三种典型开放源的粒度组成测定分析

利用激光粒度分析仪对黄河沙、建筑尘、土壤尘三种典型的开放源的粒度分布进行了测定分析,从测定结果分析得出黄河沙的颗粒比较大,100μm左右的颗粒居多,粒度分布符合正态分布;土壤尘的颗粒大部分集中在10μm～100μm左右,60μm左右的颗粒数最多;建筑尘的颗粒多数集中在90μm～160μm左右。同时,利用图像处理仪对它们的形貌进行了研究分析,为粒度分布进一步的研究提供科学依据。     

激光粒度分析仪校准规范编写

激光粒度分析仪是用于测量颗粒材料粒度分布的仪器.为了统一激光粒度仪测量量值,保证其测量结果的准确性和溯源性,我们受国家质量监督检验检疫总局委托,编写激光粒度分析仪校准规范.现将规范初稿提出,在征求广大专家意见的基础上将进一步修改,满足生产和科研的需要.     

激光粒度分析和筛分法测粒径分布的比较

分别采用筛分法和马尔文激光粒度分析仪两种方法对16种颗粒的粒径分布进行了测量。通过比较,发现两种测量手段得到的粒径分布结果存在较大的差异,马尔文激光粒度方法对颗粒粒径的测量结果偏小,受颗粒形状的影响很大;筛分法对微细颗粒的测量误差较大,但对大粒径颗粒的测量较为准确。通过对不同粒径段灰颗粒的显微照相,发现细颗粒的团聚是筛分法测量小颗粒结果偏小的主要原因。     

激光颗粒分布测定仪在橡胶助剂粒度测定中的应用

以促进剂ZDC的粒度分布测定为例,简要介绍了激光颗粒分布测量仪的工作原理、样品分散处理时助分散剂选择与最佳超声分散时间的确定方法.激光颗粒分布测定仪用于橡胶助剂产品的粒度测试,具有快速、试样用量少、结果精确等优点,可以给出颗粒在不同粒径的分布值.     

Rise-2008型激光粒度仪／粒度分析仪

Rism2008型激光粒度分析仪采用全量程米氏散射理论,充分考虑到被测颗粒和分散介质的折射率等光学性质,根据大小不同的颗粒在各角度上散射光强的变化反演出颗粒群的粒度分布数据。     

石墨微粉形状参数分布的研究

采用激光衍射法和沉降法的粒度分析结果,研究了石墨微粉颗粒的形状及其参数分布,给出了３ 种石墨微粉产品的长径比随粒径变化的分布曲线。通过对曲线的分析,可提取与颗粒制备机理有关的信息。本文从一个角度证明了颗粒的粒度分析与形状分析是相互影响、相互依存、不可分割的整体     

测定超细硅酸盐水泥粒度分布的问题探讨

GB/T35161-2017《超细硅酸盐水泥》将JC/T721-2006《水泥颗粒级配测定方法激光法》作为其特性指标D90和D50的测定方法,并将检测结果作为产品合格与否的判定依据,准确测定超细硅酸盐水泥D90和D50的数值极其重要。通过对激光法测定水泥颗粒粒度分布稳定性的分析和不同仪器之间的比对,指出了测定过程中引起水泥颗粒粒度分布发生变化的因素,在水泥颗粒粒度分布测定过程中应降低这些因素的影响。     

废玻璃粉粒度分布与活性指数的灰色关联分析

经过不同研磨时间制得4组不同粒度的废玻璃粉,采用激光粒度分析仪测定废玻璃粉的粒度分布;采用灰色关联分析方法分析废玻璃粉粒度分布对活性指数的影响。结果表明:只有当废玻璃粉的粒径小于一定的值时才具有火山灰活性;对废玻璃粉活性指数起关键作用的粒径范围为6.414~20.710μm。     

粉煤灰粒度分布及其活性的灰系统研究

用激光粒度仪测定不同细度粉煤灰的粒度分布,以灰色关联方法分析了粉煤灰粒度分布与其胶砂性能之间的相关性,并建立了粉煤灰粒度分布与其活性指数的灰系统模型。结果表明:粉煤灰粒度分布明显影响胶砂性能;19.953～45.709μm颗粒含量与胶砂需水量的正关联度最大;5.012～19.953μm颗粒含量与粉煤灰活性的正关联度最大;根据抗压强度活性指数的灰色模型可以预测粉煤灰活性大小。     

