CN101619448A

CN101619448A - Pretreatment solution used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy

Info

Publication number: CN101619448A
Application number: CN 200910012838
Authority: CN
Inventors: 梁平
Original assignee: Liaoning Shihua University
Current assignee: Liaoning Shihua University
Priority date: 2009-07-31
Filing date: 2009-07-31
Publication date: 2010-01-06

Abstract

The invention discloses a pretreatment solution used for an electroless nickel-phosphorus alloy plating layer on the surface of an aluminum alloy, which comprises the following components: 5-40g/L of sodium molybdate, 5-30g/L of sodium hydroxide or 10-40ml/L of ammonia and the balance of deionized water. The pretreatment solution has the following advantages that: the pretreatment solution simplifies the operation steps of nickel-phosphorus deposition to 9 steps from 15 steps, thereby being easy to realize industrialization and improving production efficiency; the pretreatment solution only consists of two substances, thereby reducing cost and improving economic benefits; the pretreatment solution does not need to adopt nitric acid for carrying out zinc withdrawal treatment, thereby avoiding the pollution and the toxication to chemical nickel plating solution, prolonging the service life of the plating solution, avoiding environmental pollution and reducing influences on the health of operation staffs; and the prepared nickel-phosphorus electroless plating layer has uniform densification, good corrosion resistance, high microhardness, firm combination with an aluminum alloy base body, good metal luster and good appearance, thereby providing a good protection effect for the aluminium alloy.

Description

A kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy

One, technical field

The invention belongs to metallic corrosion and guard technology field, be specifically related to a kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy.

Two, background technology

The density of aluminium alloy is lower, strength ratio is higher, near or surpass the high-quality steel, plasticity is good, can be processed into various section bars, also have characteristics such as good electroconductibility, thermal conductivity simultaneously, its consumption is only second to iron and steel, thereby be a kind of important metallic substance, obtained widespread use in fields such as space flight and aviation, ocean, communication, traffic, military affairs, computers.

Aluminium alloy has than higher chemically reactive, and its standard potential is very negative, is about-1.67 volts, under various environment, is especially containing chlorion (Cl ^-) environment in, corrosion failures such as spot corrosion very easily take place in aluminium alloy.In addition, the hardness of aluminium alloy is also very low, and wear resistance is very poor.Therefore, further enlarge the range of application of aluminium alloy, must protect and intensive treatment, thereby improve performances such as its solidity to corrosion and wear resistance its surface.

Electroless plating is to utilize the catalyzed reaction ejected electron of reductive agent in the solution to make metal ion be reduced into the process of atoms metal, advantages such as it has that equipment is simple, easy to operate, less investment, instant effect, environmental pollution are light are the normal technology of using in metallic substance and non-metal material surface protection field.Adopt nickel phosphorus (Ni-P) alloy layer of electroless plating technology preparation to have good homogeneous, higher microhardness, performances such as good wear resistance, solidity to corrosion, weldability and magnetic have now obtained widespread use in electronic industry, petrochemical complex, precision instrument, machinery, weaving, aviation, automobile and other industries.Therefore, Ni-P alloy coating is applied to the performance that aluminum alloy surface will obviously improve alloy matrix aluminum, thereby can further expands the Application Areas of aluminium alloy.

Bad phenomenon such as but because aluminium alloy has very strong oxytropism, the surface generates oxide film easily, and the existence of this layer oxide film causes between the nickel-phosphorus coating that generates and the matrix bonding force very poor, and peeling easily takes place sedimentary coating, come off.Therefore, have good bonding force in order to guarantee to deposit between coating and the alloy matrix aluminum, it is to guarantee that nickel-phosphorus chemical plating has one of committed step of good quality that aluminium alloy is carried out suitable pre-treatment (plating pre-treatment).

