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Study on Mechanism of Wettability Improvement of Brazing Alloy on TiC Cermet by Zn Volatilization

Author: LeiMin
Tutor: ZhangLiXia
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: Zn volatile TiC Cermet Young 's equation expansion Wetting dynamics Clusters
CLC: TG425
Type: Master's thesis
Year: 2011
Downloads: 39
Quote: 0
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Abstract


Use of the TiC cermet become an important structural materials because of its high hardness, good creep resistance and high temperature performance, self-propagating high-temperature synthesis. Conventional solder on TiC poor wettability of the surface of the metal-ceramic, when using which contains vacuum evaporation elements Zn AgCuZn solder wetting TiC cermet, brazing material in the TiC cermet surface wettability significantly improved. Therefore, this article uses the method of combining the experimental results and the theoretical analysis, were studied in the the TiC cermet surface wetting mechanism of Zn volatile to promote AgCuZn solder. Through the different degree of vacuum brazing different Zn mass percentage AgCuZn the TiC cermet wetting test and the same degree of vacuum brazing the TiC cermet wetting test to determine the volatilization of the Zn in the vacuum brazing TiC cermet surface wettability and interface structure has an important influence. When the Zn content is 25wt.% AgCuZn brazing material in a vacuum wetting TiC cermet, the surface wettability of the best. Using AgCu brazing material wetting TiC cermet, the outer surface of the from the nearly AgCu brazing material to the TiC cermet side tissue sequentially illustrating Ag (ss) Cu (ss) / (Cu, Ni) Ag (ss) / TiC cermet Ag (ss) Cu (ss) / TiC cermet; while to adopt AgCuZn solder wetting TiC cermet from nearly AgCuZn solder surface to the TiC cermet side, tissue sequentially expressed as Ag (ss) Cu (SS) (Cu, Ni) / Ag (ss) Cu (ss) / (Cu, Ni,) / the TiC cermet AG (SS) Cu (SS) / TiC cermet. In addition, by the interface tissue observation can different Zn content AgCuZn brazing / TiC cermet interface of the (Cu, Ni) of the distribution form and content, quantity and diffusion distance of the drift out of TiC TiC cermet substrate is different. In this paper, by studying the solder / the TiC cermet Interface (Cu, Ni) area percentage (Cu, Ni) Ni mass percentage impact of the brazing filler metal and metal-ceramic interfacial tension of the classical Young's equation extended test measured actual wetting angle wetting angle validate the theory extended Young's equation results in good agreement. In addition, from a kinetic point of view of AgCuZn solder Zn volatile solder in the TiC cermet surface wetting process impact. And based on the Langmuir adsorption kinetics, through the correspondence relationship between the amount of adsorption and wettability of the brazing alloy on the surface of the TiC cermet wetting dynamics equation, and its amendments. In order to to explain Zn vacuum volatile improve from the perspective of quantum mechanics solder in the TiC cermet surface wettability mechanism, this paper established three different cluster model, through the calculation of the density of states of the three cluster model, the partial density of states, Mulliken population and bond length of the key, which is determined from the point of view of the First Principle of the the Zn evaporation, Ni-Cu interaction enhanced solder wetting TiC cermet surface easier.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding materials > Brazing materials
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