| Silicon Oxide | Aluminum Oxide | Magnesium Oxide |
| Titanium Oxide | Zirconium Oxide |
| 3M | AGY Holding Corp. | BCC Products |
| Chosun Refractories | CoorsTek | Corning Incorporated |
| GBC Materials | Gouda Vuurvast | Morgan Advanced Ceramics |
| Sapco | Sinotek Materials | Unifrax I LLC |