Characterization of AlN-Based Ceramic Composites for Use as Millimeter-Wave Susceptor Materials at High Temperature: Dielectric Properties of Aln:Mo with 0.25 Vol to 4.0 Vol Mo from 25 to 550 Degrees C
Abstract
Microstructural analysis and bulk dielectric property analysis ( real and imaginary permittivity at 95 GHz) were performed at temperatures ranging from 25 to 550 degrees C for ceramic composites comprising a hot- pressed aluminum nitride matrix ( containing yttria and trace carbon as sintering additives) with molybdenum powder as a millimeter- wave radiation- absorbing additive. Loading percentages in the range of 0.25 vol to 4.0 vol Mo were characterized. For the temperature regime evaluated, the temperature- related changes in real and imaginary components of permittivity were found to be relatively modest compared with those driven by Mo loading. Energy- dispersive X- ray spectroscopic analysis of Mo grains and surrounding regions showed the presence of a mixed- phase layer, containing Mo2C, at the AlN- Mo interface. The Mo2C- containing mixed- phase layer, typically a few micrometers thick, surrounded the Mo grains. Further characterization of this mixed- phase layer is required to determine its contribution to the dielectric properties of the composite.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 14, 2019
- Accession Number
- AD1097867
Entities
People
- Anthony E. Baros
- Brad W. Hoff
- Frederick W. Dynys
- I. M. Rittersdorf
- Martin S. Hilario
- Michele L. Ostraat
- Rachael O. Grudt
- Steven C. Hayden
Organizations
- United States Naval Research Laboratory