A high-performance copper-aluminum composite row with a large width-thickness ratio and its preparation method

Abstract

The present invention relates to the technical field of composite materials, and particularly relates to a high-performance copper-aluminum composite row with a large width-thickness ratio and a preparation method thereof. The high-performance copper-aluminum composite row includes a copper cladding layer and an aluminum core matrix, and an interatomic bonding layer is formed between the copper cladding layer and the aluminum core matrix. The copper-aluminum composite conductive row of the present invention has high tensile strength, high bonding strength, and high conductivity. The bonding between copper and aluminum reaches the metallurgical bonding state. The thickness of the bonding layer is less than 3μm, the shear bonding strength is ≥100MPa, the copper volume ratio is 18% - 32%, the tensile strength is 195 - 255MPa, the elongation is ≥25%, and the volume conductivity is ≥71.5% IACS; when the product width is ≥80mm, the minimum thickness can reach 2mm; when the product width is 50 - 60mm, the minimum thickness can reach 1.5mm; when the product width is ≤40mm, the minimum thickness can reach 1mm.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to a high-performance copper-aluminum composite row with a large width-thickness ratio and a preparation method thereof. Background Art

[0002] The copper-aluminum composite row is a composite conductor material with copper on the outer layer and aluminum in the core, and is a laminated composite material formed by a special process; compared with the copper row, it has the advantages of weight reduction and cost reduction, and compared with the aluminum row, it has the advantages of small contact resistance and good anti-creep performance. According to the structure, taking the aluminum substrate as the standard, the copper-aluminum composite materials include types such as partial copper cladding, single-sided copper cladding, double-sided copper cladding, and side full copper cladding. According to the preparation process, there are solid-solid welding, solid-solid pressing (hydrostatic extrusion, rolling, drawing, forging, etc.), solid-liquid composite (casting-rolling method), and liquid-liquid composite (continuous casting composite method). Among them, the copper-aluminum composite products with bonding performance meeting the market mass usage requirements are mainly GB / T 30586-2022 "Copper-Clad Aluminum Flat Bars" and GB / T 32468-2015 "Copper-Aluminum Composite Plate Strip", and the corresponding preparation processes are the continuous casting composite method and the casting-rolling method respectively. The copper-aluminum composite row prepared by the continuous casting composite method has a side full copper cladding structure type with better structural integrity. When applied in the field of electric power and electrics, it can better match the subsequent bending, processing, and electroplating requirements, and has better current-carrying effect and corrosion resistance.

[0003] For the copper-aluminum composite row with side full copper cladding, the bonding layer thickness of the GB / T 30586 product disclosed in Chinese invention patent 201611114257.5 "A High Bonding Strength Copper-Aluminum Composite Conductive Material and Its Preparation Method" is 5-35 μm, the shear bonding strength ≥ 45 MPa, the tensile strength is 100-130 MPa, the elongation rate ≥ 25%, and the volume conductivity ≥ 71.1% IACS. Combining the process methods disclosed in Chinese invention patent 201010225901.2 "A Preparation Process of Copper-Clad Aluminum Composite Busbar" and Chinese invention patent 201310304077.3 "A Hole Rolling Process of Copper-Clad Aluminum Row", after continuous casting composite, rolling, and drawing, when the width of the GB / T 30586 product ≥ 80 mm, the minimum thickness can reach 6 mm; when the product width is 50-60 mm, the minimum thickness can reach 5 mm; when the product width ≤ 40 mm, the minimum thickness can reach 4 mm.

[0004] Due to the fact that thinner products have higher current-carrying density, better cost performance and better weight reduction effect, in the actual selection process, more and more power and electrical design manufacturers tend to choose products with a larger width and a smaller thickness, that is, products with a larger width-to-thickness ratio, in order to reduce weight and cost. Moreover, due to the requirements of high-end manufacturing fields such as aerospace, rail transit, new energy vehicles, and power equipment, higher requirements are put forward for key mechanical and electrical performance indicators such as the bonding strength, tensile strength, conductivity, and processing performance of copper-aluminum composite bars. The existing technology products are difficult to meet the usage requirements.

