CN1500916A

CN1500916A - Gradient composite deposite for continuous casting crystallizer copper plate and production method thereof

Info

Publication number: CN1500916A
Application number: CNA021454825A
Authority: CN
Inventors: 王隆寿; 李宁; 张立; 武刚; 陈军; 黎德育; 杜明华; 刘向
Original assignee: Harbin Institute of Technology; Baoshan Iron and Steel Co Ltd
Current assignee: Harbin Institute of Technology; Baoshan Iron and Steel Co Ltd
Priority date: 2002-11-19
Filing date: 2002-11-19
Publication date: 2004-06-02
Anticipated expiration: 2022-11-19
Also published as: CN1229525C

Abstract

The gradient composite coating layer for continuous casting crystallizer copper plate contains Co in 50-79.9 vol%, Ni in 20-49.9 vol% and Al2O3 grains of size below 0.5 micron in 0.1-10 vol%. The coating is in gradient structure with outwards gradually increased Co and Al2O3 content and decreased Ni content. During production of the composite coating layer, inside amino sulfonate system with Al2O3 grains in 10-80 g/L and size below 0.5 micron added, gradient Co-Ni-Al2O3 coating is deposited onto copper or copper alloy via specific Al2O3 grain activating pre-treatment and electric deposition process. In the activating pre-treatment, FC-4 cation surfactant is used as ion dispersant. The composite Co-Ni-Al2O3 coating may be used in various high temperature wear resisting fields widely.

Description

Continuous casting mold copper gradient composite coating and its preparation method

Technology

Technology...

End of life casting mold is mainly produced in the meniscus at the hot thermal interface Stress will be fast or slow the mold produces permanent deformation, thus shortening the lifetime of crystallizer Life. In order to prevent the slab surface defects and extending the life of the mold, usually in the copper mold Surface of the plate surface treatment, since the presence of the coating can protect the copper substrate to reduce wear, reduce Recrystallization low copper levels, thereby reducing deformation of the copper plate, copper plate to extend the service life.

Meanwhile, the inner coating alloy plating quality is to determine the type and mold service life and replacement frequency Rate is a key factor. The crystallizer coating life limit state in two forms: (1) coating mill Loss: the lower part of the mold, solidified billet steel shell with copper contact points, under the action of the friction, the coating Wear, until the base material is exposed, that is life limit situation. (2) coating the crack: the crystallizer Because the higher upper temperature of molten steel, coating under high temperature appears recrystallization, grain growth, combined Power down; the copper plate under the action of thermal stress in the coating near the meniscus of molten steel inevitably generates heat fatigue Lo cracks, local reflex-like cracks appear, even a partial loss. This situation generally occurs in copper Over the course of the board. ...

Although nickel-plated copper despite high hardness than 180 ~ 250HV, chemical stability, sealing ability Very strong, and can plated to 3 ~ 8mm, but the hardness of the wear billet stand still, so the coating Life is not high. Electroplated nickel plus chromium plating process complexity, mainly by nickel layer from abrasion effect, and thus its Coating lifetime is still limited, and the thin porous chrome plating at high temperature and corrosive environment in addition to not Resistant to corrosion, nickel and chrome plating easily produce between potential corrosion. As a slab mold plating Layer of nickel-iron alloy iron content is generally controlled within 3% to 12%, its hardness at room temperature, 320 ~ 420HV, wear resistance increased, but compared with the nickel layer, nickel-iron alloys drawback is chemical stability Lower, especially at high temperature conditions of hot corrosion or erosion prone to rapid expansion of the crack; and Increased brittleness and high internal stress, and the bonding strength of the base metal is also affected, Ni Iron plating heat alternating poor performance. In addition, the electrolyte used to deposit this alloy also has the unstable Given the characteristics, easy to cause decrease in yield. These factors explain why the application of the nickel-iron ratio Nickel-cobalt alloy is restricted causes. Ni-Co alloy, while retaining the physical and chemical properties of nickel-plated outside, There are two major advantages: significantly improved hardness and high hardness at high temperatures; chemical stability, especially It is a very good thermal stability. Slab mold is an ideal coating, but the high cost of Co, Thus the coating costs are high, while its high hardness and alloy coating stress, alternating resistance properties of the coating Also poor, so that the Ni-Co alloy application is limited. ...

