| 摘要 |
A tube expansion plug (1) to be used for expanding the outer diameter of a metal tube (2) by forcibly inserting the tube expansion plug, which has an outer diameter larger than the inner diameter of the tube, into the metal tube, and a tube expansion method using same. The tube expansion plug has a main plug body section (10), a ground layer (11) covering the surface thereof, and a DLC film (12) covering the ground layer. The ratio (AH)/(AC) of the proportion (AH) (atm%) of hydrogen atoms in the DLC film to the proportion (AC) (atm%) of carbon atoms is 0.03 to 0.15 on average. The ratio (PIG)/ (PID) of the G-band peak intensity (PIG) to the D-band peak intensity (PID) in the Raman spectrum of the DLC film is less than 3. |
