چكيده
Abstract:
In situ process is one of the methods for synthesis TiB2 in molten copper. Nano sized TiB2 particles that cause high mechanical properties can be achieved by this method. In this study, Cu, Ti, B2O3 and C were used as starting materials for vacuum induction melting (VIM) process. The weight ratio of B2O3 to C (MB2O3/MC) was different in each sample. As-cast samples were homogenized at 800ºC for 8 hours, afterwards homogenized samples were suspended in a salt bath with 800ºC temperature for 10 minutes and quickly quenched in water. Finally, some slices were cut from as-cast samples and leached in nitric acid. SEM pictures showed some hexagonal particles in some samples. EDS results of sample 2 (MB2O3/MC=6) and sample 4 (MB2O3/MC=8) showed the peak of boron element. Furthermore, XRD results of powders derived from leaching process showed that TiB2 particles were oxidized by nitric acid and transformed to TiO2. Presence of carbon residual in sample 1 (MB2O3/MC=3.87) to sample 3 (MB2O3/MC=7) was confirmed by these XRD results. The homogenized sample 1 had maximum hardness (202HV) and quenched sample 3 had minimum hardness (72HV). The optimum amount of MB2O3/MC that brings maximum amount of TiB2 is related to sample 4 with MB2O3/MC=8.
Key words: TiB2, vacuum induction melting, quench, leach
