Effects of Si and Ni nanoparticles in Brazing process on fracture surfaces of 304 stainless steels
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Effects of Si and Ni nanoparticles in Brazing process on fracture surfaces of 304 stainless steels H. M. Hdz-García1, J. L. Acevedo-Dávila1, L. A. García-Cerda2, M. I. Pech-Canul3, R. Muñoz-Arroyo3, F. A. Reyes-Valdes1, F. A. Hernández-García4, J. A. Aguilar-Martínez5 1
Corporación Mexicana de Investigación en Materiales, Calle Ciencia y Tecnología No. 790 Fracc. Saltillo 400; Saltillo, Coah. CP. 25290. e-mail: [email protected]. 2Centro de Investigación de Química Aplicada, Blvd. Enrique Reyna Hermosillo, Saltillo, Coah. 3 Centro de Investigación y Estudios Avanzados del IPN, Carr. Monty-Saltillo km. 13; Ramos Arizpe, Coah. CP. 25900. 4Universidad Politécnica de Querétaro carr. Est. 420 s/n; El Marques, Qro. C.P. 76240. 5Centro de Investigación en Materiales Avanzados, Alianza Norte 202, Autopista Mty-Aeropuerto Km. 10, Parque de Investigación e Innovación Tecnológica (PIIT), Apodaca, NL, C.P. 66600 Abstract In order to increase the wettability and capillary forces of the filler metal between microcracking and micro-porous on the fracture surfaces of 304 stainless steels, methods of impregnation of Si and growth of Ni nanoparticles were used. These nanoparticles have a role inside the Transient Liquid Phase (TLP) and the substrate when using Brazing process. TLP can react with the nanoparticles previously deposited between micro-cracking and microporous and therefore promotes the nucleation and growth sites of phases and decreases the formation of eutectic structures. This method increases the effectiveness of metallic components reparation using Brazing process. Such effectiveness is indicated by an inspection of microstructural failure analysis, as a first stage, in the covered zone by the filler metal. Keywords: Brazing, Transient Liquid Phase, Stainless steel 1.Introduction Stainless steels are widely used not only because of their corrosion resistance but because they are readily formable, fabricable and durable. They are used as structural support and containment and medical products [1]. However, like other austenitic steels that contain a substantial amount of chromium, they are highly susceptible to heat affected zone cracking during welding. Commonly, the melting filler in the Brazing process contain silicon and boron as melting point depressants and reduce the eutectic structures [2, 3, 4]. Must keep in mind, these are extremely hard and contain very brittle intermetallic compounds with chromium which are detrimental to the mechanical properties of the brazed joint. Other way to prevent the formation of these deleterious phases is transient liquid phase (TLP) bonding or using silicon content [5]. In this way, the high-diffusivity of boron can reach the solidus value during the holding period and avoid the formation of eutectic phases [6]. TLP is an excellent bonding technique, but the time to complete isothermal solidification is usually long enough to discourage their potential applications in many industries. Grant et. al [7] suggest that the TLP bonding is a relatively new bonding process that r
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