Influence of 4ZnO–B2O3 Addition on Dielectric Properties and Microstructures of Barium Strontium Titanate

This study investigates the effect of 4ZnO–B₂O₃ on the sintering behavior, dielectric properties, and microstructures of Ba_0.6Sr_0.4TiO₃ (BST) ceramics. These ceramics were sintered in air at temperatures ranging from 900°C to 1080°C. BST ceramics with 4ZnO–B₂O₃ addition can be sintered to a theoretical density higher than 95% at 1050°C. A secondary phase (Ba₂ZnTi₅O₁₃) is produced in the BST ceramics during 4ZnO–B₂O₃ addition. Compositional analysis using TEM-EDX of the BST ceramics with 3 wt% 4ZnO–B₂O₃ revealed that the Zn ion is generally located at the triple points. This result indicates that BaO, TiO₂, and ZnO form a liquid phase that acts as a secondary phase at the lower sintering temperatures. The amount of secondary phase was observed to increase as the amount of 4ZnO–B₂O₃ additives increased. In addition, the original Ba_0.6Sr_0.4TiO₃ phase was shifted to the Ba_0.5Sr_0.5TiO₃ phase by the addition of 3 wt% 4ZnO–B₂O₃ at 1050°C. The Ba_0.6Sr_0.4TiO₃ ceramic with 2 wt% 4ZnO–B₂O₃ sintered at 1050°C in air for 2 h exhibited dielectric properties of ɛ_r=1883 and dissipation loss=0.36%. Moreover, BST with 1 wt% 4ZnO–B₂O₃ addition sintered at 1080°C exhibits dielectric properties of ɛ_r=2330, dissipation loss=0.29%, and bulk density >95% of theoretical density.     

The System Bi2O,—B2O3

The phase diagram for the system Bi₂O₃-B₂O₃ has been determined experimentally. The melting point of Bi₂O₃ has been redetermined as 825° C with an estimated overall uncertainty of about ±3°C, and the molal heat of fusion of Bi₂O₃, calculated from the slope of the liquidus curve, is 2050 cal per mole. The system contains a body-centered cubic phase of approximate composition 12Bi₂O₃·B₂O₃, which melts incongruently at 632°C. Four congruently melting compounds exist in the system: 2Bi₂O₃· B₂O₃·5B₂O₃, Bi₂O₃·3B₂O₃, and Bi₂O₃·4B₂O₃, with melting points, respectively, of 675°, 722°, 708°, and 715°C. The Bi₂O₃·4B₂O₃ compound exhibits a sluggish transformation at 696°C. Compositions containing up to 97.5 wt% (85 mole %) Bi₂O₃ can be partly or totally quenched to glass. Indices of the quenched glasses are greater than 1.74. A region of liquid immiscibility extends at 709°C from almost pure B₂O₃ to 19.0 mole % Bi₂O₃. The extent of immiscibility theoretically calculated agrees with the experimentally determined value when 1.20 A is used for the ionic radius of Bi³⁺.     

