CN101445923A - Passivation method for brass antitarnish - Google Patents

Abstract

The invention provides a passivation method for brass antitamish, which comprises the steps: a new passivating solution is adopted, which comprises 5-8g/l of benzotriazol (BTA), 2-4g/l of 1- phenyl- mercapto-tetrazole (PMT), 14-18g/l of tartaric acid (or citric acid), 2-4g/l of sodium molybdate (or sodium tungstate), and 0.5-1g/l of sodium dodecyl sulfate. When the solution is used for passivation, the pH value of the solution is 2-3, and the temperature is 50-60 DEG C, and the time is 3-5 min. The passivation effect can be achieved by putting the brass in the solution for passivation. The passivation method is simple in operation, fast, convenient, and environmental friendly; the brass antitarnish time in salt, acids, alkaline solutions media is durable.

Description

A kind of passivating method of brass antitarnish

Technical field

The present invention relates to a kind of brass antitarnish passivating method, belong to the surface anticorrosive technical field.

Background technology

Brass alloys are easy to be corroded in the atmosphere of moisture vapor, carbonic acid gas and sulfide, lose its ornamental color and luster.Therefore, usually must prevent the variable color processing to it.Passivation Treatment is the brass antitarnish technology of using always.

Traditional brass Passivation Treatment adopts chromic acid or chromating more, and dividend is superseded gradually because of there is severe contamination in it.Existing brass Passivation Treatment adopts organic inhibitors such as benzotriazole mostly, though obtain effect, but usually can not satisfy the anti-variable color requirement under acidity, alkalescence, the neutral different condition, and the anti-variable color time is also durable inadequately, can not satisfy the requirement of some expensive goods to its beautiful decoration.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, propose the brass antitarnish passivating method of a kind of environmental friendliness, weather resistance, to satisfy of the requirement of some expensive goods its beautiful decoration.

The objective of the invention is to be realized by following technical solution:

A kind of passivating method of brass antitarnish, described step is:

A, with brass with sand papering-wipes of alcohol eccysis oil-washing,

B, normal temperature washing agent oil removing-hot water wash-cold wash,

C, place acidic solution pickling bright dipping, activation,

D, hot water wash-cold wash-change passivating dip over to keep 3-5min,

Use cold washed with de-ionized water after e, the passivation, taking-up dries up;

F, brass is placed 50-60 degree centigrade of down baking 20-30min;

Wherein, the passivating dip among the described step e contains:

Benzotriazole 5g-8g (weight percent);

2-phenyl-5 mercapto tetrazole 2g-4g (weight percent);

A kind of or its mixture 14g-18g (weight percent) of tartrate, citric acid;

A kind of or its mixture 2g-4g (weight percent) of Sodium orthomolybdate, sodium wolframate;

Sodium lauryl sulphate 0.5g-1g (weight percent); The pH value of described solution is 2-3.

As optimal way, described passivating dip contains:

Benzotriazole 6g-7g (weight percent);

2-phenyl-5 mercapto tetrazole 3g (weight percent);

A kind of or its mixture 15g-17g (weight percent) of tartrate, citric acid;

A kind of or its mixture 3g (weight percent) of Sodium orthomolybdate sodium wolframate;

Sodium lauryl sulphate 0.5g-1g (weight percent).

In addition, the described acidic solution of described step c comprises:

Sulfuric acid 400-450ml/l,

Nitric acid 40-50ml/l,

Hydrochloric acid 5-7ml/l,

Gelatin 0.5-1g/l,

Polyoxyethylene glycol 1-2g/l,

OP emulsifying agent 10-20ml/l;

The temperature of described solution is 25-35 degree centigrade, and the pickling time is 15-30s.

The feature of passivating dip composition is: (1) selects 1-phenyl-5 mercapto tetrazole (PMT) and the composite use of benzotriazole (BTA) for use, as main inhibiter composition; PMT with kind of a medium (atmosphere, sulfide, muriate) in, better again than 2-mercaptobenzimidazole (MBI) environment; (3) simple to operate, quick.

Embodiment

Be illustrated with following specific embodiment:

Example 1

1, test materials: H62 brass, 20mm x 40mm x 2min.

