The battery container steel band of a kind of plated nickel-cobalt/nickel/nickel-cobalt multilayer film
Technical field
The utility model relates to steel band of a kind of plating multilayer film that is used for battery container and preparation method thereof.
Background technology
In recent years, along with people are more and more higher to the requirement of battery performance, the performance of the case material of batteries such as alkaline Mn cell, Ni-MH battery and lithium-ion-power cell also more and more receives numerous professional persons' concern.Battery case is as the container of a sealing, because the filling of severe corrosive electrolyte requires it that enough strong decay resistance is arranged.In addition, battery case also serves as battery plus plate current-collecting body in alkaline Mn cell, so the electrical conductivity of property material for battery shell also is a key factor that influences battery performance.
Chinese patent CN1600904A discloses a kind of nickel-plated deeply-draw steel strip and production method thereof, continuous electroplating 2~3 μ m nickel films on mild-carbon steel strip, handle by heat treatment and laser-impact, make nickel coating and base material form nickel/iron diffusion layer, obtain the corrosion-resistant steel band of desired thickness then by finishing procedure by thermal diffusion.The coating percentage elongation is not less than 8%, and decay resistance reaches 8 grades, has good percentage elongation and decay resistance, is mainly used in the heavy-duty battery shell.
U.S. Pat 4760002 discloses a kind of battery steel band and production method thereof, the one deck of plating one deck nickel film on mild-carbon steel strip, and then plating earlier cobalt thin film, and the process heat diffusion treatment forms the alloyed steel strip of nickeliferous-cobalt or nickel-cobalt-iron diffusion layer at last.Under equal conditions, with the battery case of this steel band deep-draw, compare with the nickel plating battery case, the memory property of alkaline Mn cell has improved 30%, and the discharge performance of battery also has raising by a relatively large margin simultaneously.The battery steel shell that its reason is to contain cobalt can effectively reduce the internal resistance of battery, and decay resistance is better.
Japanese patent laid-open 10-172521 communique, spy open and disclose a kind of plating nickel-cobalt alloy coating in the flat 10-152522 communique, battery container steel band of perhaps first nickel plating nickel plating again-cobalt alloy coating and preparation method thereof.Because the hardness height of nickel-cobalt alloy when punch process, easily generates very thin crackle in the coating, cause that coating surface is uneven, roughness ratio is bigger, thereby improved and the contacting of positive electrode, improved battery performance.
Present many research work mainly concentrate on the aspects such as process optimization of electroplating steel strip with nickel or nickel-base alloy, and have obtained considerable progress.But the accurate control of the optimization of coating structure and coating crystallite dimension also is the effective way that improves battery container steel band decay resistance and punching performance.
The utility model content
The purpose of this utility model provides the steel band that a kind of plating has multi-layer film structure, multi-layer film structure by the preparation various grain sizes, the performance of whole coating is optimized, and then obtained having the battery container steel band of excellent corrosion resisting performance and punching performance.
The purpose of this utility model realizes by following manner.
The battery container steel band of a kind of plated nickel-cobalt/nickel/nickel-cobalt multilayer film is substrate with the steel band, the two sides of steel band respectively plating nickel-cobalt/nickel/nickel-cobalt multilayer film.The bottom of multilayer film is a nickel-cobalt alloy coating, and thickness is 0.1~0.5 μ m; The intermediate layer is a nickel coating, and thickness is 0.5~2 μ m; The top layer is a nickel-cobalt alloy coating, and thickness is 0.1~0.5 μ m.
The plated underlayer layer crystal particle size of multilayer film is 50~100nm; Crystallite dimension 0.2~0.5 μ m of intermediate layer coating; The crystallite dimension of top layer coating is 20~50nm.
The bottom of multilayer film and the cobalt content on top layer are 0.5~5wt%, and wherein most preferred content is 2wt%.
The steel band that is used for the plated nickel-cobalt/nickel/nickel-cobalt of battery container described in the utility model, its coating structure as shown in Figure 1, adopt mild-carbon steel strip as substrate (1), the bottom of multilayer film (2) is nanocrystalline nickel-cobalt alloy coating, intermediate layer (3) is the brilliant nickel coating of micron, and top layer (4) are nanocrystalline nickel-cobalt alloy coating.Because the utility model has adopted multi-layer film structure, and utility model people has carried out well-designed to the thickness of the film of each layer and the crystallite dimension that constitutes film, make material of the present utility model demonstrate the advantageous property that obviously is different from the conventional monolayers material aspect the decay resistance of mechanics, electricity, magnetics and material.Multi-layer film structure has higher intensity, can improve the adhesion of substrate and coating, reduce the space in the coating, can improve the distribution of coating internal stress and crackle, thereby improved the decay resistance of material, reduced the contact resistance of box hat inwall and positive electrode.
