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

Roberta Licheri; Roberto Orrù; Clara Musa; Giacomo Cao

doi:10.4028/www.scientific.net/AST.65.118

Paper Titles

Hot Rolling Steels and Super Alloys with Silicon Nitride Tools
p.92

Processing and Thermal Properties of Cu-AlN Composites
p.100

Microstructural Evolution during High-Temperature Oxidation of Ti₂AlN Ceramics
p.106

Phase, Structural and Microstructural Changes in the TiC_1-x – Cr₃C₂ Materials
p.112

Processing and Characterization of Zr-, Hf- and Ta-Based Ultra High Temperature Ceramics
p.118

Oxidation Mechanism of ZrB₂-SiC Tested in a Solar Furnace above 2200°C
p.124

Stereological Microstructure Description of Structural SiC Ceramics as Composite Material
p.130

Oxidation Resistance of Coated and Uncoated SiC-Based Refractories
p.135

Defect Detection in Ceramic Armor Using Phased Array Ultrasound
p.143

HomeAdvances in Science and TechnologyAdvances in Science and Technology Vol. 65Processing and Characterization of Zr-, Hf- and...

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

Abstract:

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.