CB*/Z 54-1981 Electrolytic zinc plating CB*/Z54-1981 Standard download decompression password: www.bzxz.net

Guiding Technical Documents of the National Technical Committee for Ship Standardization Electrolytic Plating
This document applies to the zinc plating of steel,
copper and copper alloy parts.
Pre-plating treatment
CB*/Z54-81
Group: 84
Replace CZ54—62
1.1 Pre-plating treatment should be treated by different methods according to the degree of oil and rust on the surface of the parts. After treatment, the surface of the parts should be clean and free of dirt, showing a metallic luster, and the crystalline structure of the matrix should be exposed. 1.2 If the oil pollution of the parts is particularly serious, the oil pollution should be removed by brushing first, and then the alkaline solution with the formula and process requirements in Table 1 can be used to clean according to the different degrees of oil pollution. After taking out, soak it in a hot water tank for 1 to 2 minutes, and then rinse it with compressed air and cold water. When there is no compressed air, it can also be rinsed with running water, and then put it in a hot water tank with a temperature of 80~100℃ for cleaning, and pay attention to the replacement of hot water according to the actual situation. Table 1
Content (g/L)
Degree of oil pollution
Sodium cyanide NaOH
Sodium carbonate Na;CO;
Trisodium phosphate Na:PO;
Water glass Na2SiO;
OP or other emulsifiers
Solution temperature ℃
80~100
80~100
Until removed
Turn over parts
Until removed
Turn over parts
Degree of oil pollution
Until removed
Turn over parts
When the surface of parts is severely rusted, mechanical rust removal should be carried out before galvanizing, and then etching should be carried out according to the formula in Table 2. After taking out, rinse off the residual acid with cold water and compressed air, and immediately put them in the tank for galvanizing. After degreasing, general rusted parts can be directly degreased and derusted by sulfuric acid one-step method according to Table 2 and process requirements. After taking out, use cold water and compressed air to flush away the remaining acid, and then galvanize. Composition
Sulfuric acid H2SO4
Sulfur (NH,)CS
OP or other emulsifier
Sodium dodecyl sulfate
Solution temperature
Amount (g/L)
200~250
Around 40℃
Until completely removed
Note: After the pre-plating treatment, small parts and light damaged parts should be weakly corroded (activated) before galvanizing, and then rinsed with clean water for electroplating. It is not necessary for large parts, just use a larger current to impact.
National Ship Standardization Technical Committee 1982-03-04 Issued 1982-03-04 Approved
CB*/Z 5481
Pre-treatment of barrel-plated parts should be placed in a barrel and rolled in alkaline acid solution for many times until clean and scale-free. 1.4
2 Zinc plating
Ammonium fluoride-nitrilotriacetic acid type zinc plating according to Table 3. Table 3
Ammonium fluoride
Zinc fluoride
Content (g/L)
Nitrilotriacetic acid
Polyethylene glycol
[(CH, CHi)2O],OH
(NH2)2CS
Seagull detergent
Acidity (PH)
Solution temperature (C)
Current density (A/dm2)
Anode area ratio
Deposition rate (μm/h)
Drum speed
Alkaline zincate roller plating method is according to Table 4.
Zinc oxide ZnO
Sodium hydroxide NaOH
DE additive
Disodium ethylenediaminetetraacetic acid EDTA
Vanillin
Current density (A/dm2)
Solution temperature
Ratio of cathode to anode
Hanging (hanging) plating
220~260
1:0.3~0.4
Use pure front plate (stainless steel, iron plate, carbon rod are allowed to be used as insoluble anode) rolling
200~220
4~5 rpm
Content (g/L)
100~150
10~45C
Note: ①Controlling the ratio of zinc and alkali to 11~14 is very important to ensure the dissolution of zinc anode. ② After passivation and aging, the zinc parts should be spun off water marks in a water spinner, dried in a drying oven at 100-200°C and taken out in time. After galvanizing, wash in a clean water tank, polish in nitric acid solution, passivate in passivation solution, age in hot water at about 70°C, and finally blow dry with compressed air.
Polishing liquid composition:
Nitric acid HNO3
About 3%
CB*/Z54-81
2.5 Passivation According to the process requirements, any of the following three methods can be selected for passivation. 2.5.1
White passivation solution according to Table 5.
Chromic anhydride Cro,
Carbonate Baco:
Degree (pH)
Color passivation solution according to Table 6.
Aluminum sulfate
A2(SO)3-18Hz0
Air burst time
Tri-acid passivation solution according to the table.
Anhydride Cro,
Air burst time
Choice of coating thickness
Content (g/L)
Not less than 15 seconds
Amount (g/L)
10~15 seconds
10~15 seconds
250~300
(ml/1)
(ml/1)
About 5~10 seconds
About 5~10 seconds
10~35cbZxz.net
Parts coating thickness shall be in accordance with the requirements of the drawings and process specifications. If there is no requirement, refer to Table 8. Tightening
Pitch s<1mm
Pitch s=~1.5mm
Pitch s-1.5~2.5mm
Climbing distance s>2.5mm
Other parts and materials (excluding pipes with inner diameter of 25mm or more) Note: ①The meanings of various working environments are as follows: Bad CB*/Z 54-81
Minimum coating thickness
Outer atmosphere containing fresh water and sea water, often with condensed water, the air inside, relative humidity 80~100%, occasionally with condensed water, and may also be contaminated by smoke Good relative humidity does not exceed 80~90%, no water. ②The maximum coating thickness of fasteners should ensure that their external dimensions do not exceed the limits specified in the relevant tolerance standards. Generally
Badly heated and ventilated cabins
Well heated and ventilated cabins, the air inside, ③ The conditions for the use of plated parts in seawater are: the parts are not easy to paint and are not frequently corroded by seawater. 4 Quality inspection
4.1 The surface of the parts should be covered with a coating, and there should be no black spots, roughness, etc. 4.2 The bonding strength of the coating is good, and there are no defects such as bubbles, cracks, peeling and scratches. 4.3 2% of small galvanized parts are extracted for quality inspection according to CB744-78 "Quality Inspection of Electroplating and Chemical Coatings". The coating thickness of human-shaped and non-batch galvanized parts (iron matrix) is measured by thickness gauge. 5 Safety Precautions
5.1 The workshop should have good ventilation equipment to remove harmful gases generated during work. 5.2 Strengthen the treatment of "three wastes" and do a good job in environmental protection. 5.3 Chemicals should be stored in a storage room and kept by a dedicated person. 5.4 Protective equipment should be worn during operation to avoid accidents such as burns and poisoning. Additional Notes:
This standard was proposed by the Shipbuilding Process Group and drafted by the Jiangnan Shipyard under the jurisdiction of the 11th Institute of the Sixth Ministry of Machinery.
The main drafter of this standard is Huang Xilong.
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