CN102011115B - Pretreatment liquid and pretreatment method before rare earth conversion - Google Patents
Pretreatment liquid and pretreatment method before rare earth conversion Download PDFInfo
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- CN102011115B CN102011115B CN 201010291204 CN201010291204A CN102011115B CN 102011115 B CN102011115 B CN 102011115B CN 201010291204 CN201010291204 CN 201010291204 CN 201010291204 A CN201010291204 A CN 201010291204A CN 102011115 B CN102011115 B CN 102011115B
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Abstract
The invention discloses pretreatment liquid and a pretreatment method before rare earth conversion. The pretreatment liquid consists of acid, a buffering agent, a complexing agent, a surfactant and a surface adsorbent. The pretreatment method comprises the following steps of: immersing an aluminum alloy in the pretreatment liquid, impregnating for 1 to 5 minutes, taking out and washing by using running water; and immersing in alkaline solution for 2 to 60 seconds, taking out and washing by using the running water. Uniform and dense cathode spots can be generated on the surface of the aluminum alloy after the treatment of the method, and good film forming conditions can be provided for the generation of a subsequent rare earth conversion coating. In the pretreatment method, the pretreatment liquid does not need to be heated in the treatment process, and the defects of non-uniform film formation and high aluminum loss in the traditional strong alkali pretreatment can be well overcome. The method is simple, and easy and convenient to operate, and low in cost, and industrialization is easy to realize.
Description
Technical field
The present invention relates to a kind of metallic surface pre-treating process, be specifically related to a kind of rare earth conversion processing preceding pretreatment fluid and pretreatment process of being used for.Use present method to the aluminum alloy surface pre-treatment after, when aluminum alloy surface is carried out the rare earth chemistry conversion processing, can obtain even, the fine and close golden yellow rare earth oxide coating of composition again in aluminum alloy surface, improve the corrosion resistance of rare-earth conversion coatings.
Background technology
Duraluminum is because its activity is bigger, and corrosion need be carried out anti-corrosive treatment to the surface easily.Method commonly used is to generate the method that sprays again behind complete, fine and close, the uniform passivation layer of one deck in aluminum alloy surface.Traditional chromating is a kind of the most frequently used passivating method, but because Cr
6+Poisonous, its application is restricted.The passivation treatment technology of exploitation Chrome-free is extremely urgent, and wherein rare earth chemistry conversion film technology is considered to one of technology that most possibly substitutes chromating.
But metallic surface has a lot of pollutents to stop or disturb the conversion reaction of metallic surface in a different manner, stops conversion fluid to contact with the metallic surface like residual organic pollutant, and wherein inorganic pollutant will destroy the integrity of conversion film; The MOX of aluminum alloy surface or stain impurity will become the place that the galvanic corrosion effect takes place under the following organic coating, and the product that film bottom corrosive result will cause metal finishing to be crossed is failed in early days; The rare earth conversion processing is a cathodic reaction deposition process, and whether successful can cleaning process obtain fine and closely woven equally distributed negative electrode point (position) in aluminum alloy surface is follow-up conversion film key.Therefore, the aluminum alloy surface pre-treatment is one of most important factor of successful development cerium base chemical conversion film.
The research and development of the substitute technology of chromate conversion treatments receive extensive concern, many generations the chromium technology occur in succession, like phosphatization, zinc phosphatization, based on the complex compound treatment process (CARBDOBOND) of titanium zirconium and fluorine, Envirox series of processes technology etc.Application number is that serial Chinese invention patent applications such as 200410021031,200480031392,200510100993.0,20058002127,200610046292,200610046516,200680002318 all relate to these technology.In numerous chromium-free deactivation technology, the rare-earth conversion coatings technology is considered to be expected to most one of technology that replaces chromating.Application number is that 200810027556 and 200710030893 Chinese patent discloses a kind of rare-earth salts and strong oxidizer is the chemical conversion treatment solution of main ingredient.
In the chemical conversion treatment process of duraluminum, the surface preparation before the chemical conversion has material impact to chemical membrane process and film performance.Pre-treatment before the chemical conversion not only can be removed the aluminium oxide on surface, grease etc., and also the element that can change aluminum alloy surface distributes, and makes the fully exposure of negative electrode point in the chemical conversion film process, thereby is accelerated into membrane process, raises the efficiency.But above-mentioned relevant Chrome-free chemical conversion patent does not all relate to the technical problem of the surface preparation aspect before the conversion processing.
