Effects of siloxane plasma coating on the frictional properties of polyester and polyamide fabrics

Hydrophobic siloxane plasma coatings (pp-HMDSO) were deposited on flexible polymeric substrates in order to investigate their performance within different tribo systems. The frictional properties of plasma-coated foils and fabrics were thus examined using the Textile Friction Analyzer. The friction measurements were realized under dry, wet and saturated conditions to simulate sweating during running and using two different tribo-partners (i.e. steel and mechanical skin model). Steel is a common counterpart to measure the frictional properties of fabrics. But it does not reproduce the real skin-to-textile friction like using a mechanical skin model as counterpart. Scanning electron micrographs were taken to visualize the fibers at different stages to check adhesion and wear of the coating. Results showed that the hardness of the coating and the nature of the counterpart strongly influence the coating delamination and the friction properties of the textiles. The water repellence of the siloxane-coated fabrics had a positive effect on reducing friction coefficient under wet conditions.     

Silica xerogel coating on the surface of natural and synthetic fabrics

SiO₂ thin films prepared from tetraethylorthosilicate by sol-gel method are coated on the fabric substrates of natural and synthetic fibres. The add-ons and leaching behaviors of silica xerogel coating on the surface of cotton, flax, nylon-66 and poly(ethylene terephthalate) fabrics are studied to compare the interaction and adhesion of the silica coating with different fabrics. Scanning electron microscopy (SEM) for the morphology of surface, BET specific surface area, FTIR-ATR analysis and X-ray diffraction (XRD) for the microstructure of fibres are used to characterize the surface changes induced by the silica coating. The results show that the chemical composition and structure of fibres play a dominant role in influencing the adhesion of the coating on the fabric surface.     

Pilot scale sonochemical coating of nanoparticles onto textiles to produce biocidal fabrics

The pilot installation is designed for the scale up of sonochemically assisted coating of textile fabrics with various kinds of nanoparticles. The installation can coat up to 50 m of continuous cotton fabric per run with CuO or ZnO nanoparticles. The structure and morphology of the metal oxides adhering to the fabric on the coated cotton have been characterized by XRD and HR SEM, and shown to be nanocrystalline oxides (~ 10–20 nm in size). The coating is homogeneous, stable and retains its biocidal properties through at least 20 washing cycles. The CuO–cotton bandages demonstrated good antimicrobial properties against E. coli bacteria.     

Studies on enhancement of surface durability for steel surface by camphor oil modified epoxy polyamide coating

Epoxy polyamide coatings are generally used to protect mild steel structures from corrosive atmosphere due to their better adhesion over under prepared surface and effective barrier protection. But the coating has the ability to disintegrate due to UV radiation and high humidity condition. To improve the weatherability and chemical resistance performance of epoxy polyamide, there is a need to modify it with suitable cross linking agent. In this work, it has been found that camphor oil at 5 wt.% as the optimum level to protect the mild steel structures from corrosive electrolyte. Further the impedance study has shown that the resistance exerted by the Camphor oil incorporated coating in 0.5 M NaCl solution after 60 days is 3 × 10⁷ Ω cm² where as the resistance of the coating without this modifier is 3 × 10⁶ Ω cm². The FTIR spectral study indicates that the formation of ether linkages in the dried film and also the other functional groups present in the epoxy polyamide polymer is completely disappeared in the modified coating. Similarly the TG and DTA analysis showed that considerable shift in the degradation temperature has been noticed for the polymer coating with modifier.     

Improvement of adhesion of conductive polypyrrole coating on wool and polyester fabrics using atmospheric plasma treatment

In this paper wool and polyester fabrics were pretreated with atmospheric plasma glow discharge (APGD) to improve the ability of the substrate to bond with anthraquinone-2-sulfonic acid doped conducting polypyrrole coating. A range of APGD gas mixtures and treatment times were investigated. APGD treated fabrics were tested for surface contact angle, wettability and surface energy change. Effect of the plasma treatment on the binding strength was analyzed by studying abrasion resistance, surface resistivity and reflectance. Investigations showed that treated fabrics exhibited better hydrophilicity and increased surface energy. Surface treatment by an APGD gas mixture of 95% helium/5% nitrogen yielded the best results with respect to coating uniformity, abrasion resistance and conductivity.     

