| 摘要 |
<p>A hole (30) is drilled in a turbine blade (10) by laser drilling. The turbine blade (10) comprises a superalloy substrate (12), a bond coating (14) and a ceramic thermal barrier coating (16). The hole (30) is produced by firstly focusing the laser beam (26) such that the focal point (28) is on the surface of the ceramic thermal barrier coating (16) to drill a small diameter hole (18) through the turbine blade (10). The laser beam (26) is refocused such that the focal point (28) is spaced from the surface of the ceramic thermal barrier coating (16). The laser beam (26) is pulsed on and off to drill a large diameter hole (30) coaxially with the small diameter hole (18). The small diameter hole (18) allows the molten material and heat to be expelled from the hole ( 18) and reduces heating of the superalloy substrate (12) to reduce the thickness of the oxide layer and recast layer around the hole and prevent delamination of the ceramic thermal barrier coating (16).</p> |