It should be noted that alkali washing process is modal method in the pretreatment technology before aluminum alloy chemically transforms.The general industry statistic data shows, in the duraluminum alkalescence grease removal process loss of aluminium bigger, as handle 1 ton of aluminium, utilizing alkaline grease removal to handle the loss of back aluminium can be up to more than 40 kilogram.Comparatively speaking, 1 ton of its loss of aluminium of every processing has only several kilograms during acid skimming treatment.
Weak point for fear of prior art; The present invention proposes pretreatment fluid and pretreatment process before a kind of rare earth conversion processing, promptly utilize alkali cleaning activation again after the pickling grease removal, can reduce the loss of aluminium on the one hand; Utilize the alkali cleaning activation that the aluminum alloy surface alloy element is evenly distributed simultaneously; It is evenly fine and close more that aluminum alloy surface negative electrode point is distributed, and can quicken the film forming speed of chemical conversion film, and the conversion film of generation is even, fine and close and smooth.
Summary of the invention
The objective of the invention is to overcome the shortcoming of prior art, a kind of rare earth conversion processing preceding pretreatment fluid and pretreatment process of being used for is provided, the present invention can be used as the pre-treating process that improves aluminum alloy surface chemical passivation film erosion resistance.It is low both can to have solved present chromium-free treating liquid film forming efficiency, can obtain even film layer, densification, solidity to corrosion is strong, sticking power is good golden yellow composite passivation film again.
The present invention can realize above-mentioned purpose through following technical scheme:
Be used for the preceding pretreatment fluid of rare earth conversion processing, consist of acid, buffer reagent, complexing agent, tensio-active agent and surface adsorption agent, each components contents is following:
Buffer reagent 20～100g/L
Complexing agent 1～10g/L
Tensio-active agent 1～3.0g/L
Surface adsorption agent 0.1～1g/L
Said acid is one or more the mixture in sulfuric acid, phosphoric acid or the nitric acid;
Said buffer reagent is one or more the mixture in phosphoric acid, sodium phosphate, sodium hydrogen phosphate or the SODIUM PHOSPHATE, MONOBASIC;
Said complexing agent is one or more the mixture in hydrogen fluoride, Sodium Fluoride or the Neutral ammonium fluoride;
Said tensio-active agent is one or more the mixture in sim alkylphenol Soxylat A 25-7, AEO or the polyoxyethylene carboxylate;
Said surface adsorption agent is one or both the mixture in thiocarbamide or the urea.
Use the pretreatment process of described pretreatment fluid, may further comprise the steps:
(1) aluminum alloy surface is polished to 1000# through water-proof abrasive paper step by step;
(2) duraluminum was immersed in the described pretreatment fluid of claim 1 after 1～5 minute, clean, dry;
(3) the air dried duraluminum is immersed in the alkaline solution, behind 2～60s, clean, dry.
Said alkaline solution is the solution of one or both compositions in sodium hydroxide or the yellow soda ash, and concentration is 1～30g/L.。
The present invention is with respect to advantage and beneficial effect that prior art had.
(1) improved film forming speed, traditional highly basic is handled back rare-earth conversion coatings film forming needs 15min, use pre-treatment of the present invention after the rare-earth conversion coatings film forming only need 5min, improved film forming efficiency, reach the requirement of industrialized production.
(2) improved the corrosion resistance nature of rete, the corrosion electric current density that traditional highly basic is handled the back rare-earth conversion coatings is 0.7411 μ A/cm
2, the corrosion electric current density of rare-earth conversion coatings is 0.1015 μ A/cm after the pre-treatment of the present invention
2～0.425 μ A/cm
2Better improved the corrosion resistance of rare-earth conversion coatings.
(3) traditional highly basic processing need at high temperature be carried out, and the present invention can carry out at normal temperatures, has reached energy-conservation to purpose.
(4) compare with traditional pretreatment process, the disclosed preconditioning technique of the present invention can reduce the loss of aluminium in the treating processes.The every 1000g of loss that traditional highly basic is handled aluminium reaches 62g, and the every 1000g of the loss of aluminium has only 4.2g～6.3g among the present invention.
Description of drawings
The SEM of aluminum alloy surface figure after Fig. 1 embodiment 1 alkali cleaning;
The EDS of aluminum alloy surface figure after Fig. 2 a embodiment 1 alkali cleaning;
The EDS of aluminum alloy surface figure after Fig. 2 b embodiment 1 alkali cleaning;
The EDS of aluminum alloy surface figure after Fig. 2 c embodiment 1 alkali cleaning;
The face scintigram of aluminum alloy surface after Fig. 3 a embodiment 1 alkali cleaning;
The face scintigram of aluminum alloy surface after Fig. 3 b embodiment 1 alkali cleaning;
The face scintigram of aluminum alloy surface after Fig. 3 c embodiment 1 alkali cleaning;
The face scintigram of aluminum alloy surface after Fig. 3 d embodiment 1 alkali cleaning;
Surface topography map after Fig. 4 embodiment 1 film forming;
Electrokinetic potential polarization curve after Fig. 5 embodiment 1 film forming;
The electrokinetic potential polarization curve of the naked aluminium of Fig. 6;
The SEM figure of aluminum alloy surface after Fig. 7 embodiment 2 mixing pickling;
The EDS figure of aluminum alloy surface after Fig. 8 a embodiment 2 mixing pickling;
The EDS figure of aluminum alloy surface after Fig. 8 b embodiment 2 mixing pickling;
The face scintigram of aluminum alloy surface after Fig. 9 a embodiment 2 alkali cleanings;
The face scintigram of aluminum alloy surface after Fig. 9 b embodiment 2 alkali cleanings;
The face scintigram of aluminum alloy surface after Fig. 9 c embodiment 2 alkali cleanings;
The face scintigram of aluminum alloy surface after Fig. 9 d embodiment 2 alkali cleanings;
Surface topography map after Figure 10 embodiment 2 film forming;
Electrokinetic potential polarization curve after Figure 11 embodiment 2 film forming;
Electrokinetic potential polarization curve after Figure 12 embodiment 3 film forming;
Electrokinetic potential polarization curve after Figure 13 embodiment 4 film forming.
Embodiment
In order to understand technical characterstic of the present invention better, the present invention is further described below in conjunction with embodiment.Embodiment 1: duraluminum tradition alkali cleaning method comprises the steps:
(a) polishing: cutting volume is 60cm * 6cm * 1cm, and the sample of quality 1000g is polished to 1000# with 180#, 400#, 650# and 1000# water-proof abrasive paper step by step;
(b) degreasing: configuration removes oil solution, and concentration is Na
2CO
3: 40g/L, Na
3PO
4: 40g/L, Na
2SiO
3: 15g/L is immersed in sample 70 ℃ the 5min in the oil solution that removes;
(c) caustic corrosion: NaOH (8g/l), N
A3PO
412H
2O (12g/L), Na
2CO
3(8g/L) solution leaves standstill 2min in 70 ℃;
(d) bright dipping: bright dipping solution is that concentration is the HNO of 20% (volume(tric)fraction)
3, sample is flooded 60s in light-emitting solution;
(e) activation: activation solution is that concentration is the NaOH of 5% (weight fraction), and sample is flooded 3s in activation solution;
After above-mentioned pretreatment technology is handled, weigh, the quality of aluminum alloy specimen is 938g, loss duraluminum 62g in the preprocessing process.
Take out test piece, and will be immersed in thereafter in the rare earth conversion treating solution, the prescription of rare earth conversion treating solution is: 50g/LCe (NO
3)
3, 4g/L KMnO
4, 2g/L NaHF
2, 1g/L NH
4Cl.Through observing, the treatment time needs 15min.
The aluminum alloy surface SEM pattern that obtains as shown in Figure 1, to ultimate analysis such as Fig. 2 a of character zone among the figure, shown in Fig. 2 b and Fig. 2 c.Simultaneously face scanning is carried out on surface after the alkali cleaning, analyzed Si, Fe, Cu and Zn, like Fig. 3 a, Fig. 3 b is shown in Fig. 3 c and Fig. 3 d.After the chemical conversion film forming was handled, the apparent pattern of rete was as shown in Figure 4, and it is as shown in Figure 5 to measure corrosion electric current density with the electrokinetic potential polarization curve then.
Can find out that from SEM figure the alkali cleaning scheme is handled the surface, back and had white point and white circle evil mind shape.Use EDS and analyze discovery, white bright spot (a point among Fig. 1) principal element that 6063 aluminum alloy surface exist is Al, Fe and Si, considers the composition of 6063 duraluminums can infer it is Si, β-AlFeSi and FeAl
3Phase.β-AlFeSi and FeAl appear in the surface
3With the corrosive medium in the preprocessing process, treatment temp is relevant with the time of washing, because free Si, Al-Fe-Si and FeAl
3In the poorness district that often occurs the ferrosilicon element near the crystal boundary of intermetallic compound, this poor district is close to and is fine aluminium, and current potential is more negative, is anode, and (Si, β-AlFeSi and FeAl dissociate for it and intermetallic compound
3Be negative electrode) constitute microbattery, under the effect of corrosive medium, aluminium (the being the anode phase) optimum solvation in the Si in the microbattery around the negative electrode phase, the poor district of Fe, the dissolving of Al has on every side exposed the negative electrode phase (like free Si, Al-Fe-Si, FeAl
3), when etching condition continue to worsen (rise like temperature, long between alkali cleaning etc.), matrix Al continues dissolving, and the negative electrode of exposure is just more mutually.
Simultaneously, 6063 duraluminums are that Al-Mg-Si is an alloy, contain a large amount of Mg
2The Si phase, Mg in duraluminum
2Si is the anode phase, Mg when corrosion
2Si also dissolves, and forms corrosion pit (c point among Fig. 1).Along with corrosion pit constantly develops, form scraggly surface in aluminum alloy surface at last.According to corrosion scientific principle opinion, the anode aluminium around the negative electrode particle, the Al of generation
3+To the negative electrode diffusion, and the OH in the solution
-The anode diffusion, finally the interphase precipitate in anode and cathode goes out the cotton-shaped Al (OH) of white
3(b point among Fig. 1) forms the phenomenon of white snare evil mind.
Fig. 3 a, Fig. 3 b, Fig. 3 c and Fig. 3 d are the face scintigrams of aluminum alloy surface after embodiment 1 alkali cleaning; From Fig. 3 a, Fig. 3 b, Fig. 3 c and Fig. 3 d can find out the distribution of Fig. 1 interalloy elements Si, Fe, Cu and Zn.From Fig. 3 a, Fig. 3 b, Fig. 3 c and Fig. 3 d can see that the white point that Si and Fe have appearred in the surface is relative enrichment region, and as the negative electrode point, the negative electrode point of the relative rich region of Si and Fe is intensive in film process for the compound of Si and Fe, cathodic reaction (O
2+ 4e+2H
2O → 4OH
-) will be too fierce, the film compactness of generation is poor, causes corrosion resistance nature to reduce at last.
When carrying out pre-treatment according to the traditional alkali cleaning method of duraluminum among the embodiment 1 simultaneously, the Zn of solid solution dissolves (Zn+4OH with the dissolving of aluminium in the duraluminum
-→ ZnO
2 2-+ 2H
2O), generate ZnO
2 2-Ion.Because zinc element electropotential in alkaline solution is-1.216V, and aluminium element is-2.350V, aluminium can come out zinc from the solution displace, makes zinc that deposition (Al+2ZnO again take place
2 2-+ 2H
2O → 2Zn+AlO
2 2-+ 4OH
-).For obtaining electronics, zine ion must be to the intensive cathodic zone migration of electronics, and at the cathodic area deposition, forms the rich region of zinc at last.The rich region that similar reaction forms copper also takes place in copper.The zinc that pre-treatment generates during film formation reaction, the rich region of copper are also participated in film formation reaction as negative electrode point, since the regional enrichment of zinc and copper, cathodic reaction (2H
++ 2e → H
2) very fierce, forming aperture during film forming, the film compactness of generation is poor, causes corrosion resistance nature to reduce at last.
The apparent pattern homogeneity and the compactness of rete is poor after the film forming, and corrosion electric current density is 0.7411 μ A/cm
2, as shown in Figure 5.Also measured the corrosion electric current density of undressed duraluminum in the present embodiment, corrosion electric current density is 5.248 μ A/cm
2, as shown in Figure 6.The corrosion electric current density of embodiment 1 gained rete drops to 1/7 of naked aluminium.The more naked aluminium of its corrosion resistance nature of chemical conversion film that is gained has improved 7 times.Embodiment 2: duraluminum mixing pickling+alkali pre-activated treatment process.
The pretreatment fluid preparation:
Pretreatment fluid before the first step preparation 1000mL rare earth conversion processing; Wherein middle nitric acid 250mL/L, phosphoric acid 60g/L, sim alkylphenol Soxylat A 25-7 2g/L, hydrogen fluoride 5g/L, thiocarbamide 0.5g/L; All the other are water; Nitric acid 250mL, phosphoric acid 60g, sim alkylphenol Soxylat A 25-7 2g, hydrogen fluoride 5g and thiocarbamide 0.5g is water-soluble, stirring and dissolving, adding water to the treatment solution volume is 1000mL.
The sodium hydroxide solution 1000mL of second step preparation 10g/L.
Pretreatment process of the present invention comprises the steps:
(1) cutting volume is 60cm * 6cm * 1cm, and the sample of quality 1000g is polished to 1000# with 180#, 400#, 650# and 1000# water-proof abrasive paper step by step;
(2) immerse in the pretreatment fluid before the rare earth conversion processing 3 minutes; Washing is dried;
(3) the air dried duraluminum is immersed in the alkaline solution 30 seconds; Washing is dried.
After above-mentioned pretreatment technology is handled, weigh, the quality of aluminum alloy specimen is 993.7g, loss duraluminum 6.3g in the preprocessing process.
Take out test piece, and will be immersed in thereafter in the rare earth conversion treating solution, the prescription of rare earth conversion treating solution is: 50g/LCe (NO
3)
3, 4g/L KMnO
4, 2g/L NaHF
2With 1g/L NH
4Cl.Through observing, the treatment time only needs 5min to generate complete conversion film in aluminum alloy surface.
The SEM pattern is as shown in Figure 7 through above-mentioned pretreatment process aluminium alloy treated surface, to the ultimate analysis of character zone among the figure like Fig. 8 a with shown in Fig. 8 b.Simultaneously face scanning is carried out on surface after the alkali cleaning, analyzed Si, Fe, Cu and Zn, like Fig. 9 a, Fig. 9 b is shown in Fig. 9 c and Fig. 9 d.The apparent pattern of the rare-earth conversion coatings layer that generates is shown in figure 10, and it is shown in figure 11 to measure corrosion electric current density with the electrokinetic potential polarization curve then.
Fig. 7 is the aluminum alloy surface SEM figure that after pretreatment process of the present invention is handled, obtains.From SEM figure, can see that aluminum alloy surface is smooth, not observe the enrichment point, the indistinct circle evil mind shape in vain that occurs, corrosion pit is less.Use power spectrum and micro-zone analysis is carried out on the surface found that white bright area mainly is white lake (an a point among Fig. 7) among the figure, residual in the corrosion pit (b point among Fig. 7) mainly is Mg, Si and Al (OH)
3
Face scanning (Fig. 9 a, Fig. 9 b, Fig. 9 c and Fig. 9 d) shows, the aluminum alloy surface that after pretreatment process of the present invention is handled, obtains, and Fe and Si are evenly distributed, and rich region do not occur, and the content of copper and zinc is seldom.This mainly is to adopt mixing acid in the soda acid two groove pre-treatment schemes, and the effect of nitric acid is dissolved oxygen film and greasy dirt, simultaneously as metals such as oxygenant dissolving Cu, Fe and Zn.Buffer solvent and emulsifying agent play pH value and the saponification of keeping solution, strengthen soil removability.Tensio-active agent improves the wettability of solution.Complexing agent is as part and the sour copper that dissolves, and zinc and iron ion coordination form coordination compound, and avoiding aluminium is that atom is attached to aluminum alloy surface with Cu, Fe and Zn ion exchange.Inhibiter is not adsorbed in metal oxide surface, but preferentially adsorbed is in base metal surface, has hindered the excessive erosion and the generation that prevented Cu, Fe and Zn ion from dissolving resedimentation of acid to metal like this.
According to film forming liquid among the embodiment 1, the apparent pattern homogeneity and the compactness of rete is good after the film forming, and corrosion electric current density reaches 0.1015 μ A/cm
2, shown in figure 11, be respectively 1/50 of naked aluminium, 1/7 of embodiment 1.Embodiment 2 corrosion resistances are superior to naked aluminium and embodiment 1.
For further understanding process characteristic of the present invention, below aluminium alloy rare-earth conversion coatings film forming mechanism is described below:
According to cathode filming mechanism, because aluminum alloy surface exists different potentials to reach impurity atoms mutually, cause forming countless galvanic cells and electrochemical reaction taking place at surperficial microcell: dissolving metal: M-2e takes place in the micro anode district
-→ M
E+(M represents the metallic element in the duraluminum), H takes place in the micro cathode district
2Separate out: 2H
++ 2e
-→ H
2Or O
2Reduction: O
2+ 2H
2O+4e → 4OH
-Thereby, OH-ionic concn in micro cathode district is increased, the pH value raises, and is Ce (OH)
3Or Ce (OH)
4Deposition create favorable conditions, thereby the favourable membrane process that is accelerated into makes its film forming speed improve more than 1 times.
Whether successful can cleaning process obtain fine and closely woven equally distributed negative electrode point (position) in aluminum alloy surface is follow-up conversion film key.Therefore the focal point that cleans the pre-treatment process should be placed on how to obtain duraluminum just on the equally distributed negative electrode point of face.The present invention is just for after solving pre-treatment, and aluminum alloy surface negative electrode point distribution problem can be in thick being evenly distributed and fine and close negative electrode point of aluminum alloy surface through the present invention.Therefore the anticorrosion effect of embodiment 2 is better than embodiment 1.
Embodiment 3: duraluminum mixing pickling+alkali pre-activated treatment process.
The pretreatment fluid preparation:
Pretreatment fluid before the first step preparation 1000mL rare earth conversion processing, wherein phosphatase 11 0mL/L, SODIUM PHOSPHATE, MONOBASIC 20g/L, AEO 1g/L, hydrogen fluoride 1g/L, thiocarbamide 0.1g/L, all the other are water.Phosphatase 11 0mL, SODIUM PHOSPHATE, MONOBASIC 20g, AEO 1g, hydrogen fluoride 1g and thiocarbamide 0.1g is water-soluble, and stirring and dissolving adds water to 1000mL.
The sodium hydroxide 1000mL of second step preparation 10g/L.
Pretreatment process comprises the steps:
(1) cutting volume is 60cm * 6cm * 1cm, and the sample of quality 1000g is mechanical grinding to 1000#;
(2) immerse in the pretreatment fluid before the rare earth conversion processing 1 minute; Washing is dried;
(3) the air dried duraluminum was immersed in the alkaline solution 2 seconds; Washing is dried.
After above-mentioned pretreatment technology is handled, weigh, the quality of aluminum alloy specimen is 995.8g, loss duraluminum 4.2g in the preprocessing process.
Take out test piece, and will be immersed in thereafter in the rare earth conversion treating solution, the prescription of rare earth conversion treating solution is: 50g/LCe (NO
3)
3, 4g/L KMnO
4, 2g/L NaHF
2, 1g/L NH
4Cl.Through observing, the treatment time only needs 5min to generate complete conversion film in aluminum alloy surface.Film forming post-etching current density reaches 0.1998 μ A/cm
2, shown in figure 12, be respectively 1/26 of naked aluminium, 1/4 of embodiment 1.Embodiment 3 corrosion resistances are superior to naked aluminium and embodiment 1.
Embodiment 4: duraluminum mixing pickling+alkali pre-activated treatment process.
The pretreatment fluid preparation:
Pretreatment fluid before the first step preparation 1000mL rare earth conversion processing, wherein middle sulfuric acid 500mL/L, sodium phosphate 100g/L, polyoxyethylene carboxylate 3g/L, Sodium Fluoride 10g/L, urea 1g/L, all the other are water.Sulfuric acid 500mL, sodium phosphate 100g, polyoxyethylene carboxylate 3g, Sodium Fluoride 10g and urea 1g is water-soluble, and stirring and dissolving adds water to 1000mL.
The sodium hydroxide 1000mL of second step preparation 30g/L.Pretreatment process before the rare earth conversion processing comprises the steps:
(1) cutting volume is 60cm * 6cm * 1cm, and the sample of quality 1000g is mechanical grinding to 1000#;
(2) immerse in the pretreatment fluid before the rare earth conversion processing 5 minutes; Washing is dried;
(3) immerse in the alkaline solution 60 seconds; Washing is dried.
After above-mentioned pretreatment technology is handled, weigh, the quality of aluminum alloy specimen is 994.2g, loss duraluminum 5.8g in the preprocessing process.
Take out test piece, and will be immersed in thereafter in the rare earth conversion treating solution, the prescription of rare earth conversion treating solution is: 50g/LCe (NO
3)
3, 4g/L KMnO
4, 2g/L NaHF
2, 1g/L NH
4Cl.Through observing, the treatment time only needs 5min to generate complete conversion film in aluminum alloy surface.Film forming post-etching current density reaches 0.4251 μ A/cm
2, shown in figure 13, be respectively 1/12 of naked aluminium, 1/2 of embodiment 1.Embodiment 4 corrosion resistances are superior to naked aluminium and embodiment 1.
Claims (3)
1. be used for the preceding pretreatment fluid of rare earth conversion processing, it is characterized in that consist of acid, buffer reagent, complexing agent, tensio-active agent and surface adsorption agent, each components contents is following:
Said acid is one or more the mixture in sulfuric acid, phosphoric acid or the nitric acid;
Said buffer reagent is one or more the mixture in phosphoric acid, sodium phosphate, sodium hydrogen phosphate or the SODIUM PHOSPHATE, MONOBASIC;
Said complexing agent is one or more the mixture in hydrogen fluoride, Sodium Fluoride or the Neutral ammonium fluoride;
Said tensio-active agent is one or more the mixture in sim alkylphenol Soxylat A 25-7, AEO or the polyoxyethylene carboxylate;
Said surface adsorption agent is one or both in thiocarbamide or the urea;
Said pretreatment fluid is to be applied to the aluminum alloy surface pre-treatment.
2. application rights requires the pretreatment process of 1 described pretreatment fluid, it is characterized in that, may further comprise the steps:
(1) aluminum alloy surface is polished to 1000# through water-proof abrasive paper step by step;
(2) duraluminum was immersed in the described pretreatment fluid of claim 1 after 1～5 minute, clean, dry;
(3) the air dried duraluminum is immersed in the alkaline solution, behind 2～60s, clean, dry.
3. pretreatment process according to claim 2 is characterized in that, said alkaline solution is the solution of one or both compositions in sodium hydroxide or the yellow soda ash, and concentration is 1～30g/L.
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| CN104514000B (en) * | 2013-09-30 | 2016-09-28 | 苏州博洋化学股份有限公司 | A kind of preparation method of aluminum alloy surface treatment fluid |
| CN104388916A (en) * | 2014-10-30 | 2015-03-04 | 青岛昌安达药业有限公司 | Metal product phosphating liquid |
| CN104894546B (en) * | 2015-05-20 | 2017-09-29 | 广东坚美铝型材厂（集团）有限公司 | A kind of pretreatment fluid and its application method for being used to prepare conversion film in aluminum alloy surface |
| CN104928670B (en) * | 2015-05-20 | 2018-05-29 | 广东坚美铝型材厂（集团）有限公司 | A kind of method for preparing conversion film in aluminum alloy surface |
| CN107034471B (en) * | 2017-06-16 | 2019-01-01 | 哈尔滨哈船新材料科技有限公司 | A kind of photochemical treatment fluid of aluminum or aluminum alloy surface preparation and the method for chemical cleaning |
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|---|---|---|---|---|
| US5194138A (en) * | 1990-07-20 | 1993-03-16 | The University Of Southern California | Method for creating a corrosion-resistant aluminum surface |
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| 吴建锋.镁合金耐蚀性稀土转化膜的制备与室温快速沉积机制研究.《广东工业大学硕士学位论文》.2009, * |
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