Abstract: The paper presents some aspects regarding tribological characteristics of composite tops of the electrodes for spot welding. The solution aims to improve the resistance to deformation and high intensity electric current conductibility without loses and excessive local heating. The composite material was obtained by mechanical alloying process, from a mixture of tungsten carbide, chromium, CuNiAl alloy and cooper powder which has been heated in furnace at 1100°C. The embedding process aims to avoid the toxic effects of metallic elements such as Be and Zr, which are usually introduced in cupper alloys for improving the mechanical characteristics. The tribological characteristics and microhardness of the melted zone were measured in order to estimate the strengthening effect obtained by the tungsten carbide presence for different mixture recipe.
Abstract: Photosensitive single mode optical fibers have been embedded in composite sample in order to be used in optical sensors which monitor the health of civil engineering structure.A simple composite with epoxy vinyl ester matrix reinforced with E-glass unidirectional fibers was implemented using two embedded optical fibers. Interfacial adhesion stress was determined using pull-out test and stress values are correlated to fracture mechanisms based on SEM observations.
Abstract: The morphological characteristics as well as important physical and chemical characteristics rice husks were evaluated by different techniques to analyze the suitability of rice husk to adsorb metal ions from water and wastewater. The raw rice husk (RRH), sodium carbonate treated rice husk (NCRH) and metal adsorbed rice husk were analyzed by SEM-EDAX study. Batch sorption kinetics studies were also conducted for Cu (II) to find the corresponding equilibrium time and the percentage removal for each of the experiment in the sorption process. The results of material characteristics and morphological aspects pointed out some properties that can make the sorption processes possible. The copper removal was observed in the range of 90 to 97 % depending upon the other physicochemical parameters of the sorption experiment. The highly efficient low cost and the rapid uptake by the proposed material indicated that it could be an excellent alternative for the removal heavy metal by sorption process.
Abstract: The paper presents research made to achieve environmental powder precursors from a CuSnP alloy, used in the manufacturing process of brazing materials, such as coated rods. The innovation of the paper consists in the elemental participation of the components in the new alloys, procedure that takes place in the alloying process, through coat conditions of the addition materials and by simultaneous obtaining the new precursors that fulfill high friability and deoxidation conditions of the participants in the brazing process. Developing the copper alloy batches is conditioned by a good protection to oxidation and gas absorption from the melting oven atmosphere. In order to protect the melt from the above mentioned phenomena’s we developed a slagging flux, boron-cryolithe type, which has melting proprieties below those of the copper phosphorus alloy, approx. 700°C. The load calculation was made based on the technical characteristics of the industrial base materials that were used, taking into account the loss coefficient of 5%. The melting, casting and cooling of the samples, dimensioned so they will be friable, was accomplished through classic procedures. The grinding of the sample, including the moistening thermic treatments, was achieved by experimental research, followed by calculations, based on the criteria of maximum yield for grinding. Estimating the sample friability, in the preliminary phase of the experimental determinations, was needed in order to restrain the testing domain, through structural and hardness analyses. The chemical composition of the samples was spectral determined on the copper and copper phosphorus programs.
Abstract: The paper presents research conducted in order to achieve some self-shielding armor with high and pre-established strength to intense wear abrasion combined with corrosion, in damp environment, with sulfur content, at temperatures up to 500°C. The first stage was dedicated to the elaboration of the concept of armor and the hardfacing technology, using a hyper-entropic filler metal which assures a self-protection characteristic. The samples used in the experiment were mild steel plates covered with weld in the rhomboid form. In the next stage some investigations were conducted in order to manufacture of new welding materials such as Fe-22%Cr-Mo-V deposited by welding in certain circumstances, having the hardness after welding about 30 HRC. This weld deposit becomes harder after a short working time, having average hardness value of 55 HRC. In stage three some exploratory research was done in order to establish the welding parameters for obtaining the self-protection layers of hyper-entropic material. In the final stage the armor element achieved was tested, to determine performance characteristics during working into the mill fan. After 2 weeks, some samples were sectioned in order to measure the hardening effect during working.
Abstract: The use of laser cladding (LC) technology for the improvement of surface properties in various mechanical design applications has given rise to the development of application-oriented composites. The present paper furnishes relevant notes on an experimental approach to the design optimization of experiments regarding WC-Co based layers obtained by laser cladding. The current paper emphasizes the influence of parameter variation on the characteristics of the deposited layer and reports the manner in which the heat input and the laser power density influence the microstructure.
Abstract: This paper presents the erosion behavior of the metallic structure of the roller coaster’s carriage using an experimental method for erosion evaluation which permits a comparison with several theoretical models. The roller coaster’s carriage body is a rigid metallic structure and most of the times, for an appealing design, the surface of the carriage is coated with a composite material which uses a non-metallic matrix. It is expected that the experimental study to be extrapolated to another mechanical system which is moving outside.
Abstract: This paper presents a numerical analysis of the inlet-combustor interaction and flow structure through a scramjet engine at a flight Mach 6 with cavity based injection. Fuel is injected at supersonic speed of Mach 2 through a cavity based injector. These numerical simulations are aimed to study the flow structure, supersonic mixing and combustion for cavity based injection. For the reacting cases, the shock wave pattern is modified which is due to the strong heat release during combustion process. The shock structure and combustion phenomenon are not only affected by the geometry but also by the flight Mach number and the trajectory. The inlet-combustor interaction is studied with a fix location of cavity based injection. Cavity is of interest because recirculation flow in cavity would provide a stable flame holding while enhancing the rate of mixing or combustion. The cavity effect is discussed from a view point of mixing and combustion efficiency.
Abstract: Detonation is the supersonic mode of combustion process which is essential for energy release from combustion process. Detonation is the more energetic process compare to deflagration mode of combustion process. The turbulence combustion flame cannot transit itself into detonation combustion process. So objective of this paper is to investigate the effect of obstacles configuration landed in detonation tube channel to propagate the detonation wave and diffraction encounters in an obstacles site. Four different cases of obstacles blockage ratio (BR) 0.4, 0.5, 0.6 and 0.7 were studied for detonation flame acceleration in detonation tube. A three dimensional computational simulation was done using unsteady green-gauss cell based solver for adopting the combustion simulation. As a result detonation flame propagation, detonation flame velocity and detonation flame pressure were increase in reducing blockage ratio from 0.7 to 0.4 and eddy viscosity of combustible mixture was increase with increasing the blockage ratio. From the analyzed four blockage ratio BR=0.4 is suitable for detonation mode of combustion and flame acceleration.