Synthesis of TiB2 metal matrix composite on plain steel substrate:: microstructure and wear properties

Metal matrix composites (MMC) synthesised on steel or on titanium substrates can be used in industry for parts demanding high wear resistance. In particular, TiB2 can be used as reinforcing material in MMCs due to its high melting point, high hardness and good wear and corrosion resistance. In the present paper, a titanium diboride composite is deposited on low carbon steel by the plasma transferred arc technique (PTA). Layers with similar to 1 mm in thickness and 600 HV in hardness are obtained and their microstructure and wear resistance are studied. The wear rate of the alloyed layer against a tool steel counterbody is in the order of 10(-5) mm(3) m(-1), while that for the alloyed layer against alumina is in the order of 10(-4) mm(3) m(-1). The friction coefficient for the alloyed layer-tool steel system is 0.12 and for the alloyed layer-alumina system is 0.59. These differences in friction and wear behaviour are due to the different wear mechanisms of the corresponding tribosystems.