Oxidation resistance zirconium diboride

Most borides are chemically inert in bulk form, which has led to industrial applications as engineering materials, principally at high temperature. The transition metal borides display a considerable resistance to oxidation in air. A few examples of applications are given here. Titanium and zirconium diborides, alone or in admixture with chromium diboride, can endure temperatures of 1500 to 1700 K without extensive attack. In this case, a surface layer of the parent oxides is formed at a relatively low temperature, which prevents further oxidation up to temperatures where the volatility of boron oxide becomes appreciable. In other cases the oxidation is retarded by the formation of some other type of protective layer, for instance, a chromium borate. This behavior is favorable and in contrast to that of the refractory carbides and nitrides, which form gaseous products (carbon oxides and nitrogen) in air at high temperatures. Boron carbide is less resistant to oxidation than the metallic borides. 

EINECS 234-963-5 Zirconium boride Zirconium boride (ZrB2) Zirconium diboride Zirconium diboride (ZrB2). Refractory for aircraft and rocket applications, thermocouple protection tubes, high-temp, electrical conductor, cutting-tool component, coating tantalum, cathode in high-temp, electrochemical systems oxidation-resistant composites. Atomergic Chemetals Cerac Noah Cham. 

ZS-7. [Advanced Refractory Tech.] Zirconium diboride for oxidation-resistant ctxnposites, burble absorber of neutrons, elec, contacts, mdten metal crucibles, refractory roughener, cutting tool composites, structural ceramics, wear conqxxients, metal matrix omi-posites. 

Ceramic borides, carbides and nitrides are characterized by high melting points, chemical inertness and relatively good oxidation resistance in extreme environments, such as conditions experienced during reentry. This family of ceramic materials has come to be known as Ultra High Temperature Ceramics (UHTCs). Some of the earliest work on UHTCs was conducted by the Air Force in the 1960 s and 1970 s. Since then, work has continued sporadically and has primarily been funded by NASA, the Navy and the Air Force. This article summarizes some of the early works, with a focus on hafnium diboride and zirconium diboride-based compositions. These works focused on identifying additives, such as SiC, to improve mechanical or thermal properties, and/or to improve oxidation resistance in extreme environments at temperatures greater than 2000°C. 

Zhang, S. C., Hilmas, G. E., Fahrenholtz, W. G. (2008). Improved Oxidation Resistance of Zirconium Diboride by Tungsten Carbide Additions. Journal of the American Ceramic Society, 97(11), 3530-3535. doi 10.1111/j.l551-2916.2008.02713.x. 

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