Advanced Materials Research Vols. 887-888

Abstract: Oxygen coefficients of 396 explosives, including liquid and solid explosives, 177 dangerous materials, including oxidants, combustible substances, chemical hazards and narcotics, and 9 common packing materials were collected and compared. It can be seem that the explosives can be distinguished from non-explosives by oxygen coefficient with boundary 0.3 to 1.2. This result can support a convincing proof for explosive neutron detection.

Abstract: Through a qualitative analysis of the combustion outcomes, almost no aldehydes have produced after the burning of the tea-leaves. However, the aldehydes can be produced obviously after the burning of tobacco. When tea-leaves were mixed with tobacco, the harmful substances can be drastically reduced in the burning, such as nicotine. Also, the difficulty of smoking will be intensified with the increase of the content of tea-leaves. People can feel the difficulty of smoking when the content of tea-leaves is over 50%, the feeling can be obviously when the content of tea-leaves is over 60%. It is necessary to control the content of tea-leaves less than 40% to ensure the health of human body.

Abstract: Quantitative fractography is the important tool for evaluating the fatigue propagation life about material research and manufacturing process perfect, it is very useful in the circumstances that crack expands inside of the material or the crack cannot be observed because of the hidden part of the component. In-service components are usually suffered different load spectrums, and the fracture characteristics are combined created by random load spectrum and block spectrum, which are beach marks, small beach marks and fatigue striations. The most important thing for fractography quantitative analysis is to confirm the parameter used for evaluating the fatigue life and determine the relationship between the parameter and load spectrum. The relationships between different fracture characteristics and load spectrums are analyzed, and the selection means of characteristic parameter for different load spectrums are proposed. This paper also discussed a case of fatigue propagation life estimation of some aircraft lower wall panel suffered in-service aircraft flight load spectrum.

Abstract: This study focuses on the process of the matte roughening technique of Sapphire. In order to effectively improve the shortcomings of conventional chemical etching, research adoptsthe micro abrasive jet machining technology with the experimental design method related experiments planned in order to effectively obtain the appropriate surface roughness and processing uniformity. Study found that # 800 Zirconium applied on the surface of sapphire with the initial surface roughness of about 0.9 μmRa for two minutes forms a surface roughness of about 1.1 μmRa. Not only does this conforms to the industrys sapphire surface specifications, it also effectively reduces the coarsening time and associated costs of sapphire.

Abstract: The research progress of conductive coating was introduced. The advantages and disadvantages of the latest technologies of filler modification and coating preparation were all analyzed. The application in power grounding system and research focus in future of conductive coating were explained and predicted respectively, indicating that conductive coating with high conductive performance and being economic and environment friendly would be the main development target in future.

Abstract: In recent years, super hydrophobic surfaces for fluid drag reduction effectively promote the development of drag reduction technique. For the experiment of surface friction test, traditional water tunnel device and popular PIV technique are both complicated and expensive. It is significant to design an experimental device which can be applied easily with little error. In this paper, we design a simple and demountable experimental device for drag reduction based on the calculation of resistance, friction and the specimen strain and deflection. Application technology of strain gauge sensor, the device could realize the drag resistance test on small friction. By means of analyzing the hydrodynamic of test section, we change and simulate partial structure of the test section to optimize the experimental apparatus. With the help of this device, we can measure small friction resistance directly by amplifying and output the small mechanical signals.

Abstract: New waterborne Al-Zn-Si-RE coatings with improved corrosion resistance were introduced in this study. The corrosion resistance of Al-Zn-Si-RE coatings was evaluated by electrochemical measurements and salt spray test. Evolution of microstructure and phase composition at different exposure time in salt spray test was investigated by scanning electron microscopy and X-ray diffraction technique. The results indicate that Al-Zn-Si-RE coatings provide effective sacrificial protection to the steel substrate but exhibit lower corrosion rate and higher corrosion resistance compared to zinc aluminum coatings. The dense continuous corrosion layer formed on Al-Zn-Si-RE coating acts as a barrier layer, limiting the transport of aggressive species towards the coating-substrate interface and the corrosion rate of the coating; Zinc aluminum hydroxy carbonates are the dominant components in the corrosion layer of Al-Zn-Si-RE coatings.

Abstract: Through the analysis of light trapping structures on the surface, the micro nanostructure can play light trapping effect is good. The theoretical analysis is made using the optical principle and metal surface plasma resonance. And through the repeated processing on non-magnetic steel 20Mn23AlV using EDM in different electrical parameters and can be observed in the surface of micro nanostructure through JSM-6360LA type scanning electron microscope.

Abstract: Since the oil price has been significantly jumped for recent some years, the diesel engine of the merchant ship has been mainly used the heavy oil of low quality. Thus, it has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the most parts surrounded with combustion chamber is more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these parts is very important to prolong their lifetime in a economical point of view. In this study, Inconel 718 filler metal was welded with GTAW method in the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal zone, heat affected zone and base metal zone were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H₂SO₄ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. Furthermore, the corrosion current density of the weld metal zone indicated the lowest value, having the highest value of hardness. The corrosive products with red color was more or less observed in the base metal zone, while the weld metal zone exhibited the general corrosion without corrosive products of red color. The microstructure of the pearlite with black color was predominantly observed in the base metal zone, however, the microstructure of ferrite with white color increased increasingly in the heat affected zone, and the microstructure of ferrite with white color was significantly observed in the weld metal zone. In particular, the polarization characteristics such as impedance, polarization curve and cyclic voltammogran associated with corrosion resistance property were well in good agreement with each other. Keywords : Repair welding, Inconel 718 filler metal, GTAW, Weld metal zone, Electrochemical method, Corrosion current density, Hardness. Microstructure

Abstract: The objective of the present study was to find the influence of laser beam shape on macroscopic morphology and microstructure of single Ni60 laser clad tracks. Laser cladding of Ni60 alloy powder can be used to manufacture and remanufacture backup rollers for the steel industry. Controlling temperature distribution can assist with achieving favorable macroscopic morphology and microstructure. Five different beam profiles were used in our experiment to prepare clad tracks. The beam profiles varied in terms of the ratio of energy densities between the internal and external parts. The macroscopic morphology and microstructure was tested using SEM. The study founds decreasing the ratio is possible to achieve wider clad tracks with a larger cross section area. It was found that microstructure in upper region tended to form net-like dendrite microstructure at low energy density ratios.