Studies in Lithium Oxide Systems: I, Li2O B2O3–B2O3

Phase relationships in the system Li₂O, B₂O₃-B₂O₃ were studied by the quenching method using twenty compositions. The crystalline phases encountered were (a) Li₂O, B₂O₃, which melts congruently at 849°± 2°C., (b) Li₂O.-2B₂O₃, which melts congruently at 917°± 2°C., (c) a new compound, 2Li₂O-5B₂O₃, which melts incongruently at 856°± 2°C. and dissociates below 696°± 4°C., (d) Li₂O.3B₂O₃, which melts incongruently at 834°± 4°C. and dissociates below 595°± 20°C., and (e) probably Li₂O.4B₂O₃, which melts incongruently at 635°± 10°C. Reactions were sluggish at temperatures near 600°C., resulting in metastable relations. Hence phase equilibrium data relating to the lower stability limit of Li₂O.3B₂O₃ and to the upper stability limit of Li₂O.4B₂O₃ are considered to be tentative. Properties of the glasses and crystalline phases were studied. The refractive index of the glasses increased with the addition of Li₂O up to 22%, but further additions up to 40% had no substantial effect. Glasses containing less than 30% Li₂O were water soluble. Limited data on the density and thermal expansion of the glasses are presented. Li₂OB₂O₃ was euhedral, lath-shaped, length-fast, biaxial negative (2V = 27°), with n_α= 1.540, n_β= 1.612, n_γ= 1.616. Li₂O.2B₂O₃ was uniaxial negative, with n_e= 1.560, n_w= 1.605. Li₂O.3B₂O₃ was biaxial negative (2V = 75° to 80°), with n_α= 1.576, n_β= 1.602, n_γ= 1.605. X-ray powder diffraction data for the five crystalline compounds are presented. Thermal expansion data for Li₂O-B₂O₃ and Li₂O.2B₂O₃ and limited data on the fluorescent properties of the compounds are given. X-ray diffraction data are also presented for Li₂O.B₂O₃.4H₂O and Li₂O.-5B₂O₃. 10H₂O. Li₂O B₂O₃ was obtained by heating the first hydrate at 450° to 680° C. X-ray diffraction showed Li₂O.4B₂O₃ and Li₂O-3B₂O₃ to be the crystalline products obtained during heating the decahydrate at 500°C. and 600°C., respectively.     

Dielectric Properties and Low‐Temperature Sintering of the Ba0.6Sr0.4TiO3 Ceramics with B2O3/CuO Additions

The sintering behaviors and dielectric properties of Ba_0.6Sr_0.4TiO₃ ceramics were investigated as a function of B₂O₃ and CuO content. The addition of both B₂O₃ and CuO reduced the sintering temperature of Ba_0.6Sr_0.4TiO₃ about 500°C. It was suggested that a liquid phase BaCu(B₂O₅) was formed and assisted the densification of Ba_0.6Sr_0.4TiO₃ ceramics. Ba_0.6Sr_0.4TiO₃ ceramics co‐doped with 3.0 mol% B₂O₃, and 2.0 mol% CuO, sintered at 950°C for 5 h, had a dense microstructure and showed good microwave dielectric properties of a moderate dielectric constant (ε = 1048), low dielectric loss (0.0090) and high tunability (42.2%) at dc electric field of 30 kV/cm.     

Effect of compositional modifications on microstructure development and dielectric properties of Pb(Mg1/3Nb2/3)O3–PbTiO3 solid solutions

The effect of minor additions of excess MgO and PbO on the sintering characteristics, microstructure development and dielectric properties of perovskite-based Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ solid solutions was investigated. Both MgO and PbO are compatible with the Pb(Mg_1/3Nb_2/3)O₃-based solid solutions and thus, these phases co-exist with one another during sintering at elevated temperatures. On sintering a solid solution composition Pb[(Mg_1/3Nb_2/3)_0.9Ti_0.1]O₃ with minor additions of MgO, the excess MgO remained as a discrete phase in the ceramics at temperatures up to 1230 °C and inhibited grain growth. Above this temperature, MgO combined with the solid solution to form a liquid phase, which caused an enhancement of the densification process. On sintering the solid solution with excess PbO, a low-temperature melting PbO-rich liquid phase was formed, which promoted the densification process with inhomogeneous grain growth. Simultaneous additions of 1.0 wt.% MgO and 2.0 wt.% PbO to the Pb[(Mg_1/3Nb_2/3)_0.9Ti_0.1]O₃ solid solution and sintering the resulting material at 1000 °C for 3 h led to the formation of a dense and homogeneous microstructure consisting of evenly distributed grains with an average grain size of 10 μm. The peak dielectric constant of this composition (at ≈38 °C), measured at a frequency of 1 kHz, was 18,000 with a dissipation factor of <2%.     

