Rajkumar Singh

Effect of Coolant Pressure on Machinability of Titanium Alloy Ti6Al4V

Titanium alloy Ti6Al4V comes with several desirable and undesirable properties. Its low thermal conductivity and high chemical reactivity makes it difficult for machining producing high cutting temperature and adhesion tendency. Cutting fluids are used to remove the heat generated at the chip tool interface during the machining process. The coolant with low pressure and improper delivery is not able to break the vapor barrier created by high cutting temperature. The current research investigates the effect of using high pressure coolant system (60 Bar) on the machinability of Ti6Al4V. The machinability was measured in terms of chip breaking, chip thickness, surface finish, tool wear, etc. A detailed statistical and chip mechanism analysis was performed emphasizing the phenomenon of shear band formation, crack formation, chip thickness, chip serration frequency, etc.

Effect of High Pressure Coolant on Tool Wear Phenomenon during Machining of Titanium Alloy Ti6Al4V

Titanium alloys are referred to difficult-to-cut materials because of its some inferior properties like low thermal conductivity and high chemical reactivity. To improve machinability of these alloys one way is to use cutting fluids which removes the heat generated at the chip tool interface during the machining process. But coolant with low pressure and improper delivery is not able to break the vapor barrier created by high cutting temperature. The present work investigates the effect of using high pressure coolant system (50 Bar) on machinability of Ti6Al4V. The machinability was measured in terms of tool wear. The dominant tool wear mechanism was investigated by using scanning electron microscopy and energy dispersive X-ray analysis of worn out cutting tool surfaces. Abrasion wear on flank face and crater wear on the rake face was observed as a dominant tool wear mechanism. Along with this diffusion of titanium from the work surface to tool face is also confirmed.

Influence of heat treatment on mechanical properties and microstructure of EN AW 6082 aluminum alloy

The mechanical properties and microstructure of heat treated 6082 wrought aluminum alloy was studied. The aim of this work was to study the merits and demerits of natural aging and artificial aging on material properties. The precipitation hardening of aluminum alloy usually undergoes a thermal treatment consisting of heat treatment, quenching and aging. Experiments were carried out for different natural aging time (10 min, 30 min, 60 min and 120 min) and at different artificial aging temperatures (150 °C–210 °C at an interval of 10°C). The results were analyzed with optical microscope, scanning electron mic roscope (SEM), XRD and transmission electron microscope (TEM). The results showed that the type and distribution of precipitates significantly affect the mechanical properties. Natural aging affect the formation of metastable (Mg5Si6) precipitates and stable (Mg2Si) precipitates, Peak hardness (strength) is achieved by metastable precipitates. As the natural aging time increases sides for the nucleation of precipitated decreases, hence the strength decreases.

Parametric Analysis of Cylindrical Plunge Grinding on Micro-Alloyed Steel Using Taguchi Analysis

In the automotive industry, grinding of round diameters is an important process, to achieve desired tolerances and finish. While the effect of grinding parameters namely cutting velocity, work velocity and infeed (or downfeed) on grinding forces and surface integrity (that includes finish, residual stresses and subsurface damage) have been studied extensively in the literature, the effect on material removal rate (MRR) and dimensional accuracies has been given very limited attention. This work involves the analysis of effect of grinding parameters namely cutting velocity, work speed and infeed on MRR, surface finish (Ra) and dimensional accuracies by performing experiments on micro-alloyed steel bars. A series of cylindrical plunge grinding experiments were performed on round bar using CBN grinding wheel. The results show that, to achieve minimum surface roughness (Ra), infeed is the most influencing input parameter, whereas to achieve maximum MRR, work speed influences the most. An increase in infeed and a reduction in cutting velocity and work speed, leads to an increase in finish on ground surface. Also, an increase in infeed and cutting velocity, and a reduction in work speed results into an increase in MRR. The results show that, dimensional accuracies such as diameter, ovality and taper of ground surfaces have not been affected significantly.

