Pengaruh Pretreatment Larutan Zinkat terhadap Elektroplating Nikel-Krom pada Logam Aluminium

Abstract

Electroplating nickel-chrome in aluminum base metal is an electroplating process on aluminum metal using direct current in a medium of nickel and chrome solution gradually. Electroplating on aluminum metal is not like electroplating using carbon steel base metal, because the aluminum workpiece needs to be pretreatment in zincate solution. This study aims to study the effect of process time and concentration of zincate solution. The processing time is 15, 30 and 45 seconds, and the zincate concentration (ZnO) is 2.5%, 5%, 7.5%, 10% and 12.5% in 50% NaOH solution. Nickel electroplating electrolytes using a solution of  nickel sulfate, nickel chloride, and boric acid with a process time of 15 minutes, at a temperature of 50⁰C with a current density of 20A/dm², while electroplating chrome in a solution of chrome and sulfuric acid with a ratio of 100: 1 at 60⁰C with time 20 minute process. Electroplating results are tested for thickness, adhesion, visualization and micro photographs. The results showed that nickel-chrome electroplating on aluminum metal through the zincate process pretreatment produced the highest layer at 45-second zincate processing time with nickel 48.8 μm and 26.5 μm chrome thickness and had a good adhesion. Coating the thickness produced was achieved on 7.5% zincate concentration. The results of nickel-chrome coating on aluminum metal through zincate pretreatment process have better thickness and adhesion and are based on photomycronics which have a thin layer with a thin zincate layer followed by a layer of nickel and chrome attached to the surface of aluminum metal.