CN104831327A - Method for coating aluminum alloy by using micro-arc oxidation green film layer - Google Patents
Method for coating aluminum alloy by using micro-arc oxidation green film layer Download PDFInfo
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Abstract
The invention relates to a method for coating aluminum alloy by using a micro-arc oxidation green film layer. The method comprises the following steps of using the 6063 aluminum alloy as a matrix; adding glycerinum and potassium fluoride (KF) in a system in which Na2SiO3-KOH serves as main electrolyte; preparing coloring electrolyte by using NH4VO3 as coloring agents; and preparing a green micro-arc oxidation ceramic film layer. Influences of electrolyte parameters and electric parameters on an organization structure and the performance of the micro-arc oxidation film layer are researched. Phase composition, microstructure and element contents of the film layer are respectively represented through an X-ray diffractometer (XRD), a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDS), the thickness of the micro-arc oxidation ceramic layer and the strength of bonding between the micro-arc oxidation ceramic layer and the matrix are detected by an eddy coating thickness gage and a scratch spectrometer, the electrochemistry corrosion resisting property of the ceramic layer is analyzed by using an electrochemical corrosion method, technological parameters are optimized, and a green micro-arc oxidation film with high performance is prepared.
Description
Technical field
The invention belongs to field of new, particularly a kind of aluminum alloy differential arc oxidation the method for green rete.
Background technology
Aluminium is active metal, and in the air of drying, its surface can form that one deck loosens, the aluminum oxide film of porous at once, although can stop the further oxidation of aluminium, effectively can not play protective and ornamental effect.Meanwhile, the electropotential of aluminium is lower, causes it to be easily corroded in malaria, bronsted lowry acids and bases bronsted lowry liquid.So, prepare at aluminium and aluminum alloy surface thereof the rete that one deck has color and a certain barrier propterty and there is very important actual application value.
The novel dye technology in Aluminum-aluminum alloy surface comprises: chemically transformed film technique, electrophoretic technique, electrostatic spraying technology for powder paints and differential arc oxidization technique etc.Wherein, differential arc oxidation, as a kind of emerging technology, is more and more deep in daily life, although this technology is not also very perfect, and does not put in enormous quantities in the middle of production, is widely used in some fields.
But along with the increasingly mature and widespread use of micro-arc oxidation of aluminum alloy surface ceramic film technology, ornamental new demand is proposed to micro-arc oxidation of aluminum alloy surface ceramic film technology, because the color of Micro-Arc Oxidized Ceramic Coating is comparatively single, and great majority are white and grey, so the ceramic film producing different colours is very important.Compared with other dye technology, the ceramic film that differential arc oxidation dye technology generates has color even, is not easy to fade, the features such as the eliminate optical property that quality of colour is good He good.At present, differential arc oxidation dye technology is mainly through research processing parameter and add that excellent performance prepared by tinting material and have the ceramic film of different colours, and it is long to solve the development life-span, can be well excessive, the industrial problem such as the recycling of electrolytic solution.Differential arc oxidation dye technology is at decoration, and the aspect such as material protection and opticinstrument has great application prospect and practical significance.
Chinese patent CN1554807A discloses the electrolytic solution of a kind of aluminum alloy casting differential arc oxidation process, this electrolytic solution by weight with cumulative volume ratio, comprise sodium phosphate 10g/L-20g/L, water glass 5g/L-10g/L, potassium hydroxide 1g/L-4g/L, Sodium orthomolybdate 10g/L-15g/L, and the pH value of electrolytic solution is 8-12.Adopt this electrolytic solution to carry out differential arc oxidation process to aluminum alloy casting surface, improve the wear resistance on aluminum alloy casting surface.But after the electrolytic solution adopting this invention to provide carries out differential arc oxidation to aluminium alloy, the resistance to soiling of the micro-arc oxidation films obtained, scratch resistance and compactness are poor.Chinese patent CN102797024B discloses a kind of method that aluminum alloy differential arc oxidation blue rete, and the composition concentration of electrolytic solution is: water glass 5-11g/L, potassium hydroxide 0.5-2.0g/L; Sodium Fluoride 0.3-0.6g/L, rose vitriol 0.4-1.1g/L, aluminium alloy after the process of employing the method, surface presentation is blue, and even compact, but solidity to corrosion has much room for improvement.
Summary of the invention
For solving the problem, the present invention with 6063 aluminium alloys for matrix, at water glass-potassium hydroxide (Na
2siO
3-KOH) as adding glycerine and Potassium monofluoride (KF) in main electrolyte system, with ammonium meta-vanadate (NH
4vO
3) be tinting material, prepare painted electrolytic solution, prepare green Micro-Arc Oxidized Ceramic Coating, this rete has that hardness is high, good toughness, porosity are low, the feature of even film layer, wear-resisting, corrosion resisting property and good insulation preformance.