Rise-2008型激光粒度仪／粒度分析仪

工作原理： Rise-2008型激光粒度分析仪采用全量程米氏散射理论，充分考虑到被测颗粒和分散介质的折射率等光学性质，根据大小不同的颗粒在各角度上散射光强的变化反演出颗粒群的粒度分布数据。     

蒸发冷凝法中气体压强和蒸发温度对粒子大小的影响

在Ｎ＿２气氛中，用蒸发冷凝法，制备了Ｓｎ细微粒和Ｆｅ及Ｆｅ－４７（ｗｔ）％Ｎｉ合金超细微粒。分别用ＳＥＭ和ＴＥＭ，直接观测粒子大小及其分布。结果表明，平均粒径不是随Ｎ＿２气压强增加单调上升，而是在某一压强Ｐ＿（ｍａｘ）下，出现最大值。随蒸发温度提高，Ｐ＿（ｍａｘ）值迅速增大。粒子大小及其分布与粒子生长机制密切相关。对粒子凝聚生长条件进行了简要讨论。     

Spray forming of ultra-fine SiC particle reinforced 5182 Al-Mg

This paper describes the spray forming of SiC particle reinforced Al metal matrix composites (MMCs) with particular emphasis on microstructure characterization of SiC particle distribution. A 5182 Al-Mg alloy was used as matrix material, and SiC particles with a mean diameter of 1.2 m and 2.0 m as reinforcement. The reinforcing particle distribution and microstructural characteristics of MMCs were analyzed in the current study using TEM, SEM and optical microscopy. The distribution of SiC particles in the as-spray deposited and hot-extruded conditions was characterized. SEM results indicate that the SiC particles are homogeneously distributed although some clustering was evident in the matrix. TEM and OM examinations show that most of SiC particles are present intergranularly in the Al matrix. EDS analysis indicated that Mg tends to segregate and form oxide phases in the vicinity of SiC particles and that there is no compositional variation of Mg across grain boundaries in the Al matrix.     

不同形貌碳酸钙颜料粒子的制备及在喷墨印刷中的应用

目的研究碳酸钙颜料粒子的形貌对喷墨打印涂层性能的影响。方法通过改变分散剂的种类制备不同的碳酸钙颜料粒子,并通过扫描电子显微镜(SEM)、傅里叶变换红外光谱仪(FT-IR)、粒径分析仪对制备的颜料粒子进行表征,研究分散剂种类对颜料形貌和粒径的影响。将4种不同形貌的碳酸钙分别作为颜料,将其应用于喷墨打印纸的表面涂层,并测试涂布纸张的动态渗透性、物理性能、喷墨打印性能。结果 CMC作为分散剂有助于形成粒径分布均匀的球形碳酸钙颜料粒子;纺锤形碳酸钙颜料粒子有助于提高涂布纸的平滑度和光泽度;球状体碳酸钙颜料粒子有助于改善涂布纸的喷墨印刷性能和渗透性;颜料粒子的粒径分布均匀性对涂布纸的动态渗透性影响较大,其影响超过颜料粒子形貌对涂布纸渗透性的影响。结论粒径分布均匀的球状体碳酸钙颜料粒子最适合用于喷墨印刷涂层,可以提高纸张的物理性能、印刷性能和动态渗透性能。     

表面活性剂对相反转法制备金属颗粒的影响

采用相反转悬浮液体系中不同表面活性剂同步修饰的方法制备超细低熔点金属颗粒,研究阳离子和阴离子表面活性剂对金属颗粒的影响。通过沉降实验观察不同表面活性剂修饰的金属颗粒在水中的分散及稳定性,并采用激光粒度仪、扫描电镜对低熔点金属颗粒的粒径和形貌进行表征分析。结果表明:表面活性剂的种类对制备低熔点金属颗粒有重要的影响,其中阴离子表面活性剂的效果最好。对几种阴离子表面活性剂的研究表明:油酸钠的作用最明显,其浓度大小对低熔点金属颗粒的粒径、形貌和分散效果有显著的作用。采用质量分数为1%的油酸钠水溶液可制备出分散稳定、粒径分布窄和球状的超细低熔点金属颗粒,平均粒径为0.343μm。     

