Dissimilar joining of carbon/carbon composites to Ti6Al4V using reactive resistance spot welding

A 2D C/C composite with a high porosity (low strength) and a 3D C/C composite with a low porosity (high strength) were investigated for dissimilar joining to Ti6Al4V via reactive spot welding. It was determined that infiltration of melted metal into the composite and formation of a continuous thin TiC layer at the interface of the joints were the dominant joining mechanisms. The 2D C/C composite with a flat surface was successfully joined to Ti6Al4V due to the infiltration of the melted Ti6Al4V into its porous content. On the other hand, it was necessary to drill rectangular grooves onto the surface of the 3D C/C composite to facilitate the infiltration of the melted Ti into the composite, which produced high-strength joints. Surface patterning was determined to be necessary to join the components with mismatching coefficients of thermal expansion. The strength of the 2D C/C composite and Ti6Al4V joints was found to be 7 MPa, while the maximum strength of the groove-patterned 3D C/C composite and Ti6Al4V joints reached 46 MPa.