International Journal of Microstructure and Materials Properties (13 papers in press)
Vegetable Oil Quenchants: A Review
by Rosa L. Simencio Otero, Lemmy Meekisho, Lauralice C.F. Canale, George E. Totten
Abstract: For thousands of years, vegetable oils have been used as cooling media to heat treat metals. However, the motivation for employing quenchants formulated with biodegradable, non-toxic and renewable base stocks has seen significant increase due to the environmental appeal to replace petroleum based quenchants. This paper presents an overview of the main aspects and characteristics of vegetable oils that directly influence their commercial application such as structure, classification, biodegradability and toxicity, quenching properties, oxidation and inhibition, and wetting. Further, some applications of vegetable oils as quenchants will be discussed here.
Keywords: Quenching; Heat Treating; Heat Transfer; Vegetable Oil; Triglycerides; Hardening.
Surface Morphology Analysis of AISI-D3 Tool Steel Using Rotary Tool Electric Discharge Machining Process.
by Anand Prakash Dwivedi, Sounak Kumar Choudhury
Abstract: Electric Discharge Machining is one of the most prominent machining processes, which is used across the world for machining and creating intricate shapes in very hard-to-cut electrically conducting materials.
This comprehensive study aims to investigate the surface modification and characterization of thin AISI-D3 tool steel sheets and provides a thorough information about the material characteristics, which are quite vital from the design and reliability point of view.
The analysis shows that the average improvement in the final surface finish of the machined surface is close to 12%. In addition, the energy dispersive spectroscopy images confirm the presence of 2.1% copper and 25.22% of carbon on the workpiece surface, showing the tool material transfer at the workpiece surface. Moreover, the scanning electron microscope images confirm the presence of a thinner recast layer, fewer micro-cracks and very less embedding of tool material on the workpiece surface as compared to the stationary tool process.
Keywords: Electric Discharge Machining (EDM); Energy Dispersive Spectroscopy (EDS);
Scanning Electron Microscope (SEM); Micro-cracks; Recast layer.
Determination of temperature-dependent Youngs modulus of Bulk Metallic Glass
by Suresh Kaluvan, Haifeng Zhang, Sanghita Mridha, Sundeep Mukherjee
Abstract: Bulk metallic glasses are fully amorphous multi-component alloys with homogeneous and isotropic structure down to the atomic scale. Some attractive attributes of bulk metallic glasses include high strength and hardness as well as excellent corrosion and wear resistance. However, there are few reports and limited understanding of their mechanical properties at elevated temperatures. We have used two methods in this paper to determine the Youngs modulus of a bulk metallic glass, Zr41.2Ti13.8Cu12.5Ni10Be22.5 at elevated temperatures: sonic resonance method and nanoindentation. In the sonic resonance method, the measurement system was designed using a laser displacement sensor to detect the sonic vibration produced by a speaker on the specimen in high-temperature furnace. The OMICRON Bode-100 Vector Network Analyzer was used to sweep the frequency and its output was connected to the speaker which vibrated the material in its flexural mode. A Polytec OFV-505 laser vibrometer sensor was used to capture the vibration of the material at various frequencies. The flexural mode frequency shift due to the temperature variation was used to determine the Youngs modulus. The temperature range of measurement was from 50
Keywords: Metallic glass; Young’s Modulus; Nondestructive test; Sonic resonance; Elevated Temperature; Flexural mode vibration.
Study of Crystal-Amorphous Phase Transition and Morphologies of Metal Nanoparticle Fe under Annealing
by Kien Pham Huu
Abstract: The present work investigates the crystal-amorphous phase transition and morphologies of metal nanoparticles Fe (NPs) using means of molecular dynamics (MD) simulation. Tracing the number of crystal atoms and the analysis of radial distribution functions, we found that the amorphous Fe NP is transformed into bcc crystal one when it was annealed for long times at 900K. At the early stage of the annealing, small nuclei form in different places of NP and dissolve for short times. After long times some nuclei form and gather nearby which creates the stable clusters in the core of NP and to spread into the surface of NP. Based on the mean potential energy per atom analysis and MD data visualization technique, the effect of B atoms that prevent the growth of crystallization as well as the different morphologies of Fe and FeB NPs have been investigated in detail.
Keywords: phase transition; annealing; morphologies; crystallization; amorphous.
