Flash X Ray: A Diagnostic Tool for Shaped Charge Studies

At present many antitank weapon systems are employing shaped charge warheads. It is, therefore, extremely important for a designer to avail of the methods capable of predicting performance of shaped charges, mainly to achieve maximum penetration. For this purpose, it is necessary to study the behaviour of the shaped charge during actual firing tests. These tests are difficult because of high speed of events that take place, production of intense light, smoke, debris, etc, and the large scale destruction caused. To overcome these difficulties, flash x-ray system during the jet studies on 30, 60 and 90 mm shaped charges and the evaluation of jet characteristics parameters

Processing of Lead Zirconate Titanate-graphite 3-3 Piezocomposites

The lead zirconate titanate (PZT)-graphite piezocomposites have potential for higherpiezoelectric sensitivity, lower acoustic impedance, higher piezoelectric voltage constants, higherelectromechanical coupling coefficient, and higher hydrostatic coefficients as compared to densePZT materials. In addition, the properties of piezocomposites can be tailored for various weightpercentage of graphite powder. To study the phenomena, PZT-graphite 3-3 composites wereprepared by mixing calcined PZT and commercially available graphite powder. The mixed powderwas compacted, sintered, and poled by corona poling technique. Scanning electron microstructureswere recorded to study the effect of graphite on processing of 3-3 piezocomposites. The polarisingbehaviour, piezoelectric and dielectric properties of PZT-graphite composites were studied

Computer-controlled Sophisticated Ultrasonic Cleaner

The significant advantage of ultrasonic cleaning technique is the abilities to clean the delicateand complex shape materials without damaging their surfaces quickly. Ultrasonic cleaners havefound increasing applications in a variety of industries because these offer an environmentallygood alternative to ozone-depleting compounds and hazardous solvents. Also, ultrasonicvibration is one of the methods for chemical synthesis (chemical reaction) and of yieldenhancement of chemical engineering process. Consequently, there is a need to developmultipurpose ultrasonic cleaner/vibrator using computer control, which can be used to set thevarious performance parameter of ultrasonic vibrator such as frequency, duty cycle, continuous/pulsed mode, duration of operation, and thermal profile of tank during the process. An ultrasoniccleaner was developed using an oscillator circuit and the duration of oscillator circuit functioningcan be set through the computer. Computerised ultrasonic cleaner using indigenously madepiezoceramic transducers and their advantages over the conventional ultrasonic cleaners are discussed

Effect of Temperature on Aging of Ferroelectric Lead-Strontium-Zirconate-Titanate Ceramics

The effect of aging on Sr2+ modified Lead Zirconate Titanate (PSZT) ceramics have been studied. Aging was assessed by the measurement of dielectric constant and dielectric loss tangent as a function of time and temperature. Dielectric constant and dielectric loss tangent measured at different temperature range. Absolute rate of aging and relative rate of aging was determined. The PSZT ceramic showed sharp dielectric peak at temperature 300oC. The result showed that with increased temperature both the dielectric constant and rate of aging increased.Defence Science Journal, 2010, 60(6), pp.683-686, DOI:http://dx.doi.org/10.14429/dsj.60.5

Polymeric Piezoelectric Transducers for Hydrophone Applications

Conventional ceramic piezoelectric materials have been used in hydrophones for sonarapplications since 1940's. In the last few years since the discovery of polymeric piezoelectrichydrophones, the technology has matured, applications have emerged in extraordinary number ofcases such as underwater navigation, biomedical applications, biomimetics, etc. Hydrophones areused underwater at high hydrostatic pressures. In the presence of hydrostatic pressures, theanisotropic piezoelectric response of ceramic materials is such that it has poor hydrophone performancecharacteristics whereas polymeric piezoelectric materials show enough hydrostatic piezoelectriccoefficients. Moreover, piezoelectric polymers have low acoustic impedance, which is only 2-6 timethat of water, whereas in piezoelectric ceramics, it is typically 11-time greater than that of water. Aclose impedance match permits efficient transduction of acoustic signals in water and tissues. Newlydeveloped hydrostatic-mode polyvinylidene flouride (PVDF) hydrophones use a pressure-releasesystem to achieve improved sensitivity. Recently, voided PVDF materials have been used for makinghydrophones having higher sensitivity and figure of merit than unvoided PVDF materials

