Showing papers on "Nickel boride published in 2005"

Pressureless Sintering of Titanium Diboride with Nickel, Nickel Boride, and Iron Additives

Abstract: The effect of relatively small additions (1-5 wt%) of nickel, nickel boride (NiB), and iron to promote the liquid-phase sintering of titanium diboride (TiB2) has been studied. Carbon also was added to some samples, to reduce the amount of oxygen impurities in the TiB2 ceramics. Green bodies that were formed by uniaxial pressing were sintered in a graphite furnace at 1300°–1700°C, both under vacuum and in a 500 mbar argon atmosphere, and high densities (>94% of theoretical density) were obtained at temperatures greater than or equal to 1500°C. The weight loss of the samples during sintering was shown to be dependent on the densification rate and the final density and was not governed only by the thermodynamics of the system. Significant exaggerated grain growth was observed in samples with nickel, NiB, and iron during sintering at 1700°C. The exaggerated grain growth was observed to be closely related to the oxygen content of the samples and to temperature. The addition of carbon strongly reduced the density and the oxygen content and, thereby, inhibited grain growth. We have proposed that the exaggerated grain growth is enhanced by surface diffusion in a titanium-oxide-rich layer on the TiB2 grains.

Microstructures and mechanical properties of injection molded 17-4PH stainless steel powder with nickel boride additions

Abstract: This paper describes the sintering of an injection molded 17-4 PH stainless steel with additions of nickel boride (NiB), with the aim of producing high mechanical properties. Boron is evaluated as the best sintering enhancing element in terms of densifying the iron-based materials by formation the liquid phase. Sintered density and mechanical properties were increased with the increased amount of NiB while sintering time and temperature were decreased. Sintering to full density and highest mechanical properties were obtained with the addition of 1 wt% NiB at 1280∘C for 45 min. The formation of borides caused the increase of mechanical properties. This material may therefore find a wider technological application, because of its improved mechanical properties.

Material for generating hydrogen gas by hydrolyzing tetrahydroborate powder of alkaline/alkaline-earth metals

Abstract: The material for generating hydrogen gas by hydrolyzing tetrahydroborate powder of alkaline/alkaline-earth metals The powder contains grain constituents, which are uniformly covered by catalytic material particles (1-5 wt%), and has a specific surface of 1-10 m2>g-1> The catalytic material particles are constituted by (non) noble metal and an alloy or cobalt/nickel boride salt or oxides of (non) noble metal Independent claims are included for: (1) a production of the material; and (2) a fuel cell

Inhibitor of corrosion and stress corrosion cracking containing nickel boride (NiB) in the secondary side of steam generator tubes in a nuclear power plant and inhibiting method using the same

Abstract: An inhibitor of corrosion and stress corrosion cracking including nickel boride (NiB) in a secondary side of a steam generator tube in a nuclear power plant and an inhibition method using the same. The nickel boride (NiB) according to the present invention reduces stress corrosion cracking in a testing plate simulating the steam generator tube in the nuclear power plant in a highly caustic condition when compared with a reference solution, and increases corrosion resistance by reducing corrosion current density and oxide thickness. Accordingly, nickel boride may be effectively used to inhibit corrosion and stress corrosion cracking in the secondary side of the steam generator tube in the nuclear power plant.