FACTORS GOVERNING SURFACE MORPHOLOGY OF SPRAY-DRIED AMORPHOUS SUBSTANCES

Changes in particle morphology (size, shape, and appearance) have been monitored during drying of drops of foods and food-related materials. The apparatus produces a single stream of drops of uniform size, using a vibrating-orifice device for drop production. The drop size and the time-temperature history of the drops as they fall can be varied and controlled.

Qualitative observations are reported for drying of aqueous solutions of lactose, maltodextrin, skim milk, and coffee extract, with different feed concentrations. Particular emphasis is placed upon the tendency for development of folds upon the particle surface. A mechanistic model is developed, relating the tendency for folding to the extent of viscous flow of surface material in response to a surface-energy driving force. This model gives semi-quantitative agreement with observations for solutes of different molecular weight (and hence different viscosity) and for different feed concentrations.     

THE MORPHOLOGY OF SPRAY-DRIED PARTICLES A QUALITATIVE VIEW

Industrial and pilot plant spray-dried materials were obtained from various manufacturers and qualitatively examined in order to identify structural and morphological features. Three distinct categories of particle morphology were identified. Namely, crystalline, skin forming and agglomerate. A number of unusual morphological phenomena were also noted Selected properties such as powder flowability. particle size and particle friability, were found to be directly related to morphological structure. Single particles were also produced in a convective drying process analogous to spray drying, in which, different solids or mixtures of solids were dried from solutions, slurries or pastes as single suspended droplets. The localised chemical and physical structures were analysed, and the results related to experimental conditions viz. drying air temperature and initial solids concentration. There was a strong similarity between the industrial spray-dried material and those dried experimentally. The morphologies of multicomponent mixtures were found to be complex, with the respective migration rates of the solids being dependent on drying temperature. The results are of relevance to dryer optimisation and to the optimisation of product characteristics, They also go some way to validating the single droplet drying technique as a useful analytical tool in spray drying research, and possibly other particulate processing industries.     

THE MORPHOLOGY OF SPRAY-DRIED PARTICLES A QUALITATIVE VIEW

ABSTRACT

Industrial and pilot plant spray-dried materials were obtained from various manufacturers and qualitatively examined in order to identify structural and morphological features. Three distinct categories of particle morphology were identified. Namely, crystalline, skin forming and agglomerate. A number of unusual morphological phenomena were also noted Selected properties such as powder flowability. particle size and particle friability, were found to be directly related to morphological structure. Single particles were also produced in a convective drying process analogous to spray drying, in which, different solids or mixtures of solids were dried from solutions, slurries or pastes as single suspended droplets. The localised chemical and physical structures were analysed, and the results related to experimental conditions viz. drying air temperature and initial solids concentration. There was a strong similarity between the industrial spray-dried material and those dried experimentally. The morphologies of multicomponent mixtures were found to be complex, with the respective migration rates of the solids being dependent on drying temperature. The results are of relevance to dryer optimisation and to the optimisation of product characteristics, They also go some way to validating the single droplet drying technique as a useful analytical tool in spray drying research, and possibly other particulate processing industries.     

SERVICE FACTORS GOVERNING THE SLAGGING OF BOILERFURNACE REFRACTORIES1

Service factors, dependent on the type of coal burned and the method of burning, that are considered to govern slag erosion directly are: refractories temperatures, furnace gas temperatures, furnace gas compositions, furnace gas velocities, slag composition, and slag quantities. Values determined for part or all of these factors under each of the following sets of conditions are presented and their significance is discussed: eastern bituminous coals on underfeed stokers, powdered eastern bituminous coals in furnaces with extended radiant-heat absorbing surface, high-sulphur Pittsburgh coal on underfeed stokers, low-sulphur Pittsburgh coal on underfeed stokers, high-sulphur Pittsburgh coal on chain-grate stokers, Illinois coal on chain-grate stokers, and powdered Illinois coal.     

金刚石薄膜的表面成分和形貌对表面能的影响

采用微波等离子体化学气相沉积法制备了(111)面和(100)面金刚石薄膜。测量了金刚石薄膜与液体的接触角、金刚石薄膜表面粗糙度和电阻率。通过扫描电镜、X射线衍射、X射线光电子能谱研究了金刚石薄膜的表面纯度和形貌等对表面能的影响。结果表明:金刚石纯度越高、表面粗糙度越大、晶粒尺寸越小,其表面能越大。经过空气等离子体后处理的金刚石薄膜的纯度和亲水性明显提高。随着在空气中放置时间的增加,亲水性逐渐减弱。在空气中放置相同时间,O2等离子体后处理的金刚石薄膜比H2等离子体后处理的金刚石薄膜亲水性好。     

FACTORS GOVERNING ADHERENCE OF ENAMELS APPLIED TO SHEET IRON *

A series of tests were conducted to ascertain the effect of nickel deposition and firing variations upon the adherence of enamels applied to special enameling sheets. Limits were established for securing optimum adherence of zirconium-opacifid white, antimony-molybdenum-opacified white, and commercial blue ground-coat enamels.     

