Joining ceramics using capacitor discharge technique and determination of reactions at metal ceramic interfaces

The aim of this thesis is to join metals and ceramics by using capacitor discharge technique and to understand reactions occur between ceramic and metal and also to determine the compositional reaction products. Si3N4, TiCN coated Si3N4, SiAlON and PZT materials were used as a ceramic materials whereas Ti, superalloy and Ag were used as an interlayer. After capacitor discharge joining, some of the samples were heat treated of different temperatures and samples were prepared for scaninig electron microscpoy (SEM) and transmission electron microscopy (TEM) investigations. Then, joined and heat treated samples were investigated by using various SEM and TEM techniques. Analytical TEM techniques showed that N and Si diffusion were intensely increased towards the interlayer and interacted with Ti atoms. Ti3N2 reaction layer and Ti3N phases on the Ti interlayer side were formed for the as-joined Si3N4-Ti samples. Whereas, Ti3N2 reaction layer and dendritic Ti2N phase were observed instead of Ti3N for the heat treated sample. Additionally, Ti5Si3Nx phase was present at the Ti interlayer surrounding the Ti3N or Ti2N for the as-joined and heat treated samples, respectively. For the Si3N4-Supperalloy samples, similarly, N and Si diffusion were occured towards the interlayer and interacted mainly with Ni, Cr and Fe atoms. Moreover, MT-DATA studies were supported by these results.