Figure 1.
Schematics of the scanning micro electrochemical flow cell (SMEFC).
Figure 1.
Schematics of the scanning micro electrochemical flow cell (SMEFC).
Figure 2.
Layout of SMEFC setup.
Figure 2.
Layout of SMEFC setup.
Figure 3.
Electrolyte droplet moving on the surface treated by micro-electrical-discharge machining (EDM) milling.
Figure 3.
Electrolyte droplet moving on the surface treated by micro-electrical-discharge machining (EDM) milling.
Figure 4.
Explanation of the electrolyte leakage. (a) Surface tension maintains a single droplet; (b) electrolyte left on machined surface once the droplet volume is larger.
Figure 4.
Explanation of the electrolyte leakage. (a) Surface tension maintains a single droplet; (b) electrolyte left on machined surface once the droplet volume is larger.
Figure 5.
Electrolyte droplet moving on the ground surface.
Figure 5.
Electrolyte droplet moving on the ground surface.
Figure 6.
Current signal when setting 300 mA as the target.
Figure 6.
Current signal when setting 300 mA as the target.
Figure 7.
Cross-sectional profiles.
Figure 7.
Cross-sectional profiles.
Figure 8.
Channel width comparison.
Figure 8.
Channel width comparison.
Figure 9.
Roughness under different current values and concentrations.
Figure 9.
Roughness under different current values and concentrations.
Figure 10.
Microstructures of the channel bottom surface. (a) Current: 100 mA, feed rate: 0.1 mm/s; (b) current: 100 mA, feed rate: 0.2 mm/s; (c) current: 100 mA, feed rate: 0.3 mm/s; (d) current: 100 mA, feed rate: 0.4 mm/s; (e) current: 200 mA, feed rate: 0.1 mm/s; (f) current: 200 mA, feed rate: 0.2 mm/s; (g) current: 200 mA, feed rate: 0.3 mm/s; (h) current: 200 mA, feed rate: 0.4 mm/s; (i) current: 300 mA, feed rate: 0.1 mm/s; (j) current: 300 mA, feed rate: 0.2 mm/s; (k) current: 300 mA, feed rate: 0.3 mm/s; (l) current: 300 mA, feed rate: 0.4 mm/s.
Figure 10.
Microstructures of the channel bottom surface. (a) Current: 100 mA, feed rate: 0.1 mm/s; (b) current: 100 mA, feed rate: 0.2 mm/s; (c) current: 100 mA, feed rate: 0.3 mm/s; (d) current: 100 mA, feed rate: 0.4 mm/s; (e) current: 200 mA, feed rate: 0.1 mm/s; (f) current: 200 mA, feed rate: 0.2 mm/s; (g) current: 200 mA, feed rate: 0.3 mm/s; (h) current: 200 mA, feed rate: 0.4 mm/s; (i) current: 300 mA, feed rate: 0.1 mm/s; (j) current: 300 mA, feed rate: 0.2 mm/s; (k) current: 300 mA, feed rate: 0.3 mm/s; (l) current: 300 mA, feed rate: 0.4 mm/s.
Figure 11.
Droplet morphologies under different vacuum gap (VG).
Figure 11.
Droplet morphologies under different vacuum gap (VG).
Figure 12.
Current signal when setting 200 mA as the target (VG = 400 µm).
Figure 12.
Current signal when setting 200 mA as the target (VG = 400 µm).
Figure 13.
Cross-sectional profiles with different VGs (current = 200 mA).
Figure 13.
Cross-sectional profiles with different VGs (current = 200 mA).
Figure 14.
Channel morphologies under the VG of 400 µm at: (a) 0.1 mm/s; and (b) 0.2 mm/s.
Figure 14.
Channel morphologies under the VG of 400 µm at: (a) 0.1 mm/s; and (b) 0.2 mm/s.
Figure 15.
Channel width under different VGs.
Figure 15.
Channel width under different VGs.
Figure 16.
Roughness under different VGs.
Figure 16.
Roughness under different VGs.
Figure 17.
Surface microstructures under the current of 200 mA. (a) VG: 200 µm, feed rate: 0.1 mm/s; (b) VG: 200 µm, feed rate: 0.2 mm/s; (c) VG: 200 µm, feed rate: 0.3 mm/s; (d) VG: 200 µm, feed rate: 0.4 mm/s; (e) VG: 300 µm, feed rate: 0.1 mm/s; (f) VG: 300 µm, feed rate: 0.2 mm/s; (g) VG: 300 µm, feed rate: 0.3 mm/s; (h) VG: 300 µm, feed rate: 0.4 mm/s; (i) VG: 400 µm, feed rate: 0.1 mm/s; (j) VG: 400 µm, feed rate: 0.2 mm/s; (k) VG: 400 µm, feed rate: 0.3 mm/s; (l) VG: 400 µm, feed rate: 0.4 mm/s.
Figure 17.
