Metallic boro-carbides of A2BC (A = Ti, Zr, Hf and W): a comprehensive theoretical study for thermo-mechanical and optoelectronic applications. Issue 51 (18th November 2022)

• Record Type: Journal Article
• Authors: Islam, R.; Hossain, M. M.; Ali, M. A.; Uddin, M. M.; Naqib, S. H.
• Is Part Of: RSC advances. Volume 12:Issue 51(2022)
• Page Start: 32994
• Page End: 33007
• Publication Date: 2022-11-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2ra05448e
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The Ti2 BC reflectivity spectra never fall below 53% in the 0 to 10.3 eV photon range, showing as a coating material to reduce solar heating. The W2 BC has a Vickers hardness of ∼36 GPa with ductility, showing potential for hard coating application. Abstract : High-hardness materials with ductile deformation behavior have recently piqued interest due to their prospective applications, particularly as hard and protective coatings. The crack formation, especially in metal and ceramic materials, is one of the biggest problems of the surface hard coatings on heavy-duty tools. In this regard, mechanical properties (Vickers hardness, fracture toughness, machinability index, index of brittleness, as well as Pugh's ratio) have been studied for the metallic boro-carbides of A2 BC (A = Ti, Zr, Hf, and W) compounds using the state-of-the-art density functional theory in detail. The compounds under investigation are both thermodynamically and mechanically stable. The value of Vickers hardness (in GPa) for A2 BC (A = Ti, Zr, Hf, and W) compounds are 28.20, 23.12, 12.44, and 35.70, respectively, which indicates the W2 BC could be a member of the hard family ( H v > 30 GPa). Pugh's ratio suggests ductile deformation for the W2 BC compound, whereas the other three (Ti2 BC, Zr2 BC, and Hf2 BC) compounds exhibit brittle deformation behavior. The W2 BC compounds have the highest ductility among the other metallic boro-carbides (M2 BC; M = V, Nb, Mo and Ta) and some other benchmark coating materials (TiN, TiAlN, C-BN, and Cr0.5 Al0.5 N). The fracture toughness ( K IC ) values are in the following sequence: Zr2 BC < Ti2 BC < Hf2 BC < W2 BC, which indicates that, the highest resistance ( K IC = 4.96 MPam 1/2 ) found for W2 BC is suitable to prevent the crack propagation within the solid. In addition, the structural, electronic, optical, and thermal properties are also investigated for the A2 BC (A = Ti, Zr, Hf, and W) compounds. The Ti2 BC (W2 BC) reflectivity spectra never fall below 53 (45)% in the 0 to 10.3 eV (0 to 16.70 eV) photon energy range, suggesting that these compounds have promise for usage as coating materials to reduce solar heating. Hf2 BC and W2 BC compounds could also be exploited as promising thermal barrier coating materials, while Ti2 BC could be used as heat sink material based on the results of Debye temperature, melting temperature, thermal conductivity, and thermal expansion coefficient. The electronic properties reveal the metallic behavior of these compounds. The results obtained here are compared with those of some commercially known compounds, where available.