Browsing by Author "Hussain, Tanvir"
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Item Open Access Corrosion behavior of cold sprayed titanium coatings and free standing deposits(Springer Science Business Media, 2011-01-01T00:00:00Z) Hussain, Tanvir; McCartney, D. G.; Shipway, P. H.; Marrocco, T.Cold gas dynamic spraying can be used to deposit oxygen-sensitive materials, such as titanium, withoutsignificant chemical degradation of the powder. The process is thus believed to have potential for thedeposition of corrosion- resistant barrier coatings. However, to be effective, a barrier coating must notallow ingress of a corrosive liquid and hence must not have interconnected porosity. This study investigatedthe effects of porosity on the corrosion behavior of cold sprayed titanium coatings onto carbonsteel and also of free standing deposits. For comparative purposes, a set of free standing deposits was alsovacuum heat-treated to further decrease porosity levels below those in the as-sprayed condition.Microstructures were examined by optical and scanning electron microscopy. Mercury intrusion porosimetry(MIP) was used to characterize the interconnected porosity over a size range of micrometers tonanometers. Open circuit potential (OCP) measurements and potentiodynamic polarization scans in3.5 wt.% NaCl were used to evaluate the corrosion performance. The MIP results showed that in coldsprayed deposits a significant proportion of the porosity was sub-micron and so could not be reliablymeasured by optical microscope based image analysis. In the case of free standing deposits, a reduction ininterconnected porosity resulted in a lower corrosion current density, a lower passive current density, andan increase in OCP closer to that of bulk titanium. For the lowest porosity level, ~1.8% achievedfollowing vacuum heat treatment, the passive current density was identical to that of bulk titanium.However, electrochemical measurements of the coatings showed significant substrate influence when theinterconnected porosity of the coating was 11.3 vol.% but a decreased substrate influence with a porositylevel of 5.9 vol.%. In the latter case, the OCP was still around 250 mV below that of bulk Ti. Salt spraytests confirmed these electrochemical findings and showed the formation of surface corrosion productsfollowing 24-h exposure.Item Open Access High-temperature performance of ferritic steels in fireside corrosion regimes: temperature and deposits(Springer, 2016-11-17) Dudziak, T.; Hussain, Tanvir; Simms, Nigel J.The paper reports high temperature resistance of ferritic steels in fireside corrosion regime in terms of temperature and deposits aggressiveness. Four candidate power plant steels: 15Mo3, T22, T23 and T91 were exposed under simulated air-fired combustion environment for 1000 h. The tests were conducted at 600, 650 and 700 °C according to deposit-recoat test method. Post-exposed samples were examined via dimensional metrology (the main route to quantify metal loss), and mass change data were recorded to perform the study of kinetic behavior at elevated temperatures. Microstructural investigations using ESEM-EDX were performed in order to investigate corrosion degradation and thickness of the scales. The ranking of the steels from most to the least damage was 15Mo3 > T22 > T23 > T91 in all three temperatures. The highest rate of corrosion in all temperatures occurred under the screening deposit.Item Open Access Large-scale manufacturing route to metamaterial coatings using thermal spray techniques and their response to solar radiation(Springer, 2021-07-04) Faisal, Nadimul Haque; Sellami, Nazmi; Venturi, Federico; Hussain, Tanvir; Mallick, Tapas; Muhammad-Sukki, Firdaus; Bishop, Alex; Upadhyaya, Hari; Katiyar, Nirmal Kumar; Goel, SauravMetamaterials, an artificial periodic two- or three-dimensional configuration can change propagation characteristics of electromagnetic waves (i.e., reflection, transmission, absorption). The current challenges in the field of metamaterial coatings are their manufacturing in large scale and large length scale. There is a clear need to enhance process technologies and scalability of these. Thermal spraying is a method used to deposit small to large scale coatings where the sprayed layer is typically formed by successive impact of fully or partially molten particles of a material exposed to various process conditions. This work aims to investigate the feasibility to manufacture large scale metamaterial coatings using the thermal spray technique and examine their response to solar radiation. Two types of coatings namely, Cr2O3 and TiO2 were deposited onto various substrates (e.g., steel, aluminium, glass, indium tin oxide (ITO) coated glass) with a fine wire mesh (143 µm and 1 mm aperture sizes) as the masking sheet to manipulate the surface pattern using suspension high-velocity oxy-fuel thermal spraying (S-HVOF) and atmospheric plasma-sprayed (APS) methods, respectively. Post deposition, their responses subjected to electromagnetic wave (between 250 nm to 2500 nm or Ultraviolet (UV)-Visible (Vis)-Infrared (IR) region) were characterised. The additional microstructural characterisation was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), three-dimensional profilometry and optical spectroscopy. It is demonstrated that through novel application of thermal spray techniques, large scale manufacturing of metamaterial coating is possible, and such material can affect the electromagnetic wave propagation. Comparison between Cr2O3 and TiO2 coatings on aluminium substrates showed reduced three orders of reduced reflectance for Cr2O3 coatings (for 1 mm aperture size) throughout the spectrum. It was concluded that for a similar bandgap, Cr2O3 coatings on aluminium substrate will yield improved optical performance than TiO2 coating, and hence more useful to fabricate opto-electronic devices.Item Open Access Resilient and agile engineering solutions to address societal challenges such as coronavirus pandemic(Elsevier, 2020-05-28) Goel, Saurav; Hawi, Sara; Goel, Gaurav; Thakur, Vijay Kumar; Agrawal, Anupam; Hoskins, Clare; Pearce, Oliver; Hussain, Tanvir; Upadhyaya, Hari M.; Cross, Graham; Barber, Asa H.The world is witnessing tumultuous times as major economic powers including the US, UK, Russia, India, and most of Europe continue to be in a state of lockdown. The worst-hit sectors due to this lockdown are sales, production (manufacturing), transport (aerospace and automotive) and tourism. Lockdowns became necessary as a preventive measure to avoid the spread of the contagious and infectious “Coronavirus Disease 2019” (COVID-19). This newly identified disease is caused by a new strain of the virus being referred to as Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS CoV-2; formerly called 2019-nCoV). We review the current medical and manufacturing response to COVID-19, including advances in instrumentation, sensing, use of lasers, fumigation chambers and development of novel tools such as lab-on-the-chip using combinatorial additive and subtractive manufacturing techniques and use of molecular modelling and molecular docking in drug and vaccine discovery. We also offer perspectives on future considerations on climate change, outsourced versus indigenous manufacturing, automation, and antimicrobial resistance. Overall, this paper attempts to identify key areas where manufacturing can be employed to address societal challenges such as COVID-19.