[0005] For products with a relatively thin size and a large width-to-thickness ratio, when prepared by the existing publicly available continuous rolling or drawing process, problems such as edge cracking or plane orange peel and cracking of the product are likely to occur. And when performing longitudinal bending (along the rolling processing direction), problems such as cracking are likely to occur. The above problems are more prominent when the strength of the aluminum core material is higher, and it is difficult to meet the current market demand. Summary of the Invention

[0006] In view of the above deficiencies of the existing technology, the purpose of the present invention is to provide a high-performance copper-aluminum composite bar with a large width-to-thickness ratio and its preparation method.

[0007] To achieve the above purpose, the technical solutions adopted are as follows:

[0008] One of the purposes of the present invention is to provide a high-performance copper-aluminum composite bar with a large width-to-thickness ratio, which includes a copper-clad layer and an aluminum core matrix, that is, a copper-clad aluminum structure. An interatomic bonding layer is formed between the copper-clad layer and the aluminum core matrix, and the thickness of the bonding layer is less than 3μm. When the width of the high-performance copper-aluminum composite bar with a large width-to-thickness ratio ≥ 80mm, the width-to-thickness ratio is 20 - 60; when the width is 50 - 60mm, the width-to-thickness ratio is 20 - 40; when the width ≤ 40mm, the width-to-thickness ratio is 10 - 40.

[0009] Further, the aluminum core matrix includes aluminum, silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials, and the rare earth alloy materials include cerium, lanthanum, neodymium, and praseodymium.

[0010] Furthermore, the mass fractions of silicon, iron, copper, magnesium, zinc, and boron in aluminum are respectively: silicon 0.03% - 0.07%, iron 0.40% - 0.60%, copper 0.20% - 0.40%, magnesium 0.04% - 0.10%, zinc 0.04% - 0.10%, boron 0.01% - 0.02%; the mass fractions of cerium, lanthanum, neodymium, and praseodymium in aluminum are respectively: cerium 0.06% - 0.09%, lanthanum 0.01% - 0.03%, neodymium 0.01% - 0.03%, praseodymium 0.007% - 0.015%.

[0011] One of the purposes of the present invention is to provide a preparation method for the high-performance copper-aluminum composite bar with a large width-to-thickness ratio, which includes the following steps:

[0012] (1)Continuous casting composite

[0013] The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept static at 1150 - 1250 °C for 3 - 6 h;

[0014] After the electrolytic aluminum ingot is melted, alloying materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium, praseodymium are added in sequence. The mass fractions of silicon, iron, copper, magnesium, zinc, boron in aluminum are respectively: silicon 0.03% - 0.07%, iron 0.40% - 0.60%, copper 0.20% - 0.40%, magnesium 0.04% - 0.10%, zinc 0.04% - 0.10%, boron 0.01% - 0.02%; The mass fractions of cerium, lanthanum, neodymium, praseodymium in aluminum are respectively: cerium 0.06% - 0.09%, lanthanum 0.01% - 0.03%, neodymium 0.01% - 0.03%, praseodymium 0.007% - 0.015%. Keep warm at 750 - 850 °C, degas and skim twice to obtain aluminum liquid;

[0015] The copper liquid and aluminum liquid are respectively filled into the composite furnace through different channels, and copper - aluminum continuous casting direct composite forming is carried out to prepare a copper - aluminum composite billet, obtaining a square billet with a side length of 60 - 150 mm, and the thickness of the bonding layer of the billet is 5 - 15 μm;

