干粉酪素胶的研制

介绍了一种以酪蛋白酸钠为主要原料,以尿素、可溶性淀粉、氧化锌、硼砂、硫酸铝、防腐剂和消泡剂等为辅料的干粉酪素胶的制备方法。该胶适合用于车速为48000瓶/h的高速啤酒瓶贴标。实验结果表明,当w(酪蛋白酸钠)=10.8%～15%、w(硫酸铝)=0.3%～0.6%时,可调制出粘度为30～75Pa·s(20℃)和15～56Pa·s(25℃)胶料。干粉酪素胶在常温下溶解陈化24h即可使用,具有工艺简单、使用方便、易于贮存及运输等特点,为进一步工业化生产提供了依据。     

超声波辅助化学镀法制备CoAl_2O_4尖晶石粉体

采用超声波辅助化学镀法在室温条件下制备了Co/Al2O3复合粉体,1200℃下热处理1.5h获得了CoAl2O4尖晶石粉体。用扫描电镜、透射电镜和X射线衍射测定了粉体的微观形貌、成分和相组成;用差热分析法确定了粉体的尖晶石转变温度。结果表明:镀覆制备的Co/Al2O3复合粉体由金属钴和Al2O3两相组成,金属钴相包覆Al2O3相,Co包覆层在Al2O3颗粒表面分布均匀且结构较疏松;复合粉体的尖晶石转变温度为850℃左右;转变后获得的粉体也是一种复合粉体,由Al2O3和CoAl2O4两相组成,由粉体的生长机制可预见,它是以α-Al2O3为核心CoAl2O4尖晶石包覆在其表面的结构。     

On the Quaternary System Ti-Fe-Ni-Al

The homogeneity ranges of the Laves phases and phase relations concerning the Laves phases in the quaternary system Ti-Fe-Ni-Al at 900 °C were defined by x-ray powder diffraction (XPD) data and electron probe microanalysis (EPMA). Although at higher temperatures the Laves phase forms a continuous solid solution, two separate homogeneity fields of TiFe₂-based (denoted by λ_Fe) and Ti(TiNiAl)₂-based (denoted by λ_Ni) Laves phases appear at 900 °C. The relative locations of Laves phases, G phase, Heusler phase, and CsCl-type phase as well as the associated tie-tetrahedra were experimentally established in the quaternary for 900 °C and presented in three-dimensional (3D) view. Furthermore, a partial isothermal section TiFe₂-TiAl₂-TiNi₂ was constructed, and a connectivity scheme, derived for equilibria involving Laves phases in the Ti-Fe-Ni-Al quaternary system at 900 °C was derived. As a characteristic feature of the quaternary phase diagram, the solid solubility of fourth elements in both the TiFe₂-based and Ti(NiAl)₂-based Laves phases is limited at 900 °C and is dependent on the ternary Laves phase composition. A maximum solubility of about 8 at.% Ni is reached for composition Ti_33.3Fe_33.3Al_33.4. Structural details have been evaluated from powder x-ray and neutron diffraction data for (i) the Ti-Fe-Ni ternary and the Ti-Fe-Ni-Al quaternary Laves phases (MgZn₂-type, space group: P6₃/mmc) and (ii) the quaternary G phase. Atom site occupation behavior for all phases from the quaternary system corresponds to that of the ternary systems. For the quaternary Laves phase, Ti occupies the 4f site and additional Ti (for compositions higher than 33.3 at.%Ti) preferably enters the 6h site. Aluminum and (Fe,Ni) share the 6h and the 2a sites. The compositional dependence of unit cell dimensions, atomic coordinates, and interatomic distances for the Laves phases from the quaternary system is discussed. For the quaternary cubic G phase, a centrosymmetric as well as a noncentrosymmetric variety was observed depending on the composition: from combined x-ray and neutron powder diffraction measurements Ti_33.33Fe_13.33Ni_10.67Al_42.67 was found to adopt the lower symmetry with space group .     

Removal of plant poisoning dyes by adsorption on Tomato Plant Root and green carbon from aqueous solution and its recovery

The organic dyes directly pollute the soil, water, plants and all living systems in the environment. The dyes like cationic Methylene blue (MB) and Crystal violet (CV) adsorption has been studied on Tomato Plant Root powder (TPR) and green carbon from aqueous solution for identifying the plant poisoning nature of cationic dyes. TPR powder is a cellulose material and green carbon is prepared from TPR powder by an ecofriendly method. The dyes adsorption mechanism on basic surface of cellulose and neutral surface of green carbon are correlated to evaluate the plant poisoning nature of organic dyes. The adsorption parameters were optimized to maximum adsorption. The maximum uptake of both dyes on TPR was 97% at 15 min and on carbon is 18% (CV) & 20% (MB) at 30 min. The adsorptions of MB and CV on TPR powder followed Freundlich and Langmuir adsorption isotherms and pseudo second order kinetics. The ?S^o, ?H^o and ?G^o of adsorption on TPR are calculated. The dyes recovery has been studied from dyes adsorbed TPR and green carbon. The adsorption mechanism and dye recovery studies proved the plant poisoning nature of MB and CV.     

