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Processing, Microstructure and Mechanical Properties of TiB 2 -MoSi 2 -C Ceramics.

Processing, Microstructure and Mechanical Properties of TiB 2 -MoSi 2 -C Ceramics.

Authors :
Sajdak, Maria
Kornaus, Kamil
Zientara, Dariusz
Moskała, Norbert
Komarek, Sebastian
Momot, Kinga
Golis, Edmund
Zych, Łukasz
Gubernat, Agnieszka
Source :
Crystals (2073-4352); Mar2024, Vol. 14 Issue 3, p212, 20p
Publication Year :
2024

Abstract

Titanium boride (TiB<subscript>2</subscript>) is a material classified as an ultra-high-temperature ceramic. The TiB<subscript>2</subscript> structure is dominated by covalent bonds, which gives the materials based on TiB<subscript>2</subscript> very good mechanical and thermal properties, making them difficult to sinter at the same time. Obtaining dense TiB<subscript>2</subscript> polycrystals requires a chemical or physical sintering activation. Carbon and molybdenum disilicide (MoSi<subscript>2</subscript>) were chosen as sintering activation additives. Three series of samples were made, the first one with carbon additives: 0 to 4 wt.%; the second used 2.5, 5 and 10 wt.% MoSi<subscript>2</subscript>; and the third with both additions of 2 wt.% carbon and 2.5, 5 and 10 wt.% MoSi<subscript>2</subscript>. On the basis of the dilatometric sintering analysis, all additives were found to have a favourable effect on the sinterability of TiB<subscript>2</subscript>, and it was determined that sintering TiB<subscript>2</subscript> with the addition of carbon can be carried at 2100 °C and with MoSi<subscript>2</subscript> and both additives at 1800 °C. The polycrystals were sintered using the hot-pressing technique. On the basis of the studies conducted in this work, it was found that the addition of 1 wt.% of carbon allows single-phase TiB<subscript>2</subscript> polycrystals of high density (>90%) to be obtained. The minimum MoSi<subscript>2</subscript> addition, required to obtain dense sinters with a cermet-like microstructure, was 5 wt.%. High density was also achieved by the materials containing both additives. The samples with higher MoSi<subscript>2</subscript> content, i.e., 5 and 10%, showed densities close to 100%. The mechanical properties, such as Young's modulus, hardness and fracture toughness (K<subscript>Ic</subscript>), of the polycrystals and composites were similar for samples with densities exceeding 95%. The Vickers hardness was 23 to 27 GPa, fracture toughness (K<subscript>IC</subscript>) was 4 to 6 MPa·m<superscript>0.5</superscript> and the Young's modulus was 480 to 540 GPa. The resulting TiB<subscript>2</subscript>-based materials showed potential in high-temperature applications. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
20734352
Volume :
14
Issue :
3
Database :
Complementary Index
Journal :
Crystals (2073-4352)
Publication Type :
Academic Journal
Accession number :
176302954
Full Text :
https://doi.org/10.3390/cryst14030212