O. Sobol - Academia.edu (original) (raw)
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Indian Institute of Engineering Science and Technology, Shibpur
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Papers by O. Sobol
Journal of Nanoscience and Nanotechnology, 2012
Zr-Ti-Si-N coating had high thermal stability of phase composition and remained structure state u... more Zr-Ti-Si-N coating had high thermal stability of phase composition and remained structure state under thermal annealing temperatures reached 1180 degrees C in vacuum and 830 degrees C in air. Effect of isochronous annealing on phase composition, structure, and stress state of Zr-Ti-Si-N-ion-plasma deposited coatings (nanocomposite coatings) was reported. Below 1000 degrees C annealing temperature in vacuum, changing of phase composition is determined by appearing of siliconitride crystallites (beta-Si3N4) with hexagonal crystalline lattice and by formation of ZrO2 oxide crystallites. Formation of the latter did not result in decay of solid solution (Zr, Ti)N but increased in it a specific content of Ti-component. Vacuum annealing increased sizes of solid solution nanocrystallites from (12 to 15) in as-deposited coatings to 25 nm after annealing temperature reached 1180 degrees C. One could also find macro- and microrelaxations, which were accompanied by formation of deformation defects, which values reached 15.5 vol.%. Under 530 degrees C annealing in vacuum or in air, nanocomposite coating hardness increased. When Ti and Si concentration increased and three phases nc-ZrN, (Zr, Ti)N-nc, and alpha-Si3N4 were formed, average hardness increased to 40.8 +/- 4 GPa. Annealing to 500 degrees C increased hardness and demonstrated lower spread in values H = 48 +/- 6 GPa and E = (456 +/- 78) GPa. Zr-Ti-Si-N coatings has high wear resistance and low friction coefficient in comparison at a temperature of 500 degrees C possess with coatings TiN, Ti-Si-N.
In the current research, the effect of heat treatment on the morphology of the dispersoids and th... more In the current research, the effect of heat treatment on the morphology of the dispersoids and their phase composition were investigated in three Cr-rich ferritic oxide dispersion strengthened (ODS) steels: PM2000, MA956, and ODM751. The steels were aged at 475°C for times ranging from 100 to 1,000 h. The microstructure was characterized using transmission electron microscopy. Study of the as-recrystallized samples revealed nano-scale Y-Al-O complex-oxide particles dispersed in the ferritic matrix. These dispersoids, which differ in size (10-160 nm) and geometry (polygonal and spherical), were identified as Y 4 Al 2 O 9 , YAlO 3 , and Y 3 Al 5 O 12 . After heat treatment, a significant change in the morphology, size, and distribution of the dispersoids was observed. Changes in the phase composition of the oxide dispersoids were also observed: YAlO 3 (with perovskite structure) was identified as the most dominant phase, indicating that it is probably the most stable phase in the Cr-rich ferritic ODS steels.
Journal of Nanoscience and Nanotechnology, 2012
Zr-Ti-Si-N coating had high thermal stability of phase composition and remained structure state u... more Zr-Ti-Si-N coating had high thermal stability of phase composition and remained structure state under thermal annealing temperatures reached 1180 degrees C in vacuum and 830 degrees C in air. Effect of isochronous annealing on phase composition, structure, and stress state of Zr-Ti-Si-N-ion-plasma deposited coatings (nanocomposite coatings) was reported. Below 1000 degrees C annealing temperature in vacuum, changing of phase composition is determined by appearing of siliconitride crystallites (beta-Si3N4) with hexagonal crystalline lattice and by formation of ZrO2 oxide crystallites. Formation of the latter did not result in decay of solid solution (Zr, Ti)N but increased in it a specific content of Ti-component. Vacuum annealing increased sizes of solid solution nanocrystallites from (12 to 15) in as-deposited coatings to 25 nm after annealing temperature reached 1180 degrees C. One could also find macro- and microrelaxations, which were accompanied by formation of deformation defects, which values reached 15.5 vol.%. Under 530 degrees C annealing in vacuum or in air, nanocomposite coating hardness increased. When Ti and Si concentration increased and three phases nc-ZrN, (Zr, Ti)N-nc, and alpha-Si3N4 were formed, average hardness increased to 40.8 +/- 4 GPa. Annealing to 500 degrees C increased hardness and demonstrated lower spread in values H = 48 +/- 6 GPa and E = (456 +/- 78) GPa. Zr-Ti-Si-N coatings has high wear resistance and low friction coefficient in comparison at a temperature of 500 degrees C possess with coatings TiN, Ti-Si-N.
In the current research, the effect of heat treatment on the morphology of the dispersoids and th... more In the current research, the effect of heat treatment on the morphology of the dispersoids and their phase composition were investigated in three Cr-rich ferritic oxide dispersion strengthened (ODS) steels: PM2000, MA956, and ODM751. The steels were aged at 475°C for times ranging from 100 to 1,000 h. The microstructure was characterized using transmission electron microscopy. Study of the as-recrystallized samples revealed nano-scale Y-Al-O complex-oxide particles dispersed in the ferritic matrix. These dispersoids, which differ in size (10-160 nm) and geometry (polygonal and spherical), were identified as Y 4 Al 2 O 9 , YAlO 3 , and Y 3 Al 5 O 12 . After heat treatment, a significant change in the morphology, size, and distribution of the dispersoids was observed. Changes in the phase composition of the oxide dispersoids were also observed: YAlO 3 (with perovskite structure) was identified as the most dominant phase, indicating that it is probably the most stable phase in the Cr-rich ferritic ODS steels.