For achieving the above object, the present invention adopts following technical scheme:
Aluminum alloy differential arc oxidation a method for green rete, comprises step as follows:
(1) select aluminium alloy as matrix, preparation electrolyte system, the composition concentration of electrolytic solution is: ammonium meta-vanadate 3-9g/L, water glass 4-12g/L, potassium hydroxide 2-6g/L; Potassium monofluoride 0.3-0.6g/L, glycerol 3-6mL/L, pH8-10.
(2) aluminum alloy surface electrolytic solution after the cleaning carries out differential arc oxidation process, and electrical parameter is: forward voltage 400-450V, and negative voltage is 30-80V; Frequency is 300-500Hz; Positive and negative dutycycle is 20-40%, 15-25% respectively; Control temperature less than 60 degrees Celsius, the treatment time is 15 minutes.
Preferably, described in step (1), aluminium alloy is 6063 aluminium alloys.
Preferably, in step (1), the composition concentration of electrolytic solution is: water glass 6-10g/L, potassium hydroxide 2-6g/L; Potassium monofluoride 0.5g/L, ammonium meta-vanadate 5-8/L.
Preferably, in step (1), the composition concentration of electrolytic solution is: water glass 8g/L, potassium hydroxide 4g/L; Potassium monofluoride 0.5g/L, ammonium meta-vanadate 6g/L.
Preferably, in step (2), electrical parameter is: forward, negative voltage are 440V, 40V respectively, and frequency is 400Hz; Positive and negative dutycycle is 30%, 20% respectively.
According to Al-alloy parts prepared by above-mentioned method.
Aforesaid method is adopted to carry out coloring treatment to aluminum alloy surface.
Principle of design of the present invention:
This test adopts NH
4vO
3as additive, be because on the one hand, V element is according to the difference of its price, and its oxide compound can present distinct colors; On the other hand, NH
4vO
3comparatively be insoluble in water, according to physical chemistry knowledge, the solubleness of solute is less, and its adsorptive power is stronger, due to NH
4vO
3relatively weak with the interaction force of electrolytic solution, under the effect of highfield, NH
4vO
3more easily be adsorbed on the surface of rete, be conducive to the carrying out reacted.By analyzing contrast different electrolytes composition (NH
4vO
3, Na
2siO
3and KF) and electrical parameter (positive and negative voltage and positive dutycycle) on the impact of the color of green rete, thickness, phase composite, microtexture, bonding force intensity and corrosion resisting property etc.
The invention has the beneficial effects as follows:
1. technical process is simple, and early stage, process was simple.Utilize differential arc oxidation dye technology to prepare color even, the good green rete of film quality at 6063 alloy matrix aluminum specimen surfaces, reach satisfied certain ornamental requirement.This rete has that hardness is high, good toughness, porosity are low, the feature of even film layer, wear-resisting, corrosion resisting property and good insulation preformance.
2., in micro-arc oxidation process, the difference of bath composition has different effects to painted.Along with NH
4vO
3the rising of concentration, the color of rete deepens gradually, and in rete, the aperture of micropore becomes large gradually, and the thickness of rete linearly increases within the specific limits, and the bonding force of rete and matrix becomes large gradually, reduces again after the corrosion resisting property of rete first increases.Along with Na
2siO
3the rising of concentration, the color of rete shoals from light to dark again, works as Na
2siO
3when concentration is higher, rete just face is more coarse, and the thickness of rete linearly increases within the specific limits, the bonding force first increases and then decreases of rete and matrix, reduces again after the corrosion resisting property of rete first increases.Along with the rising of KF concentration, the color of rete shoals from light to dark again, and the thickness of rete increases within the specific limits gradually, constant after the bonding force of rete and matrix first increases within the specific limits, reduces again after the corrosion resisting property of rete first increases.Draw by analyzing contrast: work as NH
4vO
3, Na
2siO
3when being respectively as 6g/L, 8g/L and 0.5g/L with the concentration of KF, film quality is best.
3., in the painted process of differential arc oxidation, positive and negative voltage, the time etc. of positive and negative dutycycle and film forming can be considered the external factor affecting MAO layer tissue stuctures and properties.Forward voltage is conducive to the speed of growth of rete, and when coating growth is to certain thickness, is only improved forward voltage and just can reaches its energy again punctured, the continued growth of rete ability, so forward voltage is the main factor affecting thicknesses of layers.Along with the rising of forward voltage, the roughness of rete becomes large, and the thickness of rete becomes large, and the bonding force between matrix and rete becomes large, reduces again after the corrosion resisting property of rete first increases.Along with the rising of negative voltage, rete can become more and more coarse, and the thickness of rete increases, and the bonding force between matrix and rete reduces gradually, and the corrosion resisting property of rete reduces gradually.Along with the increase of positive dutycycle, the roughness of rete increases to some extent, and the thickness of rete increases within the specific limits gradually, namely rationally increasing gradually between matrix and rete, the corrosion resisting property first increases and then decreases of rete.Draw by analyzing contrast: when forward voltage, negative voltage and positive dutycycle are respectively 440V ,-40V and 30%, film quality is best.
