A kind of high anticorrosive zinc base alloy layer for the hot dip process of iron and steel solvent method
?
technical field
The present invention relates to a kind of high anticorrosive zinc base alloy layer for the hot dip process of iron and steel solvent method, belong to field of metal surface treatment technology.
background technology
Galvanizing is prevent that iron and steel from corroding in physical environment the most economic, effective surface treatment method always, is widely used in the protection of the each class formation of ferrous materials more than 50% protective coating for iron and steel all of global metallic zinc consumption.
When iron and steel parts carries out pot galvanize, workpiece to be plated must be that oxide-free Pure Iron Surface contacts and could obtain flawless hot dip galvanizing coating with melting zinc liquid.Therefore, iron and steel pot galvanize, in art breading, is divided into the zinc-plated and solvent process pot galvanize of gas reduction method process heat.
Thereby the feature of gas reduction method technique is the oxide compound that adopts hydrogen reducing to remove steel surface makes iron and steel parts to be plated obtain Pure Iron Surface, mainly be applicable to the iron and steel pot galvanize of workpiece geomery comparison rule to be plated, as the Continuous Heat pot galvanize of steel plate strip, steel wire.Its major advantage is that efficiency is high, quality of coating good, is applicable to all kinds of zinc and zinc base alloy coating, but technique and equipment complexity, invests highly, cannot adopt gas reduction method technique for the iron and steel parts pot galvanize of geomery complexity.
Solvent process pot galvanize adopts zinc-plated form in batches conventionally, carry out again galvanizing processing by iron and steel parts to be plated by operations such as oil removing, pickling, activation, painting solvents, mainly be applicable to the irregular iron and steel pot galvanize of workpiece geomery to be plated, as the pot galvanize of all kinds of steel construction pieces, iron and steel parts.Its major advantage is that technique and equipment are simple, less investment, but efficiency is low, and its technique cannot adapt to high anti-corrosion zinc base alloy coating production, this is mainly because of two reasons: the one, and the gas reduction method that is suitable for steel plate or steel wire is produced (as Galfan, Galvalume, ZAM) in these high corrosion resistant aluminium alloy coating and is contained higher aluminium, if Galfan coating is containing aluminium 5%, Galvalume coating is containing aluminium 55%, and in plating pot, high aluminium content means the irony plating pot that the serious etch solvent method zincincation of meeting is used; The 2nd, high aluminium content in plating pot, in the time adopting solvent method zincincation zinc-plated, easily causes the plating leakage of coating on the one hand, and the muriate in solvent can react and produce a large amount of poisonous aluminum chloride gas with aluminium in zinc pot on the other hand.Therefore, the batch flux method pot galvanize of steel construction piece, iron and steel parts substantially all adopts pure zinc coating at present.
Protective effect in different environments for use and the service life of ferrous materials hot galvanized layer, except with its environment of living under erosion rate mutually outside the Pass, depend primarily on the thickness of coating.Under general atmospheric environment; existing zinc coating solidity to corrosion and thickness of coating can meet service requirements; but under the situation of corrosive environment harsher (as maritime amblent air temperature, industrial pollution amblent air temperature); conventionally the thickness of coating of use is that 610g/m2(GB GB2694-2010 specify) zinc coating protection be difficult to reach service requirements; become difficulty or still cannot reach service requirements and further improve thickness of coating, needing to improve the solidity to corrosion of coating for this reason.Therefore, the better zinc base alloy coating of exploitation solidity to corrosion becomes an exigence, and exploitation simultaneously adopts the better zinc base alloy coating of solidity to corrosion, can reduce the consumption of zinc resource, is also the direction of future development.
The high corrosion resistant aluminium alloy coating of suitable gas reduction method pot galvanize has been developed many products abroad, and as Galfan, Galvalume, ZAM coating, its erosion resistance improves several times to tens times than pure zinc coating, and has obtained commercial applications.The basic characteristics of these coating are to adopt aluminium, magnesium, silicon etc. to improve its corrosion resistance.Exploitation high corrosion resistant aluminium alloy coating domestic development is more late, achievement in research is few, and as invented Zinc-based alloy used in steel hot dipping in Chinese patent (CN 102994928), this alloy is made up of zinc, aluminium, silicon, titanium and lanthanum, wherein aluminium content accounts for 20-30%, and corrosion resisting property and Galvalume are suitable.But as previously mentioned,, due to aluminium too high levels, these high corrosion resistant aluminium alloy coating are all not suitable for the batch flux method pot galvanize of steel construction piece, iron and steel parts.
