A sulfate–chloride electrolyte was used to deposit alloy layers on AISI 1018 coupons while co-introducing ZnS nanoparticles (5–20 g/L) to tune microstructure and durability under combined saline exposure and dry sliding. Cross-sectional SEM confirmed continuous deposits of ~24–26 μm, and XRD indicated γ-phase dominance with pronounced grain refinement: crystallite size decreased from 42 ± 3 nm (particle-free) to 28 ± 2 nm at 15 g/L. In 3.5 wt% NaCl, polarization data showed a progressive ennoblement of Ecorr from −1.032 to −0.981 V (vs. SCE) together with a reduction of icorr from 8.47 to 1.82 μA/cm2 at 15 g/L. Impedance fitting corroborated the trend, with charge-transfer resistance increasing from 4.8 to 32.6 kΩ·cm2 after 1 h immersion. In a 500 h neutral salt-spray test, red rust appeared at 280 ± 15 h on the particle-free alloy, whereas the 15 g/L formulation showed no red rust after 500 h and only uniform white products. Mechanical response improved in parallel: microhardness rose from 245 ± 12 to 398 ± 15 HV, and pin-on-disc testing (10 N, 0.1 m/s, 1000 m; alumina counterface) reduced wear volume loss from 1.85 × 10−3 to 0.52 × 10−3 mm3 and lowered steady-state friction from ~0.68 to ~0.45. Performance peaked at 15 g/L, while 20 g/L produced a modest regression, a trend that is consistent with classical electrodeposited nanocomposite behavior in which an intermediate particle loading optimizes incorporation and matrix refinement, whereas excessive loading promotes agglomeration and growth disruption/defect formation that offsets the benefits. For a normalized, like-for-like benchmark, a Zn–Ni/Al2O3 composite was co-deposited and tested under the same conditions (identical substrate preparation, current density, bath temperature/pH, and comparable thickness of ~24–26 μm). Under these controlled conditions, the optimized Zn–Ni/15 g L−1 ZnS coating exhibited a lower corrosion current density (icorr = 1.82 μA cm−2 vs. 3.15 μA cm−2 for Zn–Ni/Al2O3; ≈42% reduction) and a lower specific wear rate, calculated as V/(F·L), of 5.2 × 10−8 mm3 N−1 m−1 vs. 7.1 × 10−8 mm3 N−1 m−1 for Zn–Ni/Al2O3 (≈27% reduction), thereby supporting a normalized performance comparison without relying on non-equivalent test conditions.
Kang et al. (Thu,) studied this question.