FDM technology also known as a fused deposition technology is a solid based 3D printing techniques used to create prototypes and working models. It mainly uses PLA and ABS as the printing material. For the experimentation purpose, we printed two bushes, with PLA as the printing material but changing the process parameters for both the prints. The CAD model of the bush was drafted in Solidworks Software and the slicing process of the model for printing purpose was performed in Cura Software which is compatible with Ultimaker 3D printers. The main objective was to print a bush with same material but different process parameters and compare the results obtained.
Extensive experiments of diffusion annealing on zinc plated brass wire have been carried out in the temperature range between120 0 C and 280 0 C. The zinc rich diffused layer at the surface of the wire grows in the initial period of annealing and penetrates into the base of the wire.The diffusion process becomes sluggish and thickness of diffused layer stabilizes after certain time of annealing.A multiplying factor termed as Diffusion Depth Factor (F) has been established and can be used to estimate the thickness of stabilized diffused layer formed during annealing by simply multiplying it with initial plating thickness.
In this paper a comparative study is carried out on binary, NiL2, and ternary NiAL complexes. Where A=2, 24 bipyridyl amine or 2.2 bipyridyl and L=N-N or N-Ō or S-Ō or Ō-Ō donating ligand. The order of stabilities of binary & ternary complexes is explained on the basicities of the ligand & ring size of the chelate. The sequence in order is explained in terms of ML π interaction, size of chelate ring & steric factor. The same order is followed both by ternary complexes and binary complexes.
This review paper gives a brief overview of processing stages and precipitation strengthening mechanism of 6xxx series aluminum alloys. 6xxx series aluminum alloys are widely used in defense and aerospace industries in different forms like sheet, rods, etc. These alloys have high strength in terms of strength to weight ratio. For industrial application these alloys, after direct chill (DC) casting, are homogenized and processed by different fabrication process like hot working, coldworking, process annealing, and strengthened by age hardening heat treatments. This results in the improvements of mechanical properties of 6xxx series alloys for industrial applications. These processing steps and the effect of the precipitations during age hardening are investigated through literature survey.
The polyamine groups were successfully modified in the pores of hierarchical mesoporous bagasse carbon through nitric acid oxidation and ethylenediamine(EDA) polymerisation. The influence of nitric acid concentration, oxidation time, EDA dosage, and modification time on the Pb(II) adsorption ability of the modified mesoporous carbon were discussed in an L9(34) orthogonal experiment as well as the adsorption characteristics and mechanisms. The results suggested that EDA modification conditions significantly affected the Pb(II) adsorption ability. The modified carbons, under different conditions, showed a Pb(II) adsorption difference of 35%; the nitric acid concentration exerted the greatest influence, followed by EDA dosage, and modification time. The carboxylic acid group content in the pores of the biomass carbon was proved as the key agent controlling the Pb(II) adsorption ability of the modified carbon. The Pb(II) adsorption was consistent with the Langmuir model, suggesting that the energy was distributed evenly on the surface of the modified carbon.
In this paper, the stress intensity factor and the initial cracking angle of a crack with an arbitrary oriented direction in a strip material are calculated. The aim is to consider the variation of the angle with the orientation of the cracks and their position. Firstly, the problem is separated by the superposition principle into several sub-problems which are solved using Fourier transformation technique. For the sub-problem of a crack, the unknown dislocation density functions are introduced. Singular integral equations are then obtained and solved by a numerical method. The stress intensity factor and the initial angle are obtained. The results show that crack tends to propagate to the free boundary and the influence of the existence of other cracks on the initial cracking angle can be negligible when the distance between the cracks is larger.
