CN104213166A - Magnesium alloy surface chromium electroplating technology adopting pre-electroplating of zinc-nickel alloy - Google Patents

Abstract

The invention discloses a magnesium alloy surface chromium electroplating technology adopting pre-electroplating of a zinc-nickel alloy. The technology is characterized by comprising the steps of: alkali washing, acid pickling, activation, zinc dipping, electroplating of zinc-nickel, and electroplating of chromium. The technology employs a zinc-nickel electroplating process to conduct chromium electroplating pretreatment, and by adjusting the components of the zinc-nickel electroplating solution and the chromium electroplating solution, toxic and high pollution components are not employed, so that the plating process can be environment friendly and safe, and the prepared coating has high corrosion resistance, beautiful appearance, and high binding force between the substrate and the coating.

Description

A kind of Mg alloy surface electrodeposited chromium technique of pre-galvanized admiro

Technical field

The present invention relates to electroplating technology field, particularly relate to a kind of Mg alloy surface electrodeposited chromium technique of pre-galvanized admiro.

Background technology

Magnesium alloy, as a kind of lightweight engineered structured material, has high specific strength, high specific stiffness and superior damping performance, and have a wide range of applications in fields such as traffic, communication, Aeronautics and Astronautics field.But magnesium alloy chemical activity is high, and electropotential is low, surface film oxide loosens, and causes barrier propterty low, constrains the application and development of magnesium alloy.Cause the concern of people to magnesium alloy part surface corrosion and protection thus, large quantifier elimination has been carried out in Mg alloy surface anodic oxidation, chemical conversion film, organic coating, coating surface etc., particularly employing method for electroplating nickel is low as a kind of cost, technique simple, the surface coating technique of easy handling, has become the important research direction of people to magnesium alloy surface protective.

At present, the electro-plating method of magnesium alloy is mainly and could starts to electroplate other metal after zinc-plated, copper pre-plating in advance, and major part is for containing cyanogen plating.Such as, what both at home and abroad generally adopt now is the standard method of the plated metal Ni that U.S. ASTM recommends, and be the leaching zinc plating method of Dow company exploitation, its pre-treatment have employed leaching zinc and cyanide copper plating technique.But this complex technical process, repeatability is poor, and use prussiate, plating solution is poisonous, contaminate environment, and the bright property of coating and the stability of plating solution also need further improvement.

In order to overcome the shortcoming of complex process, software engineering researchers invent has gone out direct electroless nickel method, as adopted chromic anhydride in JP2003073843, etch is carried out to magnesium alloy, chemical nickel plating is carried out after fluorochemical activation, chemical nickel-plating liquid is regulated to make it be weakly alkaline with ammoniacal liquor, once bonding force was obtained good, the chemical Ni-plating layer that solidity to corrosion is high, Li De is high adopt in patent CN1699634A magnesium alloy plating method go wadding → electrochemical deoiling → bright dipping → in and the zincincation of → activation → in advance obtain reasonable pre-zinc coating, and pre-galvanizing flux is without cyanogen, nontoxic, harmless, the people such as Yang Noboru are in patent CN1737205A, by Direct Electroplating aluminium after dense hydrofluoric acid (11%) used for magnesium alloy pickling, obtain reasonable aluminium coat, Chinese patent CN1641075A is to magnesium, the surface of magnesium alloy or activating treatment process and plated surface method did detailed description, although these techniques have all departed from prussiate plating, but the treatment process before plating is mostly based on the improvement of the technique to DOW.

Summary of the invention

The object of the invention is to the Mg alloy surface electrodeposited chromium technique proposing a kind of pre-galvanized admiro, this technique adopts plating zinc-nickel technique to carry out electrodeposited chromium pre-treatment, and by the adjustment to electro-galvanizing nickel plating bath and electrodeposited chromium bath composition, do not adopt poisonous, pollute high component, make plating technic Environmental Safety, and preparation the corrosion-resistant height of coating, appearance looks elegant, matrix and binding force of cladding material high.

For reaching this object, the present invention by the following technical solutions:

A Mg alloy surface electrodeposited chromium technique for pre-galvanized admiro, described technique comprises the steps: alkali cleaning → pickling → activation → leaching zinc → plating zinc-nickel → electrodeposited chromium, wherein

Plating zinc-nickel: electro-galvanizing nickel plating bath consists of: ZnSO ₄7H ₂o32-36g/L, NiSO ₄6H ₂o15-19g/L, sodium sulfate 43-47g/L, K ₄p ₂o ₇3H ₂o164-168g/L, KF18-20g/L, C ₆h ₁₇o ₇n ₃32-36g/L, phytic acid 0.4-0.6g/L, H ₂cSNH ₂: 4-6g/L, surplus is water; Technique is: with pure zinc for anode, electroplating temperature: 35-45 DEG C, electroplating time 35-45min, current density: 1.5-2.5A/dm ²;

Electrodeposited chromium: plating solution consists of: chromium sulphate 160-170g/L, sodium sulfate 270-280g/L; Brometo de amonio 0.6-0.8mol/L; Boric acid 1.5-1.7mol/L; Inferior sodium phosphate 0.6-0.8mol/L; Oxalic acid 1.2-1.4mol/L; Sodium lauryl sulphate 0.03-0.05mol/L, ferrous sulfate 0.05-0.07mol/L, surplus is water; Electroplating technology: pH value 2.3-3.6; Technological temperature 45-55 DEG C, cathode current density 21-23A/dm ², electroplating time 20-30 minute.

The advantage that the present invention has:

This technique adopts plating zinc-nickel technique to carry out electrodeposited chromium pre-treatment, and by the adjustment to electro-galvanizing nickel plating bath and electrodeposited chromium bath composition, do not adopt poisonous, pollute high component, make plating technic Environmental Safety, and the corrosion-resistant height of coating of preparation, appearance looks elegant, matrix and binding force of cladding material high.

