氢氧化铝粉体粒度测量技术

氧化铝生产工艺分解过程中氢氧化铝粒度检测的结果对分解系统的稳定和产品氧化铝的粒度控制有着非常重要的意义。氢氧化铝粒度的测定方法很多,目前用来监测粒度的方法有筛分法、马尔文激光粒度法、库尔特全自动颗粒粒度分析、颗粒计数器分析等,综合各种分析结果可得到氢氧化铝的全粒度分布情况。     

颗粒计数仪在氧化铝生产种分过程中的应用

通过对现代粒度分析方法的分类和比较,根据氧化铝生产种分过程中粒度分析的特点,认为电阻颗粒计数法是比较适合应用于氧化铝生产种分过程的粒度分析方法.对Elzone5382颗粒计数仪的原理及其在氧化铝生产中的应用进行了介绍,并对应用该粒度仪进行粒度测试过程中的影响因素进行了初步探讨.     

Elzone 5382颗粒计数器测定氢氧化铝粒度方法的探讨

以Elzone 5382颗粒计数器为主要分析设备,对如何准确地测定氢氧化铝粒度分布进行了分析讨论.通过试验证明,此方法分析结果较为准确、稳定,能够起到指导砂状氧化铝生产控制的目的.     

氢氧化铝粒度和比表面积的表征

随着氧化铝市场的竞争日益激烈,国际价格时有跌落,冶金行业或是非冶金行业对氢氧化铝的物理和化学性质要求越来越严格,粒度和比表面积的测量及形貌的观察,在氢氧化铝生产中具有重要的地位。本文中对氢氧化了铝的粒度和比表面积研究,通过量化,更准确地了解氢氧化铝产品的性能,从而及时准确地组织生产,生产出砂状、超细、高白许多品种的氢氧化铝产品。     

铸渗法制备颗粒增强钢基复合材料的研究

通过对负压铸渗理论的分析, 得出了影响负压铸渗深度的因素及其影响规律(见式(9) ) ;用碳化钨、镍包氧化铝及不同粒度氧化铝为陶瓷颗粒、耐热钢为基体进行了负压铸渗实验, 得到了颗粒分布均匀的复合材料, 揭示和证实了颗粒与金属液间的湿润特性及颗粒粒度对铸渗的影响规律。      

铸渗法制备颗粒增强钢基复合材料的研究

通过对负压铸渗理论的分析，得出了影响负压铸渗深度的因素及其影响规律（见式（９））；用碳化钨、镍包氧化铝及不同粒度氧化铝为陶瓷颗粒、耐热钢为基体进行了负压铸渗实验，得到了颗粒分布均匀的复合材料，揭示和证实了颗粒与金属液间的湿润特性及颗粒粒度对铸渗的影响规律。     

光电离心池精确测定亚微米氧化铝和石英粉体的粒度

光电离心池精确测定亚微米氧化铝和石英粉体的粒度ＰａｕｌＤｏｗｅｎ等亚微米颗粒光电离心池粒度精确测定方法已应用于工业氧化铝粉体和标准石英粉体的粒度测量。该方法包括小颗粒光散射修正、改进的原始数据圆整程序和径向稀释作用的修正。工业氧化铝粉体的粒度测定结果...     

分散剂聚合度对纳米氧化铝粉体特性的影响

以不同聚合度的聚乙二醇(PEG)为分散剂,采用沉淀法制备氢氧化铝胶体,胶体经 800~1100℃高温煅烧得到纳米氧化铝粉体。对粉体进行了颗粒分布、XRD谱、HRTEM形貌及电子衍射等分析。结果表明分散剂(PEG)的聚合度对纳米氧化铝的粒度分布有着重要的影响。当用 PEG2000 作分散剂时制备出的粉体颗粒细而均匀,平均粒径为 25nm,无明显团聚与颗粒长大现象;经 1000℃/2h煅烧已完全转化为α Al2O3。文章对不同聚合度的分散剂的分散机理进行了讨论。     

