Journal Articles

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Subject: search.filters.subject.Coated substrates

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    Hot corrosion behaviour of HVOF sprayed Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) coatings in presence of Na2SO4-40%V2O5 at 650 °c
    (IOP Publishing Ltd custserv@iop.org, 2019) Reddy, N.C.; Koppad, P.G.; Reddappa, H.N.; Ramesh, M.R.; Babu, E.R.; Varol, T.
    Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) coatings were deposited on gas turbine based ASTM B265 titanium (Ti-15) and AISI 420 stainless steel (MDN-420) substrate materials using HVOF technique. Thermocyclic hot corrosion tests were carried out at 650 °C in molten salt environment of Na2SO4-40%V2O5 for about 50 cycles. Thermogravimetric analysis was carried out to study the hot corrosion kinetics of uncoated and coated titanium and stainless steel substrates. The weight gain per unit area showed that the coated substrate materials displayed better resistance to hot corrosion when compared with that of uncoated substrate materials. The surface morphology of uncoated and coated substrate materials were analysed using scanning electron microscopy and elemental analysis. The formation of different types of oxides and compounds were analysed using x-ray diffraction. The uncoated substrates surface showed microspalling at several regions while coated substrates surface were composed of protective oxide layers. The presence of ternary NiCr2O4 protective oxides on the surface of Ni3Ti + (Cr3C2 + 20NiCr) coated substrates leads to reduction in the diffusion of corrosive species inside the coating. © 2019 IOP Publishing Ltd.
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    The effect of nanocoatings on critical heat flux (CHF) under pool boiling conditions
    (ASTM International, 2021) Reddy, S.; Prabhu, K.N.; Nayak, U.V.
    The effect of nanomaterial coating on heat transfer characteristics of a copper substrate during pool boiling with distilled water (>99.9 %) was studied. The peak on the pool boiling curve between nucleate and transition boiling is termed the critical heat flux. Multi-walled carbon nanotubes and graphene were used to obtain coatings on the copper substrate. Experiments were carried out at atmospheric pressure. The results showed enhanced critical heat flux for the coated substrates. Graphene-coated copper showed the highest critical heat transfer characteristics compared with that on bare and multi-walled carbon nanotube-coated substrates. The study has significant implications for the enhancement of heat transfer during quench heat treatment. © © 2021 by ASTM International.
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    Graphene Oxide Assisted Humidity Sensing Antenna Sensor
    (Korean Institute of Electrical and Electronic Material Engineers, 2025) Singh, V.P.; Kandasamy, K.; Rahman, M.R.
    Abstract: In this paper, a graphene oxide (GO) coated substrate material is electrically characterized. The permittivity, loss tangent, permeability, and resistance are measured. A planar antenna with slots is designed on an RT/Duroid 5880 substrate. A thin layer of graphene oxide is coated on the identical slots of the planar antenna. The GO-assisted antenna sensor resonates at 2.51 GHz frequency. The graphene oxide-based antenna sensor performs contact-free sensing of relative humidity. The frequency sensitivity is approximately 17.5 MHz/10%RH. The design sensor gives a 93.50% linearity. The limit of detection is 30.55 RH%. Graphic Abstract: (Figure presented.) © The Korean Institute of Electrical and Electronic Material Engineers 2024.