Titanium–titanium diboride composites as part of a gradient armour material

In the world today there is an increasing use of small-calibre armour piercing projectiles and these constitute a growing threat. This threat is most eminent for wearers of body armour and to lightly armoured combat vehicles. As part of the solution to this problem, new generations of lightweight armour designs are under development. One promising possibility has been found to be the use of functionally gradient materials as armour materials. In such materials, the high hardness of ceramics is combined with the ductility of metals; in our study the system of Ti–TiB2 was used. As compaction and consolidation process the spark plasma sintering process was used. Though similar to conventional hot pressing, no external heat source is needed; instead a pulsed direct current is passed through the electrically conducting pressure die and through the sample. At low sintering temperatures with short holding times (minutes), fully dense materials can be obtained, benefiting in little grain growth. Mechanical and impact experiments of single ceramic metallic composites layers have been carried out. The ballistic tests were done on discs glued to steel backings, and tungsten core projectiles, calibre 7.62 mm, were used. The ballistic results indicate a suitable composition, which does not have to be a pure ceramic, for the outer high hardness armour layer. To verify the suitability of the spark plasma sintered material, a comparison was made on the mechanical and ballistic properties between SPS-(Ti)0.05(TiB2)0.95 and HIP-TiB2, and it was found that the SPS-material was the overall better protective material.