A narrow size distribution on a high shear mixer by applying a flux number approach

High shear granulation is a common technology for particle size enlargement, but generally the product properties are badly affected by the broad size distribution generated in the process. A recently published approach by Michaels et al. [J.N. Michaels, G. Wang, L. Farber, K.P. Hapgood, J.H. Chou, S. Heidel, and G.I. Tardos, 2006, One-dimensional scale-up of high-shear granulators, Paper 243c, World Congress Particle Technology 5, Orlando (FL)] employs low binder solution spray rates and long granulation times, whilst the solids are kept in roping flow, to avoid coarse formation. The present work applies this approach to a two-component binder system with a dry powder gum and water spray as activation agent. Similarities with fluidised bed granulation and coating processes are explored. The work shows that indeed narrow size distributions of fine granules can be achieved with ease. Dimensionless numbers for spray fluxes are useful to identify operating regimes and to steer optimisation efforts. Comparison of flux numbers for different systems shows that they are not useful (yet) for detailed product and process design. Further work on material-specific quantities controlling nucleation and growth, e.g. particle wetting, is recommended.     

Granulation of hydrophobic powders

Granulation of hydrophobic powders is frequently required in the pharmaceutical industry. The structural complexity of new drug molecules mean that is increasingly common for entire classes of drug compounds to be highly hydrophobic. This creates considerable difficulty in understanding, controlling and trouble-shooting these industrial granulation processes.There have been many recent advances in granulation theory. Essential to this theory is that wetting and spreading of the fluid through the powder particles is a prerequisite for good granulation. The possibility of a fine, hydrophobic powder spreading over the surface of the liquid during nucleation has been identified theoretically based on surface chemistry and as a potential nucleation mechanism. Recently, investigation confirmed that nucleation can occur by spreading of the sub-micron particles around the template drop to form a “liquid marble”. The hollow granule structure formed by the “solid-spreading” nucleation mechanism suggests the possibility of using the controlled, open granule structure to manufacture designer structured agglomerates with advantageous properties, including controlled granule structure and size and excellent ideal flow and handling properties. This paper describes single drop solid-spreading nucleation experiments where single fluid droplets are placed onto loosely packed powder beds of hydrophobic powders and the formation of the powder shell observed. Experimental results and observations for some model systems are presented, together with a preliminary framework for liquid marble formation.     

Kinetic modelling of nickel powder precipitation by high-pressure hydrogen reduction

The active mechanisms in the precipitation of nickel powder by hydrogen reduction were investigated by means of mathematical models based on the moment form of the population balance equation (PBE). The objective of the work was to establish the mechanisms involved in powder formation and how these are affected by the presence of impurities. The effects of two major impurities were considered namely; iron, inherently present as ferrous sulphate, and a morphology modifier, a polyacrylic acid derivative used as an additive. Experiments were conducted on a laboratory and pilot-plant scale using a 0.5 and 75 L stainless steel autoclave, respectively. Nickel powder samples were collected from the autoclaves after each successive batch reduction (densification) and the particle size distribution (PSD) analysed using a laser diffraction technique. The PSD data was then transformed into moments and the experimental values were compared with those simulated using different models based on the moment form of the PBE. Five models were tested namely: (a) aggregation-only; (b) aggregation and growth; (c) nucleation and aggregation; (d) nucleation and growth and (e) aggregation and breakage. Under standard operating conditions, the process was best simulated by a size-independent aggregation and growth model in the early stages of the cycle, with breakage and growth becoming significant in later stages of the cycle when large particles have been formed. Crystallisation in the presence of Fe was characterised by a size-independent aggregation and growth model with varying degrees of nucleation depending on the Fe concentration and the available surface area. At modifier dosages of 0.25 and 5 vol% the process was best modelled by a size-independent aggregation and growth model coupled with a constant breakage frequency model. Based on the mathematical modelling results and evidence from scanning electron micrographs, the spherically shaped nickel powder particles were proposed to be formed through the formation of a pre-cursor by secondary aggregation followed by spherulitic growth. The degree of compactness of the spherulites was proposed to be determined by the number of active growth sites on the nickel particle surface. The morphology modifier was found to act as a growth inhibitor, decreasing the number of growth sites leading to more open spherulites. Iron was found to induce surface nucleation, thus, creating more growth sites on the particle surface and leading to more compact spherulites.     

十二烷基磺酸钠在制备超细石英粉体中的应用

通过控制十二烷基磺酸钠的添加量和悬浮渡的pH,利用搅拌磨制备出了超细石英粉体。比较了不同条件下在英粉体的粒度和分散度的变化规律,并分析了产生的原因。     

重防腐熔结环氧粉末涂料与涂装

系统介绍了重防腐熔结环氧粉末涂料的特性、分类、涂装技术、涂料制造技术、主要原材料、涂层的检测标准和试验方法。     

粉末喷涂在线镀膜技术

介绍了粉末喷涂在线镀膜技术国内外发展概况,对镀膜重要工艺过程及影响因素进行了详细分析和总结,并对应用前景进行了展望.