The purpose of the present invention for the prior art and to provide a new continuous casting mold Coating material and preparation method. Which uses electro-deposition method, the deposition of cobalt-nickel alloy coating thickness when Alloy introduced a second reinforcing phase dispersed Al₂O ₃Improve the slip plane dislocations in the resistance movement, Inhibition of proliferation of dislocations, grain boundaries to improve the structure of the state, and enhance the grain boundary strengthening effect, and made Gradient alloy, the Ni-Co-Al₂O ₃. Cobalt alloy coating, Al₂O ₃. Cobalt alloy coating, Al...

. Cobalt alloy coating, Al...₂O ₃Particles.

The cobalt-nickel-based composite coating with gradient structure, Co, Al₂O ₃The content of the coating from the inside to the Gradually increases in the direction outside, and Ni is gradually decreased.

The invention also provides a nickel-cobalt-based composite plating plating method, that is added 10 ~ 80g / L, an Al particle size less than 0.5 micron₂O ₃Particles Sulphamate system, the use of specific The Al₂O ₃Particle activation pretreatment and electro-deposition process will be Co-Ni-Al₂O ₃Gradient composite coating deposited on Copper and copper alloy substrate.

The process of the present invention comprises the steps of using:

The process of the present invention comprises the steps of using:...₂O ₃The process of the present invention comprises the steps of using:...

The Al₂O ₃Particles 20Vol.% NaOH solution was boiled for 2 hours, washed with distilled water, and then 1:1 H₂SO ₄At a temperature of 50 ℃ for 2 hours, washed repeatedly with distilled water, adding 0.5 ~ 1g / L FC-4 cationic surface active, ultrasonic and mechanical agitation method fully dispersed.

(2) electrodeposited nickel-cobalt-based Al₂O ₃(2) electrodeposited nickel-cobalt-based Al...

(2) electrodeposited nickel-cobalt-based Al...

Nickel sulfamate 300 ~ 350g / L

NaCl 5～10 g/L

Carboxamide 0.5 ~ 50 mL / L

FC-4 4.0～8.0ml/L

Carboxamide 0.5 ~ 50 mL / L...

Al ₂O ₃(＜1μm) 10～80 g/L

J _k 1～15 A/dm ²

pH 3.5～4.5

T 50～60 ℃

Carboxamide 0.5 ~ 50 mL / L...

(3) varying the current density is achieved using a continuous gradient. From 15A/dm²Gradually reduced to 1A/dm²To achieve Co, Al₂O ₃The content of the coating from the inside outward direction gradually increased, while^NiThen gradually Reduced.

Sulfamate plating salt selection system, the advantage is Sulphamate solubility in water, Metal deposition speed, suitable for high current density operation, bath stability easy to manage, and access to The coating uniformity, detailed, low internal stress and depth of throwing good ability to meet the requirements of plating thickness.

BRIEF DESCRIPTION

Figure 1 is a schematic diagram of the composite plating apparatus;

Figure 1 is a schematic diagram of the composite plating apparatus;...

Figure 4 is an amino acid, cobalt-nickel alloy electrodeposition system, the proportion of cobalt ions in the electrolyte solution and deposition Layer of cobalt content relationships;

Figure 5 sediments cobalt content and Vickers microhardness relations;

Figure 6 is a alloy of cobalt content of internal stress of the coating;

Figure 7 is the particle concentration in the bath and the relationship between volume content of the coating;

Figure 8 is AL₂O ₃Content on the hardness of the coating;

Figure 9 is a FC-4 content of the composite particle;

Figure 10 is an organic additive saccharin, sodium lauryl sulfate on cobalt-nickel alloy electrolyte polarization Impact;

Figure 10 is an organic additive saccharin, sodium lauryl sulfate on cobalt-nickel alloy electrolyte polarization Impact;...

Figure 13 is a PH value of the particle content of the coating effect;

Figure 14 is a current density on the cobalt content of the coating;

Figure 15 is a current density on the cobalt coating internal stress;

Figure 16 is the current density of the coating amount of the composite particles;

Figure 17 is a temperature on the cobalt content of the coating;

Figure 18 is a temperature on the internal stress of the coating of cobalt;

Figure 19 is a temperature on the cobalt content of particles in the coating;

Figure 20 is a stirring speed on particle composite coating amount of influence;

Figure 20 is a stirring speed on particle composite coating amount of influence;...

