Applied Mechanics and Materials Vols. 490-491

Abstract: The AlN particles reinforced composite was fabricated on the surface of aluminum 6061-T6 alloy rolled plate by five passes friction stir processing (FSP). Microstructure of FSPed sample was characterized by optical microscope and scanning electron microscope. AlN particles in composite were verified by EDS and XRD. Microhardness and resistance to wear were also investigated. Results show that grains in composite were refined by dynamic recrystallization and uniformly dispersed AlN particles. Composite region bonded with the Al substrate well. No reaction occurred at the interface between AlN and Al matrix. By comparison with base metal, the FSP-produced composite exhibited improved microhardness and substantial wear weight loss reduction.

Abstract: The microscopic analysis of 93W-4.9Ni-2.1Fe (wt. %) tungsten heavy alloy by hot-hydrostatic extrusion with severe plastic deformation strengthening were experimentally investigated mainly by transmission electron microscopy. Due to the profound differences in hardness of the tungsten particles and the NiFeW matrix a special TEM specimen preparation method had to be employed.It was shown that the microstructure of the as-extruded alloy was characterized by elongated tungsten particles with refinement cellular sub-structures consisting of high-density dislocations embedded in a binding Ni-Fe-W matrix phase with fine dynamically re-crystallized grains.

Abstract: The purpose of this work is to investigate the effects of flame retardants on long-term aging and rheological characteristics of the modified asphalt binder. The flame retardants included #A (decabromodiphenyl ether, antimony trioxide, and zinc borate with the ratio of 3:1:1 by mass) and #B (tetrabromobisphenol A bis (2, 3-dibromopropyl ether), antimony trioxide with the ratio of 2:1 by mass). The results indicated that flame resistance of asphalt binder increase after PAV and UV aging processing, and the complex modulus also increase. The UV aging brings a plateau region of the phase angle master curves over the intermediate temperature range. This behavior is very weak in the studied PAV aging and unaged asphalt binder. Compared with #B modified asphalt binder, #A modified asphalt binder showed better flame retardancy and rheological characteristics before and after aging.

Abstract: This paper presents the development of the in-process surface roughness prediction in the CNC turning process of the plain carbon steel with the coated carbide tool by utilizing the dynamic cutting force ratio. The dynamic cutting forces are measured to analyze the relation between the surface roughness and the cutting conditions. The proposed surface roughness model is developed based on the experimentally obtained results by employing the exponential function with six factors of the cutting speed, the feed rate, the tool nose radius, the depth of cut, the rake angle, and the dynamic cutting force ratio. The dynamic cutting force ratio can be calculated and obtained by taking the ratio of the corresponding time records of the area of the dynamic feed force to that of the dynamic main force. The relation between the dynamic cutting force ratio and the surface roughness can be proved by the obtained frequency of them in frequency domain which are the same frequency. The proposed model has been proved by the new cutting tests with the high accuracy of 91.04% by utilizing the dynamic cutting force ratio.

Abstract: Sodium borohydride hydrolysis is one of the promising methods for the supply of hydrogen on-board in fuel cell vehicle. A suitable catalyst is required to control the hydrogen release from stable alkaline sodium borohydride solution. The present paper reports the effect of Co (II) doped zeolite-X and K-chabazite catalysts in sodium borohydride hydrolysis reaction. Kinetics of the hydrolysis reaction was observed to get enhanced by the use of these catalysts. Activation energies for Co (II) doped K-chabazite and zeolite-X are found to be 30.7 and 48 kJ mol^-1, respectively.

Abstract: The purpose of this work is to investigate the thermal aging and ultraviolet (UV) radiations aging of SBSMA. Antioxidants and UV absorbers were employed to improve the antiaging resistance of SBSMA in this study. The results indicated that the SBSMA with antioxidants has good heat aging resistance, and SBSMA with UV absorbers blends have good photostability. The compound antiaging agents containing antioxidants and UV absorbers are a best choice to prepare SBSMA with better physical and antiaging resistance. The experimental results also indicated that the effects of antiaging agents on the physical properties of SBSMA are little at low contents. Especially conventional physical properties of SBSMA with 1 wt% of ZDDP and 0.5 wt% of UV531 are close to that of SBSMA.

Abstract: In this paper, the mesoporous silica SBA-15 surface was modified by using silane coupling agent KH-540. In order to investigate the best modification conditions, effects of KH-540 dosage, reaction time and temperature were studied. The modified mesoporous silica SBA-15 was characterized by TGA, FTIR, XRD and N₂ adsorption-desorption etc. The best modification conditions were obtained as follows: KH-540 dosage is 0.5g, reaction temperature is 90°C and reaction time is 4 hours. The results showed that KH-540 is successfully grafted on the surface of SBA-15, the SBA-15-KH540 possess a well ordered hexagonal mesoporous structure. Compared with pure SBA-15, the surface area, the pore size and the pore volume of the SBA-15-KH540 are decreased slightly.

Abstract: Based on the pool film boiling, Heat transfer coefficient and cooling model are established When fogdrop jet into cutting zone to cool high temperature wall. Through the transient experiment of cryogenic gas atomization jet cooling high temperature nickel-base alloy surface with different water dose. The water dose achieving the best cooling effect is 2 ml/min, 4ml/minand 6ml/min under the nickel-base alloy surface temperature at 300 °C, 500 °Cand 650 °C. Then the effect of water density to heat transfer coefficient is discussed. It is indicated that the water dose to the best cooling effect must be equivalent to the amount of water that materials can vaporize and participate in the phase-change heat transfer under certain temperature. When achieving optimal cooling effect, the number of fogdrops participating in phase-change heat transfer to cool high temperature wall are the most , and the heat transfer coefficient reaches the maximum.

Abstract: This doc This paper is concerned with the wetting of Al melt/graphite (C) substrate and Al-Ti melt/graphite (C) under the action of AlF₃-KF salt eutectic. The results show that the intrinsic non-wetting behavior in the Al/C system was confirmed. The reason is because the existence of oxide film of Al melt obstructs the wetting between C and Al melt. However, due to assisted wetting of AlF₃-KF salt eutectic, the good wetting behavior of Al,Al-Ti/C system is attributed to the strong physics wetting and subsequent interaction wetting. During the interaction wetting, Al₄C₃ compound forms at the Al/C interfaces while Al₄C₃ and TiC compounds form at the Al-Ti/C interfaces. In the meantime, high temperature effect formed at the interfaces owing to the reaction between Al-Ti and C attains the thermodynamics transformation condition of Al₄C₃ into TiC.

Abstract: Micromachining techniques has increased the demand for precise and accurate instruments which are used in many industries. Glass materials offer higher challenges in micro machining as they are tough, non-conducting and difficult to machine with conventional machining operations. Electro Chemical Discharge Machining (ECDM) is a new non-conventional hybrid machining process which combines the features of Electrical Discharge Machining (EDM) and Electro Chemical Machining (ECM) to machine both conducting and nonconducting materials. In the present paper effect of various process parameters like voltage, concentration of electrolyte, duty factor and temperature on ECDM process are studied to obtain desired micro channels in soda lime glass. Design of Experiment (DOE) is used to plan and conduct the experiments. The Response Surface Modelling (RSM) is used for characterising non linear output responses in terms of material removal rate and surface finish. Modeled results are validated with experimental values.