颗粒增韧陶瓷裂纹扩展微观过程

对于第二相颗粒增韧的复相陶瓷，颗粒热膨胀系数ａｐ与基体热膨胀系数ａｍ之间的匹配关系是决定增韧效果的主要因素。当两相弹性模量相当，颗粒粒径小于应力诱导微开裂的粒径，且ａｐ〉ａｍ时，残余热应力场的存在将会使扩展的裂纹在颗粒周围基体中产生较大的裂纹偏转，由此产生明显的增韧效果；而当ａｐ〈ａｍ时，扩展的裂纹将首先达到两相的界面，此时裂纹有可能沿两相界面偏转，也有可能穿过颗粒，这取决于颗粒的表面能、粒径、形     

晶粒与颗粒

晶粒与颗粒是两个概念完全不同的名词，在材料科学研究中，它们常用于描述材料的微观形貌和结构特征，经常容易被混淆。本文比较了晶粒和颗粒的定义，并归纳总结了晶粒尺寸及其形貌和颗粒粒度的测试方法．     

大颗粒磷酸氢钙(药品级)生产颗粒促进剂的研究

本文介绍了一种以钾盐作为颗粒促进剂，以液态食品磷酸与处理后的石灰水(纯净氢氧化钙)反应，用于生产可用于医药工业直接压片的出口用大颗粒两水磷酸氢钙。同时提供了按此方法生产大颗粒磷酸氢钙实验及中试结果。     

颗粒检查台聚丙烯颗粒外观试验的应用

利用SH／T1541-2006方法描述了聚丙烯塑料颗粒外观试验，其操作过程繁琐，时间长，误差大，给检测过程带来了不便。用颗粒检查台分析聚丙烯颗粒外观质量有检测速度快、操作简便、误差小，测量数据准确的优点，对聚丙烯产品出厂外观的检测具有现实意义。     

催化剂颗粒的形状优化Ⅰ基本几何形状颗粒

从反应工程的角度，通过对催化剂颗粒模型的分析和计算，对催化剂外形的优化设计进行了研究，定义了形状优化的指标参数－颗粒的相对活性Ｆ，以及异形化形状描述因子－无因次开孔半径Ｘ，并提出了颗粒的最佳Ｘ的求解方法，在对基本几何形状（无限大平板，无限长圆柱，球形）颗粒的异形化后的颗粒模型进行解析求解的 提出了简化算法，并对颗粒异形化后的Ｘ，Ｔｈｉｅｌｅ模数φ对Ｆ的影响进行了探讨。     

激光颗粒分析仪器的对比评价

水泥的颗粒组成及分布是影响水泥性能的一个主要因素，过去人们大多忽略了这个问题。而随着水泥胶砂强度实验方法的变革及人们对水泥应用技术更深层次的要求，目前的水泥颗粒级配已不能满足多种工程特殊需求。我公司为适应新的行业发展趋势，准确购买1台先进的颗粒检测仪器－激光颗粒分析仪，以用于检测水泥的颗粒配，为调整我公司产品的结构提供依据。但市场上该类食品的生产公司很多，为寻求价格性能比最好的激光颗粒分析仪，从2000年初我们就开始进行市场调研。本文就市场调研结果及我们进行的对比分析作一介绍，供参考。     

大颗粒流化床中颗粒磨蚀的实验研究

为了进一步丰富和发展大颗粒流态化理论,促进其在水泥煅烧领域的应用,实验通过1个三维流化床试验台研究了大颗粒流化床中颗粒的破损方式为磨蚀,即颗粒在流化过程中表面磨碎后生成细粉,颗粒自身的粒径逐渐变小。实验表明,颗粒粒径、风速以及流化时间对大颗粒流化床中颗粒的磨蚀影响较大,静床高对磨蚀几乎没有影响。最后提出了大颗粒流化床合适的控制参数:粒径范围4—7 mm,表观风速1.3um f—1.6um f,静床高H0/D<2。     

流化床内颗粒混合研究

分析了流化床内颗粒混合机理，综合了床内水平方向和垂直方向上颗粒混合，将床内颗粒混合过程分成两部分：一是向上运动的尾迹相和向下运动的乳化相之间的对流交换，二是乳化相内横向扩散。建立了二维的对流扩散模型，数值结果和实验数据吻合。     

非磁性粘性颗粒在添加磁性大颗粒磁场流化床中的流化性能

通过添加磁性大颗粒，破碎活塞及沟流，显著改善了非磁性粘性颗粒在磁场流化床中的流化性能。为了评价非磁性粘性颗粒在磁场流化床中的流化性能，测量了最小流化速度、床层压力降和床膨胀高度。实验结果表明，非磁性粘性颗粒的最小流化速度，由于添加磁性大颗粒，而显著降低。磁性大颗粒添加量对非磁性粘性颗粒的最小流化速度有较大影响，随磁性大颗粒添加量的增加，最小流化速度降低，但当磁性大颗粒添加量增大到40％后，非磁性粘性颗粒和磁性大颗粒的混合物的最小流化速度就不再降低。     

