S. Banerjee

Investigation to Study the Applicability of Solid Lubricant in Turning AISI 1040 steel

Recent developments in different methods of machining have significantly increased the potential for widespread industrial applications of turning. Although a high surface quality had been achieved in earlier investigations 1‐3, widespread industrial applications of turning technology necessitated a better understanding of the effects of process parameters on surface quality. The surface quality of machined parts is affected by many factors, such as tool geometry and cutting conditions. It is generally considered that the heat produced during the turning process is critical in terms of workpiece quality. Relatively high friction effects in machining cause heat generation that can lead to poor surface quality of a machined part. Coolant and lubrication therefore play decisive roles in machining. Cutting fluids are introduced in the machining zone to improve the tribological characteristics of machining processes and also to dissipate the heat generated. However, the application of conventional cutting fluids creates some techno-environmental problems, such as environmental pollution, biological problems to operators, water pollution, etc. 4. Further, the cutting fluids also incur a major portion of the total manufacturing cost 5. All these factors prompt investigations on the use of biodegradable cutting fluids or the elimination of the use of cutting fluids. However, any attempt to minimize or avoid the coolant can be dealt with only by replacing the functions normally met by the coolants with some other means. Machining with solid lubricants 6 and cryogenic coolants by liquid nitrogen 7 are some of the alternative approaches in this direction. Application of solid lubricant in machining has proved to be a feasible alternative to fluid coolants, if it can be applied properly. If friction at the tool and workpiece interaction can be minimized by providing effective lubrication, the heat generated can be reduced to some extent. Advancement in modern tribology has identified many solid lubricants, which can sustain and provide lubricity over a wide range of temperatures. If suitable lubricant can be successfully applied in the machining zone, it leads to process improvement. The feasibility of application of graphite as a solid lubricant in surface grinding was investigated by applying it in a suitable paste form to the working surface of the wheel, with a special attachment 8. The effective role of graphite as solid lubricant was evident from the process results related to frictional factors. However, wheel clogging in the absence of proper flushing and nonuniformity of lubricant admission were found to be major hindrances in achieving desirable results. If lubricant can be applied in a more refined and defined way, just sufficient for effective lubrication, improved process results may be expected. Therefore, the aim of present study is to investigate the effect of molybdenum disulphide as solid lubricant in the zone of machining. In the first stage of this work, experiments were carried out to investigate the role of solid lubricant such as molybdenum disulphide on surface finish and chip thickness of the product in machining a AISI 1040 steel by uncoated cemented carbide inserts of different tool geometry approach angle and rake angle under different cutting speeds and feeds. An experimental setup was envisaged and built. In the second stage, a comparative performance analysis of molybdenum disulphide assisted machining with wet machining was conducted. 2 Design and Development of Experimental Setup

Influence of Al Particle Size and Lead Zirconate Titanate (PZT) Volume Fraction on the Dielectric Properties of PZT-Epoxy-Aluminum Composites

Two-phase PZT-epoxy piezoelectric composites and three phase PZT-epoxy-Al composites were fabricated using a poling voltage of 0.2 kV=mm. The influence of aluminum inclusion size (nano and micron) and (lead zirconate titanate) PZT volume fraction on the dielectric properties of the three phase PZT-epoxy-aluminum composites were experimentally investigated. In general, dielectric and piezoelectric properties of the PZTepoxy matrix were improved with the addition of aluminum particles. Composites that were comprised of micron scale aluminum inclusions demonstrated higher piezoelectric d33-strain-coefficients, and higher dielectric loss compared to composites that were comprised of nanosize aluminum inclusions. Specifically, composites comprised of micron sized aluminum particles and PZT volume fractions of 20%, 30%, and 40% had dielectric constants equal to 405.7, 661.4, and 727.8 (pC=N), respectively, while composites comprised of nanosize aluminum particles with the same PZT volume fractions, had dielectric constants equal to 233.28, 568.81, and 657.41 (pC=N), respectively. The electromechanical properties of the composites are influenced by several factors: inclusion agglomeration, contact resistance between particles, and air voids. These composites may be useful for several applications: structural health monitoring, energy harvesting, and acoustic liners. [DOI: 10.1115/1.4004812]

An Analytical Model for the Effective Dielectric Constant of a 0-3-0 Composite

An analytical expression for prediction of the effective dielectric constant of a three phase 0-3-0 ferroelectric composite is presented. The analytical results are verified with the experimental results from Nan (2002, “Three-Phase Magnetoelectric Composite of Piezoelectric Ceramics, Rare-Earth Iron Alloys, and Polymer,” Appl. Phys. Lett., 81(20), p. 3831). The analytical model is extended to include the shape of a third phase inclusion to examine the influence of the shape (of the inclusion) on the effective dielectric constant of the composite. The dielectric constant increases as much as seven times when the aspect ratio of the conducting inclusion particle is increased from 1 (sphere) to 10 (spheroid). A comparison of the analytical predictions with the experimental values, which indicate that the increase in aspect ratio of the inclusions has a significant effect on the overall dielectric constant of the composite.

