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Phenomena of tribocorrosion in medical and industrial sectors
Published in J.-P. Celis, P. Ponthiaux, Testing tribocorrosion of passivating materials supporting research and industrial innovation: Handbook, 2017
When stainless steel, titanium-based alloys and Co–Cr–Mo alloys are implanted as orthopaedic devices, they become covered with a protective passive film consisting mainly of metal oxides and hydroxides which prevent corrosion. However, in the presence of fretting or any tribological contact such as rolling or sliding, the protective films may be abraded and removed exposing bare metal to the body fluid. The bare metal may then undergo corrosion. Both effects affect the long-term durability of implants.
Re-configurable, expandable, and cost-effective heterogeneous FPGA cluster approach for resource-constrained data analysis
Published in International Journal of Parallel, Emergent and Distributed Systems, 2022
Dulana Rupanetti, Hassan Salamy, Cheol-Hong Min, Kundan Nepal
After constructing the fundamental IP design, the Perceptron IP block is added, and the bit-stream is then generated. The produced bitstream is imported into the Xilinx SDK suite, where a real-time C program is developed to interface with the host application through TCP/IP by implementing a bare-metal network protocol provided by the lWiP library. DMA access is used to transfer the data to the custom IP block. Four FPGAs were used in the experiment, which was clustered via a gigabit Ethernet switch that dynamically assigns IP addresses to connected devices. Figure 4 illustrates the resource utilisation following the modification of a single FPGA board. With the Neural Network design implemented, the Place and Route procedure in Vivado yielded a maximum clock speed of 254.3 MHz with a slack time of 12.736 ns. The cluster control panel software is shown in Figure 2(b), which also illustrates the 4-FPGA cluster connection with the Ethernet switch and a PC running the cluster control panel software.
Steel reinforcement corrosion in concrete – an overview of some fundamentals
Published in Corrosion Engineering, Science and Technology, 2020
The chloride ions enter the passive film (via predominantly the ‘Transitory Complex Theory’) and give rise to soluble products such that a small bare area of metal surface is formed. Ferrous ions (Fe2+) diffusing away from the anodic area will react with the high pH environment to form rust product (Fe(OH)2 initially) which will shield the bare metal from oxygen. Further Fe2+ ions will no longer be able to be oxidised by the dissolved oxygen and so may be hydrolysed leading to the production of H+ ions in the incipient pit. The production of H+ ions reduces the pH in the pit. Tinnea [12] has in fact measured reductions in pH to below 4 within pits for conventional steel reinforcement in chloride contaminated concrete.
Anodization of Titanium Alloy (Grade 5) to Obtain Nanoporous Surface Using Sulfuric Acid Electrolyte
Published in IETE Journal of Research, 2022
Anodization was carried out on titanium alloy, specifically named grade 5 (Ti6Al4V) in ASTM classification, which is most workable titanium grade and has the following chemical composition in wt% carbon (C): 0.03%, ferrous (Fe): 0.22%, oxygen (O): 0.16%, aluminum (Al): 6.12%, vanadium (V): 3.93% and titanium (Ti): balance. Oxide coating was investigated on sample-sized 100 mm × 20 mm × 0.4 mm. The surface roughness of bare metal was 800 ± 10 nm, thus first of all the specimens were degreased and burnished, for this they were abraded using emery papers indexed 300–1500 grades followed by the immersion of acetone bath for 5 min and then rinsed in deionized water, to develop nanopores, surface finish must be superior, to achieve highly finished surface electrolytic alkaline cleaning was formulated for this a mixture of Na2CO3 (sodium carbonate), Na2SiO3 (sodium metasilicate) and CH3 (CH2)11OSO3Na(sodium dodecyl-sulfate) in the ratio of (by weight) 25 gm: 25 gm: 10 gm per liter, respectively, at 10 volts, for 5 min at 70°C of temperature. Burnished surface with a surface finish of ≈12 nm was achieved. Anodization was performed in dilute sulfuric acid electrolyte on small coupons of size 10 mm × 50 mm × 0.4 mm were cut from the highly finished surface (as discussed earlier), anodization was performed by two-cell electrode, D.C power source in varied concentration level of sulfuric acid electrolyte. The solution was agitated through a mechanical stirrer to dissipate extra heat generated during the chemical process, specified details are given in Table 1, a schematic diagram of set-up used for anodic deposition is shown in Figure 1.