Tribological studies of monolithic chromium diboride against cemented tungsten carbide (WC–Co) under dry condition

Bhatt, Bhaskar; Murthy, T.S.R.Ch.; Limaye, P.K.; Nagaraj, A.; Singh, Kuldip; Sonber, J.K.; Sairam, K.; Sashanka, A.; Rao, G. Appa; Rao, T. Srinivasa

doi:10.1016/j.ceramint.2016.06.208

Cited by 25 publications

(5 citation statements)

References 17 publications

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“…We found that CrB 2 produced the most stable and highest concentration dispersions in PVA. CrB 2 also has good wear resistance, 14 high hardness, high melting point (2200 °C), and high performance under extreme temperature and pressure conditions. 67 These bath-sonicated CrB 2 /PVA dispersions were concentrated and formed into films by a casting process (see the Methods section for more details).…”

Section: ■ Resultsmentioning

confidence: 99%

“…The interactions between the alternating layers of metal atoms and boron atoms have a mixed ionic and covalent character. Depending on the identity of the metal atoms, the M–B and B–B bond lengths and bonding strengths vary, leading to dramatic composition-dependent differences in properties. , Metal diborides exhibit a diverse range of remarkable physical properties. ,− For example, several of them have very high melting points, including some that exceed 3000 °C, such as HfB 2 and ZrB 2 which are considered ultrahigh-temperature ceramics (UHTCs). ,, Other examples of remarkable properties exhibited by the metal diborides include high mechanical strength and hardness (Young’s modulus above 480 GPa for ZrB 2 and HfB 2 ), exceptional mechanical performance at temperatures above 1500 °C for ZrB 2 ceramics, high thermal conductivity, resistance to chemical attack, ,, high fracture toughness, high wear resistance, high electrical conductivity, and electrocatalytic activity for the hydrogen evolution reaction . In contrast, MgB 2 has a substantially lower melting temperature of 830 °C but is well known as a superconductor with a transition temperature of 39 K, which ranks among the highest of the conventional superconductors. − …”

Section: Introductionmentioning

confidence: 99%

“…1,[4][5][6] For example, several of them have very high melting points, including some that exceed 3000ºC, such as HfB2 and ZrB2 which are considered ultrahigh temperature ceramics (UHTCs). 1,7,8 Other examples of remarkable properties exhibited by the metal diborides include high mechanical strength and hardness (Young's modulus above 480 GPa for ZrB2 and HfB2), exceptional mechanical performance at temperatures above 1500ºC for ZrB2 ceramics, 9 high thermal conductivity, 10 resistance to chemical attack, 1,11,12 high fracture toughness, 13 high wear resistance, 14 high electrical conductivity, 15 and electrocatalytic activity for the hydrogen evolution reaction. 16 In contrast, MgB2 has a substantially lower melting temperature of 830°C but is well known as a superconductor with a transition temperature of 39 K, which ranks among the highest of the conventional superconductors.…”

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Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

et al. 2021

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The metal diborides are a class of ceramic materials with crystal structures consisting of hexagonal sheets of boron atoms alternating with planes of metal atoms held together with mixed character ionic/covalent bonds. Many of the metal diborides are ultrahigh temperature ceramics like HfB2, TaB2, and ZrB2, which have melting points above 3000ºC, high mechanical hardness and strength at high temperatures, and high chemical resistance, while MgB2 is a superconductor with a transition temperature of 39 K. Here we demonstrate that this diverse family of non-van der Waals materials can be processed into stable dispersions of two-dimensional (2D) nanosheets using ultrasonication-assisted exfoliation. We generate 2D nanosheets of the metal diborides AlB2, CrB2, HfB2, MgB2, NbB2, TaB2, TiB2, and ZrB2, and use electron and scanning probe microscopies to characterize their structures, morphologies, and compositions. The exfoliated layers span up to micrometers in lateral dimension and reach thicknesses down to 2-3 nm, while retaining their hexagonal atomic structure and chemical composition. We exploit the convenient solution-phase dispersions of exfoliated CrB2 nanosheets to incorporate them directly into polymer composites. In contrast to the hard and brittle bulk CrB2, we find that CrB2 nanocomposites remain very flexible and simultaneously provide increases in the elastic modulus and the ultimate tensile strength of the polymer. The successful liquid-phase production of 2D metal diborides enables their processing using scalable low-temperature solution-phase methods, extending their use to previously unexplored applications, and reveals a new family of non-van der Waals materials that can be efficiently exfoliated into 2D forms.The metal diborides are a family of ceramic compounds with the general formula MB2, where M can be a variety of metals from Groups II, IVB and VB such as Hf, Cr, Ti, Zr, Mg, etc.The most common crystal structure for these materials is the AlB2 type, belonging to the P6/mmm space group symmetry, which has the boron atoms in covalently bound hexagonal sheets separated by layers of close-packed metal atoms, 1 as shown in Figure 1a. The interactions between the

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Section: ■ Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

et al. 2021

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“…Another weakness of TMB 2 films is their relatively high coefficient of friction in humid air [17][18][19], which excludes these materials from a large number of tribological applications. Concerning the tribological properties, several authors report the coefficient of friction (COF) of bulk ZrB 2 to be in the interval from 0.2 to 0.9 depending on the choice of measurement, load, surface morphology, chemical composition, environment, and material of the counterpart.…”

Section: Introductionmentioning

confidence: 99%

First Approach to ZrB2 Thin Films Alloyed with Silver Prepared by Magnetron Co-Sputtering

et al. 2023

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Hexagonal ZrB2 belongs to the group of ultra-high temperature ceramics representing an important class of materials with the potential to meet the high demands of today’s industry. However, this potential is limited by inherent brittleness and poor tribological properties. Here, the combination of density functional theory and experiment is used to investigate the effect of silver alloying on the mechanical and tribological properties of hexagonal ZrB2 thin films. Calculations indicate strong insolubility of Ag atoms in the ZrB2 metal sublattice and a significant effect on the mechanical properties, pointing out an improvement in ductility and tribological properties but at the cost of reduced hardness. The experiments confirmed the theoretical predictions of the strong insolubility of silver, where the magnetron-sputtered Zr1−xAgxB2+Δ films form a segregated nanostructure consisting of separated hexagonal ZrB2 and cubic Ag phases. With increased Ag content, values of Young’s modulus decrease from EZrB2.31 = 375 GPa to EZr0.26Ag0.74B0.89 = 154 GPa, followed by a decrease in hardness from HZrB2.31 = 30 GPa to a value of HZr0.26Ag0.74B0.89 = 4 GPa. The suppression of crack formation is also shown with the material flow around cube corner indents, indicating enhanced ductility. The improvement of tribological properties was also confirmed when the coefficient of friction (COF) was reduced from COFZrB2.31 ~0.9 to a value of COFZr0.26Ag0.74B0.89 ~0.25 for all counterpart materials—steel (100Cr6), Si3N4, and WC/Co.

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“…Refractory metal borides, carbides and their composites are natural candidates for these tribological applications due to their exceptional hardness, elastic modulus and thermal stability at elevated temperatures [32][33][34][35][36][37][38]. Among these, boron carbide is one of the potential materials for wear resistant applications [25].…”

Section: Introductionmentioning

confidence: 99%