TiB2-AlN-Gr Composite Prepared by Spark Plasma Sintering: Microstructure, Thermodynamic Behavior, and Simulation of the Orthogonal Cutting Process

Abstract

The thermodynamical analyses of in-situ phase formation during the spark plasma sintering (SPS) process were utilized to investigate the correlation between the mechanical properties of the TiB₂-20 wt.% AlN-5 wt.% graphene (Gr) composite and its microstructural features. It was demonstrated that the initial admixture of TiB₂, AlN, and Gr, as well as the original phases in the surface oxides (TiO₂, B₂O₃, and Al₂O₃), interact in chemical reactions during the SPS process, forming the in-situ h-BN phase and TiB_xN_y solid solution. According to thermodynamic calculations, TiN was the result of the reaction between TiO₂, AlN, TiB₂, and C. The incorporation of Gr into the TiB₂-AlN matrix not only prevented excessive grain growth but also led to high compaction, which improved the composite's mechanical characteristics. Evaluation with x-ray photoelectron spectroscopy confirmed the presence of B-N and Ti-N bonds, whereas electron probe microanalysis mapping of the generated composite indicated the probable formation of a TiB_xN_y solid solution. In addition, based on the design of the experiments conducted to examine the various parameters of the cutting process by using the investigated TiB₂-AlN-Gr sample properties as a cutting tool, during the orthogonal cutting of titanium Ti5553AMTC (the workpiece), the effects of various parameters, including cutting speed, the radius of the tool tip on the cutting and feeding force, the maximum temperature of the tool and workpiece, and the shape of the chip, were simulated. The orthogonal cutting numerical results confirmed that when cutting speed and tool edge radius increase, the maximum temperature of the cutting tool and the workpiece rises.