[0016] (2)Rolling the copper - aluminum composite billet

[0017] Through a two - high reversing mill, pass - type reciprocating rolling is carried out, with horizontal rolling and vertical rolling alternating. That is, the first, third, fifth, seventh and ninth passes (add subsequent passes according to actual requirements) are horizontal rolling, and the second, fourth, sixth and eighth passes are vertical rolling (add subsequent passes according to actual requirements); The thickness of the rolled copper - aluminum composite strip is 10 - 14 mm, and the width after rolling is 0.5 - 2.5 mm larger than the width of the final product;

[0018] (3)Intermediate drawing and intermediate heat treatment

[0019] The incoming material continues to be drawn or coiled and drawn. The reduction of thickness in the first pass of drawing is 20% - 35%, and the reduction of thickness in subsequent drawing is 10% - 30%; The reduction of width is 0.05 - 1.0 mm per pass, and the process drawing is carried out until the thickness is 3.0 - 5.5 mm; Then the first intermediate heat treatment is carried out; Continue to carry out multiple draws until the size of the last process draw before the finished product specification, and the size of the process draw is 0.2 - 0.8 mm larger than the thickness of the final finished product and 0.05 - 0.3 mm larger than the width of the final finished product; Then the second intermediate heat treatment is carried out;

[0020] (4)Final drawing and final heat treatment

[0021] Final drawing: when the width of the product ≥ 80 mm, the minimum thickness can reach 2 mm; when the width of the product is 50 - 60 mm, the minimum thickness can reach 1.5 mm; when the width of the product ≤ 40 mm, the minimum thickness can reach 1 mm. Final heat treatment: the thickness of the bonding layer of the finished product is less than 3 μm, the shear bonding strength ≥ 100 MPa, the copper volume ratio is 18% - 32%, the tensile strength is 195 - 255 MPa, the elongation ≥ 25%, and the volume conductivity ≥ 71.5% IACS.

[0022] (5)Surface treatment

[0023] Use 180 - 240 - mesh abrasive belts for surface grinding and wire drawing for 1 - 2 groups, and each group of grinding includes two grindings.

[0024] Furthermore, in step (2), the reduction of thickness in the first pass of blanking flat rolling is 35% - 60%, the reduction of thickness in a single pass of the remaining flat rolling is controlled between 10% - 35%, the reduction of thickness in a single pass of vertical rolling is controlled between 3% - 20%, and the total number of rolling passes is 10 - 25 passes.

[0025] The beneficial effects of adopting the above technical solutions are as follows: If the reduction of thickness in the rolling process is inappropriate, it will lead to the inability to reach the final rolling size, or it will require too many passes to achieve, resulting in an increase in the number of required rolling rolls and cost; if the reduction of thickness in the drawing process is inappropriate, it will lead to problems such as edge cracking or plane orange peel and cracking of the product, and the product will be scrapped and unable to be used continuously.

[0026] Furthermore, in step (3), the first intermediate heat treatment is at 185 - 205 °C for 1 - 2 h; the second intermediate heat treatment is at 165 - 185 °C for 1 - 2 h.

[0027] Furthermore, in step (4), the final heat treatment of the finished product is at 230 - 255 °C for 0.5 - 1.5 h.

[0028] Still further, in step (5), the angles between the abrasive belts for the two grindings and the length direction of the product are 30 - 60° and 120 - 150° respectively.

[0029] The beneficial effects of adopting the above further technical solutions are as follows: The wire drawing pattern of the grinding has an angle with the rolling and drawing processing direction, weakening the adverse effect of the texture on bending in the specified direction. While taking into account the connection contact resistance and bending processing performance, it improves the radiation heat dissipation coefficient, enhances the current - carrying capacity, and improves the adhesion of the subsequent coating.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1)The present invention discloses a copper - aluminum composite row with high tensile strength, high bonding strength, high conductivity, ultra - thin, and large width - thickness ratio;

[0032] (2) The present invention adopts a rare earth aluminum alloy formula to achieve high tensile strength and high electrical conductivity of the copper-aluminum composite busbar. Through the cooperation of subsequent drawing and intermediate heat treatment processes, the negative impacts of the high strength of the core material and alloying elements on the processing and bonding strength of ultra-thin materials are eliminated;

