Client Citation Analysis
The Dropometer measured the water contact angle on each of the four plated coatings, using a 5 µL drop of deionized water. It did not measure corrosion. Open circuit potential, Tafel slopes, corrosion current and corrosion rate all came from a Corrtest CS350 potentiostat. No roughness, thickness or particle size data came from the Dropometer.
Static water contact angle on four copper silver coatings, reported as one value per coating in Fig. 3. Replicates, temperature and fitting method are not stated in the paper.
How do silver particle size (20 nm or 3 µm) and plating bath pH (acidic or alkaline) change the corrosion resistance and wettability of selective plated copper coatings on 316L stainless steel?
Coatings plated from the alkaline bath corroded slowest, but coatings from the acidic bath had the higher water contact angles. The authors conclude that wettability alone does not rank corrosion protection; compactness and electrochemical stability matter more.
This paper uses water contact angle to compare the wettability of copper silver coatings plated from two different baths.
Static water contact angle of a 5 µL deionized water drop on each of the four plated coatings, measured with a Droplet Lab Dropometer and shown as a bar chart in Fig. 3.
A Corrtest CS350 potentiostat in a three electrode cell (platinum counter, Ag/AgCl reference) measured open circuit potential and Tafel polarization in 3.5 wt.% NaCl at room temperature. From these the authors report Tafel slopes, corrosion potential, corrosion current density and corrosion rate (Table 1). Coating thickness was checked by cross sectional analysis; that instrument is not named.
Water contact angle of a 5 µL deionized water drop on each coating. The paper writes it as "Droplet Lab dropometer".
Open circuit potential, potentiodynamic polarization, Tafel slopes, corrosion current density and corrosion rate in 3.5 wt.% NaCl.
Selective plating of the copper silver coatings to about 20 µm.
Cutting the 316L stainless steel substrates to 30 × 20 × 3 mm with coolant.
The team used a Droplet Lab Dropometer to measure the water contact angle on all four plated coatings. Each measurement used a 5 µL drop of deionized water.
The Dropometer data form the whole wettability section of the paper. They show that acidic bath coatings were less wettable (77.9° and 82.6°) than alkaline bath coatings (69.8° and 69.7°).
The Dropometer did not take part in the corrosion testing. Every corrosion number in the paper, including the 0.028 mm/y best result, came from the potentiostat.
The paper does not report drop age, replicate count, temperature or the fitting method for the contact angle readings.
The contact angles let the authors test whether a less wettable coating also resists corrosion better. Here it did not, and that negative result is the main wettability conclusion of the paper.
If you need to check how a plating bath or particle change shows up on the coating surface, measure water contact angle on the same coupons you send for corrosion testing. See how the Dropometer handles this measurement.
Dropometer readings placed all four coatings below 90°, so every coating stayed on the hydrophilic side of the usual threshold.
Acidic bath coatings read 77.9° (3 µm Ag) and 82.6° (20 nm Ag). Alkaline bath coatings read 69.8° and 69.7°, with almost no change from particle size.
Switching from 3 µm to 20 nm silver raised the contact angle by about 4.7° in the acidic bath. In the alkaline bath the change was 0.1°.
Potentiostat data, not Dropometer data, gave this coating the lowest corrosion current (2.46 × 10⁻⁶ A/cm²) and corrosion rate (0.028 mm/y). The acidic 3 µm coating was worst at 0.103 mm/y.
The acidic 20 nm coating had the highest contact angle but corroded two to three times faster than the alkaline coatings (0.090 versus 0.039 and 0.028 mm/y). The authors conclude coating compactness and stability matter more than wettability.
Only Fig. 3 contains Droplet Lab data. Fig. 1 and Fig. 2 show potentiostat corrosion data.
Bar chart of the water contact angle on each copper silver coating, measured with the Dropometer. Licence not stated in the text and no Creative Commons statement appears, so do not reproduce without permission. Credit: Yankova et al., C. R. Acad. Bulg. Sci. 79(4), 2026.
A higher water contact angle is often expected to mean better corrosion protection. This study shows that a contact angle reading needs pairing with a corrosion test before ranking coatings for protection.
The contact angle clearly separated coatings from the two baths. It did not predict which coating corroded slowest.
A gap of about 8° to 13° between acidic and alkaline bath coatings shows that the plating bath leaves a measurable mark on the surface.
Four coatings, one probe liquid, one drop volume
Acidic bath coatings read 8° to 13° higher than alkaline ones
Best corrosion result came from a lower contact angle coating
Contact angle and potentiostat data answer different questions
Use water contact angle to confirm a bath or particle change reached the surface. Use polarization data to rank corrosion protection.
Drop age, replicate count, temperature and spread make plated coating contact angles comparable between labs and batches.
It measured the water contact angle on four selective plated copper coatings containing silver particles. Each reading used a 5 µL drop of deionized water. The corrosion data came from a separate potentiostat.
No. The acidic bath coating with 20 nm silver had the highest contact angle at 82.6°. The alkaline bath coating with 20 nm silver, at 69.7°, had the lowest corrosion rate of 0.028 mm/y.
The paper links wettability to surface chemistry and microstructure set by the plating bath. It does not report roughness or surface chemistry data, so the exact cause is not measured here.
No. All four readings were below 90°, ranging from 69.7° to 82.6°. The authors describe them as moderately hydrophilic to near hydrophobic.
Use the formal reference below when citing the original paper.
Yankova, R., Rusev, I., Koleva, I., & Veselinov, D. (2026). Corrosion resistance and wettability of selective plated copper-based coatings containing silver particles. Comptes rendus de l'Académie bulgare des Sciences, 79(4), 479–488. https://doi.org/10.7546/CRABS.2026.04.09
Yankova et al., C. R. Acad. Bulg. Sci. 2026, 79(4), 479–488. DOI: 10.7546/CRABS.2026.04.09