Enhanced oxidation resistance of low-carbon MgO–C refractories with Al3BC3–Al antioxidants: A synergistic effect

The synergistic effects of Al₃BC₃–Al antioxidants on optimizing the oxidation resistance of low-carbon MgO–C refractories were investigated. The results indicated that the oxidation index and rate constant of low-carbon MgO–C refractories with optimized Al₃BC₃–Al additions were 13% and 1.10 × 10⁻⁴ cm² min⁻¹ at 1400°C for 3 h, respectively, which is much lower than that of Al or Al₃BC₃ containing ones. Single Al₃BC₃ is not a suitable antioxidant for low-carbon MgO–C refractories; however, if Al₃BC₃ was initially protected and Al reacted as the antioxidant, enhanced oxidation resistance at high temperature can be achieved. The formation of dense MgO–MgAl₂O₄–Mg₃B₂O₆ layer contributed to superior oxidation resistance, and the temperature for the generation of this layer was as low as 1100°C due to liquid and vapor phase–assisted reactions with Al₃BC₃–Al. Furthermore, a self-repairing function was achieved at 1600°C with the combination of Al₃BC₃–Al additions in spite of the faster oxidation rate.     

Effect of B2O3 on the sintering and microwave dielectric properties of M-phase LiNb0.6Ti0.5O3 ceramics

The effect of B₂O₃ addition on the sintering, microstructure and the microwave dielectric properties of LiNb_0.6Ti_0.5O₃ ceramics have been investigated. It is found that low-level doping of B₂O₃ (≤2 wt.%) can significantly improve the densification and dielectric properties of LiNb_0.6Ti_0.5O₃ ceramics. Due to the liquid phase effect of B₂O₃ addition, LiNb_0.6Ti_0.5O₃ ceramics could be sintered to a theoretical density higher than 95% even at 880 °C. No secondary phase was observed for the B₂O₃-doped ceramics. There is no obvious degradation in dielectric properties for the ceramics with B₂O₃ additions. In the case of 1 wt.% B₂O₃ addition, the ceramics sintered at 880 °C show good microwave dielectric properties of ɛ_r = 70, Q × f = 5400 GHz, τ_f = −6.39 ppm/°C. It represents that the ceramics could be promising for multilayer low-temperature co-fired ceramics (LTCC) applications.     

Melting Relations of CaO-Manganese Oxide and MgO-Manganese Oxide Mixtures in Air

Melting relations in the systems CaO-manganese oxide and MgO-manganese oxide in air have been determined at temperatures up to 1705°C. In the system CaO-manganese oxide four crystalline phases have stable existence in equilibrium with liquids: lime (approximate composition CaO-MnO), spinel (approximate composition Mn₃O₄-CaMn₂O₄), and two ternary solid solution phases in which Ca/Mn ratios as well as oxygen contents vary over considerable ranges. One of these ternary solid solution phases may for the sake of simplicity be represented approximately by the formula CaMnO₃ and the other by the formula CaMn₂O₄. Three isobaric invariant situations exist, with temperatures and phase assemblages as follows: At 1588°± 10°C the two crystalline phases lime and CaMnO₃ coexist in equilibrium with liquid (40 wt% CaO, 60 wt% manganese oxide) in a peritectic situation. Another peritectic at 1455°± 5°C is characterized by the equilibrium coexistence of CaMnO₃, CaMn₂O₄, and liquid (25 wt% CaO, 75 wt% manganese oxide). A eutectic situation exists at 1439°± 5°C with CaMn₂O₄, spinel, and liquid (18 wt% CaO, 82 wt% manganese oxide) present together in equilibrium. In the system MgO-manganese oxide in air periclase-manganosite solid solution (approximate composition MgO-MnO) and spinel (approximate composition Mn₃O₄-MgMn₂O₄) are the only crystalline phases present in equilibrium with liquids. Liquidus and solidus temperatures increase with increasing MgO content. A peritectic situation exists at 1587°± 10°C, with the two crystalline phases coexisting in equilibrium with liquid (1 wt% MgO, 99 wt% manganese oxide).     

