weaker with depth. It is also highly permeable in places, even karst‐like, due to solution cavities. These characteristics are common to all duricrusts and result from processes of solution, replacement and redeposition by silica‐laden groundwater. Such processes may have been intermittently active through most of the Cenozoic and there is evidence that they continue to the present. The upper 2–4 m of the porcellanite profile is made up of a brittle, high‐strength rock with a silica content approaching that of silcrete. The underlying altered and porous siltstone is much weaker and deforms plastically under loading, due to a cellular microfabric composed largely of opaline silica replacing clay minerals. Porcellanite has long been used as the main building stone in Darwin and is now quarried for shoreline filling. Although some of it is of select fill or road sub‐base quality, crushed porcellanite contains an excess of plastic fines making it unsuitable for basecourse. Porcellanite has been a failure as breakwater stone, despite producing blocks of adequate size. 相似文献
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针对隧道突水灾害防治对注浆材料的特殊要求,在水泥浆中加入外掺剂改善其力学特性与抗冲刷特性。通过测试不同水灰比、纤维掺量、硅灰掺量下水泥石的抗压与抗折强度,得出各水灰比下的强度最佳配合比,并测试最佳配合比下浆液的流动性与抗冲刷特性。试验发现,纤维与硅灰的掺入能够显著提高水泥石的强度,且对浆液的流动度影响不大;低流速下纤维硅灰水泥浆的抗冲刷特性较纯水泥浆改善显著,但流速较高时其抗冲刷特性仍较差。基于此,在纤维硅灰水泥浆中再掺入可再分散性乳胶粉进一步改善浆液抗冲刷特性。试验结果表明,可再分散性乳胶粉能明显改善浆液抗冲刷特性,即使在较高流速（0.6 m/s）下,其浆液留存率仍达到60%以上。研究结果为隧道突水灾害防治与动水注浆浆液选择提供了参考。 相似文献