HfC- and HfB2-based UHTC materials densified by spark plasma sintering
2008 (English)In: Journal of American Ceramic Society, Vol. 91, no 5, 1433-1440 p.Article in journal (Refereed) Published
Hafnium diboride (HfB2)- and hafnium carbide (HfC)-based materials contg. MoSi2 as sintering aid in the volumetric range 1-9% were densified by spark plasma sintering at 1750-1950C. Fully dense samples were obtained with an initial MoSi2 content of 3 and 9 vol% at 1750-1800C. When the doping level was reduced, it was necessary to raise the sintering temp. obtain samples with d. >97%. Undoped powders had to be sintered at 2100-2200C. For doped materials, fine microstructures were obtained when the thermal treatment was <1850C. Silicon carbide formation was obsd. in both carbide- and boride-based materials. Nanoindentation hardness values were in the range of 25-28 GPa and were independent of the starting compn. The nanoindentation Young's modulus and the fracture toughness of the HfB2-based materials were higher than those of the HfC-based materials. The flexural strength of the HfB2-based material with 9 vol% of MoSi2 was higher at 1500C than at room temp.
Place, publisher, year, edition, pages
2008. Vol. 91, no 5, 1433-1440 p.
Borides, carbides, spark plasma sintering, mechanical properties
IdentifiersURN: urn:nbn:se:su:diva-15127OAI: oai:DiVA.org:su-15127DiVA: diva2:181647