Fabrication of low thermal conductivity yttrium silicate ceramic flat membrane for membrane distillation

This paper reports on the successful fabrication of γ-Y₂Si₂O₇ membranes with low thermal conductivity, which is an important membrane property for achieving high performance in membrane distillation process. Single-phase γ-Y₂Si₂O₇ powder was first synthesized by calcination of SiO₂ and Y₂O₃ powders, with 3 wt% LiYO₂ as a sintering aid. The membrane was produced by tape-casting of a suspension of this powder. After sintering at 1300 °C for 4 h, a flat membrane was obtained, which had a thickness of 0.5 mm, 49% porosity, 0.9 μm pore diameter, and low thermal conductivity of 0.497 W/m⋅K at 32 °C, and 0.528 W/m⋅K at 100 °C. The obtained membrane presented hydrophobic features (water contact angle was 132°) after surface modification, which resulted in formation of a strongly adhered robust hydrophobic SiNCO nanoparticle layer on its surface. The resultant hydrophobic membrane was tested in water desalination experiments using a sweeping gas membrane distillation (SGMD) device. High water flux of 10.07 L⋅ m⁻²⋅ h⁻¹ was achieved for a 20 wt% NaCl feeding solution and a temperature at the feed of 90 °C. Stable water flux and rejection rates were recorded in long-term experiments (>400 h).     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

Properties of magnesium-aluminate spinel derived from bauxite and magnesia

The synthesis of magnesium-aluminate spinel divided from bauxites and magnesias, the starting materials with different molar mass ratios (Al₂O₃: MgO) of 3, 1, and 0.6 were developed using solid-state reaction sintering at 1350-1500°C. The effects of different mass ratios and sintering temperatures on the phase composition, densification behavior, shrinkage, flexural strength, and microstructure of the synthetic materials were studied. It was found that as the relative content of bauxite decreased, the flexural strength first decreased before increasing. When n(Al₂O₃)/n(MgO) was 1, the spinel was the primary phase and the sample was dense. When the temperature became 1450°C, the flexural strength became maximized at 106.48 MPa.     

Fabrication of Gd2O3‐MgO nanocomposite optical ceramics with varied crystallographic modifications of Gd2O3 constituent

The fabrication of Gd₂O₃‐MgO nanocomposite optical ceramics via hot‐pressing using sol‐gel derived cubic‐Gd₂O₃ and MgO nanopowders was investigated. The precursor powder calcined at 600°C had an average particle size of 12 nm. The effects of hot‐pressing temperature on constituent phases, microstructure, mid‐infrared transmittance, and microhardness were studied. The crystallographic modifications of Gd₂O₃ phase varied with the increase in sintering temperature from 1250 to 1350°C. The monoclinic‐Gd₂O₃ phase was retained for the composite sintered at 1350°C and the sample had an average grain size of 90 nm, excellent transmission (80.4%‐84.8%) over 3‐6 μm wavelength range, and enhanced hardness value of 14.1 GPa.     

In-situ elongated aluminium borate grains toughening WC- 1.87 wt % Al2O3- 4.13 wt % ZrO2 composite via spark plasma sintering

In this work, a novel way was developed to facilitate the sintering of a binderless cemented carbide with Al₂O₃ contain while improving its toughness. WC- 1.87 wt % Al₂O₃- 4.13 wt %ZrO₂ cemented carbides with 1 wt % B₂O₃ as additives were consolidated by high energy ball-milling and spark plasma sintering the as-milled composite powders. The effects of 1 wt % B₂O₃ content on the sintering behaviour, microstructure and mechanical properties of the obtained cemented carbides were investigated. The presence of B₂O₃ significantly lowers the sintering temperature by forming liquid phase and react with Al₂O₃ which contributed to obtaining fully dense specimens at 1350 °C and maintains fine grain sizes of WC until the temperature exceeding 1450 °C. The sintering temperature of the specimens with optimum mechanical properties has been also reduced comparing that of the original WC- 1.87 wt % Al₂O₃- 4.13 wt %ZrO₂ cemented carbides. Furthermore, the addition of B₂O₃ triggered the reaction between B₂O₃ and Al₂O₃ resulting in forming in-situ elongated aluminium borate grains (A₄B₂O₉ and A₁₈B₄O₃₃ whiskers), which promoted the toughness. The specimens sintered at 1450 °C exhibited optimal mechanical properties: the Vickers hardness and fracture toughness were 19.26 GPa and 11.49 MPa m^1/2, respectively.     

