Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K_2Ti_6O_(13) whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol–gel process. During the preparation process, the fiber surface was coated with K_2Ti_6O_(13) whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K_2Ti_6O_(13) whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

Aluminum-silicates flotation with quaternary ammonium salts

The zeta potential measurements show that the flotation separation of diaspore from kaolinite, illite and pyrophyllite could be achieved in the range of pH 46.5 with cationic collectors. A special quaternary ammonium salts(DTAL) shows better selectivity than that the dodecyl amine(DDA) does for the flotation of three silicates. The closed circuit flotation results show that the reverse flotation de silicate can be achieved with DTAL as collector, a new inorganic reagent(SFL) as depressant and MIBC as frother to obtain a bauxite concentrate m (Al 2O 3)/ m (SiO 2) >10, Al 2O 3 recovery>86%).

Effect of aluminum silicate fiber modification on crack-resistance of a ceramic mould

To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting,aluminum silicate fibers with the diameter ranging from 5 μm to 25 μm and the length about 1 mm were dispersed in the ceramic mould.The effect of the aluminum silicate fibers on the tensile strength,shrinkage rate and the cracking trend of the ceramic mould were investigated.In the ceramic slurry,quartz sand was applied as ceramic aggregate,silica sol containing 30% silicon dioxide as bonder,and the weight ratio of quartz sand to silica sol was 2.69;the dispersed fibers changed from 0 to 0.24vol.%.The mould samples were formed after the slurry was poured and gelled at room temperature,and then sintered at different temperatures ranging from 100 to 800 ℃ to measure the tensile strength and shrinkage rate.The results show that,with the aluminum silicate fiber addition increasing from 0 to 0.24vol.%,the tensile strength increases linearly from 0.175 MPa to 0.236 MPa,and the shrinkage rate decreases linearly from 1.75% to 1.68% for the ceramic mould sintered at 400 ℃,from 1.37% to 1.31% for the ceramic mould at room temperature.As the sintering temperature was raised from 100 ℃ to 800 ℃,the tensile strength increases,and the shrinkage rate decreases at all temperatures,compared with those without fiber dispersion,but their variation patterns remain the same.Furthermore,the cracking trend of the mould and its decreasing proportion were defined and analyzed quantitatively considering both effects of the fiber dispersion on the strength and shrinkage.The cracking trend appears to decrease linearly with increasing fiber content and to reach the maximum reduction of 28.8% when 0.24vol.% fiber was dispersed.Therefore,the investigation proposes a new method to improve the crack-resistance of the ceramic mould,i.e.,inorganic fiber dispersion into the ceramic mould.

Aluminum-Magnesium Silicate enhances release of virions of cultured <i>Fowl Pox Virus</i>and inhibits the virus

Antiviral effects of a synthetic Aluminum-Magnesium Silicate (AMS) were tested on Fowl Pox Virus (FPV). Five batches of the Nigerian brand of FPV vaccine were used as sources of the virus. The reconstituted vaccines were mixed with The Synthetic AMS on equal volume to weight basis and incubated at room temperature for one hour. They were centrifuged for 10 minutes at 2000 revolutions per minute. The incubation and centrifugation were repeated on a portion of each vaccine supernatant. The two sets of supernatants were tested by the Modified Passive Haemagglutination test, for FPV titres. Portions of the vaccines, not incubated with the AMS, were served as controls. Fowl Pox Virus titres of the vaccines increased from a mean of 2.8 ± 1.10 to 11.2 ± 4.38 when incubated with the AMS once. When incubation with the AMS was repeated, the titres reduced (P< 0.05) to zero in each sample.

Preparation of Ultra-fine Aluminum Nitride in Thermal Plasma

Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11 μm measured by scanning electric mirror (SEM), and the purity is at least over 90% evaluated by X-Ray diffraction (XRD). The conversion of Al powder to aluminum nitride is strongly depended on the injection of NH3. Typical experimental parameters such as the feed rate of raw material, the flow rate of ammonia and the position of injecting aluminum powder into the reactor are given.

