二氧化硅/硅灰石复合颗粒的制备研究

以水玻璃为主要反应原料 ,利用无机化学沉积改性制备二氧化硅 /硅灰石矿物复合颗粒 ,并利用扫描电镜(SEM)与X荧光光谱分析及力学实验等测试方法表征了该实验的可行性并得出相应结论     

Regulating Drug Release Via Non-Uniform Distribution of Coating Composition in Multilayer Drug-Coated Granules

Multilayer drug-coated granules with a non-uniform distribution of the coating composition specifically the drug loading and the polymer viscosity, across the thickness of the film matrix were prepared by the fluidized bed coating process. The rate and duration of diphenhydramine hydrochloride release from the coated granules can be modified through control of the gradient change in the coating composition across the thickness of the methylcellulose (MC) film matrix. A steeper gradient change across the film matrix resulted in a slower overall release rate. Formulations with gradient drug loading distribution exhibited an extended release time that can be twice as long as that for the control formulation. Gradient layered matrices obtained by sequentially depositing different viscosity grades of MC produced release profiles that differed from film matrices prepared using MC blends.     

Regulating Drug Release Via Non-Uniform Distribution of Coating Composition in Multilayer Drug-Coated Granules

Multilayer drug-coated granules with a non-uniform distribution of the coating composition specifically the drug loading and the polymer viscosity, across the thickness of the film matrix were prepared by the fluidized bed coating process. The rate and duration of diphenhydramine hydrochloride release from the coated granules can be modified through control of the gradient change in the coating composition across the thickness of the methylcellulose (MC) film matrix. A steeper gradient change across the film matrix resulted in a slower overall release rate. Formulations with gradient drug loading distribution exhibited an extended release time that can be twice as long as that for the control formulation. Gradient layered matrices obtained by sequentially depositing different viscosity grades of MC produced release profiles that differed from film matrices prepared using MC blends.     

液相颗粒包裹法制备PbNb2O6微粉的研究

本文介绍了一种采用液相颗粒包裹技术制备功能陶瓷微粉的新方法.这种方法有如下特点:(1)方法简便,不需要特殊的设备,便于扩大应用于工业生产;(2)粉体颗粒尺寸小而均匀;(3)粉体化学组成偏离小、且均匀;(4)适应性强,从双组分至十多组分的材料微粉制备均可采用;(5)特别适用于一些含有难溶组分、用液相法无法制备的材料.本工作采用这一方法,成功地制备出 PbNb_2O_6微粉,其平均腰粒尺寸<0.5μm,分散性及化学均匀性好,烧结活性高,烧结温度可以降低近100℃,瓷坯密度可达理论密度的96%以上.     

A New Method to determine Triaxial Non-Uniform Residual Stresses from Measurements using the Hole Drilling Method

A new integral analysis technique in combination with finite element calibration data is introduced to resolve the triaxial residual stress profiles of measurements performed with the hole drilling or ring core method. The new technique uses an inverse formulation with symmetrised trigonometric basis functions or wavelets.     

Development of Fluidized-Bed Spray Coating Process for Axisymmetrical Particles

A technique was developed for uniform, reproducible deposition of coating mateials on light-weight cylindrical particles, using the Wurster air-suspension coater. The particles used in this study had a length-to-diameter ratio of approximately four. Fluidization and coating characteristics were optimized by mixing the cylindrical particles with more symmetrical filler particle of greater density. The mixed particles produced sufficient bulk density and voidage to optimize fluidization parameters and hence uniform coating. Key variables related to the coating equipment and process were identified and were used for process scale-up. The calculated rates of mixed-particle circulation and coating on the particles were approximately the same as experimental data obtained from three sizes of coating equipment.     

A Topographic Method of Assessing Coating Thickness Measures

A topographic method is proposed for measuring stepped coating thickness measures with a profile recorder, which allows one to scan the working surface to determine the thickness distribution and operate automatically to calculate the statistical parameters and present the results in graphical form. The method is recommended for checking coating thickness measures.     

TiO2包覆石墨颗粒的制备及表征

以钛酸四丁酯,二乙醇胺,无水乙醇和水为主要原料,采用溶胶－凝胶技术在石墨颗粒表面包覆了TiO2,研究了复合颗粒制备的条件,表面形貌和特性,获得了金红石相TiO2完全包覆石墨的复合颗粒。     

金属闪光漆涂膜颗粒缺陷分析

金属闪光漆由于其涂膜光亮、丰满 ,具有较强的金属感闪光效果 ,已经成为汽车涂装的装饰性漆膜。但是 ,由于金属闪光漆喷涂工艺较为复杂 ,在涂装生产中经常出现漆膜颗粒缺陷 ,车身一次性喷涂合格率低。根据自动喷涂生产线喷涂金属闪光漆的质量统计 ,金属闪光漆喷涂后出现的颗粒缺陷占涂膜质量缺陷的3 5%～ 50 % ,漆膜颗粒是金属闪光漆喷涂后出现的主要涂膜缺陷 ,是造成金属闪光漆一次性喷涂合格率低、返工修补困难的重要原因。本文结合引进的Ｂｉｎｋｓ自动喷涂线的生产状况 ,探讨了自动喷涂生产线金属闪光漆喷涂施工颗粒来源及解决办法。1　…     