4., in micro-arc oxidation process, the formation of green rete roughly can be divided into three phases.Main containing Al, Si, V and O tetra-kinds of elements in rete.O, Si and V element are almost through whole rete, and V element is more in the place distribution that hole is more, and Si is comparatively evenly distributed in surface, Al and O element is mainly distributed in protruding melt substance region, and Al mainly concentrates in rete tight zone.
5.NH
4vO
3decompose in reaction process and generate V
2o
5, V
2o
5a part is piled up at film surface, and a part enters in discharge channel.Under scattering of light effect, film surface with electric discharge micropore in V
2o
5ceramic film is made to present green.
6. detect containing Al in rete
3v, this intermetallic compound can improve the hardness of aluminum alloy surface.
Accompanying drawing explanation
The NH of Fig. 1 different concns
4vO
3the color of the green rete generated
(a)5g/L，(b)6g/L，(c)7g/L
The NH of Fig. 2 different concns
4vO
3the XRD figure spectrum of the green rete generated
The NH of Fig. 3 different concns
4vO
3the surface microscopic topographic of the green rete generated
(a1,a2)5g/L；(b1,b2)6g/L；(c1,c2)7g/L
The NH of Fig. 4 different concns
4vO
3acoustic emission-the load curve of the green rete generated
The NH of Fig. 5 different concns
4vO
3the moving electrode potential curve of the green rete generated
The Na of Fig. 6 different concns
2siO
3the Film color generated
(a)6g/L；(b)10g/L
The Na of Fig. 7 different concns
2siO
3the XRD figure spectrum of the green rete generated
The Na of Fig. 8 different concns
2siO
3the surface microscopic topographic of the green rete generated
(a1,a2)6g/L；(b1,b2)10g/L
The Na of Fig. 9 different concns
2siO
3acoustic emission-the load curve of the green rete generated
Figure 10 different concns Na
2siO
3the moving electrode potential curve of the green rete generated
The green rete exterior appearance of the KF generation of Figure 11 different concns
(a)0.4g/L；(b)0.6g/L
The XRD figure spectrum of the green rete of the KF generation of Figure 12 different concns
The surface microscopic topographic of the green rete of the KF generation of Figure 13 different concns
(a1,a2)0.4g/L；(b1,b2)0.6g/L
Acoustic emission-the load curve of the green rete of the KF generation of Figure 14 different concns
The moving electrode potential curve of the green rete that Figure 15 different concns KF generates
Concrete embodiment
Embodiment 1
The present invention selects 6063 aluminium alloys as body material, and its chemical composition is as shown in table 1, tests chemical reagent used as shown in table 2.
Table 1 6063 al alloy component (wt%)
Chemical reagent used tested by table 2
In the present invention, 6063 aluminium sheets are cut on WEDM the rectangular piece of 7mm × 7mm × 12mm, (Ф 2.5mm) is holed on one side with drilling machine, the screw tap corresponding with hole carries out tapping, so that be connected closely with the aluminium conductor after tapping in differential arc oxidation reaction process, guarantee that in reaction process, sample can not come off.Sample is polished on the SiC sand paper of different thicknesses, from 400# flint paper, through 5 polishings, until thin 1000#.Sample is placed in alcohol and soaks, to go out the grease on its surface, finally dry up with blower, wrap with preservative film, be placed in sample strip stand-by.
The 6063 aluminium alloy styles of anticipating be immersed in the electrolytic solution prepared, arrange the electrical parameter of test, carry out differential arc oxidation process to style, the treatment time is 15 minutes.Electrolyte parameter is: water glass 8g/L, potassium hydroxide 4g/L; Potassium monofluoride 0.5g/L, ammonium meta-vanadate 6g/L.Electrical parameter is: forward, negative voltage are 440V, 40V respectively, and frequency is 400HZ; Positive and negative dutycycle is 30%, 20% respectively, and the rete obtained is grass green, smooth surface and uniformity, i.e. A2.
Embodiment 2
Changing ammonium meta-vanadate concentration in embodiment 1 is 5g/L, other parameter constant, and the rete A1 color obtained is very uneven, and local, many places presents black.
Embodiment 3
The concentration changing ammonium meta-vanadate in embodiment 1 is 7g/L, and other parameter constant, the rete A3 Film color obtained is blackish green, and surface is more smooth.