Embodiment

Embodiment one

A Mg alloy surface electrodeposited chromium technique for pre-galvanized admiro, described technique comprises the steps: alkali cleaning → pickling → activation → leaching zinc → plating zinc-nickel → electrodeposited chromium, wherein

Plating zinc-nickel: electro-galvanizing nickel plating bath consists of: ZnSO ₄7H ₂o32g/L, NiSO ₄6H ₂o19g/L, sodium sulfate 43g/L, K ₄p ₂o ₇3H ₂o168g/L, KF18g/L, C ₆h ₁₇o ₇n ₃36g/L, phytic acid 0.4g/L, H ₂cSNH ₂: 6g/L, surplus is water; Technique is: with pure zinc for anode, electroplating temperature: 35-45 DEG C, electroplating time 35min, current density: 1.5-2.5A/dm ²;

Electrodeposited chromium: plating solution consists of: chromium sulphate 160g/L, sodium sulfate 280g/L; Brometo de amonio 0.6mol/L; Boric acid 1.7mol/L; Inferior sodium phosphate 0.6mol/L; Oxalic acid 1.4mol/L; Sodium lauryl sulphate 0.03mol/L, ferrous sulfate 0.07mol/L, surplus is water; Electroplating technology: pH value 2.3-3.6; Technological temperature 45-55 DEG C, cathode current density 21-23A/dm ², electroplating time 20 minutes.

Embodiment two

A Mg alloy surface electrodeposited chromium technique for pre-galvanized admiro, described technique comprises the steps: alkali cleaning → pickling → activation → leaching zinc → plating zinc-nickel → electrodeposited chromium, wherein

Plating zinc-nickel: electro-galvanizing nickel plating bath consists of: ZnSO ₄7H ₂o36g/L, NiSO ₄6H ₂o15g/L, sodium sulfate 47g/L, K ₄p ₂o ₇3H ₂o164g/L, KF20g/L, C ₆h ₁₇o ₇n ₃32g/L, phytic acid 0.6g/L, H ₂cSNH ₂: 4g/L, surplus is water; Technique is: with pure zinc for anode, electroplating temperature: 35-45 DEG C, electroplating time 45min, current density: 1.5-2.5A/dm ²;

Electrodeposited chromium: plating solution consists of: chromium sulphate 170g/L, sodium sulfate 270g/L; Brometo de amonio 0.8mol/L; Boric acid 1.5mol/L; Inferior sodium phosphate 0.8mol/L; Oxalic acid 1.2mol/L; Sodium lauryl sulphate 0.05mol/L, ferrous sulfate 0.05mol/L, surplus is water; Electroplating technology: pH value 2.3-3.6; Technological temperature 45-55 DEG C, cathode current density 21-23A/dm ², electroplating time 30 minutes.

Embodiment three

A Mg alloy surface electrodeposited chromium technique for pre-galvanized admiro, described technique comprises the steps: alkali cleaning → pickling → activation → leaching zinc → plating zinc-nickel → electrodeposited chromium, wherein

Plating zinc-nickel: electro-galvanizing nickel plating bath consists of: ZnSO ₄7H ₂o34g/L, NiSO ₄6H ₂o17g/L, sodium sulfate 45g/L, K ₄p ₂o ₇3H ₂o166g/L, KF19g/L, C ₆h ₁₇o ₇n ₃34g/L, phytic acid 0.5g/L, H ₂cSNH ₂: 5g/L, surplus is water; Technique is: with pure zinc for anode, electroplating temperature: 35-45 DEG C, electroplating time 40min, current density: 1.5-2.5A/dm ²;

Electrodeposited chromium: plating solution consists of: chromium sulphate 165g/L, sodium sulfate 275g/L; Brometo de amonio 0.7mol/L; Boric acid 1.6mol/L; Inferior sodium phosphate 0.7mol/L; Oxalic acid 1.3mol/L; Sodium lauryl sulphate 0.04mol/L, ferrous sulfate 0.06mol/L, surplus is water; Electroplating technology: pH value 2.3-3.6; Technological temperature 45-55 DEG C, cathode current density 21-23A/dm ², electroplating time 25 minutes.

Claims (1)

1. a Mg alloy surface electrodeposited chromium technique for pre-galvanized admiro, is characterized in that, described technique comprises the steps: alkali cleaning → pickling → activation → leaching zinc → plating zinc-nickel → electrodeposited chromium, wherein

Plating zinc-nickel: electro-galvanizing nickel plating bath consists of: ZnSO ₄7H ₂o32-36g/L, NiSO ₄6H ₂o15-19g/L, sodium sulfate 43-47g/L, K ₄p ₂o ₇3H ₂o164-168g/L, KF18-20g/L, C ₆h ₁₇o ₇n ₃32-36g/L, phytic acid 0.4-0.6g/L, H ₂cSNH ₂: 4-6g/L, surplus is water; Technique is: with pure zinc for anode, electroplating temperature: 35-45 DEG C, electroplating time 35-45min, current density: 1.5-2.5A/dm ²;

Electrodeposited chromium: plating solution consists of: chromium sulphate 160-170g/L, sodium sulfate 270-280g/L; Brometo de amonio 0.6-0.8mol/L; Boric acid 1.5-1.7mol/L; Inferior sodium phosphate 0.6-0.8mol/L; Oxalic acid 1.2-1.4mol/L; Sodium lauryl sulphate 0.03-0.05mol/L, ferrous sulfate 0.05-0.07mol/L, surplus is water; Electroplating technology: pH value 2.3-3.6; Technological temperature 45-55 DEG C, cathode current density 21-23A/dm ², electroplating time 20-30 minute.