Composition control of tin–zinc electrodeposits through means of experimental strategies

Tin–zinc coatings offer excellent corrosion protection and do not suffer the drawback of the voluminous white corrosion product of pure zinc or high zinc alloy coatings. The aim of this study was to determine the suitable electroplating conditions (i.e. electrolyte composition and cathode current density) to produce 70Sn–30Zn electrodeposits. Thus, a fractional factorial design (FFD) was carried out to evaluate the effects of experimental parameters (ZnII concentration, SnIV concentration, pH and current density) on the Zn content of the electrodeposit. On the other hand, the electrodeposits were characterised by glow discharge optical emission spectroscopy (GDOES) and scanning electron microscopy (SEM). Correlation between operating conditions, composition and morphology was attempted.