Adhesion Characteristics of Carbon Black Embedded Glass/Epoxy Composite

The surface of glass/epoxy composite material was embedded with carbon black which was dispersed in methyl ethyl ketone (MEK) during the curing process to enhance the adhesion strength of the glass/epoxy composite structure. The morphological effect of the carbon black on the surface of composite was observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative chemical bonding analysis with X-ray photoelectron spectroscopy (XPS) was also performed to observe chemical bonding states on the surface. The lap shear strength of the glass/epoxy composite adhesive joints where composite adherends were embedded with carbon black was investigated with respect to the type and amount of embedment. Also, the tensile properties of the carbon black embedded glass/epoxy composites were measured to observe the mechanical degradation of the composite due to the MEK. The surface free energies of carbon black embedded composites were determined from the van Oss–Chaudhury–Good equation to correlate the lap shear strength of the adhesive joints with the surface free energies of composite adherends. From the experimental results, it was found that the carbon black embedment of the composite adherend improved much the bond strength due to the increased surface roughness on nano-scale as well as increased surface free energy.     

25—THE DETERMINATION OF PENTACHLOROPHENYL LAURATE IN TEXTILE AND PAPER MATERIALS

Methods for the quantitative determination of pentachlorophenyl laurate (L.P.C.P.) in textile materials, described in British Standard 2087 and elsewhere, are reviewed, and it is demonstrated that a closer control of the quantities of added reagents is necessary. A modification in this respect to the existing British Standard method is proposed.

A further modification is proposed whereby the existing 2-hr boiling with 4N aqueous sodium hydroxide is replaced by boiling for 30 min with an ethylene glycol solution of sodium hydroxide. This modification gives good recovery of L.P.C.P. for materials containing components such as wax or elastomers, for which low recovery had previously been obtained, and, in addition, considerably shortens the time of the determination.     

Investigation of properties of electric arc ion deposited TiN coating on Al2O3-based ceramic composite

Electric arc ion deposition technique was adopted to deposit TiN coating on Al2O3-based ceramic composite. Scanning electron microscopy and secondary ion mass spectrometry were used to analyze the microstructure, phase constitution, and quality of the TiN coating and the interface. Surface roughness and micro-hardness of the TiN coating were measured to evaluate its quality. Flexural strength of ceramic materials is dependent on both their inherent resistance to fracture and the presence of defects, thus it was used to investigate the effect of electric arc ion deposition technique on the surface modification of Al₂O₃-based ceramic composite. Experimental results show that the higher the deposition bias voltage, the better the coating quality. The TiN coating is homogeneous, with a uniform surface, and free of defects when the deposition bias voltage is 300 V. The TiN coating strongly adheres to the Al₂O₃-based ceramic composite, and the observed elemental interface diffusion strengthens the interface bonding.     

Plastic stresses at the interface crack tip between two different elastic-plastic bonded solids

The stresses in the plastic region near the crack tip in a composite material of two different bonded materials, with an interface debonding zone being free of tractions, have been studied. The constituent materials were assumed to be elastic-perfectly plastic materials in this study. It was shown that, generally, this problem had a unique solution; however, for a particular homogeneous case, when there is one material only instead of two different materials, this problem was found to have two solutions. The first (continuous) solution coincides with that found earlier by Prandtl and later modified by Hill and Sokolovsky. Additionally, a second (discontinuous) solution, unnoticed by Prandtl, Hill, and Sokolovsky, was unveiled. Some reasons are suggested for prefering the second solution, since evidently both solutions cannot be valid simultaneously.     

Welding current prediction in GMAW and UGMAW processes using response surface methodology

Abstract

Among all process variables in gas metal arc welding (GMAW) process, welding current is the most influential variable affecting heat input and weld quality. Its dependence on other process variables in GMAW and universal gas metal arc welding (UGMAW) processes (which makes use of a specially designed torch to preheat the filler wire independently, before its emergence from the torch) has been investigated using four factor five level central composite rotatable design to develop relationship for predicting welding current, which enables to quantify the direct and interactive effects of four numeric factors, namely wire feedrate, open circuit voltage, welding speed and electrode stickout and one categorical factor preheat current. Mathematical models developed show that welding current increased linearly with increaseing wire feedrate and open circuit voltage, whereas it decreased with increasing electrode stickout and preheat current. Numerical optimisation was carried out, and the optimal solutions generated indicate that under the same input conditions higher deposition rates are achievable in UGMAW process.     

Evaluation of airliner cabin textile materials after vapour phase hydrogen peroxide decontamination

Abstract

Decontamination of airliner cabins may be required, for example, in the event of an epidemic or pandemic. To be performed safely, decontamination must be compatible with aircraft materials and systems. This paper examines the suitability, with respect to cabin textiles, of vapour phase hydrogen peroxide for airliner decontamination applications. The effect of vapour phase and liquid hydrogen peroxide on common airliner interior textile materials, namely wool, nylon, polyester, and Nomex, has been studied by examining the physical and chemical changes and the resulting effect on mechanical properties caused by decontamination. The physical changes induced by the sorption of moisture had an effect on the mechanical properties of all of the materials examined. However, only wool attacked chemically by hydrogen peroxide experience a significant effect on its mechanical properties.     

17—WOOL-BALE TIE TENSIONS AND STRENGTHS

The tensions in steel ties around compressed Australian-wool export bales vary with the type and weight of wool, the amount of compression, and the tightness of application of the ties. A cube law relating the tie tension and the clean-wool shipping density of a compressed bale has been found. Design data for a variety of packages of wool are presented from which probable tie tensions in projected high-density wool bales may be predicted. Some aspects of safe working practice in banding compressed-wool bales are considered.     

Sample Processing with Hydrophobic Microfluidics

Hydrophobic microfluidics is a method for controlling fluid flow in microfluidic systems using short restrictions in channel diameter that act as passive valves. Systems designed using hydrophobic microfluidics have the advantage of easily interfacing with external hardware and integrating with external analysis equipment. This allows it to take advantage of both the micro and macro realms, whichever is most suited for the application, as well as allowing for an inexpensive integration of microfluidics into a company's sample analysis protocols. This method of fluid control is excellent for highly parallel sample analysis, such as DNA processing.     

棒形合成绝缘子的雷电冲击放电特性

在实验室中进行了 110、2 2 0kV不同伞盘结构的棒形合成绝缘子的雷电冲击放电特性试验 ,还与瓷绝缘子的特性进行了比较 ,用计算机处理分析试验数据得出了 5 0 %雷电放电电压与绝缘子结构长度的关系曲线。试验结果表明 ,伞盘结构影响因素较大 ,一大一小伞型结构最佳