Titanium Diboride

In this study, densification of TiB 2 with the addition of 316L grade stainless steel powder by using the vacuum arc melting (VAM) process was investigated. 316L and TiB 2 powders were mixed in predetermined amounts and pressed to form pellet shaped samples which were later heated in the VAM. Microstructures of the samples were examined by SEM and an optical microscope. It was observed that TiB 2 grains in the samples were wetted by the molten stainless steel phase. Furthermore, it was noted that the sample composition and arc current in the VAM affected the densification behavior of the samples. This kind of a material processing technique can be used to build up a composite layer over different substrates as well as over selected surfaces of machine parts.

In this thesis, non-pressurized sintering and characterization of TiB2 particulate reinforced aluminum matrix composites were studied. As a matrix material 96% Al – 4% Cu alloy was used. Al-TiB2 powder mixtures containing 10%, 15%, 20% and 30% TiB2 by volume were prepared and were cold pressed uniaxially at 800 MPa. Non-pressurized sintering was performed in a nitrogen gas atmosphere at 620 oC. Obtained composites were subjected to density measurements, microstructure examinations, 3 point bending tests, hardness tests and wear resistance tests. Same tests were repeated after age hardening of the composites.
    After age hardening treatment, unreinforced sample presented a maximum 3 point bending strength of 940 MPa, 28% strain and 100 HB10 hardness value. Wear rate was 12,16 ± 3,16 x 10-3 mm3 / N.m in the unreinforced sample. The least wear rate was seen in 20% TiB2 containing samples. This composite presented 867 MPa bending strength, 7,41% strain and 130 HB10 hardness.