CN103898582A

CN103898582A - Pretreatment solution for electroplating chromium on surface of magnesium alloy die casting

Info

Publication number: CN103898582A
Application number: CN201310217885.6A
Authority: CN
Inventors: 钱永清
Original assignee: WUXI XISHAN DISTRICT EHU TOWN DANGKOU QINGDANG METAL PRODUCT FACTORY
Current assignee: WUXI XISHAN DISTRICT EHU TOWN DANGKOU QINGDANG METAL PRODUCT FACTORY
Priority date: 2013-06-03
Filing date: 2013-06-03
Publication date: 2014-07-02

Abstract

The invention discloses a pretreatment solution for electroplating chromium on the surface of a magnesium alloy die casting. The solution comprises alkali washing solution, acid washing solution and activating solution, wherein the alkali washing solution comprises 16-22g/L of NaOh, 13-17g/L of Na2CO3.10H2O, 0.5-0.9g/L of sodium dodecyl sulfate and the balance of water; the acid washing solution comprises 24-28g/L of phosphate acid, 17-21g/L Na3PO4.12H2O, 15-25g/L of ferric nitrate, 31-35g/L of potassium permanganate, 4-8g/L of zinc sulfate and the balance of water; and the activating solution comprises 125-145g/L of K4P2O7.3H2O, 18-32g/L of Na2CO3, 9-11g/L of NH2HF and the balance of water.

Description

A kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution

Technical field

The present invention relates to electroplating technology field, relate in particular to a kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution.

Background technology

Magnesium alloy is described as the green metal structured material of 21 century, has that density is low, a specific tenacity and specific rigidity is high and damping and amortization, machinability, castability are superior, in automotive industry, space flight and aviation industry, electronic industry, has obtained increasingly extensive application.Magnesium raw material is abundant, and in natural resources, in the 8th, but as structured material, its solidity to corrosion is poor has restricted the major cause that it uses widely.

The Standard Electrode Potentials of magnesium is-2.34V, there is very high reactive behavior, in air or solution, magnesium alloy can generate one deck passive film as thin as a wafer very soon, thereby while causing plating or electroless plating, metal plating and magnesium substrate adhesion are not strong, do not reach service requirements, in addition according to known to the observation of magnesium alloy materials metal structure, magnesium alloy is to form α phase by purity compared with high magnesium, and the β being formed by alloy ingredient forms mutually, wherein β order skewness and electromotive force are higher than α phase, therefore Mg alloy surface Potential Distributing inequality, galvanic corrosion easily occurs in treatment solution makes Mg alloy surface plating or electroless plating become difficulty, therefore wish obtains the metal plating with good combination power, before plating and electroless plating, must first carry out special pre-treatment to remove surperficial passive film and segregation layer to magnesium alloy materials, to obtain one evenly, clean surface.

Surface pretreatment common method based on magnesium alloy plating or electroless plating has at present: Dow ^[1]the zinc method of the soaking technique of company exploitation, main flow process is: oil removing → anode cleaning → acid etching → acid activation → soak zinc → cyanide electroplating.On this basis, constantly improve, as Olsen ^[2]the Norsk-Hydro technique proposing: oil removing → acid etching → alkaline purification → soak zinc → cyanide electroplating, Dennis ^[3]wCM technique is proposed: oil removing → acid etching → acid activation → soak zinc → cyanide electroplating.In these pre-treating technology plating solutions, contain hypertoxic prussiate, the liquid waste disposal expense of generation is high.

Under the pressure of increasingly serious resources and environment protection; carrying out the researchs of magnesium metallic substance and anti-corrosion method thereof is one of urgent task of world's Sustainable development; although obtaining interim progress aspect magnesium alloy protection in recent years; and be applied in certain field, but still there is no to form the method that can replace traditional magnesium alloy plating completely.Therefore the electroplating technology that, hope can be developed a kind of environmental protection meets the production requirement of modern clean energy-saving.

Magnesium alloy die casting has been widely used in the fields such as automobile, traffic, aerospace, and wherein the application of some die casting needs surface that electrolytic coating is set, but the report about the electroplating technology of magnesium alloy die casting in prior art is little.And the pre-treatment step of electrodeposited chromium has important impact to final plating effect.

Summary of the invention

The object of the invention is to propose a kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution, by the adjustment to preprocessing solution component, make pretreating effect excellence, for follow-up plating is laid a good foundation.

