Effect of gradient composite structure in cofired bilayer composites of Pb(Zr0.56Ti0.44)O3–Ni0.6Zn0.2Cu0.2Fe2O4 system on magnetoelectric coefficient

This study investigates the ferroelectric, ferromagnetic, and magnetoelectric properties of the cofired bilayer composites consisting of piezoelectric phase with formulation 0.9 Pb(Zr_0.56Ti_0.44)O₃–0.1 Pb[(Zn_0.8/3Ni_0.2/3)Nb_2/3] + 2 (mol%) MnO₂ and 40 mol% ferrite phase with formulation Ni_0.6Zn_0.2Cu_0.2Fe₂O₄ (NCZF). A bulk composite of the same composition was also synthesized for comparison. Scanning electron microscope (SEM) investigation using quadrant back scattering detector (QBSD) shows migration of ferrite phases through the interface and energy dispersive X-ray spectroscopy (EDX) analysis with X-ray mapping clarifying these as Cu-rich phases. Improved piezoelectric (d ₃₃ ~ 80 pC/N), ferroelectric (polarization of 60 μC/cm² and 0.1% strain), higher magnetization (25 emu/g) and lower coercive field (2.8 Oe) were recorded for bilayer composite. The results indicate that the gradient bilayer composites with tailored composition such that the fraction of the secondary phase is higher may lead to better magnetoelectric material.     

Preparation and characterization of vinyltrimethoxysilane and dicumyl peroxide–cured (ethylene propylene diene monomer)/polypropylene thermoplastic vulcanizates

The present investigation deals with understanding the influence of vinyltrimethoxysilane (VTMS) concentration on the mechanical, thermal, thermomechanical, rheological, morphological, gel content, crosslinking density, and compression set properties of dynamically vulcanized ethylene propylene diene monomer (EPDM)/polypropylene (PP) (60/40, w/w) ‐based thermoplastic vulcanizates. It was determined that the values of crosslinking density, gel content, tensile strength, Young's modulus, elongation at break, and viscosity increased; whereas that of compression set, melting temperature, enthalpy of melting, crystallinity, and damping factor decreased with increased addition of VTMS in the EPDM/PP‐based thermoplastic vulcanizate. This is attributed to the physical crosslinking caused because of VTMS grafting on EPDM and chemical crosslinking induced by VTMS between PP and EPDM. This has been confirmed by Fourier‐transform infrared spectroscopy spectra, whereas the thermomechanical and scanning electron microscopy analysis confirmed increased compatibility between EPDM and PP on the addition of VTMS. J. VINYL ADDIT. TECHNOL., 23:312–320, 2017. © 2015 Society of Plastics Engineers     

Effect of ZnO and CuO on the Sintering Temperature and Piezoelectric Properties of a Hard Piezoelectric Ceramic

Hard piezoelectrics with high dielectric and piezoelectric constants are used for high-power applications. However, the sintering temperature of these ceramics is high, around 1200°C, restricting the usage of cheap base metal electrodes in fabrication of multi-layer components. This study investigates the effect of CuO and ZnO on the sintering temperature of a hard piezoelectric, APC 841, which is a MnO₂- and Nb₂O₅-modified PZT. The addition of CuO decreased the sintering temperature through the formation of a liquid phase. However, the piezoelectric properties of the CuO-added ceramics sintered at ≤950°C were lower than the desired values. The addition of ZnO resulted in a significant improvement in the piezoelectric properties. This enhancement was attributed to the formation of a homogeneous microstructure with large grains. The APC 841+0.2 wt% CuO+1.1 wt% ZnO ceramics sintered at 950°C showed excellent piezoelectric and dielectric properties with values of k _p=0.532, Q _m=750, d ₃₃=351 pC/N, ɛ₃₃/ɛ_o=1337, and T _c=280°C.     

