Papers by Keyword: Treatment Time

Abstract: The paper reveals the key features of metal products deformation-strength properties obtained by them as a result of plasma-cavitating treatment. A strengthened cold-rolled tape of steel grade 08ps (Russian State Standard (GOST) 1050-88) was chosen as a model object. Samples of the tape were treated by plasma-cavitating method at certain values ​​of technological parameters (power density and time of plasma action). Then they were tested in accordance with Russian State Standard (GOST) 11701-84. It is determined that the strength of the material remains at the level before processing. At the same time, the percent elongation at break increases essentially (up to 36.3% in relation to the initial indices). It is shown that the dependencies of change in plastic properties of the material on processing time at different values of power density are non-linear with critical points of relative change of percent elongation minimum, due to those physical processes that occur during the treatment period. The location of these critical points depends on both the power density and the time of plasma-cavitating treatment.

Abstract: Natural fiber reinforced polymer composites are generally lower in mechanical performance compared to synthetic fiber reinforced polymer composites. However, this disadvantage can be improved via chemical modification of the natural fiber and hybridization with synthetic fiber. In this study, kenaf bast fiber was used as reinforcement in unsaturated polyester composites. It was subjected to chemical modification with maleic anhydride at various treatment time i.e. 60, 90 and 120 minutes prior to composites production. The untreated and MA treated kenaf bast fiber were hybridized with 10 weight percent of glass fiber to produce kenaf bast/glass fiber reinforced unsaturated polyester composites. The effect of treatment time on weight percent gain and functional group changes via infra-red spectra of kenaf bast fiber were investigated. The effect of treatment time on tensile properties of kenaf bast fiber and kenaf bast/glass fiber reinforced unsaturated polyester composites were also studied. It was revealed that the weight percent gain of kenaf bast fiber increased with the increasing of treatment time. The increasing of treatment time resulted in the enhancement of tensile strength and modulus of kenaf bast fiber and kenaf bast/glass fiber reinforced unsaturated polyester composites which were attributed to the presence of C=C bonds of maleic anhydride and has been proven through fourier transform infrared spectrum.

Abstract: The textured thin films of Aluminum-doped zinc oxide (AZO), prepared on glass substrates by magnetron sputtering, were treated under the environment of hydrogen plasma in plasma enhanced chemical vapor deposition (PECVD) chamber for different time. The structure and properties of the thin films before and after the treatment were characterized by X-ray diffraction (XRD), Atomic Force Microscopy (AFM), field-emission scanning electron microscope (FESEM), Hall effect measurements and UV-Vis –NIR spectrometer. The results obtained showed that, after the treatment, the crystal structure of the films was not obviously changed, the roughness of the films was reduced, the carrier concentration and Hall mobility of the films increased to a certain saturated level with the treatment time, and the conductivity of the films increased. The transmittance and optical band gap of the AZO films was not affected by plasma treatment.

Abstract: Carbonated hydroxyapatite (CHA) was synthesized by solid-ion-exchange reaction of hydroxyapatite (HA) powders in CO2 atmosphere. The effects of the treatment atmosphere, temperature and time on carbonate substitution were investigated. The phase composition of the powders were characterized by X-ray diffraction and the content and type of the carbonate substitution were studied using Carbon-sulfur elemental analysis and Fourier transform infrared spectroscopy, respectively. The results show that the carbonate ion can enter the HA crystal lattice to form CHA giving priority to A-type by controlling the treatment temperature, atmosphere and time. Wet atmosphere treatment favors the reconstitution of hydroxyl and treatment in dry CO2 atmosphere favors the formation of A-Type substitution. The appropriate reaction temperature is 900 . Carbonate content increases with the treatment time and a further extension of treatment time tends to a slower increase of carbonate content.