氯化聚乙烯阻燃体系的研究

本文研究了卤素—氧化锑阻燃体系在氯化聚乙烯橡胶配方设计的应用 ,指出卤素阻燃剂与氧化锑存在协同效应 ,并使其阻燃效果达到美国UL - 94V0维阻燃水平     

Boundary layer modeling of reactive flow over a porous surface with angled injection

An analytical model was developed to investigate the dynamics of nonpremixed flames in a shear layer established between a mainstream flow of fuel-rich combustion products and a porous surface with an angled injection of air. In the model, a one-step overall chemical reaction was employed, together with boundary layer conservation equations solved using similarity solutions. Parametric studies were performed to understand the effects of equivalence ratio, temperature, and mass flow rate of the fuel and air streams on the flame standoff distance, surface temperature, and heat flux at the surface. The analytical model predictions were compared with computational fluid dynamics results obtained using the FLUENT commercial code for both the laminar and the turbulent flow models. Qualitative agreement in surface temperature was observed. Finally, the flame stability limits predicted by the model were compared with available experimental data and found to agree qualitatively, as well.     

反应型含溴阻燃剂中溴含量的测定

采用一种新方法测定了反应型含溴阻燃剂中溴的含量．实验证明，该方法简单易行，且精密度较高     

新型阻燃剂磷酸二-(2,3-二氯丙基)酯三聚氰胺盐的合成

以三氯氧磷 ,环氧氯丙烷和三聚氰胺为原料合成了一种新型含氮、磷和氯的阻燃剂磷酸二 ( 2 ,3二氯丙基 )酯三聚氰胺盐 ,并研究了反应物配比 ,催化剂用量、反应温度以及中间体的处理方法对产品收率的影响。结果发现反应适宜条件为三氯氧磷∶环氧氯丙烷和三聚氰胺的摩尔比为 1∶ 2∶ 1 ,第一步反应为 6 0～70℃ ,第二步反应为 1 0 0℃ ,产品收率 82 %。其含氮量为 2 1 .75% ,含磷量为 6 .1 9%。     

粉体喷搅法在穗港码头软土层加固中的应用

粉体喷搅法是诸多加固软弱土层方法中具有代表性的一种。笔者通过穗港码头加固处理软土的实践，介绍搅拌桩在码头后方堆场和护岸带的应用方法及效果，总结了施工要点及质检方法。     

Photoresponse and donor concentration of plasma-sprayed TiO<Subscript>2</Subscript> and TiO<Subscript>2</Subscript>-ZnO electrodes

The photoelectrochemical characteristics of plasma-sprayed porous TiO₂, TiO₂-5%ZnO, and TiO₂-10%ZnO electrodes in 0.1 N NaOH solution were studied through a three-electrode cell system. The microstructure, morphology, and composition of the electrodes were analyzed using an electron probe surface roughness analyzer (ERA-8800FE), scanning electron microscopy, and x-ray diffraction. The results indicate that the sprayed electrodes have a porous microstructure, which is affected by the plasma spray parameters and composition of the powders. The TiO₂-ZnO electrodes consist of anatase TiO₂, rutile TiO₂, and Zn₂Ti₃O₈ phase. The photoresponse characteristics of the plasma-sprayed electrodes are comparable to those of single-crystal TiO₂, but the breakdown voltage is close to 0.5 V (versus that of a saturated calomel electrode). The short-circuit photocurrent density (J _SC) increases with a decrease of donor concentration, which was calculated according to the Gartner-Butler model. For the lowest donor concentration of a TiO₂-5%ZnO electrode sprayed under an arc current of 600 A, the short-circuit J _SC is approximately 0.4 mA/cm² higher than that of the TiO₂ electrodes under 30 mW/cm² xenon light irradiation. The J _SC increases linearly with light intensity. The original version of this paper was published as part of the DVS Proceedings: “Thermal Spray Solutions: Advances in Technology and Application,” International Thermal Spray Conference, Osaka, Japan, 10–12 May 2004, CD-Rom, DVS-Verlag GmbH, Düsseldorf, Germany.     

Wear behavior of a crankshaft journal bearing manufactured by powder spraying

A new crankshaft bearing material that can be an alternative to the traditional material has been improved and its wear behavior studied experimentally. Crankshaft main bearings are subjected to various stresses. A new material supposed to be adapted these operating conditions was designed composing of Pb–Sn–Cu–ZrO₂ and manufactured by HVOF spraying technique. Wear behavior of the bearing was tested with the simulation of real operating conditions. An original bearing was used for comparison. After a trial of 500 h, the weight losses were measured. SEM micrographs of both original and new bearings were examined. The effect of microhardness was discussed. The new composition was seen as promising as a bearing material for automotive engines.     

氧气-乙炔火焰法在Al2O3陶瓷上沉积金刚石薄膜

用氧气－乙炔火焰法在氧化铝陶瓷片上沉积出了金刚石薄膜，并观察了薄膜的形貌结构及其在基片上的分布规律。对基片进行了适当的预处理，可以提高金刚石薄膜在基片上的成核密度。认为氧化铝陶瓷片与沉积金刚石薄膜之间易形成过渡层，初步探讨了在氧化铝陶瓷片上沉积金刚石薄膜的机理。     

Influence of CF<Subscript>3</Subscript>I and CBrF<Subscript>3</Subscript> on Methanol–Air and Methane–Air Premixed Flames

The suppression of CH₄ and CH₃OH premixed flames with CBrF₃ and CF₃I is examined, using computational techniques. By combining sensitivity analysis, reaction pathway analysis (based on carbon, hydrogen, bromine and iodine atom fluxes) and heat release estimation, we develop an explanation for the difference of suppression efficiencies which is qualitatively consistent with experimental cup burner data. The key reaction steps and channels responsible for the (apparent) higher inhibition efficiency of CF₃I compared to CBrF₃ in CH₃OH premixed flames are disclosed, by combining reaction pathway and heat release contribution analysis. The reaction of bromine atom dominates the decomposition channel for CH₃OH but plays a relatively minor role in the activation of CH₄, while I atom plays a minor role in CH₃OH or CH₄ activation. Accordingly, the rate of production of flame propagating radicals CH₂O and OH is higher in a CH₃OH–air–CBrF₃ system than in a CH₃OH–air–CF₃I system. The overall conclusion is that CBrF₃ contributes significantly to flame propagation for CH₃OH fuel reactions and consequently more CBrF₃ is required to extinguish a CH₃OH flame than CF₃I. Finally the explanation is validated by applying the reaction “switching-off” test.     

Operating parameters for suspension and solution plasma-spray coatings

The interest to manufacture on large surfaces thick (i.e., 10 to 20 μm, average thickness) finely structured or nano-structured layers is increasingly growing since about 10 years. This explains the interest for suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS), both allowing manufacturing finely structured layers of thicknesses varying between a few micrometers up to a few hundred of micrometers. SPS aims at processing a suspension of sub-micrometric-sized or even nano-metric-sized solid particles dispersed in a solvent. The liquid solvent permits to inject particles in the thermal flow (i.e., due to their size, a carrier gas cannot play this role). SPTS aims at processing a solution of precursors under the same conditions. Upon evaporation of the liquid, the precursor concentration increases until precipitation, pyrolysis and melting of small droplets. Compared to conventional plasma spraying, SPS and SPPS are by far more complex because fragmentation and vaporization of the liquid control the coating build-up mechanisms. Numerous studies are still necessary to reach a better understanding of involved phenomena and to further develop the technology, among which injection systems, suspension and solution optimizations, spray kinematics, etc. This review presents some recent developments in this field.