燃烧过程中石油焦表面形态的变化

用氮气等温吸附/脱附法对石油焦燃烧过程中表面形态的变化进行了分析.通过BET法和t-plot法对不同燃尽率的石油焦进行了比表面积和孔容积的测定.结果表明,石油焦燃烧过程中孔隙结构变得发达,比表面积和孔容积较原样明显增大且变化趋势基本一致.验证了石油焦燃烧具有分形动力学的行为特征,用FHH模型求得燃烧中表面分形维数值接近3,表明燃烧反应是在空间网格结构的内、外部同时发生的;同时发现,石油焦表面分形维数与比表面积和孔容积在变化趋势上存在明显差异.     

UHMWPE 纤维表面形貌及表面含氧量表征

本文用低温等离子、液态氧化、电晕、紫外接枝聚合等方法对UHMWPE纤维进行了表面处理,并用扫描电镜和XPS对纤维的表面形貌和含氧量作了表征.结果表明,经表面处理后UHMWPE纤维表面变得粗糙,表面积增大,表面含氧量增加.     

抗静电剂对抗静电PET纤维表面形态的影响

以己二酸聚乙二醇胺盐,己二酸己二胺盐和ε－己内酰胺为单体,经真空共缩聚合成共缩聚醚酰胺,用ＤＳＣ和ＴＧＡ测定了其热性能。将共缩聚醚酰胺和ＰＥＴ熔融共混熔纺成纤维,测定了纤维的抗静电性能并用扫描电镜研究了抗静电纤维的微区形貌。     

两种HIPS的冲击断裂形貌与冲击曲线分析

对两种牌号的工业化高抗冲聚苯乙烯树脂YB2710、SK622的冲击断面微观形貌分区进行了观察,并对其内在关系进行了分析.结果表明,YB2710的橡胶相粒径约为1～5 μm,其冲击能量主要为裂纹形成能量,增韧机理以银纹化、空穴化为主;SK622的橡胶相粒径约为0.2～2 μm,其冲击能量由裂纹形成能量和裂纹扩展能量两部分组成,其增韧机理以银纹化、空穴化为主,同时有轻微的剪切形变.     

平流沉淀池设计表面负荷的影响因素

本文通过试验测试了平流沉淀池的水力特性，研究了表面负荷率与悬浮物分离效率及短流率的关系。     

光催化多孔TiO2薄膜的表面形貌对亲水性的影响

从含聚乙二醇（ＰＥＧ）的钛醇盐溶胶前驱体中通过溶胶－凝胶工艺在普通钠钙玻表面制备了多孔锐钛矿型ＴｉＯ２纳米薄膜。用扫描电镜（ＳＥＭ）,Ｘ射线光电子能谱（ＸＰＳ）和红外光谱（ＩＲ）分析了ＴｉＯ２薄膜表面的微结构,结果表明,随着前驱物中聚乙二醇的加入量和分子量的增加,聚乙二醇热分解后的薄膜中产生的气孔就越多且孔径越大,同时ＴｉＯ２薄膜表面的羟基含量增加且表面粗糙度增大。接触角测试表明：随着薄膜中气孔数     

纳米结构陶瓷涂层精密磨削表面/亚表面的形貌

用扫描电镜对纳米(以n表示)结构WC／12Co(n-WC／12Co)和Al2O3／13TiO2(n-Al2O3／13TiO2)涂层经立式精密平面磨削后的磨削表面／亚表面的形貌进行观察，测量了n-WC／12Co和n-Al2O3／13TiO2涂层精密磨削的磨削力分力比、比磨削能。结果表明：在大多数磨削条件下，n-WC／12Co磨削的材料去除机理主要是非弹性变形方式，即以塑性变形为主，伴随一定的材料粉末化。材料较少以脆性碎裂去除。n-Al2O3／13TiO2陶瓷涂层磨削的材料去除机理主要是脆性去除，同时也存在一定的材料粉末化以及极少的显微塑性变形。     

