| 501 / | HD | COMPOSITIONS: CERAMIC |
| 1 | DF | CERAMIC COMPOSITIONS {15} |
| 94 | DF | .~ Refractory {8} |
| 96.1 | DF | .~.~ Boride, silicide, nitride, oxynitride, carbonitride, or oxycarbonitride containing {7} |
| 98.4 | | .~.~.~ Aluminum nitride containing (AIN) {2} |
| 98.5 | DF | .~.~.~.~> With alkaline earth metal compound |
| 98.6 | DF | .~.~.~.~> Composites (continuous matrix with dispersed phase) |