The nanocrystalline nickel-cobalt alloy coating of bottom of the present utility model (2) is prepared from by the technology of pulse plating, and its crystallite dimension is 50~100nm.Bottom (2) nickel-cobalt alloy the is particles filled slit of the micron-sized intergranule of base material, and form good engagement with the brilliant particle of micron of base material, so improved the adhesion between coating and the substrate.The thickness of the utility model bottom (2) nickel-cobalt alloy coating is elite in the scope of 0.1~0.5 μ m, be because when thickness of coating during less than 0.1 μ m, nanocrystalline nickel-cobalt alloy crystal grain can not the micron-sized intergranule of fine filling base material the slit, can not form effective engagement, cause the adhesion of coating and substrate to descend, also will cause leaking the iron rate increases; When thickness of coating during, can cause cost to increase greater than 0.5 μ m.
Micron brilliant nickel coating in intermediate layer of the present utility model (3) is prepared from by the technology of direct current electrode position, and this method is the preparation method of a kind of routine in the art, and its crystallite dimension is 0.2~0.5 μ m.Thickness is elite in the scope of 0.5~2 μ m, is because when nickel coating thickness during less than 0.5 μ m, can not reach anticorrosion ability preferably; When nickel coating thickness during, can cause the increase of cost greater than 2 μ m.
The nanocrystalline nickel-cobalt alloy coating in top layer of the present utility model (4) is prepared from by the impulse jet electroplating technique, and its crystallite dimension is 20~50nm, and thickness of coating is 0.1~0.5 μ m.Because top layer nanocrystalline nickel-cobalt alloy coating crystallite dimension is less, so case hardness is than higher.Surface hardness is higher following advantage: 1, can reduce the surface tear of steel band in striking out the battery steel shell process; 2, stamping forming the time, can reduce frictional resistance, make the efficient of punching press improve; 3, be convenient to battery smooth and easy flowing in assembling line, avoid the head of battery or bottom to produce scuffing; 4, easy inner surface at battery case forms trickle crackle, and the positive electrode material that helps battery fully contacts with box hat, reduces the contact resistance of battery.In addition, the nanocrystalline nickel-cobalt alloy coating in top layer of the present utility model also has characteristics such as surfacing, densification, porosity be low, makes nanocrystalline nickel-cobalt alloy coating have excellent corrosion resisting performance.Its mechanism is as follows: on the one hand, because the formation of corrosion surface passivating film is subjected to DIFFUSION CONTROLLED, the diffusion rate of nanocrystalline coating is higher than the brilliant coating of micron, so the corrosion resistance of nanocrystalline coating is higher than the brilliant coating of micron; On the other hand, because passivation reaction starts from the lattice defect of coating surface, and nanocrystalline coating has the crystal boundary and the dislocation of higher density, so nanocrystalline coating has the passivating film nucleating point of higher density, makes nanocrystalline coating have high-quality passivating film and lower rate of corrosion.
To sum up analyze, the multi-layer film structure that the utility model adopted, crystallite dimension of each layer and thickness all have special design, have remedied shortcoming separately again mutually in the advantage that merges each monofilm.The plating that the utility model provides has the steel band of multi-layer film structure coating, possesses the excellent properties of the following aspects at least: 1, have good bonding force between coating and the steel band; 2, this bottom and top layer are nanocrystalline nickel-cobalt alloy coating in the utility model, middle multi-layer film structure for the brilliant nickel coating of micron makes the coating structure densification, porosity is low, effectively reduce the possibility that battery box hat coating spot corrosion in use takes place, improved the decay resistance of battery case; 3, the top layer of multilayer film is a nickel-cobalt alloy coating, experimental results show that the nickel-cobalt alloy coating that is applied to the battery container inwall than nickel coating, has improved the memory property of battery.This may be because cobalt element has participated in cell reaction, has formed the oxide or the hydroxide of cobalt, and is favourable to the memory property of battery.In addition, the utility model has also adopted the impulse jet electroplating technique, further improved the hardness of top layer coating, the inner surface of battery container forms a large amount of blind cracks in the punch forming process of battery case, it is more abundant to make that positive electrode material contacts with battery container, has reduced the contact resistance of battery container.
Bottom nickel-cobalt alloy coating hardness can reach HV 260 ± 10 in the utility model, and wherein the coating hardness of nickel coating can reach HV 180 ± 10; The coating hardness of top layer nickel-cobalt alloy coating can reach HV 310 ± 10.
