12228-69-2Relevant articles and documents
Multiple crystal phases of intermetallic tungsten borides and phase-dependent electrocatalytic property for hydrogen evolution
Li, Qiuju,Wang, Lina,Ai, Xuan,Chen, Hui,Zou, Jiayun,Li, Guo-Dong,Zou, Xiaoxin
, p. 13983 - 13986 (2020)
Four stoichiometric W-B intermetallic phases, including W2B, WB, WB2 and WB3, are synthesized, and their hydrogen-evolution electrocatalytic properties and electronic structures are investigated comparatively. The electrocatalytic activity for the hydroge
Titanium diboride-tungsten diboride solid solutions formed by induction-field-activated combustion synthesis
Shibuya, Masachika,Kawata, Makoto,Ohyanagi, Manshi,Munir, Zuhair A.
, p. 706 - 10 (2003)
Solid solutions of titanium diboride-tungsten diboride (TiB2-WB2) were synthesized by induction-field-activated combustion synthesis (IFACS) using elemental reactants. In sharp contrast to conventional methods, solid solutions could be formed by the IFACS method within a very short time, ～2 min. Solutions with compositions ranging from 40-60 mol% WB2 were synthesized with a stoichiometric ratio (Ti + W)/B = 1/2; however, samples with excess boron were also made to counter the loss of boron by evaporation. The dependence of the lattice constants of the resulting solid solutions on composition was determined. The a parameter decreased only slightly with an increase in the WB2 content, whereas the c parameter exhibited a significant decrease over the range 40-60 mol% WB2. Solid-solution powders formed by the IFACS method were subsequently sintered in a spark plasma sintering (SPS) apparatus. After 10 min at 1800°C, the samples densified to relative density 86%. XRD analysis showed the presence of only the solid-solution phase.
Superhard Tungsten Diboride-Based Solid Solutions
Pangilinan, Lisa E.,Turner, Christopher L.,Akopov, Georgiy,Anderson, Mackenzie,Mohammadi, Reza,Kaner, Richard B.
, p. 15305 - 15313 (2019/01/04)
Solid solutions of tungsten diboride (WB2) with increasing substitution of tungsten (W) by tantalum (Ta) and niobium (Nb) - ranging from 0 to 50 at. % on a metals basis - were synthesized through resistive arc melting. Samples were characterized using a combination of powder X-ray diffraction (PXRD) for phase identification, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy for elemental composition, Vickers microindentation for hardness measurements, and thermogravimetric analysis for thermal stability. The solubility limit was found to be less than 8 at. % for Nb and less than 10 at. % for Ta, as determined by PXRD. Vickers hardness (Hv) values were measured to be 40.3 ± 1.6 and 41.0 ± 1.2 GPa at 0.49 N for 6 at. % Nb and for 8 at. % Ta substitution, respectively. In addition, the hardest solid solution (W0.92Ta0.08B2) showed oxidation resistance up to ～570 °C, approximately 70 °C higher than that of tungsten carbide (WC). Although pure WB2 is known not to be superhard, these results demonstrate the formation of superhard solid solutions through the substitution of tungsten by small amounts of transition metals. This increase in hardness can be attributed to solid solution hardening.
THERMAL EXPANSION STUDIES ON THE GROUP IV-VII TRANSITION METAL DIBORIDES.
Loennberg
, p. 145 - 156 (2008/10/08)
The thermal expansions of the group IV-VII transition metal diborides were studied with the aid of X-ray powder diffraction. The diborides were studied over the temperature range 298 - 1500 K. All the diborides except for CrB//2 display larger thermal expansion coefficients in the c direction than in the a direction. The expansion coefficients in the c direction decrease with increasing radius of the metal atom, a fact which can be correlated to an increase in metal-boron bond strength. The thermal expansion coefficient in the a direction changes very little with the size of the metal radius, owing to the fact that the bonding strength in the basal plane is determined by the strong B-B bonds within the boron layer.