Figure 23 is the content of Ni plating layer with depth variation;

Figure 24 is a composite coating of Al content changes.

Specific embodiments

Electrolyte formula:

Electrolyte formula:...

NaCl 5～10 g/L

Carboxamide 0.5 ~ 50 mL / L

FC-4 4.0～8.0ml/L

THF 0.5 ~ 2.0g / L

Al ₂O ₃(＜1μm) 10～80 g/L

Of which:

Co-Al ₂O ₃Based composite plating bath optimal formula and process conditions orthogonal experiment with knot Fruit: Because the coating thickness requirements in 2 ~ 3mm, so we chose cobalt sulfamate [Co (H₂NSO ₃)2·4H ₂O] disposes salts. It has a deposition speed, the resulting coating uniformity, detailed, Low internal stress, bath stability and easy maintenance. In order to determine the optimum basic recipe and bath Process conditions, we did a series of experiments.

After a lot of testing, we selected 55 ℃ temperature T is doing L9 (35) orthogonal test, other Factor level parameters, see Table 1, coating thickness control at 100μm. Specimen selection cathode annealed (500 ℃ above) copper sheet, the elastic modulus of 120KN/mm2. The solution is to go through with 0.1 ~ 0.2A/dm²2h small current electrolysis to remove Fe²⁺、Zn ²⁺、Cu ²⁺Other metal ion impurities, Then heated to about 50 ℃ 2h sufficiently adsorbed with activated carbon to remove organic impurities, and finally filtered. PH of the bath with an amino acid and sodium hydroxide solution was adjusted. Plating process using cathodic shift method, Moving speed of 70 times / min.

Table 1 Factors in the table

Bisects content and appearance of the coating internal stress. The results shown in Table 2. Stress points on the table Following formula:

Stress points = 10 - (σ-0.02) × 30 (5-5)

Stress points higher stress is smaller. Total calculated as follows:

Total = Appearance points × 0.2 + stress points × 0.8 (5-6)

Thus the higher the score the better. Table 2 I, II, III, respectively, of the water at three different factors Total score obtained flat and, I / 3, H / 3, III / 3, respectively, of different levels of the factors The average of the total score, R is very poor value. From table I, II, III values see, A factors and 3 levels Factor 1 levels of factor B C D factors and 3 levels and 3 levels E Factor 1 level best result A3B1C3D3E1 for the best combination. Compare poor get: RC> RE> RB> RA> RD, instructions on the stress and Level by the combined effect of the appearance of formamide, J_k, NaCl, sulfamic acid cobalt, pH decreased sequentially. Tool Body as follows: (1) adding formamide internal stress of the coating and appearance has a significant impact. When the Dosage is 10mL / L, the coating of the internal stress is small, and the appearance of the coating with silver white, delicate are Uniform; when adding an amount of 20mL / L, the stress is further reduced, but with the added amount of formamide into Further increased, the coating will be white brittle, so the dosage should be controlled at 10mL / L. (2) Current density Degree of internal stress is also great. From the experimental results it can be seen with the internal stress of the coating cathode current Increased density increases, the deposition rate and the internal stress from the viewpoint of the current density should be controlled at 3A/dm ...², NaCl, sulfamic acid cobalt, pH decreased sequentially. Tool Body as follows: (1) adding formamide internal stress of the coating and appearance has a significant impact. When the Dosage is 10mL / L, the coating of the internal stress is small, and the appearance of the coating with silver white, delicate are Uniform; when adding an amount of 20mL / L, the stress is further reduced, but with the added amount of formamide into Further increased, the coating will be white brittle, so the dosage should be controlled at 10mL / L. (2) Current density Degree of internal stress is also great. From the experimental results it can be seen with the internal stress of the coating cathode current Increased density increases, the deposition rate and the internal stress from the viewpoint of the current density should be controlled at 3A/dm ...^-The coating also increases the presence of stress, but Cl^-The presence of increased Bath conductivity, improving the dissolution of the anode, so in order to ensure the normal anodic dissolution, can be added Add 10g / L of NaCl. (4) increase the salt concentration allows the main use of higher current densities, from And get a higher deposition rate. (5) pH value of relatively weaker. susceptible to pH below 4.2 Is a pinhole, and higher than 5.5 is easily hydrolyzed cobalt mixed hydroxide generated in the coating, so the pH controlling Built in 4.5 is more appropriate. In summary, the optimum specification can be drawn:

