Ultra-high-temperature tantalum-hafnium carbonitride ceramics fabricated by combustion synthesis and spark plasma sintering

• DOI: 10.1016/j.ceramint.2021.07.180
• Publication Date: 2021-07-21T21:26:42Z
• Authors: V.S. Buinevich; A.A. Nepapushev; D.O. Moskovskikh; K.V. Kuskov; S.N. Yudin; A.S. Mukasyan
• Keywords: Spark Plasma Sintering; Relative density; Self-propagating high-temperature synthesis; Sialon; Powder Metallurgy; MAX phases

Abstract We report the fabrication of dense single-phase (Ta,Hf)CN carbonitride ceramics using a combination of combustion synthesis (CS) and spark plasma sintering (SPS). The ceramic powder was produced by high-energy ball milling of the reactants (Ta, Hf, C) in different atomic ratios followed by CS of the obtained nanostructured composites in a nitrogen atmosphere. X-ray diffraction analysis of the combustion products revealed the formation of (Ta,Hf)CN with cubic B1 structures as the dominant phases for all investigated compositions. The SPS of the as-synthesized powders allowed both homogenization of the composition and consolidation of the bulk single-phase carbonitride ceramics with a relative density of 98 ± 1 %. Ta25Hf75CN showed the highest hardness (19.4 ± 0.2 GPa) and fracture toughness (5.4 ± 0.4 MPa m1/2) among the investigated composites and excellent oxidation resistance in air.