| 摘要 |
A silicon nitride body having a surface portion comprising alpha sialon, or alpha sialon and beta sialon wherein the ratio of alpha sialon relative to the sum of alpha sialon and beta sialon is at least 0.6; and an inner portion comprising beta sialon, or alpha sialon and beta sialon, wherein the ratio of beta sialon relative to the sum of alpha sialon and beta sialon is at least 0.6. |