Cobalt sulfamate 600g / L NaCl 10g / L

Formamide 10mL / L J_k 3A/dm ²

pH 4.5 T 55℃

Orthogonal test results in Table 2

	Amino acid cobalt NaCl formamide pH J_k (A) (B) (C) (D) (E)	Outside Watch Minute	Stress (MPa	Should Force Minute	Overall Minute
	Amino acid cobalt NaCl formamide pH J_k (A) (B) (C) (D) (E)	Outside Watch Minute	Stress (MPa	Should Force Minute	Overall Minute	1 2 3 4 5 6 7 8 9	1 1 1 1 1 1 3 2 2 3 1 2 3 3 1 2 1 3 1 2 2 3 1 3 3 2 2 2 2 2 3 1 3 3 1 3 3 1 2 2 3 2 2 1 3	6 7 9 7 8.5 8.5 9.5 8 7	80 80 40 3 3 100 50 20 80 6 5	8.2 8.2 9.4 9.6 7.6 9.1 10 8.2 8.6 5	7.76 7.96 9.32 9.08 7.78 8.98 9.90 8.16 8.32
I. II. III	25.04 26.74 23.70 25.16 26.98 25.84 26.62 25.26 25.10 26.22 26.41 24.22 28.30 26.06 24.06					1 2 3 4 5 6 7 8 9		6 7 9 7 8.5 8.5 9.5 8 7	80 80 40 3 3 100 50 20 80 6 5	8.2 8.2 9.4 9.6 7.6 9.1 10 8.2 8.6 5	7.76 7.96 9.32 9.08 7.78 8.98 9.90 8.16 8.32
I. II. III						I/ 3 II /3 II I/ 3	8.35 8.91 7.90 8.39 8.99 8.61 8.87 8.42 8.37 8.74 8.80 7.97 9.43 8.69 8.02
R	0.45 0.94 1.53 0.32 0.97					I/ 3 II /3 II I/ 3

By detecting the actual performance of the coating showed that the amino acid electrolyte, the use of plate pump or Under the conditions of the air mixing device, a method using electrodeposition of copper or copper alloy substrate prepared Co-Ni-Al₂O ₃Gradient composite coating.

Electrolyte and the choice of the concentration of metal ions: the same cathodic current density, from the amino sulfonamide Electrolyte salt obtained in Co-Ni alloy deposited layer of Co content is higher than the sulfate electrolyte; At the same Co content, and from the resulting sulfamate electrolyte Co-Ni alloy deposited layer Sulphate electrolyte obtained in hardness than the Co-Ni alloy deposited layer of high hardness (see Figure 2); From two kinds of electrolyte deposition Co-Ni alloy, its internal stress increased with Co content of sediments increases Plus the rise, the electrolyte obtained from the sulphate of Co-Ni alloy layer deposited from the internal stress ratio Sulfamate electrolyte obtained in Co-Ni alloy deposited layer is much higher internal stress. Electrolysis Solution of cobalt and nickel content and sedimentary layers of cobalt content relationship shown in Figure 3. The proportion of cobalt ions in the electrolyte and Shen Laminated between cobalt content in Figure 4. The present invention is selected sulfamate electrolyte, sulfamate Cobalt 200 ~ 300g / L and nickel sulfamate 300 ~ 350g / L to ensure that the total concentration of the main salt. This For repair requires high fatigue resistance wear parts has obvious advantages. ...