1250°C liquidus for the CaO–MgO–SiO2–Al2O3–TiO2 system in air

Ti-bearing blast furnace slags have been regarded as an important secondary material in modern society, and the efficient recycling of Ti oxides from it is of key interest. For this reason, more thermodynamic data is needed regarding the phase relations in different composition ranges and sections. Therefore, the equilibrium phase relations of CaO–MgO–SiO₂–Al₂O₃–TiO₂ system in a low w(CaO)/w(SiO₂) ratio of 0.6–0.8 at 1250 °C in air and fixed concentrations of MgO and Al₂O₃, were investigated experimentally using a high temperature equilibration and quenching method followed by SEM-EDS (Scanning Electron Microscope and Energy Dispersive X-ray Spectrometer) analyses. The equilibrium solid phases of perovskite (CaO·TiO₂), a pseudo-brookite solid solution (MgO·2TiO₂, Al₂O₃·TiO₂)_ss, and anorthite (CaO·Al₂O₃·2SiO₂) were found to coexist with the liquid phase at 1250 °C. The calculated results of Factsage and MTDATA were used for comparisons, and significant discrepancies were found between predictions and the experimental results. The 1250 °C isotherm has been constructed and projected on the CaO–SiO₂–TiO₂-8 wt.% MgO-14 wt% Al₂O₃ quasi-ternary plane of the phase diagram. The obtained results provide new fundamental data for Ti-bearing slag recycling processes, and they add new experimental features for thermodynamic modeling of the high-order titanium oxide-containing systems.     

Crystallization of glasses in the SrO-B<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The crystallization of strontium borate glasses containing 16.7–43.0 mol % SrO is investigated. New crystalline compounds of the hypothetical compositions 2SrO · 3B₂O₃ (metastable) and SrO · 5B₂O₃ (stable below 750°C), as well as the metastable diborate modification β-SrO · 2B₂O₃, are revealed, and their X-ray powder diffraction data are obtained. It is demonstrated that, with a deficit of strontium oxide, the 4SrO · 7B₂O₃ compound forms solid solutions. Strontium triborate SrO · 3B₂O₃, which was previously prepared only through the dehydration of crystal hydrates, is produced using crystallization of glasses. The thermal stability of this compound is studied. The influence of the dispersity on the stability of different crystalline phases is discussed. Variants of the phase diagram for the SrO · B₂O₃-B₂O₃ system in the case of monolithic and dispersed samples are proposed from analyzing the experimental results and the data available in the literature.     

NOTES ON REACTION BETWEEN MgO AND VARIOUS TYPES OF REFRACTORIES *

Samples of high-heat duty, superduty, 60% Al₂O₃, 70% Al₂O₃, 90% Al₂O₃, fused-alumina, kaolin base, kyanite base, chrome magnesite, silicon carbide, zircon, and chrome-magnesite compositions were tested for reaction with MgO at temperatures of 2200°, 2600°, and 2800°F. (1205°, 1425°, and 1540°C.). Silicon carbide and zircon refractories showed a slight reaction at 2800°F. and none at 2600°F. or at 2200°F. Commercial grades of firebrick containing 60% or more of Al₂O₃ in contact with powdered magnesia showed no reaction up to 2800°F.     

Dehydration,Water Vapor Adsorption and Desorption Behavior of Zn[B3O3(OH)5] · H2O and Zn[B3O4(OH)3]

The dehydration behaviors of two different hydrated zinc borate species, Zn[B₃O₃(OH)₅] · H₂O and Zn[B₃O₄(OH)₃], which are industrially important flame retardants, were studied by thermal gravimetric(TG) analysis and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Dehydration onset temperatures of Zn[B₃O₃(OH)₅] · H₂O and Zn[B₃O₄(OH)₃] were 129 and 320°C, respectively, at a 10°C/min ramp rate. A very small amount of boric acid was volatilized in addition to water vapor when both samples were heated at 250°C. A significant amount of water vapor was adsorbed by Zn[B₃O₃(OH)₅] · H₂O from air at 25°C. However, Zn[B₃O₄(OH)₃] adsorbed a very small amount of water under the same conditions. Both zinc borates did not have a tendency to cake during storage.     

