Efficient Synthesis/Sintering Routes to obtain Fully Dense Ultra High Temperature Ceramics (UHTC)

LICHERI, ROBERTA;ORRU', ROBERTO;LOCCI, ANTONIO MARIO;CAO, GIACOMO

2007-01-01

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Abstract

Two different synthesis/sintering routes are proposed in this work for the preparation of fully dense 2ZrB(2)-SiC ultra-high-temperature ceramic (UHTC) composites. Both processes start from commercial powders of zirconium, boron carbide (B4C), and silicon, and both take advantage of the spark plasma sintering (SPS) apparatus. In the first synthesis route, reactive spark plasma sintering (RSPS), it is possible to gradually synthesize and fully consolidate the UHTC material in a single step. This result is achieved within a total time (t(T)) of 20 min and with a maximum temperature (T-D) of 1900 degrees C. The second proposed synthesis method (i.e., SHS-SPS) consists in first synthesizing the composite powders, via self-propagating high-temperature synthesis (SHS), and subsequently consolidating them via SPS. In this case, the optimal operating conditions that are able to guarantee the obtainment of a fully dense material are T-D = 1600 degrees C and t(T) = 30 min or TD = 1800 degrees C and t(T) = 20 min. Based on the results reported in this work, it can be stated that the two proposed methods represent particularly rapid and convenient preparation routes, in comparison to the techniques that are available in the literature for the preparation of analogous materials.