Electrolyte and the choice of the concentration of metal ions: the same cathodic current density, from the amino sulfonamide Electrolyte salt obtained in Co-Ni alloy deposited layer of Co content is higher than the sulfate electrolyte; At the same Co content, and from the resulting sulfamate electrolyte Co-Ni alloy deposited layer Sulphate electrolyte obtained in hardness than the Co-Ni alloy deposited layer of high hardness (see Figure 2); From two kinds of electrolyte deposition Co-Ni alloy, its internal stress increased with Co content of sediments increases Plus the rise, the electrolyte obtained from the sulphate of Co-Ni alloy layer deposited from the internal stress ratio Sulfamate electrolyte obtained in Co-Ni alloy deposited layer is much higher internal stress. Electrolysis Solution of cobalt and nickel content and sedimentary layers of cobalt content relationship shown in Figure 3. The proportion of cobalt ions in the electrolyte and Shen Laminated between cobalt content in Figure 4. The present invention is selected sulfamate electrolyte, sulfamate Cobalt 200 ~ 300g / L and nickel sulfamate 300 ~ 350g / L to ensure that the total concentration of the main salt. This For repair requires high fatigue resistance wear parts has obvious advantages. ...₂O ₃Coating Component. Sedimentary layers of cobalt content and Vickers microhardness relationship shown in Figure 5, Co content within the coating should be Force of Figure 6.

Deposition of solid particles determined by: a single phase α-Al₂O ₃The chemical properties of very unreactive, it does not Soluble in water, not soluble in acid and alkali, corrosion resistance and electrical insulation, and its physical parameters are shown in Table 1.

Table 1 α-Al₂O ₃The physical parameters

Density g / cm³	Mp ℃	Boiling Point ℃	Linear expansion Coefficient × 10^-6(l/ k)	Specific heat (KJ / Kg.k )	Microhardness (Hv)	Compressive strength (MPa)
Density g / cm³	Mp ℃	Boiling Point ℃	Linear expansion Coefficient × 10^-6(l/ k)	Specific heat (KJ / Kg.k )	Microhardness (Hv)	Compressive strength (MPa)	3.9～4.02	1975	3500	8	0.84	2000～2400	1470～3100

In the invention, an Al particle size less than 0.5 micron₂O ₃Granules, purity greater than 99.9%, the quality of Surface area of 1.5m²/g。

To determine the concentration of particles in the bath: The experimental results show that the composite layer deposition of Al₂O ₃Composite With the amount of Al in the bath₂O ₃The increase of the content, when the Al bath₂O ₃The content of 70g / l, the Composite volume in a stable value, the content continues to increase, for the deposition layer of Al₂O ₃Complex Aggregate amount not obvious, the present invention Select Al bath₂O ₃The concentration of 10 ~ 80g / l between (see Figure 7, Figure 8).

Select NaCl anode activator: NaCl was added later, in the bath, there Cl^-There may be Improve the conductivity of the bath, to improve the dissolution of the anode to prevent the anode passivation. But Cl^-An increase in the Will increase the internal stress of the coating, therefore, the present invention determined based bath (Co-Al₂O ₃Composite plating Basic bath system) the optimum formulation and process conditions a series of tests to determine the amount of added NaCl in 5 ~ 10g / l between.

Selected fluorocarbon (FC-4) a cationic surfactant: FC-4 with high chemical stability And high surface activity, the ability of acids, alkalis, strong oxidizing agents and high temperatures. Surfactants in the cathode Interfacial adsorption, the particles take the same charge, so that the accelerated particles dispersed mutually exclusive, anti- Only particles reunion. Experimental results show that the amount of particles eutectoid with the FC-4 concentration significantly increased while Improved. But in order to control the particle content in the coating proper, the present invention controls the concentration of FC-4 Is 4.0 ~ 8.0ml / L. FC-4 content of the particle composite of Figure 9.

Selected formamide as stress relieving agents: adding formamide, and the internal stress of the coating appearance Significant effect, when the amount of 10ml / l ~ 20ml / l, the coating of the internal stress is small, and Coating Appearance silvery white, fine uniform. But with the added amount of formamide is further increased, plating Whitish brittle layer, the present invention is added to control the amount of formamide 0.5 ~ 50ml / l between.

