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Determination of Thermal Barrier Coatings Layers Optimum Thickness via PSO-SA Hybrid Optimization Method concerning Thermal Stress - Pages 1-9 Ali Ghaseminezhad Koushali, M. Nazari and Masoud Roudneshin DOI: https://doi.org/10.6000/2369-3355.2019.06.01.1 Published: 14 October 2019
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Keywords: Thermal barrier coating, Thickness, Optimization, PSO-SA, Thermal stress. |
Diamond Deposition on Graphite in Hydrogen Microwave Plasma - Pages 12-18 Kaili Yao, Bing Dai, Victor Ralchenko, Guoyang Shu, Jiwen Zhao, Kang Liu, Lei Yang, Andrey Bolshakov, Jiecai Han and Jiaqi Zhu DOI: https://doi.org/10.6000/2369-3355.2018.05.01.2 Published: 16 August 2018
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Abstract: Hydrogen plasma etching of graphite generates radicals that can be used for diamond synthesis by chemical vapor deposition (CVD). We studied the etching of polycrystalline graphite by a hydrogen microwave plasma, growth of diamond particles of the non-seeded graphite substrates, and characterized the diamond morphology, grain size distribution, growth rate, and phase purity. The graphite substrates served simultaneously as a carbon source, this being the specific feature of the process. A disorder of the graphite surface structure reduces as the result of the etching as revealed with Raman spectroscopy. The diamond growth rate of 3 – 5 µm/h was achieved, the quality of the produced diamond grains improving with growth time due to inherently nonstationary graphite etching process. Keywords: Microwave plasma, diamond deposition, hydrogen plasma, graphite, etching. |
DLC Coatings in Oil and Gas Production DOI: http://dx.doi.org/10.6000/2369-3355.2014.01.01.7 Published: 25 June 2014
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Abstract: Diamond-like carbon (DLC) coatings are recognized in many sectors as a promising way of controlling wear and the corrosion performance of components. DLC coatings are well established in the automotive industry where they are applied to the moving parts of direct injection fuel systems operating under frictional conditions at high pressures and in the aggressive environment of the combustion chamber. Over the last few years, there have also been an increasing number of reports of DLC coating applications in oil and gas production contexts, including in pipes, shut-off gates and various types of valves. This paper reviews current efforts to use DLC coatings in the oil and gas sectors and analyses typical coating degradation mechanisms including wear and wear-accelerated corrosion regimes. DLC coating deposition techniques including Physical (PVD) and Chemical Vapor Deposition (CVD) techniques are elaborated and the unique coating properties obtained from those two methods are assessed. Surface functionalization is discussed including dopants (W and Si) and gradient interlayers. Finally, the outlook for future use of DLC coatings in oil and gas production is discussed. Keywords: Diamond-like carbon, DLC, surface engineering, functional coatings, tribology, corrosion. |
Diamond Deposition on Graphite in Hydrogen Microwave Plasma - Pages 12-18 Kaili Yao, Bing Dai, Victor Ralchenko, Guoyang Shu, Jiwen Zhao, Kang Liu, Lei Yang, Andrey Bolshakov, Jiecai Han and Jiaqi Zhu DOI: https://doi.org/10.6000/2369-3355.2018.05.01.2 Published: 16 August 2018
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Abstract: Hydrogen plasma etching of graphite generates radicals that can be used for diamond synthesis by chemical vapor deposition (CVD). We studied the etching of polycrystalline graphite by a hydrogen microwave plasma, growth of diamond particles of the non-seeded graphite substrates, and characterized the diamond morphology, grain size distribution, growth rate, and phase purity. The graphite substrates served simultaneously as a carbon source, this being the specific feature of the process. A disorder of the graphite surface structure reduces as the result of the etching as revealed with Raman spectroscopy. The diamond growth rate of 3 – 5 µm/h was achieved, the quality of the produced diamond grains improving with growth time due to inherently nonstationary graphite etching process. Keywords: Microwave plasma, diamond deposition, hydrogen plasma, graphite, etching. |
Effect of Extrusion Parameters on Properties of Powder Coatings Determined by Infrared Spectroscopy DOI: http://dx.doi.org/10.6000/2369-3355.2017.04.02.1 Published: 05 October 2017
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Abstract: In polymer extrusion, compounding is a continuous mixing process that is also used to produce highly reactive powder coatings. A premixed batch of powder coating is added to the feeding section and extruded, preferably by a co-rotating twin-screw extruder. One essential parameter in the processing of highly reactive materials is the melt temperature: If it is too high, pre-reactions occur during the extrusion process, which may cause high rejection rates. We studied the melt temperature of an epoxy/carboxyl-based powder coating using a retractable thermocouple at 3 different axial positions along the barrel of a ZSK34 co-rotating twin-screw extruder. The influence of different processing conditions on the reactivity of a highly reactive powder coating was examined by infrared spectroscopy and differential scanning calorimetry. Furthermore, the specific energy input and the color change in the finished powder coating at different processing points were investigated. Multivariate data analysis was used to correlate mid-infrared spectra, melt temperatures, specific energy inputs, enthalpies of reaction and changes in color.
Keywords: Extrusion, twin screw, infrared spectroscopy, ATR, DSC. |