jcst

Plasma Cleaning of Metallic Mirrors from Carbon-Containing Films – New Possibilities for In Situ Monitoring of the Efficiency of Wall Conditioning in Fusion Devices - Pages 79-84

V.S. Voitsenya, V.G. Konovalov, A.I. Timoshenko, S.I. Solodovchenko, I.V. Ryzhkov, A.F. Shtan’ and A.N. Shapoval

DOI: https://doi.org/10.6000/2369-3355.2018.05.03.2

Published: 14 March 2019

Abstract: The method proposed for measuring the erosion rate of the carbon film, pre-deposited on the mirror-like surface of the test metallic samples, directly during wall conditioning procedures in a fusion device. The practical realization of the method provided at the DSM-2 stand where deuterium plasma produced in conditions of electron resonance at frequency 2.45 GHz used for cleaning the samples. For controlling C-film thickness the time variation of electrical conductivity of the circuit ‘film+plasma+entire scheme’ was measured. The final cleaning stage sets according to the saturation section corresponding to the resistance of the entire measuring scheme. To check the state of full purification of samples from a carbon-containing film the reflectance at normal incidence in the wavelength 220-650 nm was measured before C-film deposition, just after C-film deposition, and after finishing the cleaning procedure. In all cases (16 experiments) the approach of total resistance to the ‘entire resistance’ of the scheme in use was supported by restoration of the reflectance of stainless steel samples to its initial value. The method can be reversed, i.e. allows one to control in situ the appearance of a contaminating layer growing on the surface of a metal sample, preliminary cleaned before being installed in a vacuum vessel.

Keywords: Fusion devices, plasma, wall cleaning, electrical resistance, carbon film thickness.

Download

New Flame Retardant and Antimicrobial Paints Based on Epoxy Paint Incorporated by Hexachlorocylodiphosphazane Derivatives for Protective Coating - Pages 85-96

H. Abd El-Wahab, Salah A.A. Mohamed and Islam Gomaa

DOI: https://doi.org/10.6000/2369-3355.2018.05.03.3

Published: 20 June 2019

Abstract: Flame retardants can be incorporated into polymeric material either as additives or as reactive materials. Additive type flame retardants are widely used by means of blending them with a specific polymeric material. In this particular research, hexachlorocylodiphosphazane derivatives type (I-II) were synthesized for use as flame retardant and antimicrobial additives with epoxy varnish. These additives are physically incorporated into the epoxy varnish formula. Experimental coatings were manufactured on a laboratory scale and applied by brush on wood and steel panels. The fire retardant ability of each coating type was characterized using the limiting oxygen index (LOI) test. The mechanical properties of these flame retardants were also examined to evaluate the drawbacks of the additives. Results of the LOI indicated that coating with these compounds containing chlorine, nitrogen and phosphorus exhibit a very good retardant effect, when blended with epoxy varnish comparing with the blanket sample which not contain on the hexachlorocylodiphosphazane derivative as a additives. The hexachlorocylodiphosphazane derivative also exhibit mild results as preservative against microbiological attack. The mechanical properties of the painted dry films were investigated acordinting to ASTM.

Keywords: Protective coatings, flame retardant additives hexachlorocylodiphosphazane, Epoxy paint.

Download

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

Abstract: Turbine entry temperature of turbo-engines has been increased to improve proficiency. Consequently, protecting the hot section elements experiencing aggressive service conditions necessitates the applying of thermal barrier coatings (TBC). Developing TBC systems and improving performance is an ongoing endeavour to prolong the lifetime. Thus, various studies have been conducted to find the optimum properties and dimensions. In this paper, the optimum thickness of intermediate bond coat (BC) and top coat (TC) have been determined via a novel hybrid particle swarm and simulated annealing stochastic optimization method. The optimum thicknesses have been achieved under the constraint of thermal stress induced by thermal fatigue, creep, and oxidation in the TC while minimizing the weight during twenty cycles. The solutions for BC and TC thicknesses are respectively 50 μm and 450 μm. Plane stress condition has been adopted for theoretical and finite element stress analysis, and the results are successfully compared.

Keywords: Thermal barrier coating, Thickness, Optimization, PSO-SA, Thermal stress.

Download

PTFE-Doped CeO2 Films: Synthesis, Characterization and Properties - Pages 36-40

Y. Taga, K. Nishimura and Y. Hisamatsu

DOI: https://doi.org/10.6000/2369-3355.2019.06.02.1

Published: 08 January 2020

Abstract: Multi-functional hybrid films were developed by doping PTFE into CeO2 by co-sputtering of CeO2 and PTFE targets. The hybrid films formed on borosilicate glass substrate containing from 5 to 15 vol. % PTFE in CeO2 showed UV shielding, high indentation hardness, hydrophobicity, optical transmittance in visible light, and high bending crack resistance. Optical properties of 100 nm thick CeO2 -5 vol. % PTFE film revealed UV light shielding of more than 80 % at 380 nm and visible light transmittance higher than 80 %. Indentation hardness measured under the load of 0.001mN was more than 16,000N/mm2 of 2.7 times higher than the glass substrate. No crack in the film was observed by bending 1.5 cm in diameter. Furthermore, the hydrophobic surface property was evaluated by the water contact angle to be higher than 90 degrees. Preliminary characterization of the CeO2-PTFE film using XPS and XMA revealed that chemical states of F in sputter doped PTFE in CeO2 can be considered to exist as C-F and Ce-F compounds. On the other hand, chemical states of Ce changed partially from Ce+4 (CeO2) to Ce+3 (Ce2O3 or CeF3) with increasing doped PTFEF in the film.

In this rapid communication, we preliminary described the optical, mechanical and chemical properties of newly developed hybrid CeO2-PTFE films prepared by sputtering.

Keywords: Hybrid sputtering films, CeO2-PTFE film, Super-hard, UV shieldinng, Water repellamt, Bending rsistance, Transparent in visible light, PTFE doping, XPS, Nanoindentor.

Download