At present, pretreatment process is before the plating of aluminium alloy commonly used: produce intermediate layer in aluminum alloy surface earlier and (require this layer transition layer both and good bonding force arranged between the matrix, again and good binding intensity arranged between coating), and then carry out the chemical nickel phosphorus plating layer.These class methods are because the electrochemical behavior that overcome aluminium alloy to the disadvantageous effect that ni-p electroless plating caused, thereby is a successful method comparatively.At present in these class methods practical application get at most be that zincate soaks the zinc method.Zincate zinc dipping solution main component commonly used is: ZnO 120g/L, NaOH 500g/L, KNaC ₄H ₄O ₆15g/L, FeCl ₃1-2g/L.This treating processes generally comprises once soaks zinc and two consecutive steps of secondary soaking zinc, adopts sometimes even also and soaks zinc three times.Soak zinc for twice and adopt identical zinc dipping solution.Zinc-impregnating layer need be at HNO for the first time ₃: H ₂O=1: move back zinc in 1 the solution and handle,, just can carry out soaking the second time zinc then to guarantee that aluminum alloy surface does not have oxide film to exist fully when soaking zinc for the second time.Soak zinc and at room temperature carry out, galvanizing time is about 60～120s for the first time, and galvanizing time is about 30～60s for the second time.Can obtain the good nickel layer of bonding force through soaking for twice after zinc is handled, but this method also exists the following shortcoming, is mainly: (1) operating procedure complexity.Employing is soaked the pretreated technical process of zinc and is comprised that material polishing → alkali lye or acetone and other organic solvent oil removing → washing → soak first time zinc → washing → nitric acid moves back and soak zinc → washing → alkaline nickel preplating → washing → acid chemical plating nickel phosphorus → wash → dry up → detect zinc → washing → second time, amount to ten five processes, process is more loaded down with trivial details; (2) in a humid environment,, thereby soak the zinc middle layer and easily produce lateral encroaching,, easily cause the coating peeling to come off in case corrode because zinc is anode with respect to Ni-P coating; (3) zinc dipping solution is brought into as not cleaning up in the nickel plating solution, causes solution to pollute easily, thereby wastes raw material, and scrap rate increases; (4) soak for the second time and need to move back zinc with nitric acid before the zinc and handle, this easily pollutes production environment; (5) also there is the not firm situation of coating and matrix bond in some cases.This shows many weak points such as the pretreatment technology that soaks zinc exists solution composition complexity, cost height, technological process is loaded down with trivial details, the production cycle is long.At these problems that double zincate process exists, the investigator studies the pretreatment technology of aluminum alloy chemically plating both at home and abroad.Wang Airong adopts preplating Zn-Ni alloy layer, employing preplating Zn-Ni-Fe alloy layers such as Liu Bo wait and replace double zincate process, but prussiate and other additives such as minor N aCN have been added in this solution, solution composition is comparatively complicated, also there is bigger pollution in environment, human health is had very big harm, and operational danger is big.Patent of invention 02133822.1 is soaked nickel liquid before disclosing a kind of aluminium and Electroless Nickel Plating of Aluminum Alloy plating, and Electroless Nickel Plating of Aluminum Alloy technology has been simplified in this invention, but the contained component of pretreatment fluid reaches eight kinds more than, and composition is comparatively complicated, and obtain solution is loaded down with trivial details time-consuming, and cost is higher.Patent of invention 200510100994.5 has been reported the method for the chemical nickel plating on surface of aluminum alloy of a kind of Si of containing, Cu, Mg, though technology has been simplified in this invention, but process object only is applicable to the aluminium alloy that contains Si, Cu, Mg, use range is limited, and passivation also need be carried out in the surface behind the nickel plating phosphorus and oven dry is handled.

Three, summary of the invention

The purpose of this invention is to provide a kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy, adopt this solution that aluminum alloy surface is carried out pre-treatment before the electroless plating, can overcome many deficiencies of the prior art effectively.

For achieving the above object, the technical solution used in the present invention is: the composition of this preprocessing solution and content are: Sodium orthomolybdate 5-40g/L; Sodium hydroxide 5-30g/L or ammoniacal liquor 10-40ml/L; Deionized water is a surplus.

Adopt above-mentioned preprocessing solution that aluminium alloy is handled, nickel phosphorus depositing operation flow process is: preplating body material polishing → alkali lye or acetone and other organic solvent oil removing → washing → pretreatment fluid processing → washing → acid chemical plating nickel phosphorus → wash → dry up → detect.

Above-mentioned pretreatment fluid treating processes is: will put in the preprocessing solution through the preplating body material after polishing and the oil removal treatment and flood.

When adopting above-mentioned pretreatment fluid to handle, solution temperature is controlled at 15-40 ℃, and the treatment time is controlled at 15-180 second, and pH value of solution is controlled at 9.5-14.0.