The high corrosion resistant aluminium alloy coating research and development that are suitable for flux method pot galvanize are few.At present in the exploitation of batch flux method hot dip galvanizing coating alloy, in order to improve quality of coating, often in galvanizing kettle, add some elements, these elements comprise aluminium, magnesium, silicon, nickel, titanium, mishmetal etc., its Main Function is the surface quality in order to improve galvanized workpiece, associated with raising solidity to corrosion little.Even if some alloys are improved the effect of corrosion resistance of coating, be zinc as invented a kind of multicomponent alloy: Al 0.5-0.6%, RE (La, Ce, P r mishmetal) 0.2-0.3%, Si 0.01-0.02%, Mg 0.01-0.02%, surplus in Chinese patent (CN 102146536).But the one, Aluminum in Alloy content is still higher, be not too applicable to flux method pot galvanize; The 2nd, in alloy, contain a large amount of valuable rare earths, and rare earth element easy scaling loss and cause waste in hot galvanizing process, rare earth oxide forms slag on zinc liquid surface simultaneously, is unfavorable for the surface quality of workpiece; The 3rd, corrosion resistance coating is improved little, is only the ability that improved the resistance to white rust of coating (CN 102146536 introduces " the neutral salt spray test rust time is that 70-90 is hour, than pure zinc plating high 20-40% "), instead of the overall anti-corrosion capability of coating.For this reason, research and develop a kind of high anticorrosive zinc base alloy layer for the hot dip process of iron and steel solvent method, be suitable for the galvanized anticorrosive of steel construction piece, iron and steel parts (as all kinds of power communication steel towers, all kinds of municipal administrations, road and bridge steel structure etc.), be metal plating technical field in the urgent need to.
summary of the invention
The object of the invention is, in order to overcome the deficiency of existing alloy for hot-dip coating, improving outside the solidity to corrosion of iron and steel solvent method hot dip process zinc-base alloy layer, make again zinc base alloy coating be suitable for the solvent method immersion of existing steel construction piece, iron and steel parts.
Technical scheme of the present invention is, realize by add a small amount of magnesium, nickel, aluminium, vanadium in Zn-based plating layer, by the acting in conjunction of magnesium, nickel, vanadium, improve the solidity to corrosion of coating, it is characterized in that the interior concrete composition quality content of plating pot of this alloy layer is:
Magnesium (Mg): 0.03-0.30%
Nickel (Ni): 0.01-0.06%
Aluminium (Al): 0.01-0.10%
Vanadium (V): 0.001-0.05%
Pb, Fe, the impurity summations such as Cd are not more than: 0.01%
Surplus is zinc (Zn).
Optimal components content of the present invention is:
Magnesium (Mg): 0.20%
Nickel (Ni): 0.04%
Aluminium (Al): 0.05%
Vanadium (V): 0.04%
Pb, Fe, the impurity summations such as Cd are not more than: 0.01%
Surplus is zinc.
In the high anticorrosive zinc base alloy layer of the present invention, the mechanism of action of each component is specific as follows:
Magnesium (Mg) add the solidity to corrosion that can significantly improve zinc base alloy coating.Magnesium and zinc can form intermetallic compound Mg Zn on the one hand
2, Mg
2zn
11, these compounds have lower anodic dissolution current mutually than pure zinc, and the formation of these intermetallic compounds causes zinc magnesium alloy to have than pure zinc coating having higher solidity to corrosion; On the other hand, adding of magnesium can make the corrosion product of coating finer and close, is loose ZnO and a small amount of fine and close Zn because the corrosion product of pure zinc comprises main body
4cO
3(OH)
4h
2o, and the corrosion product of zinc-magnesium alloy coating is ZnCl
24Zn (OH)
4h
2o, Mg(OH)
2, Zn
4cO
3(OH)
4h
2o, they are comparatively fine and close, and Mg(OH)
2existence can suppress the oxygen uptake reaction of negative electrode, the participation of Mg can also reduce the pH value of coating surface, and under low pH value condition, is more conducive to fine and close, insoluble ZnCl
24Zn (OH)
4h
2the production of O corrosion product, thus delay the corrosion process of zinc coating.
Aluminium (Al) can improve mobility that coating melts liquid, improve quality of coating and improve the solidity to corrosion of coating, needs a certain amount of content but improve solidity to corrosion.The Main Function that in the present invention, aluminium adds is mainly in order to overcome because magnesium adds the zinc liquid thickness and the surperficial slagging scorification problem that cause, be no more than 0.10% add-on little to corrosion resistance of coating effect, but can not cause the disadvantageous effect to flux and galvanizing kettle in solvent technique heat galvanizing process, need not change the technology and device of existing solvent method galvanizing.
Adding of nickel (Ni) contributes to hot galvanizing process on the one hand, particularly thickens problem and improves surface quality for the zinc-iron alloy layer of active silicon containing steel; Contributing on the other hand the raising of corrosion resistance of coating, is mainly after nickel element adds, to be conducive under atomospheric corrosion situation, the passivating process of coating.