激光粒度分析仪测定氢氧化铝细颗粒方法的探讨

针对马尔文2000型激光粒度分析仪在氢氧化铝分析中对25μm粒径以下细颗粒的分析不太敏感，难以满足氧化铝生产分解过程对粒度控制的要求，对试验样品采用一些非常规的特殊处理方法，以提高细小颗粒在处理过样品中所占的体积百分比；研究了不同的样品处理方式对分析结果的影响。试验结果表明，只有对洗涤、过滤后的湿样进行分析，才能对分解料浆样品中的细颗粒的粒度分布进行准确地分析，得到满足试验和生产过程控制精度的结果。     

氢氧化铝粒度及掺量对不饱和聚酯树脂性能的影响

以不饱和聚酯树脂为基体,氢氧化铝为阻燃剂填料,研究氢氧化铝掺量及粒度对不饱和聚酯树脂-氢氧化铝体系阻燃及力学性能的影响。结果表明,掺加氢氧化铝的质量分数大于40%时,不饱和聚酯树脂-氢氧化铝体系阻燃性能得到显著改善;氢氧化铝的质量分数为60%时,不饱和聚酯树脂阻燃材料的极限氧指数为34.3%,垂直燃烧测试达到最高阻燃级别V-0级;不饱和聚酯树脂-氢氧化铝体系的冲击强度随着氢氧化铝掺量的增大而增大,弯曲强度在氢氧化铝的质量分数为40%时达到最大;氢氧化铝粒度对不饱和聚酯树脂-氢氧化铝体系的阻燃和力学性能有较大影响,氢氧化铝超细化后体系的弯曲强度、冲击强度、氧指数均有较大增大;制得的不饱和聚酯树脂-氢氧化铝阻燃材料的热失质量速率比纯不饱和聚酯树脂的明显减小,残碳量显著提高。     

3D structuring of dense alumina ceramics using fiber-based stereolithography with interparticle photo-cross-linkable slurry

In this paper, we demonstrated optical fiber-based stereolithography of alumina ceramics using concentrated slurry with low monomer content for enabling rapid firing of the printed green objects. Photo-cross-linkable alumina slurries were designed using a partial complex of polyethyleneimine and oleic acid (PEI-OA) as reactive polymer dispersants and multifunctional acrylates (MA) as monomers. The effects of the processing parameters, such as oleic acid contents, MA contents, particle contents, and particle sizes, on photocuring properties were systematically investigated. We found that the reactive amine sites of PEI-OA attached to particles and MA volume concentrations in the liquid phase were the most dominant factors to improve the photocuring properties. Therefore, a slurry composed of larger alumina particles with higher solid contents and PEI-OA with lower OA contents was more favorable for achieving photocuring under reduced MA content. The designed photocurable slurry was then applied to ceramic stereolithography using optical fiber. 3D alumina green parts were drawn by passing blue laser beam through an optical fiber in a droplet of photocuring slurry and dense sintered alumina were successfully fabricated by rapid drying (<10 min) and debinding (<1 h) without any structural collapse.     

Effect of ultrasonic waves on crystallization from a supersaturated solution of alum

The effect of ultrasonic waves on the particle size and distribution of precipitated crystals from a slowly cooled supersaturated solution of ammonium aluminium sulphate hydrate was investigated. It was found that ultrasonic irradiation greatly promoted the homogeneity in particle sizes of the crystals precipitated. Average particle sizes of both the mechanical stirred and the ultrasonically treated samples did not change much if the initial solute concentration was beyond the saturation solubility of the solution. The higher acoustic intensity of the higher frequency ultrasonic transducer resulted in a larger average particle size in the recrystallization process.     