<i>In Vivo</i>Antiretroviral Effects of the Medicinal Synthetic Aluminum-Magnesium Silicate

Viral loads (copies of RNA per ml of plasma) of HIV/AIDS patients, who volunteered for clinical trial of the Medicinal synthetic Aluminum-magnesium silicate, were assessed, before and after they were treated. The treatment lasted 4 weeks, 8 weeks and 12 weeks respectively. A patient who could not access approved laboratory for viral load test on time, continued the treatment?for 24 weeks. Following treatment with the medicine, mean viral load of HIV/AIDS patients reduced (P < 0.05) from 18875.00 ± 17059.18 to 327.50 ± 226.84. Rates of the viral load reduction were: 86% after 4 weeks, 96% after 8 weeks and 99.71% after 12 weeks. Clinical signs complained of, by the patients during the treatment, included, fever, dermatitis, boils, joint pain, leg edema and sore throat. These clinical signs ceased when they were treated, so that the antiretroviral treatment was completed. The patient who was on the medication for 24 weeks had no adverse drug reaction.

Microstructural Evolution and Thermal Stability of Ultra-fine Grained Al-4Mg Alloy by Equal Channel Angular Pressing

Experiments were conducted to evaluate the grain refinement and thermal stability of ultra-fine grained Al-4Mgalloy introduced by equal-channel angular pressing (ECAP) at 473 K. The results show that the intensities of X-ray(111/222) and (200/400) peaks for the alloy processed by ECAP decrease significantly and the peak widths of halfheight become broadening compared with the corresponding value in the annealed alloy. The microstructure of 2passes ECAPed alloy consists of both elongated and equiaxed subgrains. The residual strain in the alloy increaseswith increasing passes numbers, that appears as increasing dislocation density and lattice constant of matrix. Anequiaxed ultra-fine grained structure of～0.2μm is obtained in the present alloy after 8 passes. The ultra-fine grainsare stable below 523 K, because the alloy retains extremely fine grain size of～1μm after static annealing at 523 Kfor 1 h.

Crystallinity and crystallization mechanism of lithium aluminosilicate glass by X-ray diffractometry

The crystallinity of lithium aluminosilicate(LAS) glass after crystallization were studied at different temperatures by X-ray diffractometry and the crystallinity of the standard glass ceramic with known crystal and glass phases was examined. The crystallization mechanism of LAS glass was analyzed by the crystallinity, with a formula relating the crystallinity (X) and temperature (T). The results show that the calculated crystallinity of LAS glass by XRD increases with the crystallization temperature, in the range of 40%?50%, which is close to the calculated ones of standard samples with spodumene quartz ratio of 40%?70%. The activation energy of LAS glass is different within different temperature ranges; nEc is 125.44 kJ/mol at 710?810 ℃ and nEc is 17.42 kJ/mol at 810?980 ℃, which indicates different crystallization mechanisms. It has been proved that the required energy for crystallization of glass in the lower temperature range includes the interfacial energy between glass and crystalline phase and the free energy difference of atoms in structures of glass and crystal, and in the higher temperature ranges only the interfacial energy between glass and crystalline phase is considered.

组成对钠铝硅玻璃中钇锆酸盐纳米晶析晶性能的影响

基于含Y2O_(3)和ZrO_(2)的钠铝硅玻璃体系,研究了玻璃组分中Al_(2)O_(3)/Na2O摩尔比值(MAN)与SiO_(2)/Al_(2)O_(3)摩尔比值(MSA)对玻璃析晶性能的影响。研究结果表明,当MAN<1时,玻璃经热处理后表面析出钠霞石晶体;当MAN≥1时,玻璃热处理后析出钇锆酸盐纳米晶体,且此时微晶玻璃仍然具有不小于90%的高可见光透过率。对于固定MAN的玻璃,调整其MSA也能实现钇锆酸盐纳米晶的析出,且析出晶体尺寸随MSA增加而减小。随着热处理温度升高微晶玻璃样品中纳米晶体尺寸增大,维氏硬度也增大。

铝硅酸盐玻璃的渗锡特性

盖板玻璃(以下简称铝硅酸盐玻璃)作为显示器件的基础材料,玻璃的沾锡、渗锡现象严重影响玻璃的后加工过程与玻璃性能,本文研究了不同厚度铝硅酸盐浮法玻璃的渗锡深度、渗锡量及渗锡机理。浮法盖板玻璃厂家可通过渗锡深度及渗锡量确定一些玻璃成型工艺参数。研究发现当铝硅酸盐玻璃厚度由0.33 mm增加至1.1 mm时,渗锡深度由4μm增大至15μm。对玻璃原片、减薄1μm、减薄2μm和减薄3μm的玻璃表面进行渗锡量测试,得出玻璃由表面至内部渗锡量逐渐减少,且减少幅度逐渐降低。玻璃锡面的锡离子有Sn、Sn^(4+)和Sn^(4+)三种价态,但主要以Sn^(4+)为主,约占总渗锡量的80%,随着玻璃深度的增加,玻璃内部Sn^(4+)含量逐渐增多,但仍以Sn^(4+)为主。这种渗锡现象是由被氧化的锡离子和玻璃中的钠离子发生离子交换反应引起的。