Synthesis and characterization of single-phase magnesium borate nanorod via solution reaction cum sintering process

Magnesium borates (MB) nanorods are widely used as reinforcing materials due to high mechanical strength and resilience to heat and corrosion. However, difficulties in synthesis of single-phase MB continue to reduce the mechanical properties of composites. Herein, a single-phase Magnesium borate (Mg₂B₂O₅) in the form of nanorod has been synthesized using an optimized molar ratio of magnesia (MgO) and boric acid (H₃BO₃) by combining solution reaction and sintering process. Phase and microstructural changes of as synthesized magnesium borate (MB) crystals during the reaction sintering process in between 700 °C and 1200 °C has been closely examined with the help of various characterization techniques. Phases of magnesium borate starts appearing on thermal treatment above 700 °C. Phase transformation of magnesium borate from monoclinic to orthorhombic followed by triclinic was also observed during the thermal treatment. The optimum temperature to obtain pure triclinic Mg₂B₂O₅ phase was found to be in between 1100°C and 1200 °C.     

Enhanced thermal conductivity and flexural strength of sintered reaction-bonded silicon nitride with addition of (Y0.96Eu0.04)2O3

Sintered reaction-bonded silicon nitride (SRBSN) with high thermal conductivity was obtained using (Y_0.96Eu_0.04)₂O₃ and MgO as sintering additives. Green compacts were nitrided at 1400°C for 4 h. Post-sintering was carried out at 1850 and 1900°C for 4 h, respectively. In reaction-bonded silicon nitride (RBSN) doped with Y₂O₃ and MgO, the β-Si₃N₄ content and nitridation degree were 51.1% and 93.8%, respectively. However, the β-Si₃N₄ content and nitridation degree were 72.6% and 96.7% in a nitrided compact doped with (Y_0.96Eu_0.04)₂O₃ and MgO. After post-sintering, the phase composition, microstructure, mechanical properties, and thermal conductivity were investigated. After sintering at 1900°C for 4 h, the thermal conductivity of SRBSN doped with (Y_0.96Eu_0.04)₂O₃ and MgO was increased by 16.5% compared to that of the samples doped with Y₂O₃ and MgO. The highest hardness of 1639 HV and the good flexural strength of 776.4 MPa were also achieved in the sample doped with 2-mol.% (Y_0.96Eu_0.04)₂O₃ and 5-mol.% MgO.     

Thermal properties of ZrB2-TiB2 solid solutions

Zirconium diboride ceramics were prepared with additions of up to 50 vol.% TiB₂. The resulting (Zr,Ti)B₂ ceramics formed complete solid solutions based on x-ray diffraction. The addition of TiB₂ resulted in grain size decreasing from 22 μm for nominally pure ZrB₂ to 7 μm for ZrB₂–50 vol.% TiB₂. The thermal conductivity at 25°C ranged from 93 W/m⋅K for nominally pure ZrB₂ to 58 W/m⋅K for ZrB₂–50 vol.% TiB₂. Thermal conductivity was as high as 67 W/m⋅K for nominally pure ZrB₂ at 2000°C, but dropped to 59 W/m K with the addition of 50 vol.% TiB₂. Electrical resistivity measurements were used to calculate the electron contribution to thermal conductivity, which was 76 W/m⋅K for nominally pure ZrB₂ decreasing to 57 W/m⋅K when 50 vol.% TiB₂ was added. The phonon contribution to thermal conductivity did not change significantly for ≤10 vol.% TiB₂. Additions of ≥25 vol.% TiB₂ reduced the phonon contribution to nearly zero for all temperatures.