Microstructure and properties of HfC and TaC-based ceramics obtained by ultrafine powder

Microstructure, mechanical properties and oxidation behavior of TaC- and HfC-based materials containing short SiC fiber

“…This hypothesis is corroborated by previous results obtained on dense HfC materials, for which the fracture toughness without any reinforcement was 3.6 MPa m 1/2 [10].…”

“…Hot pressing, spark plasma sintering and pressureless sintering have been often associated to the use of additives to improve densification and mitigate the severe sintering temperatures [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Small amounts of metals such as Fe, Mn, Co, and Ni, lower the temperature needed for densification [5][6][7]; alternative sintering additives such as B, C, and B 4 C, remove surface oxides on the starting particles enabling densification at 1900-2300 1C [8,9].…”

“…Reducing particle size of the powders has also been shown to improve the densification. TaC and HfC þ 5 vol% MoSi 2 with relative densities above 90% have been obtained starting from synthesized ultrafine powders [10]. Recently, spark plasma sintering was also used to consolidate Ta 0.8 Hf 0.2 C using MoSi 2 and TaSi 2 as sintering aids at 1650 1C under 30 MPa [19].…”

Mechanisms of pore formation in high-temperature carbides: Case study of TaC prepared by spark plasma sintering

“…Pores are a dominant type of flaw in TaC 1Àx , a consequence of the difficulty in producing dense samples [6,7,22,25,[27][28][29][30][31][32][33][34][35][36]. Grain growth during sintering is often cited as the cause for trapped porosity in the microstructure of TaC.…”

Microstructure and Scratch Resistance of TaC Dense Ceramic Layer on an Iron Matrix

“…structure (Ref 1), has attracted great attention due to its high melting point (3880°C), high hardness (15)(16)(17)(18)(19) GPa) ( Ref 2,3), and large thermal expansion coefficient of 6.29 9 10 À6 /K. In addition, TaC has some other excellent physical, mechanical, and chemical characteristics, such as (1) strong antioxidant capacity, which makes it difficult to dissolve in inorganic acids (Ref 4,5) or dissolve slightly in a mixed solution of hydrofluoric and nitric acid (Ref 6), (2) increased high-temperature deformation resistance (the high resistance of thermal shock and wear makes it useful for high-temperature and wear-resistant applications), and (3) good chemical stability that reduces its reactivity with Fe-group metals (Ref 7).…”