粉体技术在中药中的应用

简要介绍了粉体技术在中药加工中的应用,列举了粉体技术在中药制剂工艺和制剂疗效中所产生的影响,同时阐述了超微粉碎加工技术在中药现代化中的作用,简介了微米中药、纳米中药,并且引用中药超微粉碎一些实验研究,证明中药经超微粉碎后细粉比粗粉溶出的速度快,并且有效成分的溶出比较均匀。     

半导体制造业用微纳米碳化硅粉体制备工艺研究

采用水流分级和高能纳米冲击磨对原始SiC粉料进行微纳米粉体加工。研究结果表明:水流分级得到纯度98.42%、中位粒径0.404μm的SiC粉体,比表面积由0.8879m2/g提高到8.0321m2/g;高能冲击磨得到纯度95.5%、中位粒径0.257μm的SiC粉体,比表面积由0.8879m2/g提高到8.2773m2/g,SiC的粒径及比表面积达到半导体制造业用微纳米碳化硅粉体的技术标准。纯度分析表明碳化硅粉体的水流分级未引入杂质,化学成分基本不变;SiC粉体冲击磨加工纯度下降,其他杂质含量偏高。粉体形貌分析表明原始SiC粉料形貌为非球形,粒度分布不均匀,水流分级和冲击磨加工碳化硅粉体形貌为非球形,粒度分布较加工前更均匀。     

上海细创粉体装备有限公司

正产品名称:QS系列水平圆盘式气流粉碎机产品简介:压缩空气通过均匀地分布在粉碎室周围并与粉碎室半径方向成一定角度的喷嘴,把压强能转换成速度能,产生高速气流,使通过加料喷射器连续均匀地进入粉碎室的粉体物料颗粒,互相激烈碰撞、摩擦及粉碎室内腔表面碰撞,从而达到超微粉碎的目的。产品特点:*适用干式脆性物料(含水量3%)的超微粉碎。*依靠粉体间相互作用的自磨粉碎,可获得高纯度微米级和亚微米级的超微颗粒。     

碳-蒙脱石二维纳米复合粉体制备与提纯

以聚乙烯醇、钙基蒙脱石为原料,通过溶液插层、碳化和气流粉碎工艺和技术制备碳-蒙脱石二维纳米粉体。物相和粒径分析结果表明:在钙基蒙脱石、聚乙烯醇、水的质量比为5∶5∶90的反应体系中,获得层间距d(001)=2.11 nm的聚乙烯醇-蒙脱石插层型复合粉体;400℃碳化该复合粉体获得具有三明治结构特征的碳-蒙脱石复合粉体(d(001)=1.56 nm);将碳-蒙脱石复合粉体气流粉碎可得含碳质量分数为6%左右,平均片径约为2μm,厚度小于30 nm的碳-蒙脱石二维纳米粉体,以管状、单片和多片层堆积等形态存在于体系中。通过梯度离心分离法可以提取不同片径的碳-蒙脱石二维纳米复合粉体。     

机械法制备无机纳米粉体

为了实现纳米级粉体材料的低成本批量制备这一工业界亟待解决的问题,采用高能量密度搅拌磨湿法研磨制备纳米级二氧化钛、氧化铝、白云石、方解石和石英等无机粉体材料。结果表明:机械研磨的方法可以有效地制备颗粒粒径为50nm左右的无机粉体材料,用该方法生产的纳米粉体材料在工业中可以全部或者部分替代化学法制备的产品。     

重质碳酸钙颗粒气流粉碎与表面改性的一体化处理

研究重质碳酸钙颗粒在气流粉碎与表面改性一体化处理过程中,改性剂溶液流量、改性剂溶液浓度、粉碎气流温度对重质碳酸钙粉出料速度、改性效果以及粒度的影响趋势。研究表明,在气流粉碎的同时进行表面改性处理,可以提高重质碳酸钙粉体的出料速度,选择最佳的粉碎与改性参数后,重质碳酸钙的粉碎出料速率由21.0 g/min提高到56.7 g/min,出料速率提高了170%,并与液体石蜡具有良好的相容性。     

上海细创粉体装备有限公司

<正>产品名称:QS系列水平圆盘式气流粉碎机工作原理:压缩空气通过均匀地分布在粉碎室周围并与粉碎室半径方向成一定角度的喷嘴,把压强能转换成速度能,产生高速气流,使通过加料喷射器连续均匀地进入粉碎室的粉体物料颗粒,互相激烈碰撞、摩擦及粉碎室内腔表面碰撞,从而达到超微粉碎的目的。产品特点:·适用干式脆性物料(含水量3%)的超微粉碎·依靠粉体间相互作用的自磨粉碎,可获得高纯度微米级     