The present invention adopts the mixed solution of Sodium orthomolybdate and sodium hydroxide or ammoniacal liquor that alloy matrix aluminum is carried out pre-treatment, directly puts into chemical nickel-plating liquid then and deposits, and is implemented in direct chemical plating nickel-phosphorus alloy layer on the alloy matrix aluminum.Compared with prior art, this invention has following advantage: 1. adopt preprocessing solution of the present invention that aluminium alloy is carried out pre-treatment, obviously simplified the numerous and diverse treating processes of double zincate process, make nickel phosphorus depositing operation reduce to nine present procedures by ten original five processes, not only save manpower, but also saved electric energy and water resources; 2. preprocessing solution of the present invention only is made up of two kinds of materials, has reduced the cost that soaks the zinc pretreatment technology, can obtain higher economic benefit.3. adopt preprocessing solution of the present invention, do not need to handle, need not to adopt nitric acid to move back zinc and handle through soaking zinc, avoided chemical nickel-plating solution is polluted and poisons, prolonged the work-ing life of plating bath, avoided environmental pollution, reduced healthy effect operator.4. adopt preprocessing solution of the present invention to carry out plating, simplified the schedule of operation of electroless plating, realize industrialization easily, production efficiency is improved, and simultaneously, wastewater treatment also than being easier to, makes technical process environmental protection more.5. adopt preprocessing solution of the present invention to carry out plating, the nickel-phosphorus chemical plating even compact of preparation, solidity to corrosion is good, microhardness is high, combine firmly with alloy matrix aluminum, has good metal gloss and outward appearance, for aluminium alloy provides the favorable protection effect.

Four, embodiment

Embodiment 1: experiment material (preplating matrix) is 2024 aluminium alloys.

1, polishing: 2024 aluminum alloy specimens are polished through 60#, 200#, 400#, 800# water-proof abrasive paper, to surface-brightening;

2, degreasing: in stink cupboard above-mentioned experiment material is carried out wiping with the cotton ball that dips in acetone, service temperature is a room temperature, and the time is about 30 seconds, to remove the pollutents such as greasy dirt on surface;

3, washing: the experiment material surface after adopting deionized water to degreasing is washed, and service temperature is a room temperature, and the time is 40 seconds;

4, pretreatment fluid is handled: will drop into following solution impregnation 45 seconds through the experiment material that the last step handles, solution temperature is 30 ℃, pH value of solution=13-14.Solution composition is: Sodium orthomolybdate 20g/L, sodium hydroxide 10g/L, deionized water are surplus.

5, washing: adopt the experiment material surface after the deionized water rinsing preprocessing solution is handled, service temperature is a room temperature, and the time is 90 seconds;

6, chemical nickel plating: pretreated 2024 aluminium alloys of above-mentioned process are put into following plating bath carry out electroless plating, obtain final nickel-phosphorus coating.Plating bath consists of: single nickel salt 25g/L, and inferior sodium phosphate 25g/L, Trisodium Citrate 12g/L, sodium acetate 20g/L, deionized water are surplus, and plating temperature is 85 ± 2 ℃, and the pH value of solution value is 5-6, and depositing time is 1-2 hour;

7, washing: will take out from plating bath with the aluminium alloy of nickel-phosphorus coating, use deionized water rinsing then, service temperature is a room temperature, and the time is 45-60 second;

8, dry up: the aluminium alloy that dries up existing coating with hair dryer;

9, detect: the nickel-phosphorus chemical plating that 2024 aluminum alloy surface obtain has metalluster, coating deposition rate is about 17.56um/h, coating is made up of born of the same parents' shape thing, and be distributed on the alloy matrix aluminum even compact, defectives such as no bubble exist, coating combines firmly with 2024 alloy matrix aluminums, does not have bad phenomenon such as peeling, local shedding.

Embodiment 2: experiment material (preplating matrix) is the LC4 aluminium alloy.

1, polishing: the LC4 aluminum alloy specimen is polished through 60#, 200#, 400#, 800# water-proof abrasive paper, to surface-brightening;

2, degreasing: in stink cupboard the LC4 aluminium alloy after polishing is carried out wiping with the cotton ball that dips in acetone, service temperature is a room temperature, and the time is about 30 seconds, to remove the pollutents such as greasy dirt on surface;

4, pretreatment fluid is handled: will drop into following solution impregnation 45-60 second through the LC4 aluminium alloy that the last step handles, solution temperature is 25 ℃, pH value of solution=13-14.Solution composition is: Sodium orthomolybdate 30g/L, sodium hydroxide 15g/L, deionized water are surplus.

5, washing: adopt the LC4 aluminum alloy surface after the deionized water rinsing preprocessing solution is handled, service temperature is a room temperature, and the time is 90 seconds;

6, chemical nickel plating: the pretreated LC4 aluminium alloy of above-mentioned process is put into following plating bath carry out electroless plating, obtain final nickel-phosphorus coating.Plating bath consists of: single nickel salt 25g/L, and inferior sodium phosphate 25g/L, Trisodium Citrate 12g/L, sodium acetate 20g/L, deionized water are surplus, and plating temperature is 85 ± 2 ℃, and the pH value of solution value is 5-6, and depositing time is 1-2 hour;

8, dry up: the aluminium alloy that dries up existing coating with hair dryer;

9, detect: the nickel-phosphorus chemical plating that the LC4 aluminum alloy surface obtains has metalluster, coating deposition rate is about 20.09um/h, coating is made up of born of the same parents' shape thing, and be distributed on the alloy matrix aluminum even compact, defectives such as no bubble exist, coating combines firmly with the LC4 alloy matrix aluminum, does not have bad phenomenon such as peeling, local shedding.