THF selected as wetting agents: sodium lauryl sulphate is an anionic surfactant Resistance agent, due to its presence, solid-liquid interfacial tension, the hydrogen bubbles at the cathode surface is hard to stay, Thereby to prevent pinhole effect coating, it is also known to prevent pinhole THF agent. But The presence of sodium dodecyl sulfate, the deposition of cobalt-nickel alloy of a certain hindered, the present Ming selected sodium dodecyl sulfate dosage is 0.5 ~ 2g / L between adding sodium dodecyl sulfate Sodium after cathodic polarization curves in Figure 10.

Pre-treatment process:

Chemical degreasing process: NaOH 30 ~ 40g / L, Na₃PO ₄.12H ₂O 30～40g/L，Na ₂CO ₃ 30～40g/L，NaSiO ₃5 ~ 10g / L, the surface active agent 0.5 ~ 2g / L, temperature 80 ~ 90 ℃, the Between 30 minutes.

Activation process: 10% (Vol.%), H₂SO ₄Solution at ambient temperature for 1 to 2 minutes Minutes.

Al ₂O ₃Particle activation pre-treatment:

Al ₂O ₃In the preparation process of introducing a variety of harmful impurities, so before plating into the slot, Must be cleaned and activated. Specific activation process is as follows:

The Al₂O ₃Particles 20Vol.% NaOH solution was boiled for 2 hours, washed with distilled water, and then 1:1 H₂SO ₄At a temperature of 50 ℃ for 2 hours, washed repeatedly with distilled water, adding 0.5 ~ lg / L FC-4 cationic surface active, ultrasonic fully dispersed.

Electroplating process parameters

J _k 1～15A/dm ²

pH 3.5～4.5

T 50～60℃

Stirring conditions: plate pump agitation or air agitation 45 ~ 55r/min

pH value control: normal Ni plating solution, pH value is generally controlled in 3 to 6, the high will lead to Ni Ni ions form a basic salt precipitation will cause hydrogen bubbles at the cathode surface retention, crisp coating, Binding force is not good, pinholes, rough crystals and other illnesses; too low cathodic less efficient, easy out Now pinholes. Control the PH value of the present invention is 3.5 to 4.5, Figure 11 to Figure 13.

Current density control: With the cathode current density increases, as the polarization of the cathode increases, Fine crystalline coating are becoming closer. But the current density is too large, the internal stress of the coating increases, and As a serious lack of metal ions near the cathode, the entire cathode surface shaped like a sponge to produce a hydrophobic Loose coating; current density is too low, the cathode polarization is small, coarse recrystallized grains coating. The present invention Deposition rate and the internal stress from the viewpoint of the current density J_kShould be controlled within 1 ~ 15A/dm²So, see Figure 14 to 16.

The temperature control bath: the bath temperature rises, the coating can not only reduce the stress, but also the coating Ductility becomes good, but also can improve the permissible limit of the cathode current density, increase the cathode current efficiency Rate. But other conditions constant, the bath temperature is too high, will lead salts hydrolyzed to produce hydroxide The tendency of precipitation increases. Second, because the hydrogen content increases, the hydrogen bubbles on the surface of the cathode unit stranded Will be increased, prone coating pinholes. Therefore, in the present invention is controlled bath temperature between 55 ~ 60 ℃, Figure l7 ~ 19.

Stirring conditions on the choice of: mixing bath, can accelerate Co, Ni ion diffusion, narrow Poor concentration, increase the current density. Enhance mixing, to prevent the vicinity of the surface of the cathode Co, Ni ion concentration Decreased, can also be solved by the pH value and temperature generated by the hydroxide precipitation. But mixing Speed is too high, the flow of the impact force increases the cathode surface, the particles easily adhere to the surface of the cathode, The stirring speed in the present invention is selected between 45 ~ 55r/min, Figure 20.

Gradient coating preparation process: Because of the cobalt-nickel alloy deposition process, deposition of cobalt Controlled by diffusion, while nickel deposition is controlled by the activation. So when moving to a negative polarization potential is cobalt Deposition is suppressed, and deposition of nickel is promoted. By this electrodeposition process, gradually Reduce the cathode current density, the cobalt content increased with increasing the thickness of the deposited layer is increased, nickel The content gradually decreased. Meanwhile Al₂O ₃Of the alloy layer deposition and also having a current density Given relationship, that is, as the current density increases, the deposition amount increases gradually at first, when the maximum Value (point J_k＝3A/dm ²) After the sharp decline. Based on the above current density on cobalt, nickel, Al₂O ₃Deposition effect, we can during the electrolysis to control the current density of cobalt, nickel, Al₂O ₃The thickness of the deposited layer at different levels, and ultimately makes cobalt and Al₂O ₃Surface of the deposition layer Enrichment maximum quantity of material to achieve a gradient structure, surface properties of the reinforcing material.