有机硅表面活性剂改性牡蛎贝壳粉填充尼龙6复合材料的制备

采用氨基型有机硅表面活性剂对气流粉碎的牡蛎贝壳粉体进行表面改性,并与尼龙6熔融共混制备复合材料。通过激光粒度、表面元素分析、热失重分析、高压毛细管流变仪等分别研究了贝壳粉体的粒径分布、元素构成、热稳定性及相应复合材料的加工流变性和力学性能。实验结果表明,经气流粉碎和表面改性后的贝壳粉体具有粒子尺寸小(D50为5.1μm)、粒径分布窄(1~10μm)的特点。贝壳粉残留有机质和主体无机物热分解温度分别在300℃和600℃以上,表现出较好热稳定性。改性贝壳粉较未改性粉体具有更好的分散性及与树脂的界面结合,相应复合材料的熔体流动性和力学性能也明显优于后者。另外,贝壳粉因含有机质而具有一定极性,其尼龙树脂基复合材料较商品化碳酸钙填充尼龙的性能更佳。     

粉体流动性及喷流性测量方法及其应用

使用以Carr指数法为理论基础研发的、唯一符合美国材料试验协会(ASTM)标准的细川综合测粉仪器——粉体流动性-喷流性测量仪的最新型号PT-X型,采用3种粒度不同的日本工业标准(JIS)试验用粉体,综合分析评价该仪器自动测量的先进性与可靠性,并将其发展应用于纳米复合颗粒的物性评价,探讨该测量法在生产与研发中的实用价值。结果表明,通过改进Carr指数法测粉仪器的自动化水平,可以提高粉体流动性及喷流性的测量精度与再现性,并能将其应用在纳米粉体的物性评价。     

气流粉碎干燥制备超细磷酸铁锂粉的工艺

采用LNJST-120HT型闭路循环氮气保护气流粉碎分级系统对磷酸铁锂粉进行超细加工、干燥;对粉碎、分级、收集、输送和包装系统的操作参数、设备结构及系统运行过程中出现的流动性、水分增加等问题进行分析探讨,并优化改进;通过加工超细磷酸铁锂粉的工业试验,对改进后的超音速气流磨进行测试。结果表明,控制螺杆加料机和分级机转速分别为62和1 072 r/min,气源压力和温度分别为0.5 MPa和120℃,包装房露点温度控制在-20℃以下,磷酸铁锂粉成品水分含量维持在0.35‰~0.55‰,成品粒径d_(50)=0.8~1.2μm、d_(100)<8μm,产量为200~230 kg/h。     

固相剪切粉碎技术研究进展

介绍了国外近年来发展的一种连续化聚合物粉碎加工技术——固相剪切粉碎技术,它是一个固相状态下的动力学过程,利用压力场和剪切力场的共同作用使聚合物材料发生弹性变形粉碎,并对其粉碎机理、磨盘结构和设备结构进行了分析。另外,通过对固相剪切粉碎技术发展历程的回顾,指出作为一种新发展的技术,固相剪切粉碎技术已经通过了理论研究和工程实践的验证,并且给橡胶粉碎领域开拓了新的思路。     

等离子合成与雾化制粉技术及其应用

等离子体做为一种极端参数技术在粉体材料的球化处理与合成制备方面的研究和应用日益引起人们的关注。本文概述了等离子技术的主要特点及应用领域,综述了国内外有关射频等离子体对不同金属粉末、陶瓷粉末的球化处理及纳米粉末的合成方面的研究成果;介绍了北京科技大学在射频等离子体粉体处理系统开发、制备球形钨粉和钛粉方面的研究成果,在此基础上对等离子体粉体球化处理技术的应用前景进行了展望。     

新型环形复合喷嘴的数值模拟分析与研究

为解决传统气流粉碎能量利用率不高、粉碎物料所需成本高、产量低、物料加工范围有限等问题,通过对气流粉碎中喷嘴结构的改进,开发设计了一种新型环形复合喷嘴,运用数值模拟的方法对常规喷嘴和新型环形复合喷嘴进行了模拟。模拟结果表明,这种新型环形复合喷嘴比常规喷嘴具有射流速度快、射流相对集中和射程远等优点。     

Re-entrainment of particles from powder structures: experimental investigations

The effectiveness of re-entrainment of particles from powder structures into air flowing through a powder aliquot placed in channel of rectangular cross-section was investigated experimentally. The shear stream of the gas causes breakage of the powder structure and particles or their clusters move to the air stream with an efficiency that depends on airflow rates and air humidity. At higher flow rates, large agglomerates are re-entrained, especially if the powder was conditioned at higher air humidity. The modifications of particles surfaces through adsorption of surfactants or electrostaticaly active substances cause the screening of the short-range cohesive forces between particles and particle processing make the re-entrainment more effective. Reduced size of particles clusters re-entrained into the air stream is also observed for modified surfaces of powder particles.     