Laser Irradiation of Metal Oxide Films and Nanostructures: Applications and Advances

Recent technological advances in developing a diverse range of lasers have opened new avenues in material processing. Laser processing of materials involves their exposure to rapid and localized energy, which creates conditions of electronic and thermodynamic nonequilibrium. The laser‐induced heat can be localized in space and time, enabling excellent control over the manipulation of materials. Metal oxides are of significant interest for applications ranging from microelectronics to medicine. Numerous studies have investigated the synthesis, manipulation, and patterning of metal oxide films and nanostructures. Besides providing a brief overview on the principles governing the laser–material interactions, here, the ongoing efforts in laser irradiation of metal oxide films and nanostructures for a variety of applications are reviewed. Latest advances in laser‐assisted processing of metal oxides are summarized.     

Microstructural Inhomogeneity in Constrained Groove Pressed Cu-Zn Alloy Sheet

Severe plastic deformation (SPD) is routinely employed to modify microstructure to obtain improved mechanical properties, particularly strength. Constrained groove pressing (CGP) is one of the SPD techniques that has gained prominence recently. However, the efficacy of the method in terms of homogeneity of microstructure and properties has not been well explored. In this work, we examine the microstructure and mechanical properties of CGP processed Cu-Zn alloy sheet and also explore homogeneity in their characteristics. We found that CGP is very effective in improving the mechanical properties of the alloy. Although the reduction in grain size with the number of passes in CGP is not as huge (~38 µm in annealed sample to ~10.2 µm in 1 pass sample) as is expected from a SPD technique, but there is a drastic improvement in ultimate tensile strength (~230 to ~380 MPa) which shows the effectiveness of this process. However, when mechanical properties were examined at smaller length scale using micro-indentation technique, it was found that hardness values of CGP processed samples were non-uniform along transverse direction with a distinct sinusoidal variation. Uniaxial tensile test data also showed strong anisotropy along principal directions. The cause of this anisotropy and non-uniformity in mechanical properties was found to lie in microstructural inhomogeneity which was found to exist at the length scale of the grooves of the die.     

Design and synthesis of bio-based epoxidized alkyd resin for anti-corrosive coating application

Alkyd resins with long aliphatic chain in their backbone are not suitable for high-performance applications. To overcome this limitation of alkyd resins, their backbone structure is usually chemically modified. In this study, an alkyd resin was successfully synthesized from renewable resources, including itaconic acid and linseed oil. Subsequently, the unsaturated backbone of the alkyd resin was converted to oxirane ring through epoxidation reaction in the presence of hydrogen peroxide and acetic acid. The epoxidized alkyd (EA) resin backbone was modified with various amounts of 3-amino propyltrimethoxysilane (APTMS) from 10 to 40 mol percent to enhance the anti-corrosive properties of coatings prepared from the alkyd resins. The structural elucidation of synthesized resins was described by physicochemical analysis and Fourier transform infrared and ¹H nuclear magnetic resonance spectroscopies. The EA resin and APTMS-modified EA resin were cured by itaconic acid in 1:1 stoichiometric ratio on the equivalent weight basis. The differential scanning calorimetric and thermogravimetric analysis results showed that thermal properties improved with increasing APTMS content. The cured coatings were characterized for their mechanical properties, chemical and solvent resistance, gel content, and water absorption. The corrosion-resistance performance of coatings was evaluated by electrochemical impedance spectroscopy and salt-spray test. It was observed that the highly cross-linked structure of the APTMS-modified EA coatings enhanced the corrosion protective property of coating films.     

Design of Low Cost Broadband Ultrasonic Pulser–Receiver

Determination of ultrasonic propagation velocity in materials provides an insight into their intrinsic and extrinsic properties. The American National Standard, E-494–95 describes an exhaustive procedure of ultrasonic velocity measurement and various material parameters that are based on ultrasonic velocity. Ultrasonic pulser–receiver is a device, used to excite piezoelectric transducers. Further, a oscilloscope or data acquisition device is employed to display and analyze the receiver output. The quality of measured parameter mainly depends on the capabilities of the measurement device used at the receiver. Careful study of the displayed wave pattern enables the detection of deformities inside the metal blocks. In this article, a low cost pulser–receiver designed in the laboratory has been discussed. The design provided can be used by a person having considerable knowledge of electronics to build up a pulser–receiver. The designed device has been tested for its functionality to measure ultrasonic velocity and attenuation. The measured values have been compared with the literature values and are in close agreement with the measurements taken by an imported system.