What Makes Yttrium Oxide Unique?

USE-TEMPERATURES

ZYP YTTRIUM OXIDE products have the highest thermodynamic stability since they are designed to contain the highest percentage of yttrium oxide (ΔHo298 - 455.5 kcal/ mole). With a melting temperature of 2400 C, use-temperatures to nearly 2000 C are typical for the products in most atmospheres (see individual product data for specifics). Reducing conditions with graphite lower the use-temperatures to around 1500 C.
   

THERMAL PROPERTIES

ZYP YTTRIUM OXIDE products have low thermal conductivity. Yttrium oxide has one of the lowest thermal conductivities of refractory oxides at high temperatures (0.007 cal/cm-sec-K at 1400 C). This property allows yttrium oxide to be used to reduce the heat flow on many substrates. Thermal expansion of yttrium oxide is moderate, like aluminum oxide.
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ELECTRICAL PROPERTIES

ZYP YTTRIUM OXIDE products have an electrical resistivity of over 10⁸ ohm-cm at room temperature and reportedly remain more electrically insulating at 2000 C than other refractory materials. The dielectric constant is about 12 (at 102 to 106 Hz). Yttrium oxide is also transparent to microwave energy.
   

CHEMICAL RESISTANCE

ZYP YTTRIUM OXIDE products contain minimal if any additives (see specific product data) in order to preserve the ultimate high-temperature stability of yttrium oxide. Therefore, ZYP YTTRIUM OXIDE products have superior resistance to aggressive chemical attack at high temperatures and have superior thermal stability. This superior resistance to molten metals, glasses, slags, and salts leads to the products being used for coating crucibles and molds that handle the most highly-reactive molten materials, such as uranium, titanium, chromium, beryllium, and their alloys. Coatings of yttrium oxide are often used as barrier coatings to stop or prevent reactions, such as for diffusion bonding of reactive metals or for braze stop-off coatings. See our Compatibility Guide for more information.

LUBRICATING QUALITIES

ZYP YTTRIUM OXIDE products contain the highest-purity yttrium oxide which has the body-centered-cubic crystal structure and is quite soft (700 kg/mm² microhardness) at room temperature, with hardness dropping to 200 kg/mm² as the temperature increases to 1000 C. Thus, yttrium oxide becomes a very soft, formable, lubricating oxide at high-temperatures — leading to its uses for superplastic forming lubrication with titanium and specialty steels, as well as back-extrusion operations with uranium, and other forming operations.