Issued Patents 1997
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5628837 | Surface decarburization of a drill bit having a refined primary cutting edge | Robert W. Britzke, Zhigang Fang | 1997-05-13 |
| 5609447 | Surface decarburization of a drill bit | Robert W. Britzke, Zhigang Fang | 1997-03-11 |