Surface microstructures under the current of 200 mA. (a) VG: 200 µm, feed rate: 0.1 mm/s; (b) VG: 200 µm, feed rate: 0.2 mm/s; (c) VG: 200 µm, feed rate: 0.3 mm/s; (d) VG: 200 µm, feed rate: 0.4 mm/s; (e) VG: 300 µm, feed rate: 0.1 mm/s; (f) VG: 300 µm, feed rate: 0.2 mm/s; (g) VG: 300 µm, feed rate: 0.3 mm/s; (h) VG: 300 µm, feed rate: 0.4 mm/s; (i) VG: 400 µm, feed rate: 0.1 mm/s; (j) VG: 400 µm, feed rate: 0.2 mm/s; (k) VG: 400 µm, feed rate: 0.3 mm/s; (l) VG: 400 µm, feed rate: 0.4 mm/s.
Figure 18.
Cross-sectional profiles under different inter-electrode gaps (IEGs) (concentration: 250 g/L, current: 200 mA, VG: 200 µm).
Figure 18.
Cross-sectional profiles under different inter-electrode gaps (IEGs) (concentration: 250 g/L, current: 200 mA, VG: 200 µm).
Figure 19.
Channel roughness and width under different IEGs.
Figure 19.
Channel roughness and width under different IEGs.
Figure 20.
Cross-sectional profiles (current = 200 mA, VG = 200 µm).
Figure 20.
Cross-sectional profiles (current = 200 mA, VG = 200 µm).
Figure 21.
Microstructures of the channel bottom surface. (a) Current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.1 mm/s; (b) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.2 mm/s; (c) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.3 mm/s; (d) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.4 mm/s; (e) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.1 mm/s; (f) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.2 mm/s; (g) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.3 mm/s; (h) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.4 mm/s; (i) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.1 mm/s; (j) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.2 mm/s; (k) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.3 mm/s; (l) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.4 mm/s; (m) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.1 mm/s; (n) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.2 mm/s; (o) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.3 mm/s; (p) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.4 mm/s.
Figure 21.
Microstructures of the channel bottom surface. (a) Current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.1 mm/s; (b) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.2 mm/s; (c) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.3 mm/s; (d) current: 200 mA, electrolyte concentration: 250 g/L, feed rate: 0.4 mm/s; (e) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.1 mm/s; (f) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.2 mm/s; (g) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.3 mm/s; (h) current: 200 mA, electrolyte concentration: 120 g/L, feed rate: 0.4 mm/s; (i) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.1 mm/s; (j) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.2 mm/s; (k) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.3 mm/s; (l) current: 300 mA, electrolyte concentration: 250 g/L, feed rate: 0.4 mm/s; (m) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.1 mm/s; (n) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.2 mm/s; (o) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.3 mm/s; (p) current: 300 mA, electrolyte concentration: 120 g/L, feed rate: 0.4 mm/s.
Figure 22.
Electrode path.
Figure 22.
Electrode path.
Figure 23.
Cross-sectional profile with different electrode offset distances (EODs): (a) 200 µm; (b) 300 µm; and (c) 400 µm.
Figure 23.
Cross-sectional profile with different electrode offset distances (EODs): (a) 200 µm; (b) 300 µm; and (c) 400 µm.
Figure 24.
Cross-sectional profile with the current of 300 mA and EOD of 200 µm.
Figure 24.
Cross-sectional profile with the current of 300 mA and EOD of 200 µm.
Figure 25.
Volume removal rate (VRR) under different EODs.
Figure 25.
Volume removal rate (VRR) under different EODs.
Figure 26.
Cross-sectional profiles with different EODs: (a) 200 µm; (b) 300 µm.
Figure 26.
Cross-sectional profiles with different EODs: (a) 200 µm; (b) 300 µm.
Figure 27.
Current signal under 300 mA.
Figure 27.
Current signal under 300 mA.
Figure 28.
SEM pictures of the machined cavities. (a) EODs: 200 µm, current: 200 mA; (b) EODs: 200 µm, current: 300 mA; (c) EODs: 200 µm, current: 400 mA; (d) EODs: 300 µm, current: 200 mA; (e) EODs: 300 µm, current: 300 mA; (f) EODs: 300 µm, current: 400 mA.
Figure 28.
SEM pictures of the machined cavities. (a) EODs: 200 µm, current: 200 mA; (b) EODs: 200 µm, current: 300 mA; (c) EODs: 200 µm, current: 400 mA; (d) EODs: 300 µm, current: 200 mA; (e) EODs: 300 µm, current: 300 mA; (f) EODs: 300 µm, current: 400 mA.
Figure 29.
Energy-dispersive spectroscopy (EDS) analysis of the residues.
Figure 29.
Energy-dispersive spectroscopy (EDS) analysis of the residues.
Figure 30.
Schematic of different EODs.
Figure 30.
Schematic of different EODs.
