Preparation of Ti-based laminated composites through spark plasma sintering with different carbon sources as the bonding layer

Abstract

In the present study, woven carbon fabrics, graphene nano sheets (GNPs) and graphites were used as the bonding source between Ti sheets to produce Ti-TiC laminated composites through spark plasma sintering. In the case of carbon fibers, the woven fabrics were cut in a circular shape and inserted between the Ti sheets; on the other hand, in the case of graphite and GNPs, ethanol with carbon sources as the mixture was sprayed on the surface of the starting Ti sheets until reaching the specified increase in the weight of the coated Ti. After that, seven layers of Ti sheets (including six coated layers and one un-coated one) were inserted to the graphite die and the sintering process was performed with the initial and final applied pressure of 10 and 50 MPa, respectively, at the sintering temperature of 1250 °C. The XRD patterns taken from the cross-section of the prepared composites revealed the formation of the TiC crystalline phase as the product of the reaction between Ti and the carbon sources. The FESEM images also showed the proper bonding between the layers due to the formation of TiC and carbon diffusion into the Ti sheets. The fracture surfaces of the prepared sample demonstrated the almost ductile fracture for the Ti-laminated sample, as well as the Ti-GNPs laminated composite, while the brittle fracture was obtained for the composites with graphite and the carbon fabric as the bonding layers. The highest hardness of 912 ± 17 Hv was calculated for the cross-section of the Ti-CF laminated composite; also, the highest bending strength of 1215 ± 18 MPa was obtained for the Ti-GNPs laminated composite.