[0033] (3) Through the comprehensive regulation of rolling, drawing processing amount, and multiple heat treatments, the present invention realizes a relatively thin bonding layer thickness, thereby achieving high bonding strength of the copper-aluminum composite busbar;

[0034] (4) The present invention meets various bending requirements such as horizontal bending, vertical bending, side bending, and twist bending, and improves the adhesion of the coating;

[0035] (5) The present invention does not require the use of expensive and complex continuous rolling mills, and only uses existing two-high rolling mills and some intermediate drawing dies to quickly prepare large width-thickness ratio and ultra-thin copper-aluminum composite busbars at low cost.

[0036] For the copper-aluminum composite conductive busbar with high tensile strength, high bonding strength, and high electrical conductivity of the present invention, the bonding between copper and aluminum reaches the metallurgical bonding state, the bonding layer thickness is less than 3μm, the shear bonding strength is ≥100MPa, the copper volume ratio is 18% - 32%, the tensile strength is 195 - 255MPa, the elongation is ≥25%, and the volume conductivity is ≥71.5%IACS. When the product width is ≥80mm, the minimum thickness can be 2mm; when the product width is 50 - 60mm, the minimum thickness can be 1.5mm; when the product width is ≤40mm, the minimum thickness can be 1mm. Specific Embodiments

[0037] The present invention will be described below in conjunction with examples. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] Product specifications of the copper-aluminum composite busbar: width 120mm, thickness 2mm:

[0040] 1. Continuous casting and composite

[0041] The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept warm and static at 1200 - 1250°C for 4h.

[0042] After the electrolytic aluminum ingots are melted, alloy materials such as silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials such as cerium, lanthanum, neodymium and praseodymium are added in sequence. The mass fractions respectively accounting for aluminum are: silicon 0.055%, iron 0.500%, copper 0.220%, magnesium 0.045%, zinc 0.045%, boron 0.015%; the rare earth materials include elements with the following weight ratios: cerium 0.070%, lanthanum 0.015%, neodymium 0.015%, praseodymium 0.010%. Keep warm at 780 - 830 °C, degas and skim twice to obtain molten aluminum.

[0043] The copper liquid and the aluminum liquid are respectively filled into the composite furnace through different channels for direct copper-aluminum continuous casting and forming to prepare a copper-aluminum composite billet, a square billet with a side length of 135 mm, and the thickness of the bonding layer of the billet is 5 - 10 μm.

[0044] 2. Rolling the copper-aluminum composite billet

[0045] Through a two-high reversing mill, perform pass reciprocating rolling, with flat rolling and vertical rolling alternating, that is, the odd-numbered passes such as the first, third, fifth, seventh and ninth passes are flat rolling, and the even-numbered passes such as the second, fourth, sixth and eighth passes are vertical rolling. The reduction of the first pass for blooming flat rolling is 45%, and the reductions of the remaining flat rolling are 30% for the third pass, 27% for the fifth pass, 26% for the seventh pass, 25% for the ninth pass, 24% for the eleventh pass, and 19% for the thirteenth pass; the reductions of vertical rolling are 10% for the second pass, 9% for the fourth pass, 9% for the sixth pass, 8% for the eighth pass, 5% for the tenth pass, and 5% for the twelfth pass; the thickness of the copper-aluminum composite row after rolling is 13.00 mm and the width is 121.60 mm;

