• A K SHARMA

Articles written in Bulletin of Materials Science

• Design of multi-layer anti-reflection coating for terrestrial solar panel glass

To date, there is no ideal anti-reflection (AR) coating available on solar glass which can effectively transmit the incident light within the visible wavelength range. However, there is a need to develop multifunctional coatingwith superior anti-reflection properties and self-cleaning ability meant to be used for solar glass panels. In spite of self-cleaning ability of materials like TiO2 and ZnO, these coatings on glass substrate have tendency to reduce lighttransmission due to their high refractive indices than glass. Thus, to infuse the anti-reflective property, a low refractive index, SiO$_2$ layer needs to be used in conjunction with TiO$_2$ and ZnO layers. In such case, the optimization ofindividual layer thickness is crucial to achieve maximum transmittance of the visible light. In the present study, we propose an omni-directional anti-reflection coating design for the visible spectral wavelength range of 400–700 nm,where the maximum intensity of light is converted into electrical energy. Herein, we employ the quarter wavelength criteria using SiO$_2$, TiO$_2$ and ZnO to design the coating composed of single, double and triple layers. The thicknessof individual layers was optimized for maximum light transmittance using essential Mcleod simulation software to produce destructive interference between reflected waves and constructive interference between transmitted waves.

• Influence of high detonation pressure on the structural, microstructural and mechanical behaviour of IN718 superalloy: numeric simulation vis-à-vis experimental explosive shock processing

Micro-sized IN718 superalloy powder with an average particle size of 70 lm has been explosively shock-processed with high pressure of the order of 41.3 GPa. A hydrocode, AUTODYNE-2D, with Eulerian mesh is used to simulate and to compute the detonation pressure, particle velocity and shock pressure on the superalloy in the reactive zone. The grazing shock pressure at different regions in the compaction system has been calculated and compared with the experimental work. Axisymmetric cylindrical compaction geometry has been used for the shock-loading of IN718 superalloy. The shock pressure at different points was calculated experimentally by pin-oscillography with the help of electrical as well as fibre optical probes. Wide-angle X-ray diffraction study indicates the intact crystalline FCC structure within the shock-processed specimen having dominating ${\gamma}$[Ni-Cr-Fe] and strengthening $\gamma'$[Ni$_3$(Ti,Al)] phases. Laser diffraction particle size measurement points towards the reduced particle size of the shock-loaded specimen. The Linebroadening Williamson-Hall method shows a very small amount of locked-in microstrain of the order of 0.23%. Energy-dispersive analysis using X-ray examination shows no evidence of any chemical segregation within the compacts. Field-emission scanning electron microscopy shows satisfactory sub-structural strengthening and desired morphology at different regions in the fractographs of the compacted specimen without melting of the core of the specimen. Microindentation testing at variable loads of 0.98, 1.96 and 4.9 N shows a good hardness of the order of 642 H$_v$. The monolith cut-along the consolidation axes show tensile and compressive strengths of the order of 1.126 and 1.04 kN mm$^{–2}$, respectively. Uniform crack/void-free compacts have been obtained with a density close to 99.2% of the theoretical value with negligible porosity.

• # Bulletin of Materials Science

Volume 46, 2023
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020