Abstract: Commercial pure (Cp) Grade-2 Ti was borided by solid state boriding technique in order to achive a hard and adhered borided layer and to improve its tribo-mechanical properties. Boriding was applied into the mixtures including different combinations of amorphous boron as a boron source, unhydrous borax and amoniumchloride as an activator and carbon and alumina as filler materials. Boriding was carried out by annealing the samples at two temperatures of 950 ºC and 1100 ºC for 24 h in a furnace under argon atmosphere. Boriding with different mixture resulted in various borided structures which mainly consist of a monolithic TiB2 phase on the top layer and TiB whiskers beneath that layer. Boriding at 950 ºC caused the formation of a thin TiB2 phase on the top and TiB whiskers toward the substrate. Boriding at 1100ºC, a thicker TiB2 phase developed on the top of the borided layers. A borided layer with the highest thickness was achieved on the samples borided at 1100 ºC for 24 h with a mixture consisting of amoniumchloride and alumina. But hardness of that layer was 2000 HV. After boriding at1100ºC into the mixtures of unhydrous borax with alumina or carbon, the hardness increased up to 4000 HV on the top most layer. In general, boriding of Grade-2 Ti into all mixture increased broadly its wear resistance. The highest increase in wear resistance was obtained with the mixture having unhydrous borax with alumina or carbon.
Keywords: Titanium, Boriding, Boriding mixture, Wear, Hardness