Surface Modification of a-Fe Metal Particles by Chemical Surface Coating

The structure of a-Fe metal magnetic recording particles coated with silane coupling agents have been studied by TEM, FT-IR, EXAFS, Mossbauer. The results show that a close, uniform, firm and ultra thin layer, which is beneficial to the magnetic and chemical stability, has been formed by the cross-linked chemical bond Si-O-Si. And the organic molecule has chemically bonded to the particle surface, which has greatly affected the surface Fe atom electronic structure. Furthermore, the covalent bond between metal particle surface and organic molecule has obvious effect on the near edge structure of the surface Fe atoms.     

改进的Sol-gel法制备Ba0.6 Sr0.4 TiO3厚膜

采用Sol-gel法在Pt/Ti/SiO2/Si和Al2O3基片上制备厚度为2～14μm的Ba0.6Sr0.4TiO3(BST)铁电厚膜材料.经高能球磨细化和表面改性后的BST陶瓷纳米粉体分散到BST溶胶中,通过甩胶法,形成0-3型BST厚膜材料.XRD图谱显示,BST呈现纯钙钛矿相结构;SEM照片显示,BST厚膜均匀致密、无裂纹;介电性能测试结果表明,当测试频率为1kHz,温度为25℃时,介电常数为620,介电损耗为0.6.     

单分散球形纳米二氧化硅的制备新方法

在醇类有机溶剂中,以氨气(氨水)作为催化剂,在表面活性剂作用下,TEOS分解生成单分散、球形、实心、粒度分布窄的高纯纳米二氧化硅粉末.TEM研究表明:醇的种类和TEOS的浓度以及催化剂的用量影响粒子的大小、形状和粒径分布.可以在0.05～2μm范围内调节生成的二氧化硅的粒径.     

颗粒包覆厚度对磁流变液性能的影响

为了研究磁性颗粒包覆厚度对磁流变液性能的影响,通过改变水溶液中聚乙烯醇的浓度来获取不同包覆厚度的磁性颗粒,以此配制磁流变液;对包覆颗粒的表面形貌、粒径及静磁性能进行表征,并测试不同包覆厚度的磁性颗粒制备的磁流变液的零场黏度、剪切屈服应力和沉降稳定性性能。结果表明:颗粒包覆厚度对磁流变液的零场黏度影响不大,对剪切屈服应力影响作用由弱到强再减弱;包覆层厚度增大,大颗粒团聚物更易形成,导致磁流变液沉降稳定性降低。     

TiO2包覆石墨颗粒的制备及表征

以钛酸四丁酯、二乙醇胺、无水乙醇和水为主要原料,采用溶胶-凝胶技术在石墨颗粒表面包覆了TiO     

木粉的包覆催化法改性研究

木粉是粉状硝铵工业炸药常用的固体碳氢类可燃剂,同时起到了敏化剂和疏松剂的作用,然而对其的改性研究较少.提出了木粉的包覆催化改性方法,并研究了改性木粉对膨化硝铵炸药爆炸性能的影响.结果表明,该法能够在一定程度上提高膨化硝铵炸药的爆炸性能,而且是一种简单易行的改性方法.     

一种简单实用的颗粒物浓度测量检验方法

颗粒物浓度测量是计量测试技术中的一个重要方面 ,但迄今为止 ,国内外尚缺少这方面的标准物质。文中提出了一种简单可靠而又十分实用的“定量稀释法” ,能很好地解决这一困难。实验研究证实了这一方法的可用性     

一种评价颗粒堆积效果的简便方法及其应用

提出一种评价颗粒堆积效果的简便方法,将颗粒划分为多个窄粒级进行隔层充填,基于匀相微元假设,通过计算上隔层空隙率的方式计算堆积评价指标E,以此评价颗粒堆积效率,并通过水煤浆制备试验验证其可行性。结果表明,E值越大堆积效率越高,成浆浓度随之呈增大趋势,说明了方法的有效性;对于不同的煤样,E具有最优值,颗粒堆积效率足够高,且不会因为过度堆积影响流动性;Rosin-Rammler拟合模型的均匀性系数n为0.7⁰.8时,E值较大,但是通过n值判断堆积效率的优劣时会因拟合误差过大而存在失效的可能性;煤样氧化后的E值即使大于氧化前的,其成浆性仍可能降低;同一种煤制得的水煤浆,体积膨胀率具有一致性。     

激光熔覆WC颗粒增强涂层成形机理研究

利用两相流体动力学原理,讨论了含碳化钨不混溶颗粒增强涂层的成形机理,结果表明碳化钨粒子在涂层中的分布状态主要取决于熔池中的熔融主相合金材料的流动性,依据激光能量与流动性关系,建立了相应的物理模型,并列举了一个实验实例.