Bonding of glassy carbon composite by brazing with filler metal and sinter bonding with adhesive resin using direct current heating and sufficient pressing was studied after investigation of microstructure and component of composite. Al, Ag-Cu-Ti, Ni-Cr-B were used for filler metal and phenolic adhesive resin containing graphite powders and hardening material was used for adhesive resin. Joint properties were evaluated by microstructure and bending strength of joint.
Main results obtained are as follows :
(1) This carbon composite had piled structure of black color layer and white color layer containing black color layer locally. It was confirmed by XPS that black color layer was graphite powder rich layer containing glassy carbon and white color layer containing black color layer locally was glassy carbon rich layer containing graphite powder, carbon fiber. It was confirmed by microstructure observation and XPS that top surface of composite (surface of 1st black color layer) was the most glassy carbon rich layer.
(2) Polishing of joint surface is necessary for obtaining of adequate roughness and flatness. Component of bonding surface varies with this polishing of joint surface.
(3) Relationship between joint properties and various bonding surface was investigated. At Al, Ag-Cu-Ti, Ni-Cr-B brazing, wettability of filler metal to each bonding surface was very poor and 4 point bending strength of joint was zero in any bonding surface. At sinter bonding with phenolic adhesive resin, 4 point bending strength of black color layer joint was about 20 MPa and that of white color layer joint containing black color layer locally was about 10 MPa. These bending strength of joint were lower than bending strength of base carbon composite (124 MPa). Bonding did not advance at top surface of composite (surface of 1st black color layer : the most glassy carbon rich layer). It was assumed from these results that bending strength of joint decreased with increase of glassy carbon. Plasma discharge in H2O atmosphere for black color layer (polishing surface of 1st black color layer : polishing 5 μm) was effective to increase of bending strength of joint. 4 point bending strength of plasma discharged joint was about 35 MPa.