Embodiment 4
The concentration changing embodiment 1 mesosilicic acid sodium is 6g/L, other parameter constant, the rete A4 obtained.Embodiment 5
The concentration changing embodiment 1 mesosilicic acid sodium is 10g/L, other parameter constant, the rete A2 obtained.Embodiment 6
The concentration changing Potassium monofluoride in embodiment 1 is 0.4g/L, other parameter constant, the rete A5 obtained.Embodiment 7
The concentration changing Potassium monofluoride in embodiment 1 is 0.6g/L, other parameter constant, the rete A6 obtained.Embodiment 10
1.1NH
4vO
3on the impact of green Film color
Different concns NH
4vO
3the color of the green rete generated as shown in Figure 1, works as NH
4vO
3when concentration is 5g/L, Sample A 1 Film color is very uneven, and local, many places presents black; Work as NH
4vO
3when concentration is 6g/L, Sample A 2 Film color is grass green, smooth surface and uniformity; Work as NH
4vO
3when concentration is 5g/L, Sample A 3 Film color is blackish green, and surface is more smooth.As can be seen from the figure, along with NH
4vO
3the increase of concentration, the color of rete is deepened gradually, this is because, along with NH
4vO
3the increase of concentration, improves the electroconductibility of electrolytic solution, and the aperture of the micropore in rete is diminished, and the surface energy of rete is reduced, more V
2o
5enter conductive channel, be thus conducive to the formation of green ceramic rete.
1.2NH
4vO
3the impact thick on green film tunic
Different concns NH
4vO
3the thickness of the green rete generated is as shown in table 3, as the NH added
4vO
3when concentration is respectively 5g/L, 6g/L and 7g/L, the thicknesses of layers of Sample A 1, A2, A3 is respectively 10 μm, 15 μm and 20 μm.As can be seen from Table 3, the thickness of rete is along with NH
4vO
3the increase of concentration and become large, and within the specific limits, the thickness of ceramic film and NH
4vO
3concentration be directly proportional.But when additive concentration is excessive, the electroconductibility of electrolytic solution can become rapidly large, makes film surface local voltage excessive, generation has destructive electric current, causes slowing of film forming, and the rete speed of dissolving is greater than the thicknesses of layers of generation, rete is thinning, and the phenomenons such as appearance is loose, hole.
Table 3 adds different concns NH
4vO
3the thickness of the green rete of Shi Shengcheng
1.3NH
4vO
3on the impact of green rete phase composite
The NH of different concns
4vO
3as shown in Figure 2, as can be seen from the figure, rete mainly contains V to the XRD figure spectrum of the green rete generated
2o
5, Al
3v, α-Al
2o
3, γ-Al
2o
3and Al
9several phase such as Si formed.V
2o
5and Al
3the peak value first increases and then decreases of V phase, illustrates V
2o
5and Al
3the relative content of V is also first increase to diminish afterwards.γ-Al
2o
3content almost no change, and α-Al
2o
3amount few, this may cause because when differential arc oxidation reacts, current density is less.
1.4NH
4vO
3on the impact of green rete microscopic appearance
The NH of different concns
4vO
3the surface microscopic topographic of the green rete generated as shown in Figure 3, works as NH
4vO
3concentration when being 5g/L, the micropore of film surface is less, and maximum diameter of hole is at about 2 μm, and the Aperture deviation between micropore is less, and there are the indivedual small embossments in subrange, and surface is still more smooth generally.Work as NH
4vO
3concentration when being 6g/L, the micropore of film surface is more, about 5 μm, maximum diameter of hole, and Aperture deviation is less, and distribution is fine and close.Work as NH
4vO
3concentration when being 7g/L, about 7 μm, the more maximum diameter of hole of micropore of film surface, Aperture deviation is large, and there is indivedual larger projection.This is because, work as NH
4vO
3concentration higher time, too much V
2o
5can film surface be deposited in, can not enter in discharge channel, can continue under high voltages and Al element reaction, generate the Al of melting
3v.Add the NH of different concns
4vO
3the rete generated all has the feature of differential arc oxidation film layer, this is because the aluminum oxide of the melting of gushing out in discharge channel is cooled fast by the electrolytic solution of surrounding.
The NH of different concns
4vO
3in the green rete generated, the content of V element is as shown in table 4.As can be seen from table 4 and Fig. 1, NH
4vO
3concentration higher, Film color is darker, and in rete, the content of V element is also higher.Relevant research shows, within the specific limits, the concentration of the tinting material of interpolation is higher, and the color of corresponding rete is also darker.
The NH of table 4 different concns
4vO
3the content of V element in the green rete generated
1.5NH
4vO
3on the impact of green rete and basal body binding force intensity
The NH of different concns
4vO
3generate ceramic film bonding force intensity as shown in Figure 4, when add NH
4vO
3when concentration is respectively 5g/L, 6g/L and 7g/L, the bonding force of the rete of Sample A 1, A2, A3 is respectively 40N, 30N and 26N.As can be seen from Figure 4, in the process of differential arc oxidation, the resistance R of sample ceramic film
electrolyte(R
electrolytic solution) and R
coating(R
ceramic film) resistance of electrolytic solution constitutes a closed series circuit, these two resistance have been shared and have been reacted the total energy provided, resistance R
electrolytethe energy consumed can enter puncturing of rete, growth and sintering conversion.Its power is:
Wherein U is that voltage is worked as, U and R
coatingtime constant, W
coatingdepend primarily on R
electrolyte.The larger W of its numerical value
coatingless, then puncture for rete, the energy of growth and sintering conversion is less, and the area of the metallurgical binding of matrix and ceramic film is less, causes bonding force intensity and then to reduce.