Effect of Axial and Torsional Vibrations on Tapping Performance

Abrupt breakage of the taps is frequently encountered during tapping threads, especially when tapping on ‘difficult-to-cut’ material like titanium. This work therefore presents an extensive experimentation with the Taguchi approach to investigate maximum torque in tapping on titanium alloys while performing axial and, axial and torsional vibration-assisted tapping (AVAT and ATVAT). The experimentation shows that both AVAT and ATVAT reduce the tapping torqueduring tapping as compared to that of in conventional tapping process. However, ATVAT process had exhibited a higher degree of reduction in torque when compared to AVAT process.

Optimization of process parameters by using Taguchi method for bainitic steel machining

N including quantum dots, fullerenes, nanoparticles (zero dimension), nanotubes, nanowires, nanofibrils (one dimension), and graphene (two dimension) possess intriguing physical, chemical and biological properties. As a consequence, these materials form the basis of many interdisciplinary studies, where scientists have been inspired by self-assembly processes occurring in nature to construct advanced nanomaterials with applications in many fields. Self-assembly involves the organization of molecules into highly ordered structures through specific, local interactions among the components, without any external direction. Weak interactions, such as Van der Waals, electrostatic, and π-π interactions, as well as hydrogen bonding, and halogen bonding can lead to all kinds of challenging self-assembled nanostructures. The hierarchical structures of many peptides are attributed to self-assembly, therefore, could potentially act as building blocks for new materials with significant functionalities and a range of biological functions. In our recent work, non-covalent interactions including hydrogen bonding, hydrophobic interaction and electrostatic interaction were employed to modulate the peptide assembled nanostructures. We could successfully realize the peptide assembly transition from nanospheres to nanofiber by tuning hydrogen bond and hydrophobic interaction; furthermore, two dimension peptide nanopatch could be constructed instead of nanofiber by introducing the terminus intermolecular hydrogen bonding between the peptide and small molecules. The electrostatic interaction was proved to play an important role in peptide self-assembly and disassembly. Furthermore, it is significant to be addressed that the mechanical properties of peptide assemblies do changing after the nanostructure transition of peptide occurred. These peptide-based nanostructures could potentially be applied to be a candidate of biomaterials with potential importance in a wide range of technological applications.Z oxide (ZnO) nanoparticles (grown in the template of folic acid) are biologically useful, luminescent material. It can be used for multifunctional purposes, such as biosensor, bioimaging, targeted drug delivery and as growth promoting medicine. Though, ZnO is categorized as: “generally recognized as safe” (GRAS) but ZnO nanoparticle system may be cytotoxic. ZnO nanosystem could be of important relevance in the context of nanomedicine, where targeted treatment of biological systems at molecular level is a necessity. ZnO quantum dots with their surface modification and bio-conjugation for selective destruction of tumor cells and their potential use for drug delivery applications is the cardinal issue of this presentation..Nano-sized particle incorporation into metal matrix for fabrication of advance surface coatings find variety of applications in surface protection techniques. Al 2 O 3 , Cr 2 O 3 and SiO 2 nanoparticles have been codeposited with Zn using electrodeposition process to produce Zn nanocomposite coatings. The fabricated coatings were characterized using Scanning Electron Microscope affixed with Energy Dispersive Spectroscopy and X-ray diffractometer. The mechanical and tribological properties