Wide-Band Tunable Microwave-Absorbing Ceramic Composites Made of Polymer-Derived SiOC Ceramic and in Situ Partially Surface-Oxidized Ultra-High-Temperature Ceramics

2019 ◽  
Vol 11 (49) ◽  
pp. 45862-45874 ◽  
Author(s):  
Yujun Jia ◽  
Md Atiqur Rahman Chowdhury ◽  
Dajie Zhang ◽  
Chengying Xu
Keyword(s):  
High Temperature ◽  
Wide Band ◽  
Ceramic Composites ◽  
Ultra High Temperature Ceramics ◽  
Tunable Microwave ◽  
Microwave Absorbing ◽  
Ultra High Temperature

Processing and Characterization of Zr-, Hf- and Ta-Based Ultra High Temperature Ceramics

2010 ◽  
Vol 65 ◽  
pp. 118-123
Author(s):  
Roberta Licheri ◽  
Roberto Orrù ◽  
Clara Musa ◽  
Giacomo Cao
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Point Of View ◽  
Ultra High Temperature Ceramics ◽  
Plasma Sintering ◽  
High Temperature Synthesis ◽  
Spark Plasma ◽  
Energy Consuming ◽  
Ultra High Temperature

The fabrication of MB2-SiC and MB2-MC-SiC (M=Zr, Hf, Ta) Ultra High Temperature Ceramics (UHTCs) is investigated in this work by combining Self-propagating High-temperature Synthesis (SHS) and Spark Plasma Sintering (SPS). Zr, Hf or Ta, B4C, Si, and graphite powders are first reacted by SHS to successfully form in-situ the desired composites. For the case of the Tabased systems, a 20 min ball milling treatment is also required to mechanically activate the SHS reactions. The resulting powders are subsequently consolidated by SPS at 1800 °C and P=20 MPa, thus obtaining products with densities greater than 96% within 30 min of total processing time. Hardness, fracture toughness, and oxidation resistance of the resulting dense UHTCs are among the best when compared to the corresponding values reported in the literature relative to analogous products synthesized by alternative, more energy-consuming and less rapid methods. Thermogravimetric analysis results evidenced the beneficial effect of SiC on the oxidation resistance of the composite materials, while the presence of transition metal carbides appears to be inconvenient from this point of view. This is because, they rapidly oxidize at high temperature to form MxOy and carbon oxides which lead to an increase in sample porosity thus enhancing product oxidation.

Sign in / Sign up

Export Citation Format

Share Document