1.6NH
4vO
3on the corrosion proof impact of green rete
The method of usual employing potentiodynamic polarization characterizes the corrosion resisting property of differential arc oxidation film layer.The NH of different concns
4vO
3the moving electrode potential curve of the green rete generated as shown in Figure 5.Corrosion potential E
corr, corrosion current density I
corr, anode/cathode Tafel slope (b
a,b
c) and polarization impedance R
pnumerical value lists in table 5, polarization impedance R
pnumerical value is obtained by Stern-Geary formulae discovery:
As can be seen from Fig. 5 and table 5, the E of rete
corralong with NH
4vO
3the increase of concentration, I
corrfirst reduce to increase afterwards, the R of rete
pfirst increases and then decreases, occurs that this phenomenon may be because rete there are differences in porosity, thickness and tiny crack quantity etc.NH is worked as in this explanation
4vO
3concentration when being 6g/L, its corrosion resisting property is best.When electrochemical corrosion test, the corrosion current due to 6063 matrixes exceedes protective current 2mA, and test is forced to stop, and thus could not obtain the moving electrode potential curve of matrix.Differential arc oxidation film layer porous surface, rete is formed primarily of outside porous layer, intermediate layer and interior solid layer three-decker, and surface micropore does not run through whole rete, in electrochemical corrosion course, the Cl in corrosive medium
-ion can pass porous layer and transition layer, but finally due to be subject to tight zone barrier effect and cannot fast erosion matrix, therefore erosion resistance is improved.So the corrosion resisting property of rete is better than matrix.
The NH of table 5 different concns
4vO
3the moving electrode potential test result of the green rete generated
2.1Na
2siO
3on the impact of green Film color
The Na of different concns
2siO
3the color of the green rete generated as shown in Figure 6, works as Na
2siO
3concentration when being 6g/L, the color of Sample A 4 rete is light green, surperficial smoother, densification, and color distribution is more even; Work as Na
2siO
3concentration when being 10g/L, the color of Sample A 5 rete is also light green, but surface ratio is more rough, and color distribution is uneven, there is the spot in subrange.This may be because, Na
2siO
3add, not only increase the electric conductivity of electrolytic solution, and improve the quantity of granule for absorbing discharge centers, thus reduce critical sparking voltage.Namely, under constant voltage mode, overvoltage will increase (it is only poor to apply with critical sparking voltage numerical value), thus the disruptive strength of plasma body is improved, and be conducive to the quick formation of rete.Work as Na
2siO
3concentration lower time, the granule for absorbing discharge centers provided is less, so color is more shallow: work as Na
2siO
3concentration higher time, granule for absorbing discharge centers is too much, and cause overvoltage excessive, temperature is too high, causes the molten again phenomenon of multiple local area portion generation rete, cause rete to loosen, surface irregularity, and color distribution is uneven.
2.2Na
2siO
3the impact thick on green film tunic
The Na of different concns
2siO
3the thickness of the green rete generated is as shown in table 6, as the Na added
2siO
3when concentration is respectively 6g/L, 8g/L and 10g/L, the thicknesses of layers of Sample A 4, A2 and A5 is respectively 7 μm, 15 μm and 23 μm. and as can be seen from chart, the thickness of rete is along with Na
2siO
3the increase of concentration and become large, and within the specific limits, the thickness of ceramic film and Na
2siO
3concentration is proportional.This is because, Na
2siO
3the electric conductivity of electrolytic solution can be improved, also increase the strength of electric field of rete simultaneously accordingly, thus increase the motivating force in micro-arc oxidation process, be conducive to formation and the growth of rete.Process due to differential arc oxidation can be modeled as a closed loop procedure, and in reaction process, the resistance of electrolytic solution and specific conductivity are inverse relation, and the specific conductivity of electrolytic solution is larger, then the V above sample
ps(transient voltage and amp product) is larger, and formation and the speed of growth of ceramic film are faster, thus, within the scope of finite concentration, and the thickness of rete and Na
2siO
3concentration linear.
The Na of table 6 different concns
2siO
3the thickness of the green rete generated
2.3Na
2siO
3on the impact of green rete phase composite
The Na of different concns
2siO
3the XRD figure spectrum of the green rete generated as shown in Figure 7, can be found out, along with the Na added
2siO
3the increasing of amount, V
2o
5and Al
3the intensity at the peak of V obviously increases, V
2o
5and Al
3the relative content showed increased (other peak and Al coincide, and Al is mainly present in matrix) of V, wherein Al
3v can significantly improve the hardness of rete.But along with the Na added
2siO
3the increase of amount, the color of rete shoals from light to dark again, and thicknesses of layers linearly increases.This is because, work as Na
2siO
3concentration lower time, Na
2siO
3the comparatively small amt of the absorption discharge centers provided, impels NH
4vO
3the motivating force moving to matrix surface is less, and temperature of reaction is low, the metalwork compd A l of generation
3v is also less; Work as Na
2siO
3concentration higher time, produce more V
2o
5and Al
3v, and a lot of V
2o
5stay rete and just do not enter reaction channel in face, so thicknesses of layers increase is tectorium.α-Al
2o
3with γ-Al
2o
3content almost do not have anything to change.
