Investigation of mechanical and machinability properties of aluminum matrix boron carbide and carbon nanofiber reinforced hybrid composites

In this study, mechanical and machinability properties of aluminum matrix B4C (Boron Carbide) and KNF (carbon nanofiber) reinforced hybrid composite produced by powder metallurgy method were investigated. The powders used in the study were mixed by mechanical alloying and then sintered at 35 MPa pressure and 550 °C by hot pressing. Microstructure analysis, density calculations, hardness, cross-breaking tests and abrasion tests of the hybrid composite material produced were made. Machinability tests using a 5mm diameter HSS drill, with 3 different point angles (90°-118°-135°), three different cutting speeds (30-45-67,5 m/min) and three different feed quantities (0,1- 0,15-0,225 mm/rev). Basic machinability parameters such as feed force, moment, surface roughness and hole quality were investigated. The hole damage occurring in the hole drilling process was examined and the delamination factor (Fd) was calculated. The abrasions occurred by examining the surface images of the drills. As a result of experimental studies, it was found that the reinforcing elements were distributed relatively homogeneously in the matrix and the relative density of the samples varied between %99,2-96,6. As the CNF amount increased, the hardness of the samples increased. In the three-point bending test, as the amount of KNF in the samples increased, the transverse repture strengths decreased. As a result of the wear test, the friction coefficient (µ) ranged between 0,664-0,535. In the machinability experiments, as the amount of the progress increases, the measured force values also increased. With the increase in the amount of progress in surface roughness measurements, the surface roughness increased but decreased with the increase in cutting speed. When the effect of the point angle on the surface roughness is evaluated, the surface roughness values decreased with increasing point angle. However, the increase of the point angle also increased the hole exit damage. Increasing the amount of advance caused an increase in hole exit damage. When the surface images of the drills were examined, it was observed that the outer corner wear and cutter mouth wear of the drills increased with the increase in the cutting speed and the amount of feed.