A shear pan mill for preparation of ultrafine polyamide 66 powder using sodium sulfate ionic crystals as grinding aid

Fine polyamide 66 (PA66) powder was prepared in a shear pan mill that was designed and developed in our laboratories. In contrast with discontinuous impacts in the ball mill, the size reduction operation in the pan mill is characterized by application of uninterrupted strong shear forces on particles. It has been found that as compared to the ball mill, much finer pulverization of the polymer material is achieved in the pan mill, in spite of the high strength and ductility of the polymer. Sodium sulfate ionic crystals with hard and pointed edge were co-milled with PA66 to further cut the fine polymer particles into ultrafine powder (2–5?µm). Besides acting as a grinding aid, the ionic crystals also prevented conglutination and aggregation of the polymer powder. Furthermore, PA66 powder could be conveniently separated and purified from the co-milled grinding aid-polymer mixture by simple water washing and filtration. Thus, an energy efficient and environment-friendly technology has been developed to prepare the ultrafine plastic powder at room temperature. This process holds a good promise for commercial applications.     

双向拉伸聚乙烯醇/淀粉薄膜的制备工艺及性能研究

采用挤出流延和双向拉伸工艺制备了聚乙烯醇(PVA)/淀粉薄膜。探讨了水含量对PVA/淀粉共混物加工温度及流动性能的影响,结果表明水含量高于80份时,共混物具有较低的加工温度和良好的加工流动性。扫描电镜测试证实了PVA与淀粉具有良好的相容性。X射线衍射与差示扫描量热测试证明了采用流延膜急冷的工艺可以获得无定型状态的PVA/淀粉基膜。另外,通过力学性能测试分析了拉伸倍数及淀粉含量对制品薄膜力学性能的影响。     

回流法制备纳米 NiZn铁氧体及成相机理研究

采用回流法合成了纳米级的尖晶石相NiZn铁氧体．通过XRD测试和回流液反应过程中pH值变化分析，确定了最佳的回流反应时间为6h，同时对回流反应的机理进行了初步的研究．透射电镜结果显示NiZn铁氧体的颗粒为10-30nm，高分辨透射电镜分析表明回流法合成的铁氧体为单一尖晶石相．用VSM研究了纳米NiZn铁氧体粉料的软磁特性．     

Pulverization of Low Density Polyethylene and Rubber Under High Shear and Normal Forces

ABSTRACT

To obtain a fundamental understanding of pulverization of rubber and thermoplastic materials, such as low density polyethylene (LDPE), using our solid state shear extraction process (SSSE), a thin disk of the material was placed between two parallel plates of a Bridgeman Anvil. Normal forces of 300-2000 kg and rpm of 2-32 were exerted to obtain shear and normal forces needed for pulverization. Our experimental results showed that the residence time required for effective pulverization is a function of normal load. It was also determined that the minimum normal load required for pulverization is reduced at higher rates of rotation. Although increasing normal load was found to improve the pulverization, significant agglomeration was obtained at very high normal force. This indicates the existence of an optimum condition for obtaining fine particle size distribution. It was observed that the pulverization of both LDPE and rubber samples were initiated at the outer radial edge of the disk.

Computational analysis of the deformation of LDPE and rubber disks in a Bridgeman Anvil were performed using ANSYS computer code. Experimental stress-strain data from a simple extension of samples were used to calculate the constants for a Mooney-type stored energy function, and used as input to the computer code. Similar to our experimental results, our calculations showed much strain energy at the outer radial edge of the disk, and in turn more pulverization.     

Plastic behavior of agglomerated powder

The plastic properties of an agglomerated powder are investigated with the use of a material unit cell consisting of four agglomerates with a large pore between them. The contribution of the friction sliding of agglomerates and the existence of cohesionless contacts between agglomerates are taken into account in the modeling. The numerical results are obtained by utilizing a finite-element approach for the prediction of the rigid-plastic flow of the powder material. It is shown that the use of pressing with high level of shear stresses considerably reduces stresses necessary for consolidation. The analysis of the porosity evolution has confirmed that plastic deformation promoted the closure of large inter-agglomerate pores. The obtained results are important for better understanding of the consolidation of nano-powders.     

Properties of ceramic injection moulding formulations

The rheological properties of nine ceramic injection moulding compositions based on polypropylene with a fled silicon powder loading were measured. Minor components of the polymer-ceramic blend were shown to have a considerable effect on the properties of the melt. An attempt was made to derive, from capillary rheometer flow curves, the parameters which are thought to influence moulding quality. !n particular, the shear rate dependence of viscosity at the nozzle temperature, fluidity ate shear rate of 100 sec^?1, the temperature dependence of viscosity in the region of the nozzle temperature and at o shear rate of 100 sec^?1 and the yield stress are discussed. !n Part 2 the influence of these variables and other properties of the formulations, on quality of moulding will be considered.