莫来石晶须/陶瓷纤维增强堇青石质隔热材料

基于改善高温工业使用的堇青石质隔热材料强度较低的问题,以蓝晶石、黏土、氧化镁粉为原料,以小麦淀粉为造孔剂和固化剂,引入适量的硅酸铝陶瓷纤维和MoO_(3),通过MoO_(3)催化莫来石晶须在陶瓷纤维表面的原位形成,制备了具有莫来石晶须/陶瓷纤维互锁多级结构增强的堇青石质隔热材料。研究了硅酸铝陶瓷纤维在MoO_(3)的作用下于不同温度(1200、1250、1300和1350℃)热处理后对材料显微结构、常温力学性能和热导率的影响。结果表明:在MoO_(3)的作用下,莫来石晶须在硅酸铝纤维表面生长,基本呈现垂直趋势,部分穿插于发育良好的堇青石晶粒中;随着热处理温度的升高,硅酸铝陶瓷纤维表面的莫来石晶须由短棒状转变为细长针状,且长径比逐渐增大;这种具有纤维/晶须多级结构的堇青石质材料,其力学性能得以提高的同时热导率也降低,其中1350℃热处理后试样的性能最佳。

超宽地面抗震变形缝施工技术

目前在建筑施工领域,普通结构抗震变形缝的预留宽度通常控制在50~500mm,当抗震变形缝的变形量大于500mm时,尚无标准的构造作法。依托北京大兴国际机场航站楼800mm宽抗震变形缝的特点,基于传统变形缝构造,在其基础上进行深化设计,将整个变形缝划分为阻火防水系统、滑移钢箱系统、定型装饰系统,在结构变形时,通过钢箱与结构间的相对平移来消耗变形量,满足在外力震动作用下设计要求的变形需求,上部装饰部分采用定制成品变形缝放置于滑动钢箱两侧,满足变形缝日常温度变形量的需求,解决了超宽地面抗震变形缝施工难题,并取得了良好的应用效果。

Factors effecting aluminum speciation in drinking waterby laboratory research

Effects of aluminum on water distribution system and human health mainly attribute to its speciation in drinking water. Laboratory experiments were performed to investigate factors that may influence aluminum speciation in water supply system. The concentration of soluble aluminum and its transformation among other aluminum species were mainly controlled by kinetics processes of related reactions. Total aluminum concentration had a notable effect on the concentrations of mononuclear and soluble aluminum in the first 4 day; then its effect became weak. At pH above 7.50, both fluoride and orthophosphate had little effect on aluminum speciation; while, when the solution pH was below 7.50, the concentrations of mononuclear and soluble aluminum were proportional to the concentration of fluoride and inversely proportional to the concentration of orthophosphate. Both mononuclear and polynuclear silicic acids could complex with mononuclear aluminum by forming soluble aluminosilicates. In addition, the adding sequence of orthophosphate and aluminum into drinking water would also affect the distribution of aluminum species in the first 4 day. In order to minimize aluminum bioavailability in drinking water, it was suggested that orthophosphate should be added prior to coagulant process, and that the concentrations of fluoride and silicic acids should be controlled below 2.0 and 25 mg/L, respectively, prior to the treatment. The solution pH in coagulation and filtration processes should be controlled in the range of 6.50-7.50.

Flotation de-silicating from diasporic-bauxite with cetyl trimethylammonium bromide

Using cetyl trimethylammonium bromide （CTAB） as collector, the flotation de-silicating from diasporic-bauxite was investigated. And the Zeta potentials and contact-angles of silicate minerals and diaspore were also stu-（died.）The results show that in the presence of 2×10-4 mol·L-1CTAB, the surface charges of pyrophyllite, kaolinite and illite become more positive, and the contact angles of these three silicates also increase evidently in the pH range of 2-8, but the Zeta potentials and contact angles of diaspore change little. So, the floatability of the four minerals is in the following order: pyrophyllite>kaolinite≈illite>diaspore. The open-circuit flotation results also show that a bauxite concentrate with m（Al2O3）/m（SiO2） over 9.3 and Al2O3 recovery over 76% can be obtained from diasporic-bauxite ore. The result of XRD of the bauxite concentrate shows that pyrophyllite is easier to be removed from diasporic-bauxite than illite and kaolinite due to its better floatability.