[0046] 3. Process drawing and intermediate heat treatment

[0047] The incoming material continues to be drawn or coiled and drawn. The reduction of the thickness of the first pass of drawing is 23% and the reduction of the width is 0.55 mm. The reduction of the thickness of the second pass of drawing is 22% and the reduction of the width is 0.20 mm. The reduction of the thickness of the third pass of drawing is 21% and the reduction of the width is 0.15 mm. The reduction of the thickness of the fourth pass of drawing is 19% and the reduction of the width is 0.15 mm; at this time, the thickness of the process drawing is 5.00 mm and the width is 120.55 mm; perform the first intermediate heat treatment, keep warm at 195 °C for 1.5 h; continue the fifth pass of drawing with a reduction of the thickness of 24% and a reduction of the width of 0.20 mm, the sixth pass of drawing with a reduction of the thickness of 18% and a reduction of the width of 0.10 mm, the seventh pass of drawing with a reduction of the thickness of 11% and a reduction of the width of 0.10 mm. At this time, it is the last process drawing size before the finished product specification, with a thickness of 2.60 mm and a width of 120.15 mm, 0.60 mm larger than the final finished product thickness and 0.15 mm larger than the final finished product width; then perform the second intermediate heat treatment, keep warm at 170 °C for 1.5 h;

[0048] 4. Finished product drawing and finished product heat treatment

[0049] The reduction of thickness in finished product drawing is 23%, and the reduction of width is 0.15 mm. At this time, the width of the product is 120 mm and the thickness is 2 mm. For finished product heat treatment, it is kept at 240 °C for 1 h. The thickness of the finished product bonding layer is 0.50 - 1.50 μm, the shear bonding strength is 115 MPa, the copper volume ratio is 25%, the tensile strength is 215 MPa, the elongation is 27%, and the volume conductivity is ≥71.9% IACS.

[0050] 5. Surface treatment

[0051] Use a 230 - mesh abrasive belt for surface grinding and wire drawing in 1 group. Each group of grinding includes two grindings. The angles between the abrasive belt and the length direction of the product for the two grindings are 40° and 130° respectively. The wire - drawing pattern of grinding has an angle with the rolling and drawing processing direction, weakening the adverse effect of texture on bending in the specified direction. While taking into account the connection contact resistance and bending processing performance, it improves the radiation heat dissipation coefficient, enhances the current - carrying capacity, and increases the adhesion of the subsequent coating.

[0052] Example 2

[0053] The product specifications of the copper - aluminum composite busbar: width 50 mm, thickness 1.5 mm:

[0054] 1. Continuous casting composite

[0055] The electrolytic copper plate is melted into copper liquid and covered with charcoal and kept at 1200 - 1250 °C for static settlement for 4 h.

[0056] After the electrolytic aluminum ingot is melted, alloying materials silicon, iron, copper, magnesium, zinc, boron and rare - earth alloy materials cerium, lanthanum, neodymium, praseodymium are added in sequence. Their mass fractions in aluminum are respectively: silicon 0.060%, iron 0.450%, copper 0.210%, magnesium 0.047%, zinc 0.045%, boron 0.017%; The rare - earth materials include the following elements with weight ratios: cerium 0.080%, lanthanum 0.020%, neodymium 0.020%, praseodymium 0.012%. It is kept at 780 - 830 °C for heat preservation, degassing and slag - skimming twice to obtain aluminum liquid.

[0057] The copper liquid and aluminum liquid are respectively filled into the composite furnace through different channels for direct copper - aluminum continuous - casting composite forming to prepare a copper - aluminum composite bar blank, a square bar blank with a side length of 110 mm, and the thickness of the bar - blank bonding layer is 5 - 10 μm.

[0058] 2. Rolling the copper - aluminum composite bar blank

[0059] Through a two-high reversing rolling mill, pass rolling is carried out, with horizontal rolling and vertical rolling alternating, that is, odd-numbered passes such as the first, third, fifth, seventh, and ninth passes are horizontal rolling, and even-numbered passes such as the second, fourth, sixth, and eighth passes are vertical rolling. The reduction of the first pass for blooming horizontal rolling is 37%, and the reductions of the remaining horizontal rolling passes are 23% for the third pass, 23% for the fifth pass, 23% for the seventh pass, 22% for the ninth pass, 20% for the eleventh pass, 20% for the thirteenth pass, and 20% for the fifteenth pass; the reductions of the vertical rolling passes are 19% for the second pass, 19% for the fourth pass, 19% for the sixth pass, 18% for the eighth pass, 10% for the tenth pass, 4% for the twelfth pass, and 4% for the fourteenth pass; the thickness of the copper-aluminum composite strip after rolling is 12.90 mm and the width is 51.30 mm.

