Processing, mechanical properties and oxidation behavior of TaC and HfC composites containing 15 vol% TaSi₂ or MoSi₂

Abstract

Fully dense HfC and TaC-based composites containing 15 vol% TaSi2 or MoSi2 were produced by hot pressing at 1750–1900 °C. TaSi2 enhanced the sinterability of the composites and nearly fully dense materials were obtained at lower temperatures than in the case of MoSi2-containing ones. The TaC-based composites performed better than HfC composites at room temperature, showing values of mechanical strength up to 900 MPa and a fracture toughness of 4.7 MPa·m1/2. However, preliminary oxidation tests carried out in air at 1600 °C revealed that HfC-based composites have a superior high temperature stability compared to TaC-based materials.

Graphene NanoPlatelets reinforced tantalum carbide consolidated by spark plasma sintering

“…Hot pressing (HP) has been reported to be one of the most effective techniques for obtaining high density UHTCs [22,44,47,58,59]. Ta [30].…”

Nano-(Ta, Zr)C Precipitates at Multigrain Conjunctions in TaC Ceramic with 10 mol% ZrC and 5 mol% Cu as Sintering Aid

“…Because TaC ceramics are extremely hard to densify [2], sintering aids such as C [3][4][5][6], Si [7,8], B 4 C [9,10], SiC [11,12], TaSi 2 [13,14], MoSi 2 [13,15], TaB 2 [9,10,16], and Si 3 N 4 [17] were used to increase densification. In a previous work, TaC ceramics were hot pressed with ZrC plus Cu as sintering aids [18].…”

Microstructure and Mechanical Properties of Nanofiller Reinforced Tantalum-Niobium Carbide Formed by Spark Plasma Sintering

“…Tantalum Carbide, as well as other UHTC materials such as NbC, VC, and HfC, has been consolidated into bulk form using various processing approaches (outlined in Table 3) including hot pressing [26][27][28][29][30][31], pressureless sintering [32,33], vacuum plasma spraying [34], high frequency induction heating [35,36], and spark plasma sintering [37][38][39][40]. Differences in heating and cooling rates, temperatures, dwell times, and pressures will impact the phase formation, microstructures, and densification of the final product.…”

“…Liu et al While these additives enhanced the densification of the ceramic composite, the composites failed when heated to just 1200-1600°C due to their extreme susceptibility to oxidation. Furthermore, the presence of the liquid phase at the grain boundaries formed by metallic additives limits the usefulness of the UHTCs for the high temperature applications [31].…”

“…Other sintering additives that have previously been shown to enhance densification while better maintaining the high temperature properties of the ceramic include carbon, TaB 2 , TaSi 2 , MoSi 2 , SiC, B 4 C, and Si [28,30,31,33,37,39].…”