The effect of polyamine 70000 (BT70) on the zinc plating process in the non-cyanide alkaline plating bath

Abstract

The effect of polyamine having molecular weight 70,000u (BT70) in the non-cyanide alkaline plating bath on the morphological zinc electrodeposited coating was investigated. The obtained results from the reflectance of electrodeposited zinc coating by a suitable range of electro-current density and SEM images showed that BT70 had effect on the zinc plating in comparison with the zinc deposits from plating bath without BT70. The electrodeposited coating surface was rough and poor adhesion. However, adding BT70 into the plating bath led to the surface roughness of electrodeposited coating and grand size being reduced. Zinc electrodeposited coating from a plating bath containing BT70 at 0.5 g/L, respectively, experienced the highest reflectance, equal 46 % of the electrodeposited coating from the bath containing commercial additives. Hull method showed that the zinc deposited coating surface became smoother with the presence of polyamine in non-cyanide alkaline zinc plating solution. The zinc deposited coating had a semigloss scope at 10 A/dm 2. If the BT70 content increased, the semi-gloss scop and the gloss of samples' surfaces also grew up.

Effects of number of substituents and molecular weight of polyamines on the non-cyanide alkaline zinc plating process

“…8 and Tab. 1 are Hull cell patterns obtained from the alkaline zinc plating solutions including Bt700 from reference [7]. In the case of same number of substituents of polyamines, the brightness (BN) and semi-bright ranges (SBR) of the deposits using polyamines with low molecular weight Bt18 (BN = 14 and SBR < 3 A/dm 2 ) and Q7-20 (BN = 4.6 and SBR < 2 A/dm 2 ) were poorer than those of the deposits using polyamines with high molecular weight Bt700 (BN = 56.7 and SBR < 10 A/dm 2 ) and Q7-700 (BN = 15.3 and SBR < 4.5 A/dm 2 ), respectively.…”

“…In Viet Nam, nowadays, additive systems for the noncyanide alkaline bath used in the industries are all imported, and no published documents of the additives have been found. In our previous research, we have investigated the effects of molecular weight of polyamines on the non-cyanide alkaline zinc plating process [7]. The results showed that molecular weight of polyamines had strong effects on the non-cyanide alkaline zinc plating process in which the heavier molecular weight, the stronger effects.…”