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

A kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution, described solution comprises alkali cleaning, pickling and activated solution, wherein, soda-wash solution consists of: NaOH16-22g/L, Na ₂cO ₃10H ₂o13-17g/L, sodium lauryl sulphate 0.5-0.9g/L, surplus is water; Acidwash solution consists of: phosphoric acid 24-28g/L, Na ₃pO ₄12H ₂o17-21g/L, iron nitrate 15-25g/L, potassium permanganate 31-35g/L, zinc sulfate 4-8g/L, surplus is water; Activated solution consists of: K ₄p ₂o ₇3H ₂o:125-145g/L, Na ₂cO ₃: 18-32g/L, NH ₂hF:9-11g/L, surplus is water.

Preferably, wherein, soda-wash solution is: NaOH19g/L, Na ₂cO ₃10H ₂o15g/L, sodium lauryl sulphate 0.7g/L, surplus is water; Acidwash solution is: phosphoric acid 26g/L, Na ₃pO ₄12H ₂o19g/L, iron nitrate 20g/L, potassium permanganate 33g/L, zinc sulfate 5g/L, surplus is water; Activated solution is: K ₄p ₂o ₇3H ₂o:135g/L, Na ₂cO ₃: 25g/L, NH ₂hF:10g/L, surplus is water.

The present invention has advantages of:

The present invention, by the selection to pretreated alkali cleaning, pickling and activated solution and the adjustment of content, makes pretreating effect excellence, for follow-up plating is laid a good foundation, provides assurance for obtaining the strong coating of bonding force.And the fluorochemical amount ratio prior art of selecting is few, technique environmental protection.

Embodiment

Embodiment mono-

A kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution, described solution comprises alkali cleaning, pickling and activated solution, wherein, soda-wash solution is: NaOH16g/L, Na ₂cO ₃10H ₂o17g/L, sodium lauryl sulphate 0.5g/L, surplus is water, Acidwash solution is: phosphoric acid 24g/L, Na ₃pO ₄12H ₂o21g/L, iron nitrate 15g/L, potassium permanganate 35g/L, zinc sulfate 4g/L, surplus is water; Activated solution is: K ₄p ₂o ₇3H ₂o:125g/L, Na ₂cO ₃: 32g/L, NH ₂hF:9g/L, surplus is water.

Embodiment bis-

A kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution, described solution comprises alkali cleaning, pickling and activated solution, wherein, soda-wash solution is: NaOH22g/L, Na ₂cO ₃10H ₂o13g/L, sodium lauryl sulphate 0.9g/L, surplus is water; Acidwash solution is: phosphoric acid 28g/L, Na ₃pO ₄12H ₂o17g/L, iron nitrate 25g/L, potassium permanganate 31g/L, zinc sulfate 8g/L, surplus is water; Activated solution is: K ₄p ₂o ₇3H ₂o:145g/L, Na ₂cO ₃: 18g/L, NH ₂hF:11g/L, surplus is water.

Embodiment tri-

A kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution, described solution comprises alkali cleaning, pickling and activated solution, wherein, soda-wash solution is: NaOH19g/L, Na ₂cO ₃10H ₂o15g/L, sodium lauryl sulphate 0.7g/L, surplus is water; Acidwash solution is: phosphoric acid 26g/L, Na ₃pO ₄12H ₂o19g/L, iron nitrate 20g/L, potassium permanganate 33g/L, zinc sulfate 5g/L, surplus is water; Activated solution is: K ₄p ₂o ₇3H ₂o:135g/L, Na ₂cO ₃: 25g/L, NH ₂hF:10g/L, surplus is water.

Claims

1. a magnesium alloy die casting electroplating Cr onto surface preprocessing solution, is characterized in that, described solution comprises alkali cleaning, pickling and activated solution, and wherein, soda-wash solution consists of: NaOH16-22g/L, Na ₂cO ₃10H ₂o13-17g/L, sodium lauryl sulphate 0.5-0.9g/L, surplus is water; Acidwash solution consists of: phosphoric acid 24-28g/L, Na ₃pO ₄12H ₂o17-21g/L, iron nitrate 15-25g/L, potassium permanganate 31-35g/L, zinc sulfate 4-8g/L, surplus is water; Activated solution consists of: K ₄p ₂o ₇3H ₂o:125-145g/L, Na ₂cO ₃: 18-32g/L, NH ₂hF:9-11g/L, surplus is water.

2. a kind of magnesium alloy die casting electroplating Cr onto surface preprocessing solution as claimed in claim 1, is characterized in that, wherein, soda-wash solution is: NaOH19g/L, Na ₂cO ₃10H ₂o15g/L, sodium lauryl sulphate 0.7g/L, surplus is water; Acidwash solution is: phosphoric acid 26g/L, Na ₃pO ₄12H ₂o19g/L, iron nitrate 20g/L, potassium permanganate 33g/L, zinc sulfate 5g/L, surplus is water; Activated solution is: K ₄p ₂o ₇3H ₂o:135g/L, Na ₂cO ₃: 25g/L, NH ₂hF:10g/L, surplus is water.