of the coatings were investigated using diamond microhardness indenter and dry abrasive wear tester. Zn-10g/L Cr 2 O 3 nanocomposite exhibited the highest microhardness of 228 HV and Zn-5g/L Al 2 O 3 nanocomposite possessed the highest corrosion resistance and lowest wear loss. Zn-5g/L SiO 2 nanocomposite showed good stability as compared to other composite coatings. The incorporation of the nanoparticles of Al 2 O 3 , Cr 2 O 3 and SiO 2 induce grain refinement and modify crystallographic orientation of Zn matrix. Zn-5g/L Al 2 O 3 and Zn-5g/L SiO 2 proved to be better coatings which can find variety of industrial applications where both mechanical and electrochemical properties are required.The existence of vibrations in undesired parts of mechanical machinery, civil structures, aerospace and automotive components,will cause overall setback and efficiency reductions in processes when the above parts are used. Hence is advising to completely get rid of the unnecessary vibrations or reduce them to a minimum possible value. This experiment is an effort to reduce these vibrations using Magneto Rheological fluids. A Magneto Rheological fluid provides viscous damping. The damping factor increases when a magnetic field is applied and is multiplied as the strength of the magnetic field is more, also the natural frequency of the body under test changes from to a value which is different from the initial value. This technique was utilized and a three layered MR fluid sandwich beam was fabricated. This beam was subjected to testing and analysis under both undamped and damped conditions. The controllability of variations in the various dynamic parameters like natural frequencies, vibration amplitudes and damping factors were observed. A reduction is natural frequency of beam was obtained in the presence of MR fluid under magnetic field, from 550 Hz to 300 Hz. Keywords: Magnetorheological fluid, MRFluid sandwich Beam, Natural frequency, Damping factor, Damping coefficient.A perovskite-like phase, K3B6O10Cl exhibits a large second harmonic response about four times that of KH2PO4 (KDP) and is transparent from the deep UV (180 nm) to middle-IR region. A high quality single crystal of K3B6O10Cl with dimensions up to 30 × 15 × 7 mm3 was successfully grown by the top-seeded solution growth method. Crystal morphologies and growth habits of K3B6O10Cl grown with seeds oriented along [101] and [211] were studied, and the best growth direction was obtained., The refractive indices of the crystal were measured by the minimum deviation technique and fitted to the Sellmeier equations. The nonlinear optical coefficients have been determined by the method of Maker fringes at λ=1064 nm. The suitable nonlinear optical coefficients as well as comparatively easy crystal growth make the K3B6O10Cl crystal a promising candidate for NLO materials.A carbon and fiberglass are the two mostly studied materials in air filtration industry due to their good performance with associated low cost. The advancement in the field of nanoscience and nanotechnology produced materials with improved properties than conventional materials. Nanofibers are one of the nanotechnology products, which have been explored for applications such as healthcare, water, energy, electronics, catalysis, environmental, air filtration, bioengineering and biotechnology. Pores and pore size distribution of nanofibers can be easily tunable. Recently, they have been explored in various air filtration products such as high efficiency particulate absorption (HEPA) filters and so on. In this talk, various nanofibers that are electrospun and deposited on HEPA filters, process variation, additives addition, and their performances, challenges faced and their potential application in air filtration industry will be presented.O (OA) and meniscus injury are often met from injury and aging. In the USA alone, approximately 50 million people are affected by OA, and over 50% among them require replacing total joints, which cost approximately

