| Abstract |
In view of potentiality of titanium diboride (TiB2) materials for high temperature applications, this
paper presents the state of art on the processing, microstructure and properties of TiB2 ceramics.
TiB2 ceramics are of interest for applications such as cutting tools, wear resistant parts, armor
material and electrode materials in metal smelting because of their excellent combination of
properties including high hardness, elastic modulus, better strength to weight ratio, wear resistance,
good thermal and electrical conductivity. However, such broader applications of the monolithic
TiB2 are inhibited by factors like high sintering temperature and poor toughness. Hence, research
efforts are directed towards processing TiB2 at lower sintering temperature as well as to enhance the
properties with the use of various metallic and non-metallic sinter-additives. In the above
perspective, we review the existing literature in this article. In addition, our recent research results
obtained with TiB2-TiSi2 materials are also presented. A review of research results revealed that a
combination of room temperature properties, i.e. maximum Vickers hardness of 31 GPa and
indentation toughness of 11 MPa m1/2 and flexural strength of 810 MPa is obtainable with optimally
sintered TiB2. More importantly, a maximum hardness of 9 GPa (at 900oC) and flexural strength of
471 MPa can be retained upto 1200oC. From the perspective of oxidation resistance, TiB2 samples
exhibit parabolic oxidation kinetics below 1000oC as result of the formation of TiO2 (s), and B2O3
(l) and linear oxidation kinetics above 1000oC in the presence of crystalline TiO2 and volatile B2O3. |
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