Zirconium boride is used to improve resistance in zirconia-based, carbon-bonded refractories in contact with ferrous melts.
Zirconium diboride (ZrB2) is a good candidate for use as thin-film electrical components of sensors, actuators, Sensors and MEMS devices operating in high-temperature environments require stable thin films with high electrical conductivity for use as electrodes, bond pads, and other components.
Metal films are unreliable because of thermodynamically driven morphological instability and agglomeration over long times.
Zirconium diboride (ZrB2) is an ultra-high temperature conducting ceramic with a melting point of 3245°C, with low atomic diffusion rates compared to other materials.
To evaluate ZrB2 as a high-temperature film, 200 nm thick ZrB2 films were synthesized on r-sapphire substrates using e-beam co-evaporation of elemental Zr and B sources.
Film stability was characterized after post-deposition thermal treatments from 600-1000°C in both reducing (vacuum) and oxidizing (air) environments.
ZrB2 films deposited at room temperature are amorphous but have short-range order characteristics of ZrB2 bonding.
ZrB2 films grown at 600°C are polycrystalline with preferred <0001< texture, whereas at 850°C grains with preferred <10-10< and <10-11< texture become dominant.
Negligible grain growth or morphology changes occur after annealing at 850°C for 55 hours in a vacuum, and film electrical conductivity remains <105 S/m.
Annealing in air, however, leads to ZrB2 film decomposition into ZrO2 and B2O3 phases, the latter of which is volatile.
X-ray diffraction indicates that a 50 nm thick hexagonal boron nitride (h-BN) capping layer grown on top of ZrB2 via magnetron sputtering hinders oxidation, but the ZrB2 eventually transforms to ZrO2.
These results indicate that ZrB2 films are attractive for potential use in sensors and MEMS devices in high temperature-reducing environments, and for short times in oxidizing environments when covered with an h-BN capping layer.
The published data on the experimental phase relationships and the thermodynamic quantities for the binary ZrB system have been critically reviewed and a recommended phase diagram has been given.
A set of internally consistent thermochemical data has been derived using computer optimization with the LUKAS-program system.
ZrB2 microparticles form from Zr and B elements in copper melts, and nanoscale Cu5Zr precipitates form in the matrix after solid solution and aging treatments.
Due to the contradiction between mechanical properties and electrical conductivity, it is not easy to fabricate materials with both high strength and good wear resistance with favorable electrical conductivity for the application of electrical materials.
In addition, strength and wear resistance does not always present a uniform growth trend at the same time.
Herein, a novel copper matrix composite reinforced by in situ synthesized ZrB2 microparticles and nano Cu5Zr precipitates are successfully prepared by a casting method and sequential heat treatments.
The Cu/dual-scale particulate composite possesses the desired trade-off of strength, electrical conductivity, and wear resistance.
ZrB2 microparticles form from Zr and B elements in copper melts and nanoscale Cu5Zr precipitates form in the matrix after solid solution and aging treatments.
The ZrB2microparticles, nano Cu5Zr precipitates, and well-bonded interfaces contribute to high tensile strength of 591 MPa and superior wear resistance, with a relative electrical conductivity of 83.7% International Annealed Copper Standard.
ZrB2 powders were synthesized by mechanical alloying (MA) of the mixture of elemental Zr and B powders using WC vial and balls.
The effect of the initial composition, the milling time on MA, and the phase changes during MA were investigated.
Well-crystallized ZrB2 powder with micrometer size was received by direct ball milling the Zr/B powder mixtures.
Nanocrystalline ZrB2 powders were received by adding ZrB2 powder into the Zr/B powder mixture as a diluent to exhibit the ignition of the raw powders.
The phase transformation and the morphology of the powders were characterized by XRD analysis and SEM and TEM observation.
ZrB2 Sputtering Targets
Zirconium diboride (ZrB2) exhibits high hardness and high melting point, which is beneficial for applications in for e.g.metal cutting.
However, there is limited data on the mechanical properties of ZrB2 films and no data on epitaxial films.
In this study, ZrB2(0001) thin films, with thicknesses up to 1.2 μm, have been deposited on Al2O3(0001) substrates by direct current magnetron sputtering from a compound target.
X-ray diffraction and transmission electron microscopy show that the films grow epitaxially with two domain types exhibiting different in-plane epitaxial relationships to the substrate.
The out-of-plane epitaxial relationship was determined to ZrB2(0001)‖Al2O3(0001) and the in-plane relationships of the two domains to ZrB2
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