2.4Na
2siO
3on the impact of green rete microscopic appearance
The Na of different concns
2siO
3the surface microscopic topographic of the green rete generated as shown in Figure 8.Work as Na
2siO
3concentration when being 6g/L, the micropore of film surface is more, and aperture is very little, distributes dense, and the aperture difference between aperture is also smaller, and macro morphology shows rete smoother.When the micropore major part that these diameters are very little is by melt substance cooled and solidified, around escaping gas produces.Because work as Na
2siO
3concentration lower time, the discharge centers in electrolytic solution is less, and the voltage of film surface is less, and the energy of single pulse is little, and the scope that the melt substance produced in discharge channel sprays towards periphery is little.Work as Na
2siO
3concentration when being 10g/L, micropore is also many, and distribution is relatively more even, but aperture difference between aperture is very large, and some are local exists some pimples, and this causes on macro morphology, there are some speckles.This is because work as Na
2siO
3concentration higher time, the discharge centers in electrolytic solution is more, and the specific conductivity of electrolytic solution is high, and the energy of single pulse is large, and the melt substance moment in discharge channel sprays towards periphery, thus forms larger micropore.
The Na of different concns
2siO
3in the green rete generated, the content of V element is as shown in table 7.As can be seen from table 7 and Fig. 6, work as Na
2siO
3concentration lower time, film surface is more smooth and the content of V element is also lower.Work as Na
2siO
3the lower height of concentration, film surface is more coarse and the content of V element is also higher.
The Na of table 7 different concns
2siO
3the content of V element in the green rete generated
2.5Na
2siO
3on the impact of green rete and basal body binding force intensity
The Na of different concns
2siO
3generate ceramic film bonding force as shown in Figure 9, when add Na
2siO
3when concentration is respectively 6g/L, 8g/L and 10g/L, the bonding force of the rete of Sample A 4, A2, A5 is respectively 24N, 30N and 27N, can find out, along with Na
2siO
3the increase of concentration, the bonding force intensity first increases and then decreases of matrix and rete, because work as Na
2siO
3concentration lower time, absorption discharge centers comparatively small amt, strength of electric field is lower, is adsorbed onto the Al (OH) of rete
4 -jelly and NH
4vO
3less, the region that melting occurs is less, so bonding force strength ratio is lower; Work as Na
2siO
3concentration when being 8g/L, by Na
2siO
3the quantity of the absorption discharge centers provided is more, and strength of electric field is high, and the disruptive critical voltage of reaction reduces, and melt region is comparatively large, and bonding force intensity is also larger: work as Na
2siO
3concentration higher time, on the one hand, too much V
2o
5at film surface, and anti-passage cannot be entered into; On the other hand, strength of electric field is too high, causes temperatures at localized regions too high, the melting phenomenon repeatedly in subrange occurs, so bonding force intensity can reduce to some extent.
2.6Na
2siO
3on the corrosion proof impact of green rete
As can be seen from Figure 10 and table 8, work as Na
2siO
3concentration when being 6g/L, E
corr, I
corrand R
pbe respectively-1.29V, 1.85 × 10
-7a/cm
2with 0.03 × 10
7Ω/cm
2.Work as Na
2siO
3concentration when being 10g/L, E
corr, I
corrand R
pbe respectively-0.72V, 1.42 × 10
-9a/cm
2with 0.006 × 10
7Ω/cm
2.The E of rete
corralong with Na
2siO
3the increase of concentration, I
corrfirst reduce to increase afterwards, the R of rete
pfirst increases and then decreases.Na is worked as in this explanation
2siO
3concentration when being 8g/L, its corrosion resisting property is best.Because the porosity of the solidity to corrosion of rete and rete, thickness and tiny crack quantity etc. are relevant, work as Na
2siO
3concentration lower time, the rete of generation is thinner, and its tight zone is also thinner, so its corrosion resisting property is poor.Work as Na
2siO
3concentration higher time the rete that generates thicker, but the aperture of micropore in rete is very large, Cl
-ion is easily via these larger apertures, so its corrosion resisting property also can reduce.