Surface of the deposition layer Enrichment maximum quantity of material to achieve a gradient structure, surface properties of the reinforcing material....²Surface of the deposition layer Enrichment maximum quantity of material to achieve a gradient structure, surface properties of the reinforcing material....₂O ₃Gradient composite coating. With In order to control when the initial electrolytic plating and coating, low internal stress and substrate binding force, so the first mining Starting with a small current density plating. In the latter part of the electrolysis process, the current density of 3A/dm²When, Al₂O ₃Sink Accumulated amount reaches the maximum, but for the Al₂O ₃Particles are completely coated on the metal substrate and makes the cobalt Content to further increase the content of the surface, the final stage in the use of small currents plating. Specific gradient plated Preparation of layers shown in Figure 21.

Gradient Coating characterization: Co, Ni, Al₂O ₃Content increased with depth coating are shown in Figure 22 to 24.

70Co29Ni-Al ₂O ₃Gradient composite coatings prepared: electrolyte formula and electroplating process:

Cobalt sulfamate 300 ± 10g / L

Nickel sulfamate 300 ± 10g / L

NaCl 10g/L

Formamide 20ml / L

FC-4 4.0ml/L

Sodium dodecyl sulfate 0.5g / L

Al ₂O ₃(＜1μm) 80g/L

J _k 1～15A/dm ²

pH 4.5±0.2

T 55±5℃

Stirring conditions: plate pump mixing 50r/min

Plating time: 43 to 44 hours;

Plating Specifications: 70Co29Ni-Al₂O ₃Gradient composite coating Coating Co content from the inside out (59.4 ~ 70.0%), Ni content (40 to 28.5%), Al content (0.6-1.5%) range.

70Co29Ni-Al ₂O ₃The performance of the gradient composite coating with 92Co-8Ni alloy coating and the Term performance comparison in Table 4:

Table 4 Co-Ni-Al₂O ₃Composite gradient coating (70Co29Ni-Al₂O ₃) Of the performance

Project	70Co-29Ni-Al ₂O ₃Graded Coating	92Co-8Ni alloy coating
Project	70Co-29Ni-Al ₂O ₃Graded Coating	92Co-8Ni alloy coating	Thickness:	1.5～2.5mm	0.5～2.5mm
Hardness:	Electroforming after 600 ~ 650 Hv	200±30Hv	Thickness:	1.5～2.5mm	0.5～2.5mm
Hardness:	Electroforming after 600 ~ 650 Hv	200±30Hv	Tensile strength:	RT ~ 400 ℃ temperature range is: 687 ~ 248MPa;	RT ~ 300 ℃ temperature range Of 550 ~ 320 MPa
Elongation:	RT ~ 400 ℃ temperature range is: 2-3%	2～4％	Tensile strength:	RT ~ 400 ℃ temperature range is: 687 ~ 248MPa;	RT ~ 300 ℃ temperature range Of 550 ~ 320 MPa
Elongation:	RT ~ 400 ℃ temperature range is: 2-3%	2～4％	Bond strength:	＞250MPa	＞230MPa
Expansion coefficient:	In the range of 0 ~ 200 ℃ within (12.0 ~ 14.5) × 10^-6/K	13.9×10 ^-6/K	Bond strength:	＞250MPa	＞230MPa
Expansion coefficient:	In the range of 0 ~ 200 ℃ within (12.0 ~ 14.5) × 10^-6/K	13.9×10 ^-6/K	Thermal conductivity:	Thermal conductivity:...	Thermal conductivity:...