Effect of Sintering Time on Dielectric and Piezoelectric Properties of Lanthanum Doped Pb(Ni1/3Sb2/3)-PbZrTiO3 Ferroelectric Ceramics

produce electrical output in response to ambient pressures, vibrations, movements etc. In the present studies, sintering time for composition Pb0.98La0.02(NiSb)0.05[(Zr0.52Ti0.48)0.995]0.95O3 (La-PNS-PZT) was optimised to achieve properties suitable for power harvesting. Composition was processed through mixed oxide route and sintered at 1270 °C for 20 min, 40 min, 60 min, 80min and 100 min. XRD pattern indicated the presence of both, ferroelectric tetragonal and ferroelectric rhombohedral perovskite phases. The optical photographs shown the uniform and dense microstructure for the samples sintered for 60 min, resulted into optimum piezoelectric charge coefficient, voltage coefficient, electromechanical coupling coefficient and figure of merit. Power harvesting capabilities in response to impact of stainless steel ball (8.25 gm) from 150 mm height were evaluated and compared with PZT type 5A. La-PNS-PZT produced batter electrical output (5.11 W, 71.13 μJ) across the matching load resistance of 4000 Ω and 2.08 W maximum power and 20.79 μJ energy by PZT type 5A disc across the matching load resistance of 1000 Ω.Defence Science Journal, 2013, 63(4), pp.418-422, DOI:http://dx.doi.org/10.14429/dsj.63.486

Effect of Heating Rate on Electromechanical Properties ofPNN–PZT Solid Solution

Lead nickel niobate–lead zirconate titanate (Pb(Ni1/3Nb2/3)0.5 –Pb(Zr0.15Ti0.35O3), (PNN-PZT))solid solution was synthesised by columbite  process. Samples sintered at various heating ratesfor 4 h holding and their effect on electromechanical properties have been studied. When heatingrate was 8 °C/min from room temperature to 900 °C and holding for 4 h at 1280 °C, highest relativepermittivity and piezoelectric charge constant were observed, whereas heating rate of 3.5° C/min and holding for 4 h at 1280 °C have shown inferior electromechanical properties and graincoarsening. The piezoelectric charge constant (d33) ~612 pC/N and dielectric constant (e)~ 5950observed in fast heating rate specimen as against to d33~ 137 pC/N and e~4294. XRD result showsthe formation of pyrochlore-free perovskite phase. Fine grains were observed  for fast heatingrate specimens

Numerical Modelling of Regenerative Liquid Propellant Guns with Annular Piston

The development of regenerative liquid propellant guns (RLPGs) needs due consideration of numerous interdependent parameters that affect its performance. To help in this task, computer simulation was undertaken to predict internal ballistics of a conceptual liquid propellant gun. The expected pressure and other important parameters are documented which serve as an aid to the hardware, design of the regenerative liquid propellant guns

Pb(Ni1/3Sb2/3)O3-PbZrTiO3 Ceramic Sensors for Underwater Transducer Application

Cymbal is a class-V flextensional transducer that consists of thickness poled ceramic disc sandwiched between the two metal end caps which acts as a mechanical transformer. Cymbal transducers were fabricated using piezoceramic discs of compositions Pb0.988(Zr0.52Ti0.48) 0.976Nb0.024O3 (PZT type 5A) and Pb0.98La0.02 (NiSb)0.05[(Zr0.52 Ti0.48)0.995]0.95O3 (PNS-PZT). Piezoelectric and hydrostatic constants for PNS-PZT composition were on higher side. End capswere made up of brass sheet having thickness 0.5 mm. Underwater testing of the polyurethane moulded cymbal hydrophones were carried out in acoustic tank and compared. The resonance frequency for both the hydrophones was 10.1 kHz. PNS-PZT hydrophone shows higher sensitivity (-183.2 dB re 1V/μPa) compared to PZT type 5A (-191.2 dB re 1V/μPa) at resonance frequency. Directivity pattern observed for PNS-PZT is omni-directional near resonance frequency.Defence Science Journal, 2012, 62(4), pp.269-273, DOI:http://dx.doi.org/10.14429/dsj.62.171