Nanostructured nickel phosphides were synthesized via a thermal decomposition approach. The effect of synthetic conditions such as P:Ni precursor mole ratio, reaction temperature, reaction time, reductant oleylamine quantity and species of additive on the crystalline phase and size of the as-synthesized nickel phosphides was discussed systematically. The results show that lower P:Ni precursor mole ratio, higher reaction temperature, shorter reaction time and the addition of oleic acid were beneficial to form Ni12P5 phase with large size. In contrast, higher P:Ni precursor mole ratio, lower reaction temperature, longer reaction time and the addition of octadecene were beneficial to form Ni2P phase with small size. The variety of oleylamine quantity cannot realize the phase-controlled synthesis, but the size can be controlled. These synthetic method also can be used to synthesize others transition metal phosphides.
Various aspects of preparing band-structure-engineered materials involving nanostructured building blocks are examined in this review. In continuation with enjoying great success in controlling the charge carrier transport propertiesof crystalline semiconductors, it was found better to choose a periodic structure comprising of monodisperse nanocrystals, where the adjustment of the wave function overlaps between nearest neighbors provided sufficient delocalization of the electron states necessary for charge carrier transport with adequate mobility. Of course, for maximum advantage from such a situation, it was necessary to employ monodisperse nanostructured building blocks with uniform inter-dot coupling, which turned out to be rather difficult to achieve in practice. For instance, nanocrystals size variations within 5% are currently considered monodisperse. For achieving higher degree of monodispersity, it is necessary to understand the phenomenon of nucleation and particle formation in more detail by examining the existing models and introducing more refinements, if possible. In case of adjusting inter-dot spacing, molecular linkers are adequately appropriate for this purpose. Moreover, the solution processing of nanostructured species possesses the unique feature of self-assembly, which is currently being explored for hierarchical superstructures ranging from nm to cm scales in dimension. This kind of material growth, being more close to biomimetic processes, when combined with conventional lithography and patterning, would certainly offer opportunities to use these hierarchical superstructures in numerous unprecedented applications.
Aero-engine usually adopts titanium alloys as the compressor blade materials. Owing to their low hardness, however, the solid particle erosion (SPE) resistance of titanium alloys is also very low, and the TiN/Ti coating is an effective method to improve the anti-erosion performance of titanium alloys. To design the structure of TiN/Ti coating and acquire coatings with good performance, the equivalent plastic strain distribution of single layer, three layers, six layers and twelve layers of TiN/Ti coating after erosion by single sand is calculated and the results show that if the total thickness of the coating is constant (3um), the more the layers are, the better the coating’s anti-erosion performance will be. In other ways, the coating erosion-resistant experiments also prove that the SPE resistance of multi-layer coating is excellent.
For reasonable choice of mechanical parameters and keeping long-term sealing performance of cement sheath, effect laws of yield strength and elastic modulus on the interface stress of cement sheath at well head were researched. Finite element mechanical model of the casing-cement sheath-stratum combination was established. Damage conditions of cement sheath structural integrity were analyzed. Results showed that every interface stress increased with the increase of the yield strength while cement sheath yielding deformation occurred. And the yield strength could not affect all interface stresses while the deformation was elastic. For lower elastic modulus, elastic deformation occurred in cement sheath and every interface stress increased with the increase of elastic modulus. For high elastic modulus, Cement sheath was partially or fully yielded. With the increase of elastic modulus, the interface contact stress increased, the inner interface circumferential stress decreased, and the interface contact stress was turned into tensile stress after unloading.
This paper is concerned with the thermoelastic response in a functionally graded solid with an analytical method. The governing equations are proposed in the context of Lord-Shulman generalized theory (L-S theory). The Laplace transform techniques and some approximate treatments are employed to have an analytical solution for the thermoelastic response in a semi-infinite solid composed of functionally graded materials, whose boundary is subjected to a sudden thermal shock. Some important phenomena involving finite speed of heat signal are obtained. The comparison with the results for different values of non-homogeneous index is also conducted to evaluate the effect of graded material properties on thermoelastic response.