非均相沉淀法制备纳米α-Al2O3/金属复合粉体

利用非均相沉淀法制备了平均粒径小于50 nm的α-Al₂O₃/W(Ni)复合粉体,并研究对比了纳米钨和镍对α-Al₂O₃相转变温度的影响。结果表明:纳米钨和镍的存在均可降低过渡型氧化铝向α型氧化铝转变的相变温度,但降低程度有所不同,含钨氧化铝于1000℃完成相变,而含镍氧化铝于1150℃完成相变;并且纳米第二相体积比越大,对相变温度的影响也越大。     

橡胶单颗粒低温冲击破碎的实验研究

单颗粒的破碎研究是粉碎技术发展的基础，对阐明物理过程、粒度变化和能量转换具有重要的意义，是材料研究与粉碎理论之间的桥梁。在分析了橡胶低温下破碎的影响因素后，选择其中的4个因素：破碎温度、速度、颗粒粒径和冲击角度进行变参数实验研究，自行设计了橡胶颗粒低温破碎实验系统，国内首次完成了橡胶单颗粒低温冲击破碎实验。通过对破碎产物粒度分布的分析，得到了这4个因素对粉碎结果的影响，为工程设计提供了第一手的资料。     

Preparation and characterization of ceria nanoparticles using crystalline hydrate cerium propionate as precursor

Ceria nanoparticles were synthesized simply by pyrolysis method using hydrate cerium propionate as precursor. The effect of pyrolysis temperature on the physical properties of ceria was investigated. It was found that the large crystals of precursor cracked to many nano-sized ceria particles on heating, and the medium particle sizes D₅₀ determined by laser scattering (LS) method decreased firstly and then increased with minimum value around 460 nm at calcination temperature of 1000 °C. SEM observations showed that the average particle size of synthesized ceria powders ranged from 20 to 50 nm.     

胶结型含可燃冰砂土剪切特性的离散元模拟

可燃冰是一种新型清洁能源,广泛分布于深海土体和常年冻土中,对其开采需要深入认识含可燃冰土体的力学特性.该文提出了一种胶结型含可燃冰砂土离散元模型建立方法,并利用该模型完成了排水双轴剪切试验的模拟.通过与前人试验数据对比,验证了该离散元模型的准确性,结合该模型分析了剪切过程中含可燃冰砂土的宏细观变化规律.结果表明:砂土抗...     

用超重力法制备纳米二氧化硅

以 ＣＯ２气体和水玻璃为原料,采用超重力技术制备纳米级二氧化硅,研究了由超重力反应器碳化沉淀法制备二氧化硅的实验条件对产品粒径的影响,用 ＴＥＭ、 ＩＲ、 ＸＲＤ、 ＤＴＡ—ＴＧ等手段表征了纳米二氧化硅的性能,结果表明,二氧化硅颗粒平均粒径为１７～３０ｎｍ,粒度的分布范围比较窄     

Ein neues Werkstoffkonzept zur trockenen Bearbeitung mineralischer Materialien

A new material concept for machining of mineral materials For the machining of mineral materials like rock, concrete and asphalt ultra hard cutting‐tools such as diamond tools are used. During the use diamond tools are cooled with water to remove the heat and to prevent an early deterioration of the diamonds. Without water cooling the diamonds at the cutting edge as well as in lower levels are damaged. For ecological and economic reasons a dry machining of mineral materials is of great interest. The consumption of coolant and the pollution of occupied buildings by alkaline water would be decreased. But specific diamonds tools are necessary to realise a dry machining. The Institute of Materials Engineering pursues a novel material concept for diamond impregnated composites to protect diamonds in deeper layers. Materials with a very low thermal conductivity are inserted in the diamond‐composites to protect the diamonds against heat and to reduce the deterioration of diamonds in lower levels. Cobalt and bronze (CuSn 85/15) with particle sizes of 45–90 μm and < 40 μm, diamonds with particle sizes of 300–450 μm and alumina with particle sizes of 350–500 μm, 150–210 μm and < 70 μm were used. The diamond‐alumina‐composites were powder metallurgically produced and were examined by light‐ and electron microscopy and digital image analysis.     

超细粒子氧化铝的制备

本文讨论了用超临界流体干燥混凝胶制备氧化铝超细粒子的影响因素；一类为超临界流体的影响因素．其甲温度和压力具有明显的影响，有一较台适的超临界温度达最大比表面积；但超临界压力越低，比表面积越大。加热速率几乎没有影响。另一类为制备混凝胶的影响因素，包括水解温度、加水比例．异丙醇铝固体浓度等均有一最佳制备条件。