Types and chemistry Nickel electroplating

1 types , chemistry

1.1 watts baths

1.1.1 bath composition
1.1.2 operating conditions


1.2 brighteners
1.3 nickel sulfamate

1.3.1 bath composition
1.3.2 operating conditions


1.4 all-chloride
1.5 sulfate-chloride
1.6 all-sulfate
1.7 hard nickel
1.8 black nickel

types , chemistry
watts baths

watts nickel plating baths can deposit both bright , semi-bright nickel. bright nickel typically used decorative purposes , corrosion protection. semi-bright deposits used engineering nickel high luster not desired.

bath composition

operating conditions

temperature: 40-65 °c
cathode current density: 2-10 a/dm
ph: 4.7-5.1

brighteners

carrier brighteners (e.g. paratoluene sulfonamide, benzene sulphonic acid) in concentration 0.75-23 g/l. carrier brighteners contain sulfur providing uniform fine grain structure of nickel plating.
levelers, second class brighteners (e.g. allyl sulfonic acid, formaldehyde chloral hydrate) in concentration 0.0045-0.15 g/l produce (in combination carrier brighteners) brilliant deposit.
auxiliary brighteners (e.g. sodium allyl sulfonate, pyridinum propyl sulfonate)in concentration 0.075-3.8 g/l.
inorganic brighteners (e.g. cobalt, zinc) in concentration 0.075-3.8 g/l. inorganic brighteners impart additional luster coating.

type of added brighteners , concentrations determine deposit appearance: brilliant, bright, semi-bright, satin.

nickel sulfamate

sulfamate nickel plating used many engineering applications. deposited dimensional corrections, abrasion , wear resistance, , corrosion protection. used undercoat chromium.

bath composition

operating conditions

temperature: 40-60 °c
cathode current density: 2-25 a/dm
ph: 3.5-4.5

all-chloride

all-chloride solutions allow deposition of thick nickel coatings. because run @ low voltages. however, deposition has high internal stresses.

sulfate-chloride

a sulfate-chloride bath operates @ lower voltages watts bath , provide higher rate of deposition. although internal stresses higher watts bath, lower of all-chloride bath.

all-sulfate

an all-sulfate solution used electro-depositing nickel anodes insoluble. example, plating insides of steel pipes , fittings may require anode.

hard nickel

a hard nickel solution used when high tensile strength , hardness deposit required.

black nickel

black nickel plating typically plated on brass, bronze, or steel in order produce non-reflective surface. type of plating used decorative purposes , not offer protection.