The influence of polymer architecture on nanosized hydroxyapatite precipitation

In this work we present a facile way to produce hydroxyapatite (HAP) nanoparticles by wet chemical synthesis in the presence of polyelectrolytes under controlled temperature, pH, and atmospheric conditions. The resulting calcium rich carbonated HAP is sintered in an air atmosphere to investigate the thermal stability of the synthesized powders. The morphology and microstructure of the HAP nanoparticles were investigated by XRD, SEM, FTIR spectroscopy, thermal analysis, and particle size analyzer. Polyelectrolytes affect the coherent length of the crystalline domain, the dimension and particle size distribution of the crystals. The reduction in size is greater in the direction of the c-axis. The SEM micrograph shows the formation of well-crystallized, agglomerated small particles of HAP. The mean size of the subunit is smaller than that of the surface of the grain observed in SEM. X-ray analysis have shown that the resulting particles have high thermal stability.     

Al_2O_3颗粒与 Al 合金固液界面的相互作用

本文采用定向凝固技术探讨了 Al_2O_3颗粒/Al-2.0Mg-4.5Cu 合金复合材料在凝固过程中颗粒与生长着的固液界面的相互作用,得出了胞晶或胞状树枝晶生长条件下颗粒的分布规律、机制以及 Al_2O_3颗粒在试样中的分布与氢、铈之间的联系。但未发现铈对颗粒主要沿晶界分布产生显著影响。     

Magnetostrictive properties of epoxy resins modified with Terfenol-D particles for detection of internal stress in CFRP. Part 1: Materials and processes

Magnetostrictive particles like Terfenol-D are investigated with respect to their ability to detect internal stress, generated in carbon fibre-reinforced polymers (CFRP) in a non-destructive way. The results are presented in two parts. The first part elucidates the ideas for the preparation of dispersions based on these particles with high density in epoxy resins. There is particular focus on the effects of particle size and concentration. Different particle sizes in a range of 0–300?μm are selected by special separation techniques. The particle size distribution is controlled in dry state by laser diffraction method. Changing of the chemical composition, particularly by the oxidation of particles, is analysed by EDX. Use of a magnetic field is identified as a suitable means for the stabilisation of these high-weighted particle fractions dispersed in epoxy resins. The particle size distribution, as well as the alignment of particles, in the cured epoxy resins is investigated by SEM and light microscopy. The second part of the study covers the magnetostrictive properties of the modified epoxy resins which are quantified by the detection of internal stress in CFRP.     

碳化硅粒径分布对单晶硅线切割的影响

研究不同粒度分布的碳化硅磨料对线切割硅片表面损伤的影响,利用激光粒度仪和扫描电镜对切割前后碳化硅粒径的变化及切割后硅片的形貌进行表征,通过实际切割过程分析,指出粒度分布不均引起的局部切割堵塞而导致的垂直于切割方向的左右侧滑振动,是导致表面损伤的主要原因。结果表明:当碳化硅的粒度分布窄时,线切割硅片表面损伤层浅,表面粗糙度小。     

扫描电镜纳米颗粒粒径自动检测算法

基于数学几何学,提出一种扫描电镜纳米颗粒粒径自动检测方法,该方法利用电镜颗粒图像的粒径分布及形状信息,采用长短轴比值和区域面积2种不同参数对颗粒是否团簇或残缺进行判断,实现筛选单个的完整颗粒,并使用MATLAB对不同粒径参数的颗粒宽边缘形状进行提取,运用最小二乘法求出颗粒粒径的像素值,经转化后得到真实值,从而实现了微纳米颗粒粒径的自动检测。试验选取聚苯乙烯纳米颗粒对方法进行验证,结果表明:对于团簇残缺较少的图像,采用长短轴比值和面积2种参数进行筛选均能准确有效提取单点颗粒,但团簇残缺颗粒较多时,采用长短轴比值效果更加准确,且计算颗粒粒径与实际值吻合良好。     

THE STATISTICS OF THE POWDER COATING PROCESS

General expressions are developed for the limiting variance values of complete segregation and random distribution for agglomerated powder mixtures. In the limits of non-agglomeration these expressions reduce to the established values for free flowing powder mixtures.

The general expressions for agglomerating powders are of little value unless the composition distribution of the agglomerates can be predicted. This has been done for the special case of mixing by the 'coating' process in which fine particles coat the surface of larger carrier particles. The model used assumed that the particles are spherical, that only single coarse particles exist within an agglomerate, that the fine particles will either form a single layer on the coarse carrier or will agglomerate on a nucleus of a single fine particle.