Cr3+/Sb5+ co-doped Li4Ti5O12 in the form of Li4Ti5-2xCrxSbxO12 (0≤x≤0.1) compounds were successfully synthesized via solid-state reaction method. The structure and electrochemical properties of the spinel Li4Ti5-2xCrxSbxO12 materials were investigated. The Li4Ti5-2xCrxSbxO12 (x=0.05) presents the best discharge capacity among all the samples, and shows better reversibility and higher cyclic stability compared with pristine Li4Ti5O12, especially at high current rates. When the discharge rate was 1C, the Li4Ti5-2xCrxSbxO12 (x=0.05) sample presented the excellent discharge capacity of 166.7 mAhg-1, which was very close to the theoretical capacity of Li4Ti5O12 (175mAhg-1).
The paper presents the detailed experimental investigation on built parameters of the prototypes by Stereolithography process which uses SL5530 epoxy resin material. Test specimens were fabricated on a SLA 5000 machine manufactured by 3D systems and experiments were carried out for an optimal parametric combination in order to obtain favorable quality characteristic using the Taguchi based Grey relational analysis. A plan of experiments, based on the technique of Taguchi, was performed. Analysis of Variance was used to investigate the quality characteristics of Stereolithography parts. The objective was to establish a correlation between the layer thickness, Orientation, Hatch space and Density with mechanical characterization of the test parts. The optimum machining parameters were obtained by Grey relational analysis for the higher strength of the parts and confirmation tests were performed to make a comparison between the experimental results and developed model. The optimum levels of the parameter contributing to higher strength of the parts and density of the prototype are the end results of the paper, which is very useful information for machine designers as well as RP machine users.
The adhesion problem of aluminum polyethylene sandwich panels is analyzed within the scope of this study. The theoretical necessary adhesion value for maximum shear stress is calculated. A selected area of the panel is scanned with a peeling test. The set limit value of adhesion led to no customer claims within the observed period of six months. The condition of machine elements and the recycled material quality of polyethylene are also determined.
The present study is aimed at evaluating the mechanical properties of aluminium metal matrix composite (AMMC). An effort is made to enhance the mechanical properties like hardness, tensile strength, yield strength, % of elongation of AMMCs by reinforcing AA6061 matrix with Molybdinum di sulfide (MOS2) particles. AMMCs were made, AA6061 as matrix material and MOS2 as reinforcement material, through stir casting method. AMMCs with varying percentage by different wt. %, 1%, 2 %, 3%, 4%,5% MOS2 were fabricated. A systematic study of the matrix metal and AMMCs is done to evaluate the mechanical properties (hardness, yield strength and tensile strength) in as cast and heat treated condition. It was observed that in comparison to the matrix metal, the precipitation kinetic was accelerated by adding the MOS2 particles. It was noticed that, mechanical properties are increasing with the increase in wt. % of the reinforcement up to 4% MOS2 further addition there is a diminution in both the conditions (as cast and cold rolling followed by heat treatment condition). It was also thought-out that 4% MOS2 composite shows better mechanical (hardness, yield strength and tensile strength) properties and low % of elongation than all other compositions in both the conditions. Optical microscopy and Scanning electron micrographs were carried out to authenticate the mechanical properties of the matrix metal and AMMCs.
Metal matrix composites are regarded to be one of the most predominant classifications in composite materials. The thermal characterization of hybrid metal matrix composites has been increasingly important in a wide range of applications. The coefficient of thermal expansion, thermal conductivity, thermal diffusivity and specific heat capacity are the most important properties of Metal Matrix Composites (MMCs). Since nearly all Metal Matrix Composites are used in various temperature ranges, measurement of thermal properties of MMCs as a function of temperature is necessary in order to know the behaviour of the material. In this research paper, the evaluation of thermal conductivity, thermal diffusivity, thermal expansivity and thermal capacity has been accomplished for Al 6061, Silicon Carbide and Graphite hybrid metal matrix composites from room temperature to 300°C. Aluminium based composites reinforced with Silicon Carbide and Graphite particles have been prepared by stir casting technique. The thermal behaviour of hybrid composites with different percentage compositions of reinforcements has been investigated. The results have indicated that the thermal properties of the different compositions of hybrid MMCs vary by the addition of Graphite with Silicon Carbide and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity and thermal conductivity of hybrid composites.