小颗粒蕴含大学问——2006浙江丰利青年颗粒学奖在京颁奖

2006年8月21日，“2006浙江丰利青年颗粒学奖”在京举行的中国颗粒学会2006年会暨海峡两岸颗粒技术研讨会上进行了隆重的授奖仪式。     

Particle Redistribution During Dendritic Solidification of Particle Suspensions

Solidification of the liquid medium in ceramic suspensions containing less than a critical volume fraction powder leads to the formation of particle-free dendrites of the frozen medium. These particle-free dendrites create, after sublimation of the frozen vehicle, large dendrite pores. We define the conditions under which particle-free dendrites form, and relate the size and volume fraction of the dendrites to the volume fraction powder and the solidification rate.     

Measurement of Particle Density During Explosive Particle Dispersal

A gauge based on laser light attenuation has been developed to determine the temporal history of particle number density during the explosive dispersal of inert particles. The optical scheme of the gauge employs narrow band pass and spatial optical filters that protect the optical sensors from ambient light and laser light scattered by particles. The gauge is used in field experiments to measure particle density at two locations in close proximity to spherical metalized explosive charges containing a packed bed of either iron, nickel, or glass particles saturated with nitromethane. The heavy iron particles penetrate the blast wave in the near field, whereas the lighter particles remain behind the blast wave. Comparisons with multiphase calculations indicate that the particle density field inferred from the light intensity signals is consistent with the computations until the point at which the combustion products containing soot arrives at the gauge, blocking the laser light.     

Particle Migration

The difference in the definition of particle size measured by the Microtrac instrument and by sieving has been investigated. The mean Microtrac size is 1.25 times the mean sieve size for quartz, but a single

screen interval of quartz reports to seven

Microtrac size intervals. Since the Microtrac does not detect material below a lower detection limit and also misses significant amounts above an upper limiting size, there is an ambiguity when the size distribution is normalized within the instrument measurement range. A smooth overlap of uncorrected Microtrac and sieve size distribution can be obtained fortuitously when missed material compensates for the difference in the definition of size. A methodology has been developed for estimating the equivalent sieve size distribution from Microtrac size distribution, provided that the sieve size distribution can be approximated by a suitable mathematical function. The use of the technique on ball mill products which are known to have natural size distributions fitting Rosin—Rammler and Schuhmann forms is illustrated.     

Particle Chromatography

Abstract

Particle mixtures can be separated into bands by slowly increasing the freezing rate during directional solidification. Continuous size classification of spherical particles can similarly be obtained.     

Particle technology

Powders and granular materials are in common use in the chemical and allied industries yet traditional research and teaching in chemical engineering do not reflect this significance. Quite apart from the desire to advance knowledge for traditional processes and to enhance competitiveness, demands arise from the extension of chemical engineering ideas to a much broader range of products and processes. Progress in particle technology is now possible from advances in theory, from instrumentation, and from computer methods. The subjects of elasticity, plasticity and frictional flow of powders are central to an understanding of behaviour. In general, particles have a complicated internal structure and the design and engineering of this structure is a critical feature, with packing and colloidal effects, to name but two, being critical. Stress is not uniformly transmitted, this passing along preferred paths with breakage being initiated from the tips of cracks in the paths. There is now a wide range of accessible and important problems that can and should be solved; particle technology does, after all, constitute a good half of the discipline.     

Alumina Particle Degradation during Solid Particle Impact on Glass

Particle degradation limits the reuse of powders in industrial powder-blast processes. In this paper the degradation behavior of Al₂O₃ powder is studied during erosion of glass substrates. Three techniques were used on original and multiply used powders: particle size measurements, single particle crushing tests, and microstrain analysis by X-ray diffraction. Combination of the three techniques shows that the degradation is dominated by flaws present in the original particles. Fracture at repeated use decreases the particle size, but by removing flaws also increases the degradation resistance of the particles.     

悬浮法聚苯乙烯的粒径和粒径分布

通过苯乙烯悬浮聚合,研究了搅拌转速、分散剂浓度、相比、釜径和桨型对聚苯乙烯粒径和粒径分布的影响,并确定了相应的关联式,为选择最佳操作条件和聚合反应器的设计提供依据.     

聚氨酯分散体粒径及粒径分布与粒径控制

介绍了聚氨酯分散体粒径与粒径分布概念、测定粒径的方法,分析探讨了分散体内在因素和外部因素对粒径的影响以及聚氨酯分散体的粒径控制。     

Effect of Particle Shape on Inline Particle Size Measurement Techniques

The influence of the particle shape on the results of different measuring techniques was investigated. Considered were single‐frequency ultrasound technique, 3D optical reflectance measurement (advanced particle analyzing system with multi capture signal technology), and focused‐beam reflectance measurement probes as techniques which are usable inline and in suspension density ranges usually present in industrial crystallization processes. Advantages and shortcomings of these techniques are compared and discussed.