Analysis of Influence of Ultra-hydrophilicity of Oxidation Titanium Surface on Blood Compatibility Based on Density Functional Theory
by Qiongjian Huang
Abstract: Based on the density functional theory, it adopts the first-principles method to calculate the ultra-hydrophilicity of oxidation titanium surface under different oxygen vacancy concentrations. The calculation results show that under the practically feasible oxygen vacancy concentration range, with the increase of the oxygen vacancy concentration, the ultra-hydrophilicity of oxidation titanium surface is increased, and the semiconductor type of the oxidation titanium is transformed from p type to n type. When the oxidation titanium surface is in contact with blood, the n-type semiconductor and the features of the electron state occupying the bottom of conduction band of the oxidation titanium surface can suppress the transfer of charge from the fibrinogen in the blood to the oxidation titanium surface so to suppress the aggregation and activation of blood platelet, thus improve the ultra-hydrophilicity of oxidation titanium surface on blood compatibility.
Keywords: Oxidation Titanium;Oxygen Vacancy; Electronic Structure; Blood Compatibility.
Structural, optical and electrical properties of CuBiS2 thin films deposited by spray pyrolysis at different deposition times
by Abdelfatah Mansour, Islam Elradaf
Abstract: Reproducible and good quality copper bismuth sulfide (CuBiS2) thin layer were situated on preheated glassy slide substrates made implementing the spraying pyrolysis approach at distinctive times of spraying 15, 30, 45, and 60 min with a fixed substrate temperature 400 oC. The effect of spray time on the structural, morphology, optical and electrical benefits of the CuBiS2 thin films produced by spray pyrolysis methodology were studied. The structure was studied by XRD methodology. The surface texture of the produced films was considered by SEM. The optical benefits of the CuBiS2 films were inquired working with the spectrophotometric method in which the optical transmittance and reflectance beyond a wavelength range 200-2500 nm were measured. The d.c. conductivity was studied at different temperatures for all the prepared CuBiS2 thin films.
Keywords: Copper bismuth sulfide; Spray pyrolysis; Optical; Band gap; Electrical.
Modelling and Simulation of a Bending Process for S34MnV Steel
by Zhiqiang Hu, Kaikun Wang, Yan Yang
Abstract: To investigate the hot deformation behavior of S34MnV steel, hot compression tests in different deformation conditions were done. According to the experimental data, a constitutive equation was established and a mathematical model for dynamic recrystallization was established to predict the volume fraction of dynamic recrystallization. To reveal the plastic deformation, the bending process for a large S34MnV marine crank was simulated by Deform-3D. The stress and strain field of the bending process was obtained and analyzed based on the simulation. Finally, to study the effect of the bending process on the crank, a bending process of a crank produced with a hydropress in the factory was studied. The microstructure and mechanical properties in three different positions of the bending crank were analyzed. It was concluded that the bending process would reduce the uniformity of the microstructure and mechanical properties, owing to the nonuniformity of the deformation.
Keywords: Hot Deformation Behavior; Modelling and Simulation ; Bending Process.
Micro-structural and Interfacial Transition Zone investigation on Oil Palm Shell lightweight concrete.
by Muthumani Krishnamurthy, Swamy Nadh Vandanapu
Abstract: Oil palm shell (OPS) aggregates can be used as a replacement of coarse aggregate in concrete to produce lightweight concrete. OPS is found to absorb more water compared to normal aggregate. Hence, surface treatment is carried out on OPS and the effect of water cement ratio on strength of concrete is investigated. This paper presents X-ray diffraction analysis carried out for treated and non-treated OPS (NTOPS) aggregate to find the mineralogical characteristics. Microstructural analysis and interfacial transition zone is investigated for treated and NTOPS using digital image processing or digital microscope. The results of investigation is compared with conventional
Keywords: micro-structure; interfacial transition zone; treated oil palm shell; non-treated oil palm shell; lightweight concrete; conventional concrete; surface treatment.
Effect of deposition temperature on structural, optical and electrical properties of chemically deposited thermochromic Cu2HgI4 thin films
by Abdelfatah Mansour, Islam El Radaf
Abstract: Copper mercury tetraiodide thin films were grown by the chemical bath deposition technique at different deposition temperatures varying from 300 to 345 K. The structural properties of the prepared Cu2HgI4 thin films show that the Cu2HgI4 films have a polycrystalline nature. The compositional analysis confirmed the nearly stoichiometric structure of the deposited Cu2HgI4 thin films. Homogeneous and regular surface morphology, including of circular-shaped grains with a size range from 31 to 46 nm, was revealed. Thermal stability and phase transition were studied by means of thermogravimetric analysis (TGA) and differential thermal analysis (DSC), respectively. The effects of deposition temperature on the optical properties and D.C. electrical conductivity of the Cu2HgI4 films have been studied. The films were found to have an indirect optical energy gap of values increases with increasing substrate temperature. The electrical conductivity increases with increasing temperature according to grain boundary trapping model.
