Masaru Kitagawa

Elastic and plastic energies in sputtered multilayered Ti-TiN films estimated by nanoindentation

Abstract Energetic parameters for describing mechanical properties, which makes it possible to discuss deformation behavior of a film elastically and plastically, are presented. Elastic energy and dissipated energy estimated from the area surrounded by a load–displacement curve obtained by nanoindentation measurement indicate the energy to deform a film elastically and plastically. The energy dissipated ratio defined as the ratio of dissipated energy to total applied energy to a film indicates the tendency for plastic deformation of a film. By considering the two energies and the energy dissipated ratio, deformation behavior of compositionally modulated Ti–TiN films with a multilayered structure was examined. At a modulation period of 10 nm, the reduction of the dissipated energy and the energy dissipated ratio were observed. Since the dissipated energy is consistent with energy for the propagation of the dislocations related to plastic deformation, it was assumed that the reduction was caused by a pinning effect for the propagation of the dislocations at interfaces of Ti and TiN.

Titanium carbide film deposition by DC magnetron reactive sputtering using a solid carbon source

Abstract Titanium carbide films with various C/Ti ratios have been deposited by DC magnetron sputtering using carbon sheets on the Ti target erosion area as a solid carbon source. By changing the number of carbon sheets (5 × 5 × 1 mm 3 ) from 0 to 24 pieces, the C/Ti compositional ratio of the films was changed. The composition, structure, and hardness of the deposited films were estimated as a function of the ratio of the source carbon area to the titanium target erosion area. The results of X-ray photoelectron spectroscopy showed that the C contents in the films increased to Ti: C = 60: 40 as the source C/Ti areal ratio increased. By X-ray diffraction, the films obtained for C/Ti areal ratios above 0.1 were found to possess the face-centered cubic structure and that the d -value of TiC (111) increased monotonically from 0.238 to 0.249 nm as the C/Ti areal ratio increased. The hardness of the films also increased monotonically as the C/Ti areal ratio increased, yielding a maximum of 11 GPa.

Adhesion and hardness of compositionally gradient TiO2/Ti/TiN, ZrO2/Zr/ZrN, and TiO2/Ti/Zr/ZrN coatings

Abstract A technique using compositionally gradient interlayers has been applied to TiO 2 /Ti/TiN, ZrO 2 /Zr/ZrN, and TiO 2 /Ti/Zr/ZrN multi-compositional coatings to enhance the adhesion of hard coatings to substrate. The coatings were prepared by dc reactive magnetron sputtering using a combination of a Zr or a Ti metal target and a pure Ar, an Ar-O 2 mixture, or an Ar-N 2 mixture discharge gas, onto a borosilicate glass substrate. Adhesion of coatings to the substrate was estimated by a scratch method. The hardness of coatings was measured by a nano-indentation method. Without an interface, ZrN coatings showed a very poor adhesion. By using glass/ZrO 2 /Zr or glass/TiO 2 /Ti compositionally gradient interface layers, the adhesion strength of ZrN coatings was enhanced to the adhesion strength almost equal to or higher than those of TiO 2 or ZrO 2 single layer coatings. From the results of internal stress evaluation, it was found that a high internal stress causes a poor adhesion of ZrN coatings. Hardness of coatings with a ZrN overlayer were 20 to 35 GPa and larger than those of coatings with a TiN overlayer. The increase in the hardness by inserting a compositionally gradient interface was observed in ZrO 2 /Zr/ZrN and TiO 2 /Ti/Zr/ZrN systems.

Hardness of compositionally nano-modulated TiN films

Compositionally nemo-modulated films have been deposited by a reactive gas flow rate modulation sputtering using a Ti target and N2 gas. The explored modulation periods ranged from 6.7nm to 80nm. The thickness of the moduated layer was 400nm. A TiO2/Ti underlayer with a thickness of 100nm was deposited for the entire sample films. By the X-ray diffraction measurements, it was found that films consisted of polycrystalline Ti and TiN mixtures for the periods longer than 10nm and of monolithic TiN for the periods of 6.7nm and 8nm. The X-ray photoelectron spectroscopy results for the film with a modulation period of 80nm showed that the N concentration in metallic layers was about 30% and that of the nitrided layers was about 45%. The maximum hardness of 11.2GPa was obtained at a modulation period of 10nm for an indenter load of 2.94mN by nanoindentation. This value is larger than that obtained for a monolithic TiN film (8.4GPa).