	Further improve the thermal conductivity of the coating inside Sex. 200 ℃, 61.4W/m.k, large Yu Ni: 47.5W/m.k; 300 ℃ when 50.7W/m.k, greater than Ni: 45.0W/m.k;
			High temperature resistant: 300 ℃	Load: 200N, reciprocating frequency: 150 Beats / min, stroke: 50mm / second, Test time: 20min Wear: 15.1mg	Load: 200N, reciprocating frequency: 150 beats / min, stroke: 50mm / Times, test time: 20min Wear: 37.0mg
Corrosion resistance:	0.5N H ₂SO ₄Sulfuric acid solution weightlessness: 2.85mm / Year	0.5N H ₂SO ₄Loss of sulfuric acid solution Weight: 10.0mm / Year	High temperature resistant: 300 ℃

Seen from the table, the present invention is prepared by Co-Ni-Al₂O ₃Composite coating has a very good High performance, can meet a variety of areas using high temperature resistant, making the composite coating in industry Widely used, is bound to bring considerable economic benefits. Materials used in the chemical reagent ammonia removal Sulfonate easy to get cheaper than cobalt, cobalt sulfamate although it is more expensive, but in the industrialized production into This is not high, because the bath is stable and durable, cost-effective, all other reagents were mild, Good environmental compatibility, non-toxic side effects, basically no pollution to the environment is conducive to electroplating cleaner production. And the process operating conditions simple, commonly used plating apparatus only minor improvements can be used for the composite plating Preparation of layers. ...

Claims

Composite coating has a very good High performance, can meet a variety of areas using high temperature resistant, making the composite coating in industry Widely used, is bound to bring considerable economic benefits. Materials used in the chemical reagent ammonia removal Sulfonate easy to get cheaper than cobalt, cobalt sulfamate although it is more expensive, but in the industrialized production into This is not high, because the bath is stable and durable, cost-effective, all other reagents were mild, Good environmental compatibility, non-toxic side effects, basically no pollution to the environment is conducive to electroplating cleaner production. And the process operating conditions simple, commonly used plating apparatus only minor improvements can be used for the composite plating Preparation of layers. ...₂O ₃Particles.
(2) according to claim 1, wherein the inner copper mold for continuous casting of cobalt and nickel-based composite coating Coating, wherein the cobalt-nickel-based composite coating with gradient structure, Co, Al₂O ₃The content in the coating by the In the outward direction gradually increased, while Ni is gradually reduced.
3 as claimed in claim 2, wherein the nickel-cobalt-based composite plating coating, characterized in that, Supplemented with 10 ~ 80g / L, an Al particle size less than 1.0 microns₂O ₃Particles sulfamate system, Al using specific₂O ₃Particle activation pretreatment and electro-deposition process will be Co-Ni-Al₂O ₃Gradient composite plating Layer is deposited on the copper and copper alloy substrate.
4 as claimed in claim 3, wherein the cobalt-nickel-based composite coating plating method, wherein said particle Al diameter less than 1.0 microns₂O ₃Particles before activation treatment, using FC-4 as cationic surfactant The ionic dispersing agent, activating pretreatment steps of:

The Al₂O ₃Particles 20Vol.% NaOH solution was boiled for 2 hours, washed with distilled water, then 1: 1 H-₂SO ₄At a temperature of 50 ℃ for 2 hours, washed repeatedly with distilled water, adding 0.5 ~ 1g / L FC-4 cationic surface active, ultrasonic fully dispersed.
5 as claimed in claim 3 or 4, wherein the nickel-cobalt-based composite plating plating method, wherein the electrical sink Cobalt-nickel-based Al plot₂O ₃The electrolysis process recipe is:

Cobalt sulfamate 200 ~ 300 g / L

Nickel sulfamate 300 ~ 350 g / L

NaCl              5～10           g/L

Carboxamide 0.5 ~ 50 mL / L

FC-4              4.0～8.0        ml/L

THF 0.5 ~ 2.0 g / L

Al ₂O ₃(＜1μm)  10～80          g/L

J _k               1～15           A/dm ²

pH                3.5～4.5

T                 50～60          ℃

Stirring conditions: air agitation or mixing board pump
As claimed in claim 3 or 4, wherein the nickel-cobalt-based composite plating coating, wherein the gradient The implementation uses continuously changing the current density, from 15A/dm²Gradually reduced to 1A/dm²To achieve Co, Al₂O ₃The content of the coating from the inside outward direction gradually increased, while Ni is gradually reduced.