Technology of the present utility model is to be substrate with the steel band, on the two sides of steel band respectively plating nickel-cobalt/nickel/nickel-cobalt multilayer film, the nickel-cobalt alloy coating of bottom prepares by the mode of pulse plating, the nickel coating in intermediate layer prepares by the mode of direct current electrode position, and the mode that the nickel-cobalt alloy coating on top layer is electroplated by impulse jet prepares.Each goes on foot electroplating time is to be determined by the required thickness of each coating.
Described technology may further comprise the steps and process conditions:
(1) plating front surface preliminary treatment
Adopt conventional plating pre-treating method, carry out surface active after the high temeperature chemistry oil removing.
Degreasing fluid is: NaOH 70g/L
Na
2CO
3 40g/L
Na
3PO
4 25g/L
Na
2SiO
3 10g/L
Degreasing fluid temperature: 80~90 ℃
The oil removing time: 3~5min
After the oil removing fully, specimen surface is rinsed well, put into activator then and activate with distilled water;
Activator is: 1~5vol%HCl
Soak time: 0.5~2min.
(2) pulse plating nickel-cobalt alloy bottom
Plating bath comprises: NiSO
47H
2O 180~300g/L
NiCl
2·6H
2O 40~60g/L
CoSO
4·7H
2O 1~15g/L
H
3BO
3 25~35g/L
Cumarin 0.05~0.15g/L
Formaldehyde 0.2~0.3ml/L
Pulse plating technological parameter: average current density: 3~6A/dm
2
PH value: 3.5~4.5
i
on: 5~50ms
i
off: 5~250ms
Temperature: 40~60 ℃
Anode: nickel-cobalt alloy plate;
(3) direct current electrode position nickel coating
Plating bath comprises: NiSO
47H
2O 180~300g/L
NiCl
2·6H
2O 30~50g/L
H
3BO
3 30~50g/L
Direct current electrode position technological parameter: current density: 3~6A/dm
2
PH value: 3.5~4.5
Temperature: 40~60 ℃
Anode: nickel plate;
(4) impulse jet is electroplated nickel-cobalt alloy coating
Plating bath comprises: seven water and nickelous sulfate NiSO
47H
2O 180~300g/L
Six water and nickel chloride NiCl
26H
2O 40~60g/L
Seven water and cobaltous sulfate CoSO
47H
2O 1~15g/L
Boric acid H
3BO
325~35g/L
ALS 0.4~2g/L
Butynediols 0.4~0.5ml/L
Asccharin 0.8~1g/L
Impulse jet electroplating technological parameter: peak current density: 47~82A/dm
2
Dutycycle: 15~25%
Plating bath spray speed: 1000~1500L/h
PH value: 2.5~3.5
Temperature: 55~65 ℃
Anode: nickel-cobalt alloy pipe;
(5) it is clean with distilled water flushing to plate good steel band, oven dry then, insulation dehydrogenation.
Insulation dehydrogenation in described (5) step is plating steel band well to be placed be incubated under 150~200 ℃ of conditions, to remove the hydrogen that produces in the coating in electroplating process.
Description of drawings
Fig. 1 is the coating structure schematic diagram of the utility model nickel-cobalt/nickel/nickel-cobalt multilayer film, wherein 1 is substrate (steel band), 2 is the bottom (the nanocrystalline nickel-cobalt alloy coating of pulse plating) of above-mentioned multilayer film, 3 is the intermediate layer (the brilliant nickel coating of direct current electrode position micron) of above-mentioned multilayer film, and 4 is the top layer (the brilliant nickel-cobalt alloy coating of impulse jet electroplating nano) of above-mentioned multilayer film.Fig. 2 is the SEM figure of the nanocrystalline nickel-cobalt alloy surface topography of bottom.Fig. 3 is the SEM figure of the brilliant nickel surface pattern of intermediate layer micron.Fig. 4 is the SEM figure of the nanocrystalline nickel-cobalt alloy surface topography in top layer.Fig. 5 is the utility model preparation of product process flow diagram flow chart.
Following examples are intended to illustrate the utility model rather than to further qualification of the present utility model.
Embodiment
The specific embodiment
The thickness of selecting for use Shanghai Baoshan Iron and Steel Company joint-stock company to produce is that the BDCK battery special steel strip of 0.25mm is as electroplated substrates.Its chemical composition is: C:0.029% (% represents percetage by weight, down together), Si:0.02%, Mn:0.2%, P:0.09%, S:0.003%, Al:0.06%.
One, plating front surface preliminary treatment
For coating is combined with substrate well, before plating, above-mentioned steel band is carried out following surface preparation.Because the surface of used steel band is more smooth, do not need polishing and machine glazed finish before the nickel plating, directly carry out oil removal treatment.This example adopts chemical high temperature deoiling method.
