Use in cement and steel industries. A refractory material having high percentage of sic. Low iron oxide. Low permanent linear change andhigh thermal conductivity are some of its advantages. Especially used cyclone fired boilers.

| Material | Percentage | Typical |
|---|---|---|
| Al2O3 | 75-80 % | 78 % |
| SiO2 | 10-15 % | 12 % |
| CaO | 3-5 % | 4 % |