Figure 31.
Maximum depth under different current values.
Figure 31.
Maximum depth under different current values.
Table 1.
Experimental parameters.
Table 1.
Experimental parameters.
Current (mA) | Feed Rate (mm/s) | ECPL (C/mm) | Sexp (mm2) | Sthe (mm2) | η1 | η2 |
---|
100 | 0.1 | 1 | 0.0234 | 0.02327 | 100.6% | 82.6% |
200 | 0.2 | 1 | 0.0246 | 0.02327 | 105.7% | 86.8% |
300 | 0.3 | 1 | 0.0255 | 0.02327 | 109.6% | 90.0% |
100 | 0.2 | 0.5 | 0.0110 | 0.01165 | 94.4% | 77.5% |
200 | 0.4 | 0.5 | 0.0127 | 0.01165 | 109.0% | 89.5% |
Table 2.
Current efficiency.
Table 2.
Current efficiency.
VG (µm) | Feed Rate (mm/s) | ECPL (C/mm) | Sexp (mm2) | Sthe (mm2) | η1 | η2 |
---|
200 | 0.1 | 2 | 0.0498 | 0.0466 | 106.9% | 87.8% |
200 | 0.2 | 1 | 0.0246 | 0.0233 | 105.6% | 86.7% |
200 | 0.3 | 0.667 | 0.0164 | 0.0155 | 105.8% | 86.9% |
200 | 0.4 | 0.5 | 0.0127 | 0.01165 | 109.0% | 89.5% |
300 | 0.1 | 2 | 0.0499 | 0.0466 | 107.1% | 87.9% |
300 | 0.2 | 1 | 0.0246 | 0.0233 | 105.6% | 86.7% |
300 | 0.3 | 0.667 | 0.0169 | 0.0155 | 109.0% | 89.5% |
300 | 0.4 | 0.5 | 0.0122 | 0.01165 | 104.7% | 85.9% |
400 | 0.1 | 2 | 0.0499 | 0.0466 | 107.1% | 87.9% |
Table 3.
Current efficiency.
Table 3.
Current efficiency.
IEG (µm) | Feed Rate (mm/s) | ECPL (C/mm) | Sexp (mm2) | Sthe (mm2) | η1 | η2 |
---|
50 | 0.1 | 2 | 0.0498 | 0.0466 | 106.9% | 87.8% |
80 | 0.1 | 2 | 0.0477 | 0.0466 | 102.4% | 84.1% |
50 | 0.2 | 1 | 0.0246 | 0.0233 | 105.6% | 86.7% |
80 | 0.2 | 1 | 0.0245 | 0.0233 | 105.6% | 86.7% |
50 | 0.3 | 0.667 | 0.0164 | 0.0155 | 105.8% | 86.9% |
80 | 0.3 | 0.667 | 0.0161 | 0.0155 | 103.9% | 85.3% |
50 | 0.4 | 0.5 | 0.0127 | 0.01165 | 109.0% | 89.5% |
80 | 0.4 | 0.5 | 0.0120 | 0.01165 | 103.0% | 84.6% |
Table 4.
Current efficiency.
Table 4.
Current efficiency.
Concentration (g/L) | Feed Rate (mm/s) | ECPL (C/mm) | Sexp (mm2) | Sthe (mm2) | η1 | η2 |
---|
120 | 0.1 | 2 | 0.0473 | 0.0466 | 101.5% | 83.3% |
250 | 0.1 | 2 | 0.0498 | 0.0466 | 106.9% | 87.8% |
120 | 0.2 | 1 | 0.0242 | 0.0233 | 103.9% | 85.3% |
250 | 0.2 | 1 | 0.0246 | 0.0233 | 105.6% | 86.7% |
120 | 0.3 | 0.667 | 0.0152 | 0.0155 | 98.1% | 80.5% |
250 | 0.3 | 0.667 | 0.0164 | 0.0155 | 105.8% | 86.7% |
120 | 0.4 | 0.5 | 0.0116 | 0.01165 | 99.6% | 81.8% |
250 | 0.4 | 0.5 | 0.0127 | 0.01165 | 109.0% | 89.5% |
Table 5.
Feed rate (mm/s) used in the experiments.
Table 5.
Feed rate (mm/s) used in the experiments.
| ECPL (C/mm) | 1 | 2/3 | 1/2 | 1/3 | 1/4 |
---|
Current (mA) | |
---|
200 | 0.2 | 0.3 | 0.4 | 0.6 | 0.8 |
300 | 0.3 | 0.45 | 0.6 | 0.9 | 1.2 |
400 | 0.4 | 0.6 | 0.8 | 1.2 | 1.6 |
Table 6.
dmax (µm) fitting equations.
Table 6.
dmax (µm) fitting equations.
| EOD (µm) | 200 | 300 | 400 |
---|
Current (mA) | |
---|
200 | | | |
300 | | | |
400 | | | |