Properties of PA(polyamide) coating and PA/MoS2 composite coatings by flame spraying

PA and PA/MoS2 composite coatings were prepared by flame-spraying. The thermal properties, crystallinity, microstructure and tribological properties were investigated with Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy(SEM), and MM-200 model wear tester. Temperature influences the final morphological structure of the coatings. Tribological experiment results indicate that the MoS2 filled PA coating has different wear resistance compared with the PA coating without MoS2 filler. A high content of MoS2 decreases the hardness of composite coating and enhances the wear rate. The 1 %-3% content of MoS2 has advantages to the tribological ProPerties of PA composite coatings.     

Electrically high-conductive textiles

The development of textiles with high electrical conductivity, which may be further processed to flexible heating elements is described. Conductivity was obtained by establishing thin layers by impregnation of the textile with thiophene derivative monomer followed by oxidative polymerization. The characteristic flexibility of the textiles could be maintained. Especially the use of multifilament synthetic samples was found to be advantageous. As mechanical properties of treated materials are concerned one finds almost no change in tensile strength (<1%) with PETP and polyamide. With cotton a decrease in strength of about 20% (best value) was observed. The question of ageing will be studied more intensively in future.     

Low-temperature synthesis of N-TiO2 sol and characterization of N-TiO2 coating on cotton fabrics

To extend the application of N-TiO₂ to substrates with low thermal resistance, N-TiO₂ sol has been successfully synthesized at low temperature by reflux method and N-TiO₂ coating on cotton fabrics has been successfully prepared in a dip-coating process. Several characterization tools, such as X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy, were employed to study the phase structures, morphologies, the chemical states and optical properties of the samples. The photocatalytic properties of the prepared products were measured with the degradation of methyl orange at room temperature under visible light irradiation. In comparison with TiO₂-cotton, the remarkable enhancement in the visible light photocatalytic performance of the N-TiO₂-cotton could be attributed to the existence of N-TiO₂ with narrow band gap. The photocatalytic performances of the N-TiO₂-cotton were maintained for the cycling experiments, indicating that N-TiO₂-cotton could be used as stable and efficient visible-light-induced self-cleaning materials.     

Calcium phosphate nucleation on cellulose fabrics

Nonwoven cellulose (regenerated, oxidized) fabrics were coated with hydroxy carbonated apatite (HCA) using a procedure based on a biomimetic method. Simulated body fluid (SBF) with a high degree of supersaturation (5xSBF) was applied to accelerate the biomimetic formation of bonelike apatite on the cellulose fabrics. After creating calcium phosphate nuclei on the cellulose fibers in a first 5xSBF with high Mg²⁺ and HCO₃⁻ concentrations, the cellulose fabrics were additionally soaked in a second 5xSBF which was optimized with respect to accelerated crystal growth by reduced Mg²⁺ and HCO₃⁻ concentrations. The hydroxy carbonated apatite (HCA) layer thickness increased from 6 μm after 4 h of soaking in the latter solution to 20 μm after 48 h. The amount of CO₃²⁻ substituting PO₄³⁻ in the hydroxyapatite (HA) lattice of the precipitates can be varied by changing the soaking time.     

Ceramic coating on ceramic with metallic bond coating

The change in structure and adhesion strength of the interface by heating in air has been investigated for a plasma- sprayed alumina coating on a ceramic substrate with a 50Ni- 50Cr alloy bond coating. A veined structure composed of NiO, NiCr ₂O₄, and NiAl₂O₄ oxides grew from the bond coating into cracks or pores in the top coating and the alumina substrate after heating at 1273 K for 20 h in air. The NiAl₂O₄ spinel may have formed by the oxidization of nickel, which subsequently reacted with the alumina coating or the substrate. The mechanism of the penetration of the spinel oxides into the cracks or pores is not clear. The adhesion strength of the coating is increased to about 15 MPa after heating at 1273 K for 20 h in air, compared to an as- sprayed coating strength of only 1.5 MPa.     

Electrically Conductive Flame Sprayed Aluminum Coatings on Textile Substrates

In this study, electrically conductive and flexible aluminum coatings using powder and wire flame spraying were successfully deposited onto diverse textiles. The influences of various process parameters and fabric materials on the electrical conductivity and microstructure of the metal-fabric composites were investigated. Preliminary results show that to obtain excellent coating surface conductivity values a specific coating quantity of higher than 20 mg/cm² is required. After further optimization of the spraying parameters, very good specific surface conductivities (～500 S_A) could be obtained even with reduced coating quantities. Through an adequate parameter optimization a reduction in the specific coating quantity was also achieved while high conductivity values were retained. In addition, when the coating quantity was reduced, the flexibility of the fabric substrates was better conserved. This investigation illustrates that optimized electrically conductive composites with flexible fabric substrates can be produced without any preliminary thermal or chemical fabric specifications.     