Degreasing fluid is: NaOH 70g/L
Na
2CO
3 40g/L
Na
3PO
4 25g/L
Na
2SiO
3 10g/L
Degreasing fluid temperature: 80 ℃
The oil removing time: 3min
After the oil removing fully, specimen surface is rinsed well, put into activator again and activate with distilled water.
Activator is formed: 3vol%HCl
Soak time: 1min.
Two, pulse plating nickel-cobalt alloy bottom
Plating bath is: NiSO
47H
2O 250g/L
NiCl
2·6H
2O 50g/L
CoSO
4·7H
2O 5g/L
Boric acid H
3BO
330g/L
Cumarin 0.1g/L
Formaldehyde 0.25ml/L
Pulse plating technological parameter: average current density: 5A/dm
2
PH value: 3.5
i
on: 25ms
i
off: 100ms
Temperature: 50 ℃
Anode: nickel-cobalt alloy plate
Electroplating time: 30s
Under these conditions, preparing one deck crystallite dimension is 50~100nm, and thickness is the nickel-cobalt alloy coating of 0.5 μ m.
Three, direct current electrode position nickel coating
Plating bath is: NiSO
47H
2O 200g/L
NiCl
2·6H
2O 40g/L
H
3BO
3 40g/L
Direct current electrode position technological parameter: current density: 4A/dm
2
PH value: 3.5
Temperature: 50 ℃
Anode: nickel plate
Electroplating time: 75s
Under these conditions, preparing one deck crystallite dimension is 0.2~0.5 μ m,, thickness is the nickel coating of 1.0 μ m.
Four, impulse jet is electroplated nickel-cobalt alloy coating
Plating bath is: NiSO
47H
2O 300g/L
NiCl
2·6H
2O 50g/L
CoSO
4·7H
2O 5g/L
H
3BO
3 30g/L
ALS 1.2g/L
Butynediols 0.5ml/L
Asccharin 0.8g/L
Impulse jet electroplating technological parameter: peak current density: 50A/dm
2
Dutycycle: 20%
Plating bath spray speed: 1400L/h
Temperature: 55 ℃
PH value: 3.5
Anode: nickel-cobalt alloy pipe
Electroplating time: 10s
Under these conditions, preparing one deck crystallite dimension is 20~50nm, and thickness is the nickel-cobalt alloy coating of 0.4 μ m.
Five, cleaning, drying
The steel band that plating is good is clean with distilled water flushing, oven dry then.
Six, insulation dehydrogenation
The steel band that plating is good places and is incubated under 200 ℃ of conditions, to remove the hydrogen that produces in the coating in electroplating process.
By above embodiment, on the steel band two sides, prepare nickel-cobalt that thickness is 1.8 μ m/nickel/nickel-cobalt multilayer film.
Related coating crystallite dimension in the present embodiment by measuring with Japanese D/MAX-RB X-ray diffraction instrument of science, calculates according to the Scherrer formula again.
The thickness of coating of mentioning in the present embodiment measures by the Alpha-StepIQ step instrument that U.S. KLA Tencor company produces.
The coating surface hardness of mentioning in the present embodiment measures by the HV-1000 micro Vickers.
Performance test
Produce sample in the following manner, as a comparative example.
Comparative example preparation method: select substrate identical and plating pre-treating method for use with embodiment.Adopt the method for direct current electrode position, equal plating one layer thickness is the micron brilliant nickel coating (conventional nickel coating) of 2.2 μ m on the substrate two sides, and electroplating technology is as follows:
One, matt nickel plating
Plating bath is: seven water and nickelous sulfate NiSO
47H
2O 200g/L
Six water and nickel chloride NiCl
26H
2O 40g/L
Boric acid H
3BO
340g/L
Direct current electrode position technological parameter: current density: 4A/dm
2
PH value: 3
Temperature: 50 ℃
Anode: nickel plate
Electroplating time: 60s
Two, semi-glossy nickel plating
Plating bath is: seven water and nickelous sulfate NiSO
47H
2O 280g/L
Six water and nickel chloride NiCl
26H
2O 40g/L
Boric acid H
3BO
340g/L
Asccharin 0.8g/L
Direct current electrode position technological parameter: current density: 4A/dm
2
PH value: 4
Temperature: 50 ℃
Anode: nickel plate
Electroplating time: 100s
Three, cleaning, drying
The steel band that plating is good is clean with distilled water flushing, oven dry then.
Four, the obtained material of comparative example is done the insulation dehydrogenation and handled, temperature is 200 ℃, temperature retention time 3 hours.At last the gained steel band is annealed and cold-rolling treatment.
The material that embodiment and comparative example are made strikes out battery case, with identical preparation method and prescription assembling LR6 alkaline battery, makes the contrast test of battery performance then.Following table 1 is finished product battery performance test comparative analysis report.
Table 1 finished product battery performance test comparative analysis report