Evaluation of the Intermediate Layer of Graphite Bonded Metal

           This work investigates the joining between graphite and stainless steel grade (410), by using active filler metal paste. Brazing technique was chosen because it is efficient, verstile, fast and economical.High purity of metal powder of  silver, copper  and titanium in different concentrations were mixed carefully to prepare a filler paste. Stainless steel and graphite as a cubic shape were prepared to study both wetting and bonding behaviour as a function of essentially of furnace temperature.Decontamination processes were achieved on the all specimens under study according to the standard methods. The wettability was firstly studied, the paste drop of such filler ratio was lied on the both graphite and stainless steel surfaces. Good wettability was obtained wher the filler paste consist of pure titanium at the furnace temperature of 9 and furnace vacuum pressure 10-2 torr. Two Types of assembly designs were selected known butt and interlocking according to the experiments variables. For studying the bonding behaviour between the pieces to be joined, the filler paste was lied in between stainless steel and graphite as a sandwich form. Bonding processes were performed at different furnace temperatures as follows (85  mpa was obtained when the filler paste consist of (75Wt% Ti + 25Wt% Ag)by using interlocking design. The fractured surfaces were examined by Nondestructive testing involved optical microscopy, Scanning electron microscopy and Energy dispersive x-ray. X-ray diffraction used for studying the intermediate structure. New structure phases were established at the intermediate layer involved ((O20P4Ti5, O5STi and CrO9P3) , (TiO2and Ag3O4)).These new phases considered enhancement the bonding strength of theassembly.