Abstract
Joining is a crucial process for the production of complex-shaped advanced engineering materials. Deep understanding of ceramic-metal interfaces during joining or following heat-treatment steps is therefore of important concern in designing the new systems. Capacitor discharge joining (CDJ) method was firstly carried out to compose the ceramic-metal joint material by silicon nitride (Si3N4)-titanium (Ti) constituents. Afterwards, heat treatment was performed on the Si3N4-Ti joints in air atmosphere at 1000 °C temperature to reveal the interface reactions and phases. Reaction layer that occurred between the Si3N4 and Ti interfaces and new phase formations were examined by transmission electron microscopy (TEM)-based various imaging and chemical analysis techniques. Electron transparent samples for TEM characterization were prepared by focused ion beam (FIB) milling and lifting method. Based on the detailed TEM results, Si and N diffusion arising from the Si3N4 ceramic was observed towards Ti metal foil side and further interacted with Ti atoms. The upshot of current diffusion was that Ti3N2 reaction layer with 50 nm thickness was formed at the interface while titanium silicon nitride (Ti6Si3N) matrix phase including dendritic-shaped Ti2N grains occurred in the Ti interlayer. It is believed that our TEM-based microscopy results not only provide the knowledge on ceramic-metal joint materials by CDJ method, but also contribute new insights on the development of various new joint systems.
Highlights
Silicon nitride ceramics (Si3N4) are mostly used in high-temperature structure and wear-resistant components combined with metallic materials in manyJ Adv Ceram 2019, 8(4): 500–508 to be utilized since Si3N4 has some difficulty for machining and producing complex shape [7]
Based on the atomic number (Z)– contrast–high angle annular dark field (HAADF) images, the effect of heat treatment was clearly seen within Ti interlayer and ceramic– metal interface (Figs. 2(c)–2(e))
Based on Z contrast STEM–HAADF image in Figs. 2(c)–2(e), some parts of the formations and dendrites show the variable contrast from white to grey due to Z differences of phases, whereas the same regions can be discerned in opposite contrast in STEM–bright field (BF) image that was governed by diffraction contributions of equal phases (Figs. 2(d)– 2(f))
Summary
Silicon nitride ceramics (Si3N4) are mostly used in high-temperature structure and wear-resistant components combined with metallic materials in manyJ Adv Ceram 2019, 8(4): 500–508 to be utilized since Si3N4 has some difficulty for machining and producing complex shape [7]. While Si3N4 ceramics have excellent thermal, oxidation, and creep resistance, metallic material can be used as an interlayer to compensate stress or temperature gradient of structures and moving parts [8]. Some factors such as differences in thermal expansion coefficient between ceramic and metal, bonding time, and resulting reaction products can directly affect the mechanical properties of joints depending on the chosen technique parameters and properties of the filler materials [9,10]. Ultrasonic brazing technique has attracted significant attention recently, since it enables the bonding of dissimilar materials at low cost and in fast bonding time [15,16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