Table 8 different concns Na
2siO
3the moving electrode potential test result of the green rete generated
3.1KF is on the impact of green Film color
As shown in figure 11, when the concentration of KF is 0.4g/L, the color of Sample A 6 rete is greyish-green to the exterior appearance of the green rete of the KF generation of different concns, surperficial smoother, densification, but edge section color distribution is not very even; When the concentration of KF is 0.6g/L, the color of Sample A 7 rete is light green, and edge section is more coarse, and color distribution is not too even, and there is a small amount of blackspot.This is because according to the discharge principle of Albella impurity center, the increase of KF concentration, improves the specific conductivity of electrolytic solution, O atom and NH
4vO
3be adsorbed on specimen surface, form the discharge centers of impurity, thus produce the electric discharge of plasma body, the heat energy that micro-arc breakdown is formed makes the surface of matrix produce melting, sintering, this is easy to the combination of matrix and O atom, be conducive to formation and the growth of rete, when the concentration of KF is lower, be adsorbed on the NH on surface
4vO
3few, the Film color of generation is more shallow, when the concentration of KF is higher, and too much NH
4vO
3be deposited in surface, hinder the diffusion of O and the further reaction with matrix, make sintering insufficient, thus cause film surface more loose, and there is the spot in subrange.
3.2KF is on the impact of green oxidation film layer thickness
The thickness of the green rete that different concns KF generates is as shown in table 9, and when the KF concentration of adding is respectively 0.4g/L, 0.5g/L and 0.6g/L, the thicknesses of layers of Sample A 6, A2 and A7 is respectively 11 μm, 15 μm and 22 μm.As can be seen from Table 9, F
-as the negative ion that size is minimum, the specific conductivity of electrolytic solution can be significantly improved, thus add the strength of electric field of electrolytic solution, be of value to the formation of rete.Meanwhile, accelerate the speed of response of the aluminium of oxygen and melting, aluminum oxide can be allowed to be oxidized better, accelerate the speed of growth of rete.F
-be conducive to formation and the growth of tight zone, and the thickness of rete increases with the increase of KF concentration, therefore, can judge that the thickness of rete tight zone increases.
The thickness of the green rete of the KF generation of table 9 different concns
3.3KF is on the impact of green rete phase composite
The XRD figure spectrum of the green rete of the KF generation of different concns as shown in figure 12.As can be seen from the figure, along with the rising of KF concentration, the relative intensity at No. 4 peaks first reduces rear increase, the relative intensity first increases and then decreases at No. 6 peaks, and the variation tendency of other peak value is not clearly.Therefore, Al can be judged
3the content of V first reduces rear increase, and be difficult to judge V
2o
5the change of content.Due to Al
3v is present in film surface, is conducive to the elastic strength and the hardness that improve rete.
3.4KF is on the impact of green rete microscopic appearance
The surface microscopic topographic of the green rete of the KF generation of different concns as shown in figure 13.When the concentration of KF is 0.4g/L, the micropore of film surface is more, and the aperture difference between micropore is apart from larger, maximum diameter reaches about 6um, minimum is less than 1um, but their cross-distribution and distribution more even, fine and close, macro morphology shows as film surface smoother.When the concentration of KF is 0.6g/L, the micropore of film surface is more, and the generally comparatively large and very irregular in aperture, macro morphology shows as film surface color distribution in subrange uneven, and more coarse.This may be because F
-the specific conductivity of electrolytic solution can be significantly improved, when KF concentration is higher, because the strength of electric field of specimen surface is too high, cause temperature also higher, individual pulse energy is excessive, and the melt substance sputtering of generation is violent and scope is wider, so the micro-pore diameter of formation is larger and irregular.
In the green rete of the KF generation of different concns, the content of V element is as shown in table 10.As can be seen from table 10 and Figure 11, in green rete, the content of V element diminishes afterwards along with the increase of KF concentration first increases.
The content of V element in the green rete of the KF generation of table 10 different concns
3.5KF is on the impact of green rete and basal body binding force intensity
The bonding force intensity of the green rete of the KF generation of different concns as shown in figure 14, as can be seen from Fig. 4 and Figure 14, when the KF concentration of adding is respectively 0.4g/L, 0.5g/L and 0.6g/L, the bonding force intensity of Sample A 6, A2 and A7 is respectively 24N, 30N and 30N.When KF concentration is 0.4g/L, because concentration is less, do not significantly improve the specific conductivity of electrolytic solution, the strength of electric field of matrix surface is also less, and rete is also thinner, so bonding force is little.When KF concentration is 0.6g/L, because concentration is comparatively large, the specific conductivity of electrolytic solution significantly improves, the fine and close Zeng Bianhou of rete, and the local area of melting zone also increases, and therefore, bonding force increases.