[0060] 3. Process drawing and intermediate heat treatment

[0061] The incoming material continues to be drawn or coiled and drawn. The reduction of the first pass for drawing in thickness is 27% and the reduction in width is 0.30 mm. The reduction of the second pass for drawing in thickness is 24% and the reduction in width is 0.19 mm. The reduction of the third pass for drawing in thickness is 24% and the reduction in width is 0.15 mm. The reduction of the fourth pass for drawing in thickness is 23% and the reduction in width is 0.11 mm; at this time, the thickness of the process drawing is 4.20 mm and the width is 50.55 mm; the first intermediate heat treatment is carried out, with insulation at 192 °C for 1.5 h; continue with the fifth pass for drawing in thickness with a reduction of 25% and a reduction in width of 0.19 mm, the sixth pass for drawing in thickness with a reduction of 22% and a reduction in width of 0.11 mm, the seventh pass for drawing in thickness with a reduction of 20% and a reduction in width of 0.11 mm. At this time, the last process drawing size before the finished product specification has a thickness of 1.95 mm and a width of 50.14 mm, which is 0.45 mm larger than the final finished product thickness and 0.14 mm larger than the final finished product width; then the second intermediate heat treatment is carried out, with insulation at 168 °C for 1.5 h.

[0062] 4. Finished product drawing and finished product heat treatment

[0063] The reduction of the finished product drawing in thickness is 23% and the reduction in width is 0.14 mm. At this time, the width of the product is 50 mm and the thickness is 1.50 mm; the finished product heat treatment is carried out, with insulation at 237 °C for 1 h. The thickness of the finished product bonding layer is 0.30 - 1.20 μm, the shear bonding strength is 119 MPa, the copper volume ratio is 25%, the tensile strength is 222 MPa, the elongation is 28%, and the volume conductivity is ≥72.3% IACS.

[0064] 5. Surface treatment

[0065] Use a 230-mesh abrasive belt for surface grinding and wire drawing in 1 group. Each group of grinding includes two grindings, and the angles between the abrasive belt and the length direction of the product for the two grindings are 45° and 135° respectively.

[0066] Example 3

[0067] Product specifications of copper-aluminum composite busbar: width 30 mm, thickness 1 mm:

[0068] 1. Continuous casting composite

[0069] The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept warm and static at 1200 - 1250 °C for 4 h.

[0070] After the electrolytic aluminum ingot is melted, alloying materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloying materials cerium, lanthanum, neodymium, praseodymium are added in sequence. Their mass fractions in aluminum are respectively: silicon 0.065%, iron 0.550%, copper 0.220%, magnesium 0.042%, zinc 0.045%, boron 0.015%; the said rare earth materials include elements with the following weight ratios: cerium 0.070%, lanthanum 0.022%, neodymium 0.017%, praseodymium 0.013%. Keep warm at 780 - 830 °C, degas and skim twice to obtain aluminum liquid.

[0071] The copper liquid and aluminum liquid are respectively filled into the composite furnace through different channels, and copper-aluminum continuous casting direct composite forming is carried out to prepare a copper-aluminum composite bar blank, a square bar blank with a side length of 75 mm, and the thickness of the bonding layer of the bar blank is 5 - 10 μm.

[0072] 2. Rolling the copper-aluminum composite bar blank

[0073] Through a two-high reversing mill, pass rolling is carried out, and horizontal rolling and vertical rolling are carried out alternately, that is, odd passes such as the first, third, fifth, seventh and ninