The antirusting treating method of steel product
Technical field
The present invention relates to the antirusting treating method of metallic article, refer more particularly to the antirusting treating method of steel product.
Background technology
Steel pipe is as the steel product, and it is widely used in every field such as structural members such as automobile, train, aircraft, steamer and space gun, component of machine, petrochemical complex, geological drilling, textile manufacturing machine, radio communication, health care, military project.Part with steel pipe is made can improve material use efficiency, simplified manufacturing technique, economical with materials and machining period.The steel pipe of China experienced grow out of nothing, from few to many, from simple to the evolution of complicacy; Especially steel pipe is as important component parts such as mechanical parts; Its total demand constantly rises with rapid development of social economy, and technical requirements improves constantly and is tending towards strict.Because many steel pipes field of using requires oxidative phenomena can not take place to steel pipe, steel tube surface must not have rusty stain, therefore, need take antirust surface treatment method to steel pipe, makes steel pipe satisfy request for utilization in links such as follow-up production, processing.
Traditional steel pipe antirusting treating method is: employing can make steel tube surface be passive anodic corrosion inhibitor, strong oxidizer Sodium Nitrite (NaNO
2) come the passivation steel pipe, its principle is: with anodic corrosion inhibitor, strong oxidizer Sodium Nitrite (NaNO
2) directly act on steel tube surface, when metal anode dissolves, generate one deck densification, cover passive oxidation thin film layer good, the solid phase in steel tube surface.This layer film constitutes independently solid phase rete; Come the surface of steel pipe and air and other external media isolated, the electricdisplacement that makes metal is to positive dirction, and the active metallic surface state that is dissolving is undergone mutation; The dissolution rate of metal descends rapidly and changes passive state over to, avoids steel pipe to be corroded.
The conventional steel antirusting treating method, its step comprises: deoil, washing, pickling, washing, secondary water washing, phosphatization, passivation and drying.There is following defective in this traditional steel pipe antirusting treating method:
At first, steel pipe is in the process surface treatment process, after pickling and water flushing; Steel tube surface cleans very much, but very activation is easy to corroded; When the passivation film layer that adopts passivating solution to produce steel tube surface and external media isolated are opened, the difference of passivation film layer quality plays key effect to final surface passivation treatment effect so, but through the passivation film layer that sodium nitrite passivation produces have poor flexibility, porosity greatly, characteristics such as solidity to corrosion and wear resistance be not good; Therefore, the steel pipe shelf-time after Passivation Treatment is short, and oxidative phenomena generation rust staining still can take place steel tube surface again in a short time; Not only waste the passivation starting material, and increase production cost and energy consumption, and the metallic substance loss; Especially incured loss through delay the production cycle, serious obstruction and restricted normally carrying out in order of producing.
Secondly, in surface passivation treatment process process, washing is owing to produced continuous circulation, and the acid ion in the sulfuric acid cylinder can constantly be brought in the washing cylinder; PH value in the water reduces, and acid the raising increased attached to the steel tube surface acidic substance; Steel pipe is played corrosive nature, even if there is recirculated water constantly to replenish the acidity in the dilution water; But also can't stop the entering of acid ion, therefore, the acid ion in the water vat always exists.Simultaneously, because there is micropore in steel tube surface, acid solution can't effectively be permeated during pickling, and chemical reaction can not effectively take place, even if or infiltration, but the acid of infiltration is difficult to thorough removing again.Institute has directly influenced the effect of follow-up surface passivation treatment process so that steel tube surface presents acidity.
Again it, often because of long-time oxidation, there is obstinate rust staining in steel pipe, steel tube surface acid solution when sulfuric acid washing can not effectively thoroughly be removed obstinate rust staining, so follow-up surface passivation treatment process just can not get a desired effect.
At last; Because product was longer apart from duration of service after other reasonses such as transportation caused steel tube surface passivation layer destruction or Passivation Treatment; After atmospheric moisture was higher than critical humidity, the moisture film or the globule just appearred in steel tube surface, and the detrimental impurity that contains in the atmosphere is dissolved in these moisture films, the globule; Electrolytic solution, the aggravation to the steel tube surface corrosion of metal.And for example other active ion that pollutes impurity such as smog, coal ash, muriate and other acid, alkali, salt particle destroys corrosion that causes or the like to the steel tube surface passive state of metal.
Summary of the invention
Technical problem to be solved by this invention is: provide a kind of steel product its surface after transpassivation that prevents to produce the antirusting treating method of the steel product of rusty stain once more.
In order to solve the problems of the technologies described above; The technical scheme that the present invention adopted is: the antirusting treating method of steel product; Comprise: conventional rust cleaning abatement processes is carried out on steel product surface; Then, the steel product is carried out neutralizing treatment, bonderizing, hot water wash and Passivation Treatment, at last the steel product is carried out drying treatment.
Described neutralizing treatment is meant that it is that 8~12 points, temperature are to be detained 3~5min in 40~50 ℃ the neutralization solution that the steel product is immersed the concentration that obtains after being diluted by the sodium oxalate and the aqueous solution, makes steel product surface present neutrality.
Described bonderizing is meant that it is that master, total acidity 20~30 points, free acid 1~3 points, temperature are detained 20~30min in 60~70 ℃ the phosphating solution that the steel product is immersed acid phosphate, makes the surface of steel product form the water-fast crystal type phosphoric acid salt of one deck and changes film.
Described hot water wash is meant floods 3~5min with the steel product in temperature is 60~70 ℃ hot water, remove the impurity on steel product surface.
Described aftertreatment be meant with the steel product immerse that the concentration that obtains after being diluted by the chromic trioxide and the aqueous solution is 18~20%, temperature is to flood 10~15min in 75~80 ℃ the chromic trioxide solution; Generate one deck passivation film layer on the surface of steel product, separate steel product surface with the external world.
The decontamination of derusting of described routine is handled and to be comprised: deoil, at least once washing, pickling and at least twice washing.
Described deoil be meant with the steel product immerse that concentration is 5 ~ 8% by obtaining after spent meal and the aqueous solution proportioning, temperature is in 60~75 ℃ the skim soln, is detained 5~15min, removes the surperficial greasy spot of steel product; Washing after deoiling is meant floods 3~5min with the steel product in clear water, remove the greasy spot of steel product remained on surface; Described pickling is meant puts into H with the steel product
2SO
4The concentration that obtains after the dilution of (concentration 98%) solution and water is 8%~16%, temperature is in 50~70 ℃ the Acidwash solution; Be detained 5~20min; The oxide debris and the rusty stain on steel product surface are come off, and remove other residue, obtain the steel product of cleaning surfaces; Washing after the pickling is meant floods 3~5min with the steel product in clear water, remove acid solution and other impurity of steel product remained on surface.
The invention has the beneficial effects as follows: the present invention can thoroughly be removed the acid and the obstinate rust staining on steel product surface, makes the surface of steel product present clean neutrality fully, has promoted the formation of passive oxidation film in the passivation technology; Improve the passivation technology quality; Make that product passive film elasticity is big, porosity is little, solidity to corrosion and high abrasion resistance, especially, have automatic repair to passive film being destroyed because of corrosion failure and other reasons; The shelf time of the steel product after the passivation is long; The repetition passivation phenomenon declines to a great extent, and reduces starting material, the energy and drain on manpower and material resources effectively, and has reduced disposal of pollutants; Reduce a large amount of wastes of heavy metal ion in the passivating solution effectively, made the passivation cost reduce greatly.
Embodiment
Describe specific embodiments of the present invention below in detail.
The antirusting treating method of steel product of the present invention; The steps include: with the steel product of steel pipe and so on immerse that concentration is 5 ~ 8% by obtaining after spent meal and the aqueous solution proportioning, temperature is in 60~75 ℃ the skim soln; Be detained 5~15 minutes (min), remove the greasy spot on steel product surface; Then, the steel product was flooded in clear water 3~5 minutes, remove the greasy spot of steel product remained on surface; Then, the steel product is put into H
2SO
4The concentration that obtains after the dilution of (concentration 98%) solution and water is 8%~16%, temperature is in 50~70 ℃ the Acidwash solution, to be detained 5~20 minutes, and steel product surperficial oxide debris and rusty stain are come off; And remove other residue; Obtain the steel product of cleaning surfaces, the steel product after the pickling is removed acid solution and other impurity of steel product remained on surface through twice washing (crossing twice clear water); During each the washing, the steel product was flooded in clear water 3~5 minutes; Through deoiling, after washing, pickling and twice washing; It is that 8~12 points, temperature are to be detained 3~5 minutes in 40~50 ℃ the neutralization solution that the steel product is immersed the concentration that obtains after being diluted by the sodium oxalate and the aqueous solution; Make steel product surface present neutrality; Then the steel product being immersed acid phosphate is that master, total acidity 20~30 points, free acid 1~3 points, temperature were detained 20~30 minutes in 60~70 ℃ the phosphating solution; Make the surface of steel product form the water-fast crystal type phosphoric acid salt conversion of one deck film, then, the steel product was flooded 3~5 minutes in temperature is 60~70 ℃ hot water; Remove the impurity on steel product surface; The steel product was flooded 3~5 minutes in temperature is 60~70 ℃ hot water, removes the impurity on steel product surface, with the steel product immerse that the concentration that obtains after being diluted by the chromic trioxide and the aqueous solution is 18~20%, temperature is to flood 10~15 minutes in 75~80 ℃ the chromic trioxide solution; Generate one deck passivation film layer on the surface of steel product, thereby steel product surface is separated with the external world.
Principle of work of the present invention is: at first, in the surface passivation processing technological flow, adopt sodium oxalate (Na
2C
2O
4) neutralize, can ionization go out a large amount of effects that get oxalate denominationby according to sodium oxalate, oxalate denominationby combines with the residual acid ion of steel tube surface, generates slightly acidic oxalic acid, thus the pH value that improves in the water reduces acidity; With utilize sodium oxalate to have easy volatile, steel pipe is when hanging sodium oxalate solution, sodium oxalate volatilizees naturally and breaks away from steel tube surface, makes steel pipe present clean neutral surface fully; And, the ferric iron in the iron rust being reduced into ferrous iron by the extremely strong reducing power of sodium oxalate, ferrous solubleness is bigger, thereby further promotes the iron rust dissolving, can remove the remaining obstinate rust staining of steel tube surface effectively; Then, in the surface passivation treatment process, select strong oxidizer chromic trioxide (CrO for use
3) as passivator, generating the independent solid phase passivation film layer that one deck is fine and close, covering well has crystalline structure simultaneously in steel tube surface, the staple of passivation film layer is zinc chromium (ZnCrO
4) and chromic acid chromium (CrO
3Cr
2O
3NH
2O).Existing at most with chromic in the passive film, in passive film, play skeleton function, secondly is water, secondly is sexavalent chrome again.A large amount of trivalent chromium compoundses are insoluble in water, at a distance from the infiltration of having use up airborne oxygen and moisture, have sealed the hole of steel tube surface metal level.A spot of sexavalent chrome is distributed in the film, can play automatic repair to the passive film of being wiped, and can get up to make the complete again reparation of the passive film that slightly tears corrosion resisting property to improve greatly.Characteristic such as the film elasticity that the chromic trioxide passivation has is big, porosity is little, solidity to corrosion and wear resistance are good can be that current other passivation treating agent is incomparable to corrosion failure and other reasons to passive film destructive auto repair capacity especially.Therefore the passive film that adopts the chromic trioxide passivation to form just can effectively be opened steel tube surface and external media isolated, and the electricdisplacement that makes metal is to positive dirction, and active diffluent steel tube surface metallic state is undergone mutation, and the dissolution rate of metal descends rapidly and changes passive state over to.