2, method flow: sand papering-wipes of alcohol eccysis oil-washing-normal temperature washing agent oil removing-hot water wash-cold wash-pickling bright dipping, activation-hot water wash-cold wash-passivation-wash-dry up-60 degrees centigrade of baking 30min with deionized water.

3, pickling bright dipping, activation: sulfuric acid 400-450ml/l, nitric acid 40-50ml/l, hydrochloric acid 5-7ml/l, gelatin 0.5-1g/l, polyoxyethylene glycol 1-2g/l, OP emulsifying agent 10-20ml/l.25-35 degree centigrade, 15-30s.

4, passivating method of the present invention: benzotriazole (BTA) 6g/l, 1-phenyl-5 mercapto tetrazole (PMT) 2g/l, Sodium orthomolybdate 3g/l, citric acid 14g/l, sodium lauryl sulphate 1g/l.The pH value of solution is 2-3, and temperature is 55 degree, dipping 3min.

Example 2

1, test materials: with example 1

2, method flow: with example 1

3, pickling bright dipping, activation: with example 1

4, passivating method of the present invention: benzotriazole (BTA) 8g/l, 1-phenyl-5 mercapto tetrazole (PMT) 2g/l, sodium wolframate 3g/l, citric acid 14g/l, sodium lauryl sulphate 1g/l.The pH value of solution is 2.5, and temperature is 60 degrees centigrade, dipping 3min.

Example 3

1, material: with example 1

2, method flow: with example 1

3, pickling bright dipping, activation: with example 1

4, passivating method commonly used (being used for contrast): benzotriazole (BTA) 8g/l, ethanol 40ml/l sodium lauryl sulphate 0.5g/l.The pH value of solution is 4.5, and temperature is 50 degrees centigrade, dipping 3min.

Test-results: anti-corrosion test result such as following table (with the Time Calculation of beginning variable color)

Medium (temperature 50-60 ℃)	Example 1	Example 2	Example 3
				25% salpeter solution soaks	15min	12min	1.5min
25% ammoniacal liquor drop	165s	170s	35s
				20% sodium hydroxide solution soaks	48h	48h	29h
5% sodium chloride solution soaks	5?x?24h	5?x?24h	5?x?24h

Above presentation of results: compare with BTA passivating technique commonly used, passivating technique of the present invention can obtain superior comprehensive discoloration-resisting.

Claims (3)

1, a kind of passivating method of brass antitarnish is characterized in that: described step is:

A, with brass with sand papering-wipes of alcohol eccysis oil-washing,

B, normal temperature washing agent oil removing-hot water wash-cold wash,

C, place acidic solution pickling bright dipping, activation,

D, hot water wash-cold wash-change passivating dip over to keep 3-5min,

Use cold washed with de-ionized water after e, the passivation, taking-up dries up;

F, brass is placed 50-60 degree centigrade of down baking 20-30min;

Wherein, the passivating dip among the described step e contains:

Benzotriazole 5g-8g (weight percent);

1-phenyl-5 mercapto tetrazole 2g-4g (weight percent);

A kind of or its mixture 14g-18g (weight percent) of tartrate, citric acid;

A kind of or its mixture 2g-4g (weight percent) of Sodium orthomolybdate, sodium wolframate;

Sodium lauryl sulphate 0.5g-1g (weight percent); The pH value of described solution is 2-3.

2, the passivating method of brass antitarnish according to claim 1 is characterized in that: described passivating dip contains:

Benzotriazole 6g-7g (weight percent);

2-phenyl-5 mercapto tetrazole 3g (weight percent);

A kind of or its mixture 15g-17g (weight percent) of tartrate, citric acid;

A kind of or its mixture 3g (weight percent) of Sodium orthomolybdate sodium wolframate;

Sodium lauryl sulphate 0.5g-1g (weight percent).

3, the passivating method of brass antitarnish according to claim 1 is characterized in that: the described acidic solution of described step c comprises:

Sulfuric acid 400-450ml/l,

Nitric acid 40-50ml/l,

Hydrochloric acid 5-7ml/l,

Gelatin 0.5-1g/l,

Polyoxyethylene glycol 1-2g/l,

OP emulsifying agent 10-20ml/l;

The temperature of described solution is 25-35 degree centigrade, and the pickling time is 15-30s.