Organically coated steels are widely used in applications in which they are subjected to the natural environment and therefore require excellent corrosion resistance. Organic clearcoats are typically employed as a barrier that improves the overall corrosion resistance; however, they are typically derived from fossil fuel-based feedstock. A more sustainable alternative could be possible using sol-gel coatings. The application of a simple tetraethoxysilane (TEOS)-based sol-gel was applied to polyurethane-coated steels using a spray coater. The concentration of TEOS was altered to produce coatings containing either 2.5% or 10%. The 10% TEOS resulted in dense, homogeneous coatings that offered a significant improvement in corrosion resistance compared to an uncoated substrate. Whereas the 2.5% TEOS coatings were inhomogeneous and porous, which indicated a limitation of concentration required to produce a uniform coating. The successful demonstration of using a simple TEOS-based coating to improve the corrosion resistance of organically coated steel highlights the potential for further investigation into the use of sol-gels for these applications.
Mesoscopic carbon-based perovskite solar cells (CPSCs) are often cited as a potential frontrunner to perovskite commercialization. Infiltration, the extent to which perovskite fills the mesoporous scaffold, is critical for optimum performance and stability. However, infiltration data are usually presented as qualitative photographic comparisons of samples with extreme infiltration variation. This work examines how small infiltration defects impact performance using an optical microscopy examination of the base TiO2 layer to identify issues and develop targeted techniques for infiltration enhancement. Critically, the uninfiltrated area at the base of the stack was found to correlate well with PCE across multiple batches of varied print quality and ZrO2 thickness. Through reduction of mesh mark defects and improvement of print quality in the ZrO2 and carbon layers, a champion PCE of 15.01% is attained. It follows that this facile, multiscaled, nondestructive technique could enable targeted performance enhancement and quality control in future scale-up initiatives.
Ceramics are considered to be candidate materials for galvanising pot bearing materials due to their excellent corrosion resistance in many molten metals. Galvanising pot roll bearings must have excellent wear resistance, and, therefore, it is important to understand the wear behaviour of prospective bearing materials. This study investigates the friction- and wear-resistant properties of select ceramics, namely, pure hBN, BN M26, AlN-BN, Macor, 3YSZ, Al2O3 and Si3N4. The ceramics were tested at different sliding speeds using a pin-on-disc device equipped with SiC pins. The lowest coefficient of friction (COF) achieved was below 0.1, and it was measured for pure hBN at a 3.14 m/min sliding speed. However, a wear scar analysis showed that the BN grades suffered from severe wear. The highest wear rate was obtained for BN M26 at a 9.42 m/min sliding speed and was equal to 17.1 × 10-6 mm3 N-1 m-1. It was shown that the wear coefficient of the tested ceramics varied exponentially with hardness. The lowest wear was observed on the 3YSZ, Al2O3 and Si3N4 ceramics, which showed no volume loss, and, for this reason, they can be potentially used as bearing materials in continuous galvanising lines.
Copper potentially provides a cost-effective replacement for silver in printed electronic circuitry with diverse applications in healthcare, solar energy, IOT devices and automotive applications. The primary challenge facing copper is that it readily oxidizes to its non-conductive state during the sintering process. Photonic sintering offers a means of overcoming the oxidation by which rapid conversion from discrete nano-micro particles to fully or partially sintered products occurs. An experimental study of flash lamp sintering of mixed nano copper and mixed nano/ micro copper thick film screen printed structures on FTO coated glass was carried out. It shows that there may be multiple energy windows which can successfully sinter the thick film copper print preventing detrimental copper oxidation. Under optimum conditions, the conductivities achieved in under 1 s was (3.11-4.3 × 10-7 Ω m) matched those achieved in 90 min at 250 °C under reducing gas conditions, offering a significant improvement in productivity and reduced energy demand. Also present a good film stability of a 14% increase in line resistance of 100 N material, around 10% for the 50N50M ink and only around 2% for the 20N80M.
Coating degradation is a critical issue when steel surfaces are subject to weathering. This paper presents a chipless, passive antenna tag, which can be applied onto organically coated steel. Simulations indicated that changes associated with organic coating degradation, such as the formation of defects and electrolyte uptake, produced changes in the backscattered radar cross section tag response. This may be used to determine the condition of the organic coating. Simulating multiple aging effects simultaneously produced a linear reduction in tag resonant frequency, suggesting coating monitoring and lifetime estimation may be possible via this method. For coatings thinner than calculations would suggest to be optimum, it was found that the simulated response could be improved by the use of a thin substrate between the coated sample and the antenna without vastly affecting results. Experimental results showed that changes to the dielectric properties of the coating through both the uptake of water and chemical degradation were detected through changes in the resonant frequency.
A review is carried out in this paper into techniques that currently exist for, of have the potential to be used for, monitoring the performance of organic coating. Specific attention is paid to the applicability of each method to pre-finished steel used in the construction industry as these are rarely monitored in situ and their expected performance is often only estimated from lab-based accelerated corrosion testing. Monitoring could allow more accurate estimates of building cladding lifespan and required maintenance schedules; provide customers with active performance data; additionally, with a better understanding of performance, more appropriate coatings or coating weights could be selected for a construction project, offering economic benefits as part of smart building developments. An introduction to coatings, their use for corrosion protection, failure mechanisms, and relevant monitoring techniques is given before current assessment techniques are described in terms of their working principles. Examples of recent work are presented for the techniques that have been investigated for monitoring or directly relatable purposes. The review concludes that there are several good reasons why an optimum corrosion monitoring technology does not currently exist, however, promising research is emerging in the field of wireless and embedded sensor design which is providing optimistic results.
Industry , Steel
Printed carbon graphite materials are the primary common component in the majority of screen printed sensors. Screen printing allows a scalable manufacturing solution, accelerating the means by which novel sensing materials can make the transition from laboratory material to commercial product. A common bottleneck in any thick film printing process is the controlled drying of the carbon paste material. A study has been undertaken which examines the interaction between material solvent, printed film conductivity and process consistency. The study illustrates that it is possible to reduce the solvent boiling point to significantly increase process productivity while maintaining process consistency. The lower boiling point solvent also has a beneficial effect on the conductivity of the film, reducing the sheet resistance. It is proposed that this is a result of greater film stressing increasing charge percolation through greater inter particle contact. Simulations of material performance and drying illustrate that a multi layered printing provides a more time efficient manufacturing method. The findings have implications for the volume manufacturing of the carbon sensor electrodes but also have implications for other applications where conductive carbon is used, such as electrical circuits and photovoltaic devices.
Biosensing Techniques , Carbon , Electrodes , Solvents , Thermogravimetry
