34
X. Sun et al.
Fig. 3.3 Fiber laser wet cutting system (a) and electropolishing system (b)
Table 3.1 Laser parameters used in the experiment
Pulse width
(µs)
Laser power
(W)
Frequency
(Hz)
Speed (mm/s)
Argon
pressure
(MPa)
Water
pressure
(MPa)
14
135
9500
5
0.7
0.06
Table 3.2 Electrolyte composition and polishing parameters
Distill water
(vol.%)
NaCl (mol) Ethylene glycol
(L)
polar distance
(mm)
Votage (V) Time (min)
1
1
1
20
15
± 1 °C) using a non-toxic alcohol-salt system, and the electrolyte composition and
polishing parameters are shown in Table 3.2.
3.2.3 Specimens Preparation and Inspection Methods
Before laser cutting, the whole nitinol tube was clamped on the laser cutting machine.
During the cutting, the nitinol tube was cut into standard specimens (stents) according
to preset parameters. After the cutting, the marked stents were put into argon for
storage and inspection. Before electropolishing, the stents by laser cutting were put
into ethanol for ultrasonic cleaning for 6 min, and then they were electropolished.
After electropolishing, these stents after polished were put into ethanol for ultrasonic
cleaning in 90 s, and then for subsequent inspection.
The MicroXAM-100 white light interferometer was used to observe the surface
roughness of the stents. The specimens were made into metallographic specimens
according to the requirements, and the FEI Quanta 250FEG field emission scanning
electron microscope was used to observe the heat affected zone (HAZ), recast layer,
X. Sun et al.
Fig. 3.3 Fiber laser wet cutting system (a) and electropolishing system (b)
Table 3.1 Laser parameters used in the experiment
Pulse width
(µs)
Laser power
(W)
Frequency
(Hz)
Speed (mm/s)
Argon
pressure
(MPa)
Water
pressure
(MPa)
14
135
9500
5
0.7
0.06
Table 3.2 Electrolyte composition and polishing parameters
Distill water
(vol.%)
NaCl (mol) Ethylene glycol
(L)
polar distance
(mm)
Votage (V) Time (min)
1
1
1
20
15
± 1 °C) using a non-toxic alcohol-salt system, and the electrolyte composition and
polishing parameters are shown in Table 3.2.
3.2.3 Specimens Preparation and Inspection Methods
Before laser cutting, the whole nitinol tube was clamped on the laser cutting machine.
During the cutting, the nitinol tube was cut into standard specimens (stents) according
to preset parameters. After the cutting, the marked stents were put into argon for
storage and inspection. Before electropolishing, the stents by laser cutting were put
into ethanol for ultrasonic cleaning for 6 min, and then they were electropolished.
After electropolishing, these stents after polished were put into ethanol for ultrasonic
cleaning in 90 s, and then for subsequent inspection.
The MicroXAM-100 white light interferometer was used to observe the surface
roughness of the stents. The specimens were made into metallographic specimens
according to the requirements, and the FEI Quanta 250FEG field emission scanning
electron microscope was used to observe the heat affected zone (HAZ), recast layer,