Poster Presentation

¹Amirhosein Dini; ²Ali Mohammad Hadian ; ²Cyrus Zamani; ²Amir Hadian

¹School of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran

²School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran

The aim of this study was to investigate brazing of NbC-M2 based cermet to AISI 4140 steel by a nickel based (AWS BNi-2) filler metal (Ni,7Cr, 4.5Si, 3.1B, 3Fe). First, wetting behavior of the ceramic substrate by the molten filler was investigated at different time, temperature and surface roughness using a sessile drop technique. The lowest wetting angle was measured to be about 10°, which was achieved at a temperature of 1100 °C, a time of 15 minutes and a surface roughness of 0.5 micrometers. In the next step, joining of NbC-M2/AISI 4140 was performed using brazing technique. Brazing was done under argon atmosphere at different brazing time and temperature. Microstructural examination and phase analysis within the joint area were done using a X-ray diffraction (XRD) apparatus and a scanning electron microscope (SEM) equipped with an energy dispersive x-ray spectrometer (EDS). The result showed that at brazing temperature, the cermet part decomposes into Nb and C which react with the molten filler to form Nb2Ni and Cr7C3 phases along the cermet/steel interface. Formation of these interfacial phases promotes a strong bonding at the cermet/meta interface. The strength of the joints was measured using a shear testing method. The results showed that shear strength of the joints increases by increasing brazing time and temperature. The highest shear strength achieved was about 105 MPa for the joints which were brazed at 1100 °C for 10 minutes.

Cermet; Niobium Carbide; Brazing; Wettability; Shear strength