Kazuyoshi Nakao

Compositional structure of dual TiNO layers deposited on SUS 304 by an IBAD technique

Abstract Surfaces of stainless steel SUS 304 were coated with dual titanium oxynitride (TiNO) layers using a nitrogen ion beam-assisted deposition technique. The N ions were accelerated at energy of 0.5–2.0 keV with an intensity of 0.1 mA/cm 2 on the substrate surface. First, a TiNO film was deposited on substrates at 700 °C, and subsequently, another TiN film was deposited on the previous TiNO film surface at 400 °C. Hydrogen carbon nitride, CrFe, and metal carbide M 23 C 6 were produced in the near-surface region of stainless steel during the TiNO deposition at 700 °C, and three characteristic layers consisting of iron nitride, chromium nitride and nickel nitride were formed between the TiNO films deposited and the stainless steel. These characteristic layers disappeared during deposition of the TiNO layer at a temperature of 400 °C.

Relationship between hardness and lattice parameter for TiN films deposited on SUS 304 by an IBAD technique

Abstract Titanium nitride films were deposited on SUS 304 stainless steel using an ion beam-assisted deposition technique. The N ions were accelerated at energy of 0.5–2.0 keV with an intensity of 0.1 mA/cm 2 on the substrate. Substrates were held at temperatures of 400–770 °C during deposition. For the TiN films, hardness was in the range from 350 to 550 GPa, depending on the N ion-beam energy, while the lattice parameter was dependent on the N ion-beam energy and substrate temperature. The lattice parameter dependence of hardness for the TiN films deposited at temperatures lower than 600 °C differed from that for films deposited at temperatures above 700 °C.

Dependence of film thickness on nitrogen ion energy and substrate temperature for titanium nitride films on stainless steel using an ion beam assisted deposition technique

Abstract Stainless steel (SUS-304) was coated with titanium nitride (TiN) using a ion beam assisted deposition (IBAD) technique. The deposited TiN films were polycrystals oriented in the 〈1 1 1〉 〈2 0 0〉 and 〈2 2 0〉 directions. The thickness of the deposited TiN films was measured using Rutherford backscattering spectrometry with He ions. The thickness of the films decreased with increasing N ion energy, and they were not dependent on substrate temperature but significantly decreased with substrate temperature above a specific temperature for SUS-304 because the sticking coefficient of Ti to SUS-304 was less than unity.

Titanium oxy-nitride films deposited on stainless steel by an ion beam assisted deposition technique

Surfaces of stainless steel SUS304 were coated with titanium oxy-nitride (TiON) films at temperatures of 400–770°C using an ion-beam assisted deposition technique constructed from an electron beam evaporator for Ti evaporation and a microwave ion source for ionizing nitrogen gas. The N ions were accelerated at energies of 0.5–2.0 keV. Most of the deposited TiON films consisted of (60–80)% TiN and (40–20)% TiO2, and the fraction of TiO2 increased with increasing substrate temperature. Hardness of the TiNO films varied in the range from 160 GPa to 260 GPa with increasing substrate temperature. The titanium oxy-nitride film could be deposited on stainless steel without a significant deterioration surface layer at 600°C. However, when TiNO films were deposited at temperatures higher than 700°C, the thickness of the TiNO films were significantly thinner and a thick layer containing nitride such as Cr2N, CrFe, Fe2N and Fe4N was formed in a near surface region of stainless steel because more nitrogen diffused into stainless steel.

High-strength and High-conductivity Precipitation Hardenable Dilute Copper Alloys

ABSTRACT Two new high-strength and high-conductivity precipitation hardenable dilute copper alloys, one being based on the addition of small amounts of Yttrium to the traditional dilute Cu-Sn binary alloys containing 0.10 to 0.20 wt% Sn, and the other being prepared to contain 1.0 wt% of (Fe + Ti) as a stoichiometric composition of Fe 2 Ti with small amounts of Mg, have been studied to develop materials for the leadframe of semiconductor devices.

SIMULTANEOUS CHROMIZING-SILICONIZING DIFFUSION COATING ON AUSTENITIC STAINLESS STEEL

The simultaneous deposition of chromium and silicon on austenitic stainless steel SUS310S using a halide-activated diffusion coating process was performed in order to improve oxidation and wear properties at high temperatures. The specimen was placed in an Al 2 O 3 crucible filled with a powder containing Cr-Si powder, a halide activator of NH 4 Cl, NaF, and AlF 3 , and an Al 2 O 3 filler powder. The diffusion-coating treatment was carried out at 1073–1323 K for 18 ks in argon atmosphere. Simultaneous diffusion-coating layers were mainly characterized chromium silicide and alpha ferrite. An oxidation characteristic after diffusion coating was also investigated for 1000 ks at 1073 K in air. The mass increase of diffusion-coated specimen was less than that of the untreated specimen. This result indicates that the simultaneous deposition of Cr and Si markedly improved the oxidation resistance of the austenitic stainless steel.

Modification of the surfaces of stainless steel during titanium nitride deposition by a dynamic mixing method

Abstract Surfaces of stainless steel SUS304 were coated with titanium nitride (TiN) at temperatures ranging from 400°C to 770°C using a dynamic mixing technique. The N+ ions were accelerated at energies of 0.5–2.0 keV, and were implanted into the stainless steel. The composition of the prepared TiN films was measured using Rutherford backscattering spectrometry with He ions at an energy of 2.0 MeV. Intermediate layers containing compounds such as FesNq, Cr2N, and CrFe were formed between the TiN films and substrates at substrate temperatures higher than 700°C. The thickness of the TiN films decreased significantly when the intermediate layers were formed.

Nitrogen ion dose dependence of surface morphology of titanium nitride films deposited on gallium arsenide by an ion beam assisted deposition technique

A thin titanium film was deposited on GaAs surfaces by an ion beam assisted deposition technique, and subsequently a titanium nitride film was deposited on the Ti/GaAs structure. The nitrogen ions were accelerated to an energy of 500 eV. The TiN films were deposited under a constant N ion current of 0.1 mA/cm/sup 2/, and the fraction of nitrogen ions in nitrogen beams was varied by varying nitrogen flow rate. The Ti layers changed to a Ti-rich TiN layer during the TiN deposition because nitrogen ions were implanted and diffused into the Ti layer. The surface morphologies of the structures varied with the dose of nitrogen ions and on annealing temperature. The film deposited at a flow rate of 10 sccm had a surface smoother than that at 20 sccm even after it was annealed at 1000/spl deg/C. Neither blister nor crack run on the surface of the former annealed structures. That is, the nitrogen ions contributed to keep the smooth TiN film surface during high temperature annealing and to prevent blistering and cracking of the films.