Multifunctional cotton fabrics

Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole on the surface of cotton fibres. In situ oxidative chemical polymerisation were carried out in aqueous solutions of pyrrole, oxidant and doping agents, at room temperature. Polypyrrole-coated fibres were characterized by Light Microscopy, SEM, EDX, FTIR and TGA. Moreover, fabric samples were also evaluated for moisture regain, electrical resistivity, heat generation and antibacterial activity. PPy alters the combustion process of cellulose fibres that maintain the fibrous shape after heating in air. Moreover, it seems that PPy is really an antibacterial agent, apart from the oxidant or dopant used. The results highlight potential applications as technical textiles with antistatic (low electrical resistance), heat generation, hygroscopy, antibacterial and high temperature resistance properties.     

基于SimulationX的电控变速液压系统仿真研究

传统的工程机械变速系统不利于减轻驾驶员劳动强度、提高操作舒适性,而电控变速系统则能很好地解决这一问题。描述了电控变速系统的原理,应用SimulationX软件对该系统压力变化进行仿真分析,总结出影响因素和规律,为系统设计提供理论依据。     

Electrically active polymers and their application

This article reviews some of the applications of electrically active polymers. This field originated about 20 years ago with the discovery that polyacetylene became highly conductive when it was doped (i.e., oxidized). Research in the area of conductive polymers has resulted in some applications, which are discussed in this review. The field has recently, however, shifted to investigating the applications of these polymers in their undoped form, particularly in light-emitting diodes and thin-film transistors. Mary E. Galvin earned her Sc.D. in materials science from the Massachusetts Institute of Technology in 1984. She is currently a distinguished member of the technical staff at Bell Laboratories, Lucent Technologies, in Murray Hill, New Jersey.     

Electrically driven PEDOT/PSS actuators

The film made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) was prepared by casting and electrical conductivity, tensile properties, electromechanical response, and moisture sorption isotherm of the PEDOT/PSS film were investigated. A linear expansion of the PEDOT/PSS film occurred with increasing ambient humidity, where the strain of the film in a RH range from 20 to 90%RH was 3.3%. Upon application of an electric field, the film underwent significant contraction in ambient air. The degree of contraction increased as the applied voltage became higher and the value attained 2% at 35 V, which was nearly twice as that of polypyrrole films. The principle lay in the desorption of water vapor due to local Joule heating, where the electric field controlled an equilibrium of water vapor sorption. The moisture sorption isotherm of the PEDOT/PSS film indicated that the interaction between water and PEDOT/PSS was superior to that between water molecules, in which isosteric heat of sorption decreased with an increase in the sorption degree and the value reached to the heat of water condensation.     

基于PROFIBUS-DP总线的智能阀门电动执行机构的设计

对工业现场总线PROFIBUS-DP进行了详细的介绍,并从分析电动阀执行机构的功能入手,完成了阀门控制器的软、硬件设计.在此基础上,设计了一种基于PROFIBUS-DP现场总线的智能阀门电动执行机构控制系统的新方案,实现了阀门电动执行机构的自动控制、主从分机之间的数字通信等功能.     

Wear-resistant coating on titanium alloys

Perm Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 30–31, January, 1990.     

Molybdenum-on-chromium dual coating on steel

Molybdenum and chromium coatings were deposited on AISI 4130 steel using the Laser Induced Surface Improvement¹ (LISI™) process. In this process a mixture of precursor material is pre-placed on the substrate and then laser melted, resulting in the formation of a thin surface layer of alloy on the underlying material. First, a chromium coating was deposited on steel using the Cr-CrB₂ eutectic composition, and subsequently a molybdenum coating using the Mo-MoB eutectic composition was deposited on the chromium layer. Both the coatings have been individually characterized and compared using scanning electron microscope, energy dispersive spectrometry, Vicker’s hardness, X-ray diffraction, wear and erosion. The chromium layer exhibited superior erosion resistance (ASTM G76) while the molybdenum-on-chromium coating performed better in sliding wear (ASTM G77).