Methods for increasing the stability of the process and reducing the losses of electrode metal through splashing in CO2 welding

In the present research, a nickel base coating was deposited on an AISI 1020 substrate using a high-velocity oxy-fuel technique. The coating was subsequently heat treated (HT) by means of an oxyacetylene flame. For the conditions evaluated in the present study, it was found that the HT coating has 1.15 times better wear resistance for the lower level of applied load and lower sliding speed (SS), and nearly 50 times better resistance for the highest level of the applied load and highest SS when compared with the non-HT coatings. These results have been attributed to a better distribution of the hardening phases, better cohesion between particles and an increase in hardness, as a consequence of the post-deposition heat treatment process. A severe wear regime was found for all the samples, since the wear rates presented values which were higher than 1 × 10^? 5 mm³/m. The presence of the adhesion, oxidization, three-body abrasion, and cyclical deterioration phenomena, all competing with each other, was noted. For the HT coatings, the wear mechanism was mainly due to the adhesion and oxidisation phenomena, while for the steel counterpart mechanisms such as oxidization, grooving and three-body abrasion were observed.     

A zinc dipping technique for Mg–16Li–5Al–0.5RE alloy at room temperature

In order to obtain a high quality protective plating coating on Mg–16Li–5Al–0.5RE alloy, a zinc dipping technique at room temperature was investigated. The zinc dipping technique included two immersion processes, the primary immersion process and the secondary immersion process. Primary zinc transition layers (PZTLs) and secondary zinc transition layers (SZTLs) were obtained after the primary and secondary immersion processes, respectively. The polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were employed to characterize PZTLs and SZTLs. The results indicated that immersion time had obvious effects on PZTLs and SZTLs, the optimum primary immersion time and secondary immersion time were 5 min and 30 s, respectively. Then nickel‐plating coating deposited on the SZTL of Mg–16Li–5Al–0.5RE alloy was investigated via EDS, SEM, polarization curves, and EIS. The results demonstrated that the nickel‐plating coating obviously improved corrosion resistance of Mg–16Li–5Al–0.5RE alloy and had good adherence property with the alloy because of the presence of zinc transition layer on the alloy.     

Mechanical and tribological properties of TiN/Ti multilayer coating

A large area filtered arc deposition (LAFAD) technique was used to deposit TiN/Ti multilayer coatings with fixed TiN layer thickness and different Ti layer thickness. Nanoindention and pin-on-disk tribometer were used to characterize the hardness, elastic modulus, plasticity, friction coefficient, and wear rate of the multilayer coatings. The dependence of the mechanical and tribological properties of the coating on the Ti interlayer thickness was systematically studied. It was found that the increase in the Ti layer thickness resulted in a decrease in the effective hardness and elastic modulus, and an increase in the wear rate, plasticity, and toughness. The coatings with a Ti layer thicknesses of 0, 25 nm and 50 nm possess an excellent combination of high effective hardness (> 20 GPa), high plasticity (> 69%), low friction coefficient, and high wear resistance.     

聚脲弹性体涂层在海水淡化项目中的应用

介绍了聚脲的成分及性能,结合海水淡化项目,得到了将聚脲用于复杂钢结构时涂装施工及涂装检验的成功经验。     

三种FGD湿烟囱内衬涂层耐热性的比较

对三种国内常用FGD湿烟囱内衬涂层进行了耐高温和冷热交变试验,根据试验结果对其耐热性进行分析和比较。     

The use of fire‐retardant intumescent mats for fire and heat protection of glass fibre‐reinforced polyester composites: Thermal barrier properties

This study investigates the use of integral, hybrid intumescent thermal barriers (mats) to provide surface protection to the core fibre‐reinforced polyester composite structural integrity when exposed to a fire or heat source. Glass fibre‐reinforced composites protected by intumescent mats/fabrics containing silicate fibres, expandable graphite and in some cases borosilicate glass bounded together by an organic matrix have been evaluated for fire performance under a constant heat flux of 50kW/m². The effect of insulative fabric thickness as well as chemical composition on the flammability of the resultant hybrid composites is evaluated. Glass fibre‐reinforced polyester (GRP) composites without any surface protection have a relatively higher time‐to‐ignition and peak heat release rate values when compared with core composites protected by insulative fabrics. Thermograms representing the variation of temperature on the reverse side of the hybrid composites with time when exposed to a constant heat flux show that the inclusion of intumescent surface barriers results in retarded temperature increments within the core GRP composites. Copyright © 2009 John Wiley & Sons, Ltd.     

浅谈粉末涂料制造设备和生产工艺中应注意的问题

根据作者多年从事粉末涂料生产的经验,详细论述了粉末涂料制造设备的使用和在生产工艺中的控制及为了保证产品质量应该注意的具体问题。     

Nanostructured coatings produced by a novel ultrasonic-assisted method: Coating characterisation and formation mechanism

In this study, we introduce a novel method of mechanical plating to produce nanopowder coatings on a number of metal substrates by using TiN nanopowder as a representative example. This method, proposed earlier by the authors, allows a coating to be applied at room temperatures and atmospheric pressure in a relatively short time. These coatings were characterised for microhardness, roughness, and scratch adhesion. Their micro- and nanostructures were investigated by SEM and TEM. On the basis of the results of these analyses, possible mechanisms of coating formation were tentatively proposed and discussed. To further elucidate the coating formation mechanisms and to estimate the process capability, a mathematical model was developed and verified against the experimental results.     

Characteristic of cold sprayed catalytic coating for hydrogen production through fuel reforming

Cold spray was employed as a novel method to prepare NiO/Al₂O₃ primary steam reforming catalyst coating for hydrogen production. The coating microstructure was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after reforming reactions. The catalytic coating performance was examined through methane steam reforming (SRM) in a microreactor. Results showed that NiO/Al₂O₃ coating was successfully deposited on the stainless steel substrate by cold spray. The thickness of the coating was about 50 μm. It presented a rough surface and porous structure. Since temperature of the cold spray process is low, no phase changes occurred to NiO/Al₂O₃ during deposition. However the particle size in the coating became smaller compared with the feedstock due to its smashing. It was found that the cold-sprayed catalytic coating was active for SRM at high space velocity although filamentous carbon was formed on its surface. After reaction there was no obvious peeling off of the coating indicating a good bonding between the coating and substrate.     

国内外油漆涂料中苯系物安全限量标准的研究

介绍了苯系物的危害和来源,分析了国内外涂料中苯系物含量的安全限量标准,提出了控制涂料中苯系物含量的建议,为规范我国涂料生产和使用以及涂料中苯系物限量标准的制定和修订提供参考。