3.6KF is on the impact of differential arc oxidation film layer corrosion resisting property
The moving electrode potential curve of the green rete of the KF generation of different concns as shown in figure 15.As can be seen from Figure 15 and table 11, when the concentration of KF is 0.4g/L, E
corr, I
corrand R
pbe respectively-0.89V, 1.11 × 10
-7a/cm
2with 0.08 × 10
7Ω/cm
2.When the concentration of KF is 0.6g/L, E
corr, I
corrand R
pbe respectively-0.72V, 2.82 × 10
-7a/cm
2with 0.01 × 10
7Ω/cm
2.The E of rete
corralong with the increase of KF concentration, I
corrfirst reduce to increase afterwards, the R of rete
pfirst increases and then decreases.This illustrates when the concentration of KF is 0.5g/L, and its corrosion resisting property is best.Along with the increase of KF concentration, the thickness of the tight zone of rete also increases thereupon, and its corrosion resisting property is also corresponding to be mentioned
[93].But when KF concentration is larger, in rete, the aperture of micropore is comparatively large, causes rete more loose, thus reduces the solidity to corrosion of rete.
The moving electrode potential test result of the green rete that table 11 different concns KF generates
4 brief summaries
(1) along with NH
4vO
3the rising of concentration, the color of rete deepens gradually, and in rete, the aperture of micropore becomes large gradually, and the thickness of rete linearly increases within the specific limits, and the bonding force of rete and matrix becomes large gradually, reduces again after the corrosion resisting property of rete first increases.Draw by analyzing contrast: work as NH
4vO
3concentration when being 6g/L, film quality is best.
(2) along with Na
2siO
3the rising of concentration, the color of rete shoals from light to dark again, works as Na
2siO
3when concentration is higher, rete just face is more coarse, and the thickness of rete linearly increases within the specific limits, the bonding force first increases and then decreases of rete and matrix, reduces again after the corrosion resisting property of rete first increases.Draw by analyzing contrast: work as Na
2siO
3concentration when being 8g/L, film quality is best.
(3) along with the rising of KF concentration, the color of rete shoals from light to dark again, and the thickness of rete increases within the specific limits gradually, constant after the bonding force of rete and matrix first increases within the specific limits, reduces again after the corrosion resisting property of rete first increases.Draw by analyzing contrast: when the concentration of KF is 0.5g/L, film quality is best.
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.
Claims (7)
1. aluminum alloy differential arc oxidation a method for green rete, it is characterized in that, comprises step as follows:
(1) select aluminium alloy as matrix, preparation electrolyte system, the composition concentration of electrolytic solution is: ammonium meta-vanadate 3-9g/L, water glass 4-12g/L, potassium hydroxide 2.0-6.0g/L; Potassium monofluoride 0.3-0.6g/L, glycerol 3-6mL/L, pH8-10;
(2) aluminum alloy surface electrolytic solution after the cleaning carries out differential arc oxidation process, and electrical parameter is: forward voltage 400-450V, and negative voltage is 30-80V; Frequency is 300-500Hz; Positive and negative dutycycle is 20-40%, 15-25% respectively; Control temperature less than 60 degrees Celsius, the treatment time is 15 minutes.
2. aluminum alloy differential arc oxidation according to claim 1 the method for green rete, it is characterized in that, described in step (1), aluminium alloy is 6063 aluminium alloys.
3. aluminum alloy differential arc oxidation according to claim 1 the method for green rete, it is characterized in that, in step (1), the composition concentration of electrolytic solution is: water glass 6-10g/L, potassium hydroxide 2.0-6.0g/L; Potassium monofluoride 0.5g/L, ammonium meta-vanadate 5-8/L.
4. aluminum alloy differential arc oxidation according to claim 3 the method for green rete, it is characterized in that, in step (1), the composition concentration of electrolytic solution is: water glass 8g/L, potassium hydroxide 4g/L; Potassium monofluoride 0.5g/L, ammonium meta-vanadate 6g/L.
5. aluminum alloy differential arc oxidation according to claim 1 the method for green rete, it is characterized in that, in step (2), electrical parameter is: forward, negative voltage are 440V, 40V respectively, and frequency is 400Hz; Positive and negative dutycycle is 30%, 20% respectively.
6. the Al-alloy parts prepared of method according to claim 1.
7. the application of the arbitrary described method of claim 1-5 in aluminum alloy surface is painted.
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| CN115305552A (en) * | 2022-08-05 | 2022-11-08 | 河南大学 | Electrolyte formula and method for preparing high-corrosion-resistance magnesium alloy micro-arc oxidation coating based on electrolyte formula |
| CN117626377A (en) * | 2024-01-25 | 2024-03-01 | 山东理工大学 | Aluminum alloy surface carbon nano tube composite film and micro-arc oxidation preparation process thereof |
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| CN109023473A (en) * | 2018-11-02 | 2018-12-18 | 中国科学院兰州化学物理研究所 | A kind of differential arc oxidation method in non-aqueous solution electrolysis liquid system |
| CN115305552A (en) * | 2022-08-05 | 2022-11-08 | 河南大学 | Electrolyte formula and method for preparing high-corrosion-resistance magnesium alloy micro-arc oxidation coating based on electrolyte formula |
| CN117626377A (en) * | 2024-01-25 | 2024-03-01 | 山东理工大学 | Aluminum alloy surface carbon nano tube composite film and micro-arc oxidation preparation process thereof |
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