热处理对凹凸棒石结构、形貌和表面性质的影响

通过差热、热重、X射线衍射、透射电镜综合分析研究了凹凸棒石在热处理过程中脱水作用、结构、形貌变化之间的关系.结果表明:在65℃,凹凸棒石开始脱去外表面吸附水,98℃脱去孔道水,凹凸棒石结构、形貌没有任何变化,微孔孔道直径未变.到230℃,部分脱去凹凸棒石的结晶水,由于脱出部分结晶水,凹凸棒石结构开始出现折叠.在481℃,脱去凹凸棒石的剩余结晶水.在595℃左右,缓慢脱去凹凸棒石的结构水,孔道结构完全塌陷,链层结构和形貌基本保持不变.高于800℃,凹凸棒石晶体开始变形弯曲,并变为无定形态.在827℃出现放热效应,形成方石英,这与1 000℃出现严重烧结形貌特征一致.     

影响卫生陶瓷釉面粗糙度因素的研究

采用一次烧成工艺制备了卫生陶瓷用超平滑釉（Ra≤10．0nm），讨论了釉料高温物理性质以及釉浆粒度和釉面粗糙度之间的关系。结果表明：釉的高温粘度Igh在2．65～3．15之间、高温表面张力在350～380mNm^-1、D90介于4．0～7．5mm时，可以有效降低釉面的粗糙度。     

SURFACE MORPHOLOGY AND CATALYTIC ACTIVITY OF THE CONTACT MASS IN ORGANOSILANE SYNTHESIS

The contact mass in the Rochow reaction was analyzed to understand catalyst deactivation during the reaction. Changes in crystalline structure, particle surface morphology, and the elemental composition of the contact mass were measured by XRD, SEM, EDX, and XRF, respectively, at four different reaction conversions. The results indicate that the main reason for contact-mass deactivation is copper enrichment on the surface of silicon. Coke deposition may hamper Cu diffusion and result in the copper enrichment.     

SURFACE MORPHOLOGY AND CATALYTIC ACTIVITY OF THE CONTACT MASS IN ORGANOSILANE SYNTHESIS

The contact mass in the Rochow reaction was analyzed to understand catalyst deactivation during the reaction. Changes in crystalline structure, particle surface morphology, and the elemental composition of the contact mass were measured by XRD, SEM, EDX, and XRF, respectively, at four different reaction conversions. The results indicate that the main reason for contact-mass deactivation is copper enrichment on the surface of silicon. Coke deposition may hamper Cu diffusion and result in the copper enrichment.     

EPDM粘度对PP＼EPDM共混物断口形态和冲击性能的影响

用机械共混的方法制备了一系列不同ＥＰＤＭ粘度的ＰＰ／ＥＰＤＭ共混物，对其力学性能和结晶行为进行了表征，并用扫描电子显微镜（ＳＥＭ）研究了共混物冲击样条的断口形态。实验结果表明，ＥＰＤＭ粘度对共混物的冲击强度有较大影响，随着ＥＰＤＭ粘度的增大，共混物的冲击强度出现极大值，而结晶行为的变化则较小，研究共混物冲击样条的断口形态发现，共混物的冲击强度随ＥＰＤＭ粒径的变化出现极大值。     

氧化锆料浆性能对其喷雾造粒粉料性质的影响

本文研究了料浆含固量和粘度对其喷雾造粒粉料性质影响。结果表明：氧化锆料浆含固量是喷雾造粒（ＳＤ．）粉料填充密度的主要控制因素，高含固量料浆能得到高填充密度喷雾造粒粉料，且其颗粒显微结构相对致密；随着ＺｒＯ２料浆含固量、粘度增加，喷雾造粒粉料平均粒径增大，粗颗粒含量增多，细颗粒含量减少。     

表面处理工艺对碳纤维复合材料的ILSS及界面形貌的影响

考查了不同表面处理工艺对碳纤维复合材料层间剪切强度及层面、断面形貌的影响。通过材料实验机测得碳纤维及其复合材料的拉伸强度和层间剪切强度,并通过扫描电镜分析评价不同电导率对复合材料ILSS的影响。结果表明,12ms/cm是表面处理工艺中电导率的较优选择;碳纤维的层间剪切强度随电量的变化符合"层进式物化双效模型";制备高层间剪切强度碳纤维和复合材料时,较优的电解质是NaOH,较优的电解液浓度为2%,较优的电量为10C/g;本工艺条件下制得的SYT49碳纤维层面形貌与东丽T700G碳纤维相似。