Grain Refinement in Ti‐6Al‐4V Alloy during Thermo‐Mechanical Processing and Investigation of Flow Properties

15 billion per year. Tissue engineering (TE) approach to cartilage regeneration has promises to repair damaged or diseased cartilage. Biodegradable scaffolds as one of key elements in TE are expected to offer a complex biological microenvironment mimicking with native tissue to promote cell ingrowth and tissue regeneration. However, current scaffolds cannot simulate the complex microenvironment of native cartilage. To the end, our group developed a biodegradable extracellular matrix (ECM) hydrogel derived from pig cartilages. The hydrogel contained complex components including collagen, glycosaminoglycan, growth factors and peptides, which were mimetic with biological components in the cartilage. This hydrogel solution was flowable at 4oC and formed a solid hydrogel at a body temperature, which is appropriate for non-invasive surgery. The mechanical properties of the hydrogels could be tuned by altering ECM concentration. The chondrocytes survived and proliferated inside the hydrogel with a round shape due to a good cellular microenvironment. The hydrogel solution was easily injected into a mouse subcutaneous model and formed a solidified hydrogel in vivo. No severe immunogenetic response was observed till to 7 day implantation, indicating a good biocompatibility. The attractive injectability and biomimetic complexity showed that the cartilage-derived hydrogel would be a good candidate to be applied for cartilage regeneration.T development of silver nanoparticle (AgNPs) as a potent alternative to conventional antibiotics has been extensively investigated over the last decades. However, due to the prominent cytotoxic effect of silver on mammalian cells, there is always strong motivation to develop alternative technology that can compact bacterial infection without affecting the mammalian cells. Capping AgNPs with appropriate functional groups and incorporating them into a polymeric matrix is a feasible alternative to overcome these limitations. AgNPs with different chemical structures (nanocapsules and nanoparticles) and functionalities (polymer, lipid, and starch) were synthesized. To demonstrate application as antibacterial coatings, the stabilized AgNPs were then immobilized onto model surfaces made of a thin layer of allylamine plasma polymerized film. This substrate-independent technique preserves the AgNPs functionalities for a longer period of application time. All fabricated surface coatings exhibited superior antibacterial activity against four important Gram-positive and Gram-negative pathogens. This study further aimed to focus on investigating the effects of AgNPs surface components on delivery of engineered AgNPs from the coatings into the human fibroblast cell as well as bone marrow derived macrophages (BMDM). Most of the surfaces did not affect BMDM function or viability and demonstrated no toxicity toward fibroblast cells, except for lipid coated nanosilvers. Therefore, the chemical structures of nanoparticles significantly affect the coatings’ antibacterial, biofilm prevention and biocompatibility capabilities. We believe that such biocompatible nanostructures are of potential interest for various biomedical applications such as smart drug carriers and antibacterial coatings for medical devices and wound dressings.I order to develop compliant seal systems for SOFCs operating in the temperature range of 800-950°C, this project has focused on iterations in materials systems. The materials consisting of composites of a base glass with appropriate ceramic components in order to identify a stable sealing system with adequate and acceptable thermal characteristics, such as, the viscosity and coefficient of thermal expansion. Appropriate viscosity was targeted to ensure good flow behavior of the glass at temperatures where fuel cells operate and sealing effects are required. Viscosity variation in the composites was brought about by the selection of ceramic additives; a large number of candidates ranging from phase pure alumina, magnesia, ceria and barium zirconate, to ceria doped with 10 mole % gadolinium oxide (GDC). SCN1 glass (trade name of sealing glass developed by SEM-COM) was used as the base component, whose composition was such as to provide a CTE match with the SOFC system (in the RT-Tg range), when composited with a second ceramic phase. Additives in both nanoand micro-scale dimensions (as fine powders or in the form of fibers) were introduced mainly to block the bubbles from moving but also to make the composite structure stronger. In addition, their role was also to inhibit the growth of air bubbles within the glass matrix and to or prevent their coalescence during long soak-time at 850°C, with the goal of eliminating or minimizing the CTE drift in the resultant glass composition. No reaction between SCN1 glass and the GDC additives was discerned. Moreover, the bubbles remained small and did not move or coalesce. The CTE of the GDC composites was very close to the targeted value and not change significantly when aged up to 232 h at 850°C in air.

FE Modelling of Residual Stresses and Validation Using Chip-Mechanism and Microstructural Analysis of Ultrasonic Vibration Assisted Turning of Ti Alloy Ti-6Al-4V

The flow properties of thermo-mechanically processed Ti-6A1-4V alloy were investigated in this study. Two samples from as received Ti-6A1-4V alloy plate with consisting coarse s grains of ~ 170 µm size were rolled at 940°C and 550°C respectively. In hot rolled (940°C) sample fully equiaxed microstructure with average grain size ~ 2.3 µm was produced. In warm rolled (550°C) sample, heterogeneous microstructure was produced, which consists of elongated and partially equiaxed grains. To investigate flow properties of hot and warm rolled Ti-6A1-4V alloy samples, differential strain rate tests were performed. Strain rate sensitivity (m) values and apparent activation energy (Q) for were calculated for both hot and warm rolled samples.

Effect of α and β Phase Volume Fraction on Machining Characteristics of Titanium Alloy Ti6Al4V

Ultrasonic assisted turning (UAT) is a novel manufacturing technology, where high frequency vibrations are imposed on the movement of a cutting tool. A 2D FE transient simulation is developed in DEFORM, where ultrasonic vibrations of frequency 20 kHz and amplitude of 20 μm are provided to the cutting tool in the direction of cutting velocity. The prediction of residual stress distribution is carried out using elasto-plastic finite element simulations. Experimental analysis is carried out in measuring the strain at the cutting tool during CT and UAT along with the chip mechanism and chip microstructure study to validate the residual stress distribution. The ultrasonic vibrations yield a considerable improvement in compressive residual stresses which ultimately benefits in improving fatigue life of titanium alloys.