Keywords: Cu2HgI4; DSC; TGA; Optical; Electrical conductivity.
Strength and Microstructural Characteristics Evaluation of a Fibre Reinforced Fine Grained Soil Using Taguchi Technique
by Amit Kumar, Dharmender Kumar Soni
Abstract: The viability of Taguchi technique to optimise the unconfined compressive strength (UCS) of polypropylene fibre (PPF) reinforced cohesive soil has been investigated in this paper. Dominating factors for UCS optimisation have also been reported. Egg shell powder (ESP) and sodium chloride (NaCl) was used to treat the soil and 7, 14 and 21 days cured specimens were tested. The samples were prepared by design of experiments (DOE) produced by Taguchi technique those arranged in orthogonal arrays (OA). Experimental results were analysed by performing analysis of variance (ANOVA). Finally, optimised conditions were experimentally verified. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) results were also studied to explore the microstructural changes and elemental analysis of subjected soil. Results obtained from this study might be used for pavement design and ground improvement for foundation works.
Keywords: unconfined compressive strength; egg shell powder; sodium chloride; polypropylene; optimisation; Taguchi; microstructural analysis.
Asymmetric Gated Ge-Si0.7Ge0.3 nHTFET and pHTFET for Steep Subthreshold Characteristics
by Suman Lata Tripathi
Abstract: The miniaturization of transistors imposes thermal limits on MOSFET structures due to increase in leakage current and static power consumption per unit area of chip below 20nm technology node. Tunnel FET has potential to reduce static power consumption to design below 20nm technology within thermal limits thus increases the scope of future scaling trends. A new asymmetric Ge-Si0.7Ge0.3 hetero-junction tunnel FET(HTFET) is proposed with different oxide thickness from source and drain side. The asymmetric Ge-Si0.7Ge0.3 HTFET has steep subthreshold characteristic, low value of DIBL with high ION/IOFF current ratio for operating voltage less than 1V. The steep subthreshold characteristic is essential to reduce static power by reducing leakage current. The low value of DIBL ensures better control of gate over the channel with lesser variation in threshold voltage depending on drain bias conditions. The proposed design can be fabricated easily due to the similar lattice structure of Ge and Si. The tunneling current is also high due to smaller tunneling distance of narrow band gap material like Ge and SixGe1-x. Junction-less (less doping variations) behavior incorporated with Ge-Si0.7Ge0.3nHTFET enhances the ION/IOFF current ratio. The proposed nHTFET and pHTFET are designed and optimization has been done to match their characteristics in ON and OFF state for CMOS applications. The ION/IOFF current ratio greater than 108 is achieved for gate length of 15nm in nHTFET having Pt/HfO2 as gate contact and oxide material. The lowering of parasitic BJT effect in OFF state condition is also achieved in the same. The parasitic BJT effect is due to the capacitances formed between drain-gate, source-gate and gate-substrate that further responsible for transistor delay in circuit. All the design and analysis have been carried out on 2D/3D visual TCAD device simulator.
Keywords: Band to band tunneling;Drain induced barrier lowering (DIBL); Subthershold slope (SS); Hetero-junction; Narrow band gap material.
Micro hardness and corrosion properties of A390alloy + x vol. % Zirconium dioxide (ZrO2) composites processed by P/M method
by Karthikeyan S, M. Subramanian, Ashoke Ghosh, M. Prashanth, R. Karunanithi
Abstract: A390+X vol. %ZrO2 (X=5, 10, 15) composites have been fabricated through P/M technique. The mixed aluminum alloy and zirconium oxide powders were cold compacted at 200MPa and sintered at 580
Keywords: A390 alloy; Zirconium Oxide; Corrosion; Vickers micro hardness; Powder Metallurgy.
Comparison of texture evolution in low carbon steel fabricated by plane strain and multi-directional forging of the martensite starting structure
by Mahdi Saalari
Abstract: It has been clarified that deformation and annealing of martensite starting structure can produce ultrafine grained structure in low carbon steel. This study aims to investigate the texture evolution and mechanical properties of samples with martensite structure deformed by two different forging processes. The martensitic steel samples were forged by plane strain compression and multi-directional forging up to the same true strain of 2. All samples were then annealed at 450 and 550
Keywords: texture evolution; martensite treatment; multi-directional forging; plane strain compression; low carbon steel; mechanical properties.