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Wettability of Molten Ni(-Cr, W) Alloys on Alumina Ceramic Substrate

Author: LiuLanXiao
Tutor: XiaoFeng
School: Chongqing University of Technology
Course: Materials Processing Engineering
Keywords: Ni Ni-Cr Ni-W Al2O3 Wettability Interfacial reaction
CLC: TB331
Type: Master's thesis
Year: 2009
Downloads: 75
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Abstract


Ni-base alloy with high thermal strength and corrosion resistance, mainly used in the manufacture of the important parts of the aerospace, medical and other fields. Al 2 O 3 has good thermal conductivity, thermal shock resistance and oxidation resistance, often used as a structural material used in high-temperature environments, and is also used as a metal matrix The reinforcing material of the composite material. Which molten Ni-based alloys and Al 2 O 3 wettability largely determine the overall performance of metal matrix composites. 1773-1873 K temperature molten Ni-(Cr, W) alloys in the single crystal and polycrystalline Al 2 O 3 substrate Run through improved intravenous law observed wet behavior, using X-ray diffraction (XRD), environmental scanning electron microscopy, scanning electron microscopy and three-dimensional optical microscopy and other means of testing on the Ni-base alloy / Al 2 O 3 interface and Al 2 O 3 substrate surface morphology observation and composition analysis. Experimental temperature, the alloying elements, the the substrate crystal form and the protective atmosphere of the wetting behavior and interfacial reaction of the system, and interfacial reaction thermodynamic analysis. Molten Ni polycrystalline Al 2 the O 3 wettability is the study of molten Ni-base alloy / Al 2 O 3 system the wettability basis. Observed a temperature of 1773-1873 K protective atmosphere the Ar 3% H 2 Ni in polycrystalline Al 2 O 3 substrate Run wet behavior, found the molten Ni in the polycrystalline Al 2 O 3 initial contact angle on the substrate after a rapid decline in two phases and slow down the final equilibrium. According to the thermodynamic calculations and test results, we can see the molten Ni and Al 2 O 3 substrate interfacial reaction product for of NiO, NiAl2O4, Al2O and Ni-Al intermetallic compounds. As the temperature increases, the initial contact angle and the equilibrium contact angle of the molten Ni has a decreasing trend, and the time to reach equilibrium shortened; as the temperature rises, the more dramatic the reaction to generate the amount of product more. By adding alloying elements Cr to pure Ni, Cr analysis of Ni-Cr / polycrystalline Al 2 O 3 system wettability. Add 5% -10% Cr, the initial contact angle and the equilibrium contact angle, decreased the rate of decrease of the contact angle to improve. Cr addition is conducive to the occurrence of the interfacial reaction, to enhance interfacial bonding, to improve the wettability of the system. Observe and analyze the the 1823-1873 K molten Ni-10% W alloy in single crystal Al 2 O 3 substrate wetting behavior of single crystal surface has anisotropic droplets, so that the contact angle in both directions on the large differences in different directions, with different wettability show that the wettability of the system influenced by the orientation of the crystal plane. As the temperature increases, the anisotropic effect is more significant. With the polycrystalline Al 2 O 3 substrate comparison, analysis of the substrate crystal form of molten Ni-W/Al 2 O the system wettability impact. On the different protective atmosphere molten Ni-10% W alloy polycrystalline Al 2 O 3 substrate wetting behavior observed. Ar 3% H 2 compared with a protective atmosphere, the contact angle of the molten alloy under vacuum conditions fall rate is large, a shorter time to reach equilibrium and the equilibrium contact angle is small. In vacuum and Ar 3% H 2 under the protection of the atmosphere, melting of Ni-10% W / Al of 2 O 3 interface at the interfacial reaction, and interfacial reaction more intense under vacuum conditions.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Composite materials > Metal composite materials
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