Compressive deformation behavior and energy absorption characteristic of aluminum foam with elastic filler

An open-cell aluminum foam filled with silicate rubber (AFFSR) was fabricated by infiltration of the liquid silicate rubber into the open-cell aluminum foam. The experiments were carried out to investigate the compressive behavior and energy absorption characteristics of the material. It is found that the stress—strain response of the AFFSR exhibits five regions including two plateau regimes, which is quite different from the stress—strain curves of many unfilled metallic foams that usually exhibit three distinct regions. The plastic deformation of the AFFSR is prolonged because of the filled silicate rubber, compared with the aluminum foam without such a filler. The AFFSR also exhibits a higher energy capacity than the aluminum foam without filler. Additionally, for the prolonged plateau region in the stress—strain curve, the energy absorption efficiency of the AFFSR maintains a high level (above 0.6) over a wide strain range from 3% to 60%.

掺铥镧铝硅酸盐玻璃光子晶体光纤制备及光学特性

镧铝硅酸盐玻璃具有稀土离子溶解度高、热稳定性好等优异的光学性能和优良的物理化学性质,其部分物理化学性质与石英相近,易与石英玻璃结合进行特种光纤制备,被认为是一种理想的激光玻璃基质材料.本文采用传统高温熔融法成功研制出一系列不同浓度Tm^(3+)掺杂镧铝硅酸盐玻璃,以掺铥镧铝硅酸盐玻璃为纤芯,采用管棒堆叠法制备出掺铥双包层光子晶体光纤.实验研究了掺铥镧铝硅酸盐玻璃及其光纤的吸收、荧光、激光等光学特性,研究结果表明,掺铥镧铝硅酸盐玻璃及其光子晶体光纤适于2μm波段激光输出,为2μm波段高功率光纤激光器的研究提供了一种新的途径.

机械力化学法活化铝系硅酸盐矿物降解六氯苯机理研究

针对六氯苯(HCB)在土壤中长期存在难以降解的问题,本研究基于机械力化学法,系统地探究土壤中固有成分铝系硅酸盐(高岭土、白云母和膨润土)对HCB的降解效果,讨论了球磨转速、球磨时间、HCB初始浓度等条件对HCB降解效率的影响。在HCB浓度为50 000 mg/kg的条件下,600 r/min球磨2 h后,铝系硅酸盐矿物对HCB去除能力由大到小依次为高岭土、白云母、膨润土,高岭土和白云母对HCB的去除率分别为90.13%、85.72%,膨润土几乎不降解HCB。HCB的去除率随着球磨时间增加而增加,与转速呈正相关。HCB初始浓度的降低有利于HCB的降解和脱氯效率,当HCB处于高浓度水平50 000 mg/kg时,高岭土和白云母的脱氯效率较低;当HCB处于低浓度水平2 500 mg/kg时,高岭土和白云母的脱氯效果提高,高岭土的脱氯效果优于白云母。利用ESR检测自由基信号发现,高岭土在机械力化学作用下产生了高活性氧类自由基,而白云母和膨润土未产生自由基。利用GC-MS分析HCB降解中间产物,当高岭土作为添加剂时,产生的自由基导致HCB的C—Cl发生断裂,经过连续脱氯过程,HCB的稳定结构被打破,形成了一系列不稳定的含Cl中间产物。综上所述,铝系硅酸盐矿物在机械力化学作用下能够高效降解HCB,而且便宜易得,不会造成二次污染,具有广泛的应用潜力。

化学强化提升薄型锂铝硅玻璃抗冲击性能研究

新一代锂铝硅玻璃逐渐成为航空透明件的主流结构材料,由于其较高的弹性模量和优异的离子交换能力,经过化学增强处理后具有优异的力学性能,能够很好地满足航空透明件轻质、高强的需求。研究了1.8 mm厚度锂铝硅玻璃经过化学增强后的抗冲击性能变化,采用不同增强工艺制备了多组样品进行落球冲击测试,并依据应力包线进行了初步理论计算,探讨了玻璃中心张应力对抗冲击性能的影响。研究结果表明,1.8 mm厚度锂铝硅玻璃表面压应力为930 MPa左右时,应力层深度在130~160μm范围内抗冲击性能较佳,玻璃具备较好的力学性能。