Type H

Type H is a Hafnium Oxide (HfO2) coating which uses a thermodynamically stable Yttrium Aluminum Garnet (YAG, 3Y2O3*5Al2O3) binder in order to attain very high use temperatures and stability. After firing to temperatures >600 C, the coating composition is 95% HfO2 and 5% YAG. Type H yields a well-bonded Hafnium Oxide coating when applied to most substrates and is non-reactive with many ceramics and alloys, solid or molten. Hafnium Oxide has a “Normal Total Emittance” of 0.8 to 0.9 up to 2000 C, which is a quite unique property of being near blackbody, and has a very high dielectric constant.


Key Attributes

  • Non-reactivity with solid or molten metals/alloys
  • Upper use limit temperature expected to be
    over 1900 C in all atmospheres
  • Unique YAG-bonded HfO2 composition: 95%
    HfO2 and 5% YAG after firing to T > 600 C
  • High emissivity, high thermal neutron capture
    cross-section, and high dielectric constant of
    Hafnium and HfO2
  • Fired (T > 600 C) coating can be lightly
    burnished to produce a slick, lubricative finish

Ideal Uses

  • Very-high-temperature molten metal processing
    and transport
  • Aerospace, nuclear, and other demanding applications
  • Barrier coating to prevent diffusion, reactions,
    and sticking of parts during heat treating