Embodiment 3: experiment material (preplating matrix) is 2024 aluminium alloys.

2, degreasing: in stink cupboard above-mentioned 2024 aluminium alloys are carried out wiping with the cotton ball that dips in acetone, service temperature is a room temperature, and the time is about 30 seconds, to remove the pollutents such as greasy dirt on surface;

3, washing: 2024 aluminium alloy experiment material surfaces after adopting deionized water to degreasing are washed, and service temperature is a room temperature, and the time is 40 seconds;

4, pretreatment fluid is handled: will drop into following solution impregnation 120-150 second through 2024 aluminium alloys that the last step handles, solution temperature is 30 ℃, pH value of solution=11-12.Solution composition is: Sodium orthomolybdate 10g/L, ammoniacal liquor 15ml/L, deionized water are surplus.

5, washing: adopt 2024 aluminum alloy surface after the deionized water rinsing preprocessing solution is handled, service temperature is a room temperature, and the time is 90 seconds;

8, dry up: 2024 aluminium alloys that dry up existing coating with hair dryer;

9, detect: the nickel-phosphorus chemical plating that 2024 aluminum alloy surface obtain has metalluster, coating deposition rate is about 17.68um/h, coating is made up of born of the same parents' shape thing, and be distributed on the alloy matrix aluminum even compact, defectives such as no bubble exist, coating combines firmly with 2024 alloy matrix aluminums, does not have bad phenomenon such as peeling, local shedding.

Embodiment 4: experiment material (preplating matrix) is the LC4 aluminium alloy.

2, degreasing: in stink cupboard above-mentioned LC4 aluminium alloy is carried out wiping with the cotton ball that dips in acetone, service temperature is a room temperature, and the time is about 30 seconds, to remove the pollutents such as greasy dirt on surface;

3, washing: the specimen surface after adopting deionized water to degreasing is washed, and service temperature is a room temperature, and the time is 45 seconds;

4, pretreatment fluid is handled: will drop into following solution impregnation 120 seconds through the raw material that the last step handles, solution temperature is 30 ℃, pH value of solution=11-12.Solution composition is: Sodium orthomolybdate 10g/L, ammoniacal liquor 20ml/L, deionized water are surplus.

7, washing: will take out from plating bath with the LC4 aluminium alloy of nickel-phosphorus coating, use deionized water rinsing then, service temperature is a room temperature, and the time is 45-60 second;

8, dry up: the aluminium alloy stock that dries up existing coating with hair dryer;

9, detect: the nickel-phosphorus chemical plating that the LC4 aluminum alloy surface obtains has metalluster, coating deposition rate is about 18.90um/h, coating is made up of born of the same parents' shape thing, be distributed on the alloy matrix aluminum nickel phosphorus even compact, defectives such as no bubble exist, coating combines firmly with the LC4 alloy matrix aluminum, does not have bad phenomenon such as peeling, local shedding.

Claims

1, a kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy, it is characterized in that: the composition of this preprocessing solution and content are: Sodium orthomolybdate 5-40g/L; Sodium hydroxide 5-30g/L or ammoniacal liquor 10-40ml/L; Deionized water is a surplus.

2, according to the described a kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy of claim 1, it is characterized in that: adopt above-mentioned preprocessing solution that aluminium alloy is carried out pre-treatment, the sedimentary technological process of nickel phosphorus is: preplating body material polishing → alkali lye or acetone oil removing → washing → pretreatment fluid processing → washing → acid chemical plating nickel phosphorus → wash → dry up → detect.

3, according to the described a kind of preprocessing solution that is used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy of claim 2, it is characterized in that: described pretreatment fluid treating processes is: will drop in the preprocessing solution through the preplating body material of polishing and the processing of oil removing operation and flood.

4, according to claim 2 or 3 described a kind of preprocessing solutions that are used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy, it is characterized in that: when adopting above-mentioned pretreatment fluid to handle, solution temperature is controlled at 15-40 ℃, and the treatment time is controlled at 15-180 second, and pH value of solution is controlled at 9.5-14.0.