The J-V characteristics of organic hetero junction solar cell of different active layer thicknesses have been simulated by AMPS-1D software. A composite of P3HT: PCBM is used as photo active layer material, sandwiched between a transparent ITO electrode and Al back side contact. The simulation results clearly demonstrated that the dark J-V characteristics and electric field across the junction of hetero junction solar cell are affected by the active layer thickness.
Steel is an alloy EUROFER promising for use in nuclear reactors, or in applications where the material is subjected to temperatures up to 550°C due to their lower creep resistance under. One way to increase this property, so that the steel work at higher temperatures it is necessary to prevent sliding of its grain boundaries. Factors that influence this slip contours are the morphology of the grains, the angle and speed of the grain boundaries. This speed can be decreased in the presence of a dispersed phase in the material, provided it is fine and homogeneously distributed. In this context, this paper presents the development of a new material metal matrix composite (MMC) which has as starting materials as stainless steel EUROFER 97, and two different kinds of tantalum carbide-TaC, one with average crystallite sizes 13.78 nm synthesized in UFRN and another with 40.66 nm supplied by Aldrich. In order to improve the mechanical properties of metal matrix was added by powder metallurgy, nano-sized particles of the two types of TaC. This paper discusses the effect of dispersion of carbides in the microstructure of sintered parts. Pure steel powders with the addition of 3% TaC UFRN and 3% TaC commercial respectively were ground for 5 hours in the planetary mill. Each of the resultant particulate samples were cold compacted under a uniaxial pressure of 600MPa in a cylindrical die 5 mm in diameter. Subsequently, the compressed were sintered in a vacuum oven at a temperature of 1250°C with an increment of 20°C and 10°C per minute and maintained at these isotherms for 60 minutes. The distribution, size and dispersion of steel and composite particles were determined by X-ray diffraction, laser particle size and scanning electron microscopy(SEM). The structures of the sintered bodies were observed by optical microscopy(OM) and scanning electron microscopy(SEM).
We prepared high porous γ-Al2O3 samples via a modified sol-gel method in which polyvinyl-alcohol (PVA) was incorporated to hydrolysis water before the formation of boehmite sol with two different PVA contents (44 and 174 wt%). We compared our results with those of other γ-Al2O3 samples also prepared via sol-gel with different procedures; a sample without additives (sample S) and samples with the same contents of PVA but added to the already synthesized boehmite sol (A-samples); the latter as standard for evaluation of our modified sol-gel method (B-samples).Samples were characterized by means of XRD, adsorption-desorption isotherms of nitrogen at 77K and DTA-TG, and also were investigated against thermal cycling at 600 °C.Pore volume, porosity, BET area, and pore distribution were determined. B-sample with 44 wt% PVA showed similar characteristics to those of A-samples, while an important increase of pore volume, porosity and BET area (50%) was observed for sample with 174% PVA. Pore diameter of B-samples also exhibited a different behaviour with PVA content: addition of 44 wt% of PVA gave a 16% increase while 174 wt% PVA, 42%. These results indicated that adding PVA to the already sinthesized boehmite sol, mainly stabilizes the boehmite structure, without affecting it. On the contrary, incorporation of PVA before hydrolysis influences the particle size in the sol, greatly modifying the final boehmite network and giving place to larger pores in the final γ-Al2O3, this effect being significant when adding 174 wt% PVA. Results of thermal treatments at 600°C showed a decrease in BET area of all samples up to 80h, then stabilised. A minimal effect of the thermal treatments on the pore volume and porosity was observed in all samples while the pore diameter increased, this increase being most important in case of sample with 174 wt% PVA.