Piezoelectric and dielectric characterization of corona and contact poled PZT-epoxy-MWCNT bulk composites

Three-phase lead zirconate titanate (PZT, PbZr0.52Ti0.48O3)-epoxy-multi-walled carbon nanotube (MWCNT) bulk composites were prepared, where the volume fraction of PZT was held constant at 30%, while the volume fraction of the MWCNTs was varied from 1.0%–10%. The samples were poled using either a parallel plate contact or contactless (corona) poling technique. The piezoelectric strain coefficient (d33), dielectric constant (e), and dielectric loss tangent (tan δ) of the samples were measured at 110 Hz, and compared as a function of poling technique and volume fraction of MWCNTs. The highest values for dielectric constant and piezoelectric strain coefficients were 465.82 and 18.87 pC/N for MWCNT volume fractions of 10% and 6%, respectively. These values were obtained for samples that were poled using the corona contactless method. The impedance and dielectric spectra of the composites were recorded over a frequency range of 100 Hz–20 MHz. The impedance values observed for parallel-plate contact poled samples are higher than that of corona poled composites. The fractured surface morphology and distribution of the PZT particles and MWCNTs were observed with the aid of electron dispersion spectroscopy and a scanning electron microscope. The surface morphology of the MWCNTs was observed with the aid of a field emission transmission electron microscope.

Piezoelectric and Dielectric Characterization of MWCNT-Based Nanocomposite Flexible Films

PZT-epoxy-multiwalled carbon nanotube (MWCNT) flexible thick film actuators were fabricated using a sol-gel and spin coat and deposition process. Films were characterized in terms of their piezoelectric and dielectric properties as a function of MWCNT volume fraction and polarization process. Correlations between surface treatment of the MWCNTs and composite performance were made. The surface morphology and filler distribution were observed with the aid of SEM and TEM images. The volume fraction of PZT was held constant at 30%, and the volume fraction of MWCNTs varied from 1% to 10%. Two forms of dielectric polarization were compared. Corona discharge polarization induced enhanced piezoelectric and dielectric properties by a factor of 10 in comparison to the parallel-plate contact method (piezoelectric strain coefficient and dielectric constant were 0.59 pC/N and 61.81, respectively, for the parallel-plate contact method and 9.22 pC/N and 103.59 for the corona polarization method, respectively). The percolation threshold range was observed to occur at a MWCNT volume fraction range between 5% and 6%.

Energy Harvesting: Breakthrough Technologies Through Polymer Composites

Polymer composites have been extensively studied in the last few years toward application in solar-, thermoelectric-, and vibration-based energy harvesting technologies. Of late, polymer nanocomposites are being investigated successfully in hybrid organic–inorganic devices, in bulk heterojunction devices incorporating all flavors of solar cells, and through the perovskite structures. In the thermoelectric power generation arena, abundance of raw materials, lack of toxicity, and the feasibility for large-area applications are all advantages that polymer nanocomposites boast over their inorganic predecessors. Within the vibration-based energy systems, polymer nanocomposites are being used as the magnets within the harvester devices; they offer low rigidity and easy processing (spin coating, drop casting, and molding). Also, recent work has focused on utilizing polymer ceramic nanocomposites as electrostatic energy storage materials. Lastly, polymer-based piezoelectric materials can be used directly as an active material in different transduction applications.

Ionic Transport Regimes for Nanoscale Transport towards the Development of Low Energy Water Desalination Membranes

New materials, methods, and membranes are being developed for applications in water purification. One of the model systems that can be used for fundamental studies in nanoscale transport phenomena for new membrane technologies are nanocapillary array membranes (NCAMs). Toward developing more efficient membranes for water desalination, parameters such as the concentration polarization region which are influenced by the unstirred layers, surface properties (e.g., surface charge and surface energy) of the nanocapillaries, and the electric double layer (EDL) which mediates transport across NCAMs must be better understood. In this paper, a series of parametric experiments that were conducted to better understand the relative importance of unstirred layers with respect to the transport across nanocapillaries are described. Bulk salt concentration and potential drop across the NCAMs, were varied in a systematic manner to determine the influence EDL thickness and electromigration on transport regimes for ionic permeation across NCAMs. Based on previously developed methodologies, the experiments reported here were conducted in a permeation cell with an NCAM separating two reservoirs containing potassium phosphate buffer with a concentration range from 200 µM-10 mM. Methylene blue (MB) is used as an organic marker and the transport is quantified by tracking MB concentration in each reservoir with UV/VIS spectroscopy.