Vanadium (V) add the weather-resistant performance that is very beneficial for coating, be similar in weathering steel and add V, can obtain fine and close, insoluble rusty scale (corrosion product) ZnCl
24Zn (OH)
4h
2o and Zn
4cO
3(OH)
4h
2o.
The present invention adopts after abovementioned technology, compared with existing hot-dip zinc based alloy coated, the beneficial effect bringing is as follows: (1) shows through electrochemical test and neutral salt spray test test, and the solidity to corrosion of zinc base alloy coating of the present invention improves 1 times of left and right than pure zinc coating; (2) quality of coating of the present invention is good: binding force of cladding material is strong, coating surface is bright, without plating leakage phenomenon; (3) suitability of the present invention is good: need not change the technology and device of existing solvent method galvanizing, can obtain the novel alloy coating of excellent corrosion resistance.
Embodiment
Embodiment 1
In the plating pot of the present embodiment, each metal quality content is as follows:
Mg:0.30;
Ni:0.04;
Al:0.05;
V:0.05;
Pb, Fe, the impurity summations such as Cd are not more than 0.01;
Zn surplus.
By said ratio, each alloy is placed in plumbago crucible, adopt resistance furnace to be heated to alloy melting, 455 ~ 465 DEG C of insulations.Adopt solvent process to carry out hot dip process the steel plate of shearing in advance, obtain the steel plate sample with alloy layer.
Steel plate hot-dip galvanizing technique adopts conventional operation:
(1) after alkali liquor oil removing, wash;
After (2) 15% chlorohydric acid picklings, wash;
(3) ammonium chloride and zinc chloride water solvent help plating;
(4) dry;
(5) the pre-plating piece after helping plating to dry is immersed in the zinc bath preparing of the present invention, zinc liquid temperature is 455 ~ 465 DEG C, and soak time is 1 ~ 3 minute;
(6) plating piece takes the dish out of the pot, cooling.
The steel plate sample having plated is processed into electrochemistry sample sample, adopt linear polarization to carry out electrochemical test test, solution system is 0.1M aqueous sodium persulfate solution, and the corrosion current ratio that records alloy layer and pure zinc coating is 0.52, illustrates that the solidity to corrosion of alloy layer is far away higher than pure zinc coating.
The steel plate sample plating is carried out to neutral salt spray test by GB (GB/T10125-1997), and test period is 200 hours, detected result, and the corrosion of coating speed of the embodiment of the present invention 1 composition is: 0.3907 g/m
2h, the erosion rate of pure zinc coating is 0.7235g/m
2h, alloy layer and pure zinc coating erosion rate ratio are 0.54.
Embodiment 2
In the plating pot of the present embodiment, each metal quality content is as follows:
Mg:0.20;
Ni:0.04;
Al:0.02;
V:0.04;
Pb, Fe, the impurity summations such as Cd are not more than 0.01;
Zn surplus.
Adopt the process of the test identical with embodiment 1, the corrosion current ratio that records alloy layer and pure zinc coating is 0.62.
In neutral salt spray test, the corrosion of coating speed of the embodiment of the present invention 2 compositions is: 0.4302g/m
2h, the erosion rate of pure zinc coating is 0.7235g/m
2h, alloy layer and pure zinc coating erosion rate ratio are 0.59.
Embodiment 3
In the plating pot of the present embodiment, each metal quality content is as follows:
Mg:0.05;
Ni:0.04;
Al:0.05;
V:0.04;
Pb, Fe, the impurity summations such as Cd are not more than 0.01;
Zn surplus.
Adopt the process of the test identical with embodiment 1, the corrosion current ratio that records alloy layer and pure zinc coating is 0.40.
In neutral salt spray test, the corrosion of coating speed of the embodiment of the present invention 3 compositions is: 0.3517g/m
2h, the erosion rate of pure zinc coating is 0.7235g/m
2h, alloy layer and pure zinc coating erosion rate ratio are 0.48.
Embodiment 4
In the plating pot of the present embodiment, each metal quality content is as follows:
Mg:0.05;
Ni:0.05;
Al:0.02;
V:0.01;
Pb, Fe, the impurity summations such as Cd are not more than 0.01;
Zn surplus.
Adopt the process of the test identical with embodiment 1, the corrosion current ratio that records alloy layer and pure zinc coating is 0.59.
In neutral salt spray test, the corrosion of coating speed of the embodiment of the present invention 3 compositions is: 0.4223g/m
2h, the erosion rate of pure zinc coating is 0.7235g/m
2h, alloy layer and pure zinc coating erosion rate ratio are 0.58.