Effect of modification of ceramic particles by sol-gel method on the mechanical properties during the production of aluminum matrix composites via hot pressing method

In this study aluminum matrix (Al-4 % Cu) composites reinforced with 5-40 vol % TiB2 and 5-45 vol % SiC particles were produced via hot pressing method. Prepared composites were subjected to microstructural examinations, hardness and three point bending tests. Same examinations were performed after subjecting the composites to T6 heat treatment. It was revealed by optical microscopy examinations that the reinforcement particles were homogenously distributed in the composite structure. The hardness of the composites increased with increasing reinforcement amount. The highest hardness values of 140 and 160 HB10 were attained in the SiC and TiB2 reinforced composites, respectively. Three point bending strengths were in the range of 750-850 MPa, for both of the reinforcement phases. Modification of the surfaces of the TiB2 particles with silica and surfaces of SiC particles with silica and TiB2 via sol gel method have been studied. It is thought from the results of the Fourier transformed infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses that modifications have been accomplished. Strength values of the composites obtained by using silica modified ceramic particles were found to be lower than the composites obtained by unmodified particles, due to agglomeration of the particles in the composites. Strength values of the composites produced by using TiB2 modified SiC particles were found to be in the same range with the values of the composites obtained from unmodified SiC.