Process conditions affect pigment quality and yield in extracts of purple sunflower hulls

Extract of purple sunflower hulls is a potential red food colorant; however, suitable process conditions must still be identified. Selected process variables were studied using bench-scale units to prepare, clarify, concentrate and spray dry extracts. Concentration by evaporation at 32°C and addition of maltodextrin to 15% (wt/dry wt) prior to drying largely eliminated pigment degradation during those steps. Relative to water extracts, extracts prepared with 5 to 15% ethanol in water generally yielded more pigment with similar levels of degradation and loss during subsequent processing. Use of 5% ethanol/2% citric acid reduced yield by about half relative to water, but gave a powder with a lower degradation index and wetting time. Percentage recovery of pigment during concentration and drying was not greatly affected by solvent type or extraction temperature.     

Electrodeposition, composition and structure of Zn—Cr alloys

The effect of polyethylene glycol (PEG 1500) as additive and of deposition conditions on Zn—Cr alloy electrodeposition from an acidic sulfate electrolyte at room temperature, without agitation was investigated. PEG polarizes the overall cathodic reaction and inhibits Zn deposition. Cr codeposition with Zn starts at a cathodic potential of about –1,95 V vs Hg/Hg₂SO₄, which is reached at current density of about 20 A dm^–2 in galvanostatic conditions. Zn—Cr alloy coatings containing up to 28 at % Cr were obtained depending on the plating conditions. SEM observations showed an island-like structure, formed by the local growth of crystals, which covered the surface during further deposition. In the first stages of electrodeposition the powder diffraction spectra contain lines of b.c.c. -(Zn,Cr) phase (a 3.02 Å). After 30 s deposition time weak lines of Zn-based phase (a 2.67 Å, c 4.90 Å) appear, and become clearly visible in coatings deposited for 90 s. The average Cr content in the alloy coatings decreases with advancing deposition. The as-plated surface contains C in organic compounds and Zn(OH)₂. After 50 min sputtering, Zn and a mixture of Cr, Cr₂O₃ and Cr₇C₃ were found. The presence of organic C and O, probably from inclusions of PEG, were also detected.     

电沉积触媒的制备及其合成金刚石的研究

用电沉积的方法以Ni70Mn25Co5为基材制备了合成金刚石的触媒，选择适当的合成条件，在国产六面顶压机上用此电沉积触媒合成出颜色和晶型都较好的金刚石，为纯铁片做为基材制备电沉积触媒，降低合成金刚石触媒生产成本奠定了一定基础。     

Electrochemical investigations of copper behaviour in different cupric complex solutions: Voltammetric study

The electrochemical behaviour of copper has been investigated in different cupric complex solutions by cyclic voltammetry. In pyridinic and picolinic solutions the reduction of cupric complex occurred in two stages leading to Cu(I) and Cu(0), respectively. The electrodeposited copper is oxidized in two steps leading to Cu(I) and Cu(II) as in ammoniacal cupric complex solutions. In glycine, alanine, sulfamic acid and ethylenediamine solutions, the cuprous complex is an intermediate in the cupric complex reduction but it is not detected during the oxidation of the electrodeposited copper in these solutions. In EDTA and triethanolamine solutions, the cuprous complex is not observed. The rate of copper etching was determined in pyridinic and ammoniacal cupric solutions and was shown to be faster in ammoniacal cupric solutions than in the pyridinic solutions.     

轻型客车厂油漆车间的设计

本文阐述了某公司轻型客车厂涂装车间在利用原有厂房的改造中,对各工作区合理地采用分层、分区域的布置,其主要操作面在4.0 m的加层上。该涂装生产线通过采用柔性化理念,能同时满足2种不同轻型客车车身的共线生产需要。     

On the observation of inductive high-frequency impedance behaviour during the electrodeposition of Au—Sn alloys

Inductive high-frequency impedance behaviour is often observed in metal electrodeposition systems. This behaviour is typically attributed to equipment limitations or non-idealities in the cell set-up and electrical connections. Such instrumental artefacts would nevertheless be relevant to a frequency range which is expected to be well above that in which inductive behaviour is in fact observed (down to a few tens of Hz). In this paper some results on an acidic Au—Sn electrodeposition system are reported. Electrochemical impedance and potentiostatic transients were measured. These results suggest that the high-frequency inductive behaviour may be related to metal nucleation processes. A correlation is proposed between the pseudo-inductive potentiostatic nucleation transients and the pseudo-inductive behaviour of the impedance spectra.     

An Investigation of Error Sources in Computational Fluid Dynamics Modelling of a Co-current Spray Dryer

The paper is focused on identifying error sources in computational fluid dynamics(CFD) predictions of a spray drying process. Seven groups of drying and atomisation parameters were selected for analysis and 13 simulation trials were performed. The theoretical results were compared with experimental data and sensitivity of the simulation results to the analysed factors was determined. The following parameters affecting the accuracy of CFD spray modelling were found: gas turbulence model, particle dispersion, atomising air, initial parameters of atomisation and heat losses to the environment. A major difference in the errors committed during modelling of spray drying process for fine and coarse sprays was observed.     

Transfer efficiency for airless painting systems

Spray transfer efficiency (TE) is defined as the mass fraction of sprayed paint which is deposited on the intended target, the remainder of the sprayed paint becomes undesirable overspray. The relationship between TE and gun supply pressure (or paint mass flow rate), gun-to-target distance, gun traverse speed, the angle of the spray gun relative to the target (gun-to-target angle), plus spray cone angle is reported herein for a typical fan spray system. Experimental results indicate that spray momentum rate (SMR) and droplet size dictate the TE for the various combinations of parameters considered here. The key finding is that TE correlates with SMR and spray mean drop size (Sauter mean diameter, or D₃₂) via an expression of the form TE=a+b SMR − c (SMR)²+d D₃₂, where a, b, c, and d are coefficients, determined by fitting the experimental data, and SMR is estimated via SMR=m²/ρA, where the paint mass flow rate m, the paint density is ρ, and the gun exit orifice effective tip cross sectional area is A. This expression accounts for physical phenomena that govern sprayed droplet deposition characteristics, such as entrainment, bounce-back, and drop size. Experimental results also show that, for the range of parameters studied, gun traverse speed has no effect on TE, but increasing the angle of the spray gun relative to the target (gun-to-target angle), increasing the spray cone angle, or increasing the gun-to-target distance will decrease TE.     

电沉积非晶态合金镀层磁性的控制

磁性元件薄膜化促进了磁性镀层的开发与应用。综述了镀液及镀层成分、电沉积工艺、镀层厚度及热处理对电沉积非晶态镀层性能的影响，以便在实际应用中控制非晶态合金镀层的磁性。     

静电喷涂技术在溶剂型涂料中的应用

介绍了静电喷涂的原理、工艺和静电漆料的配方设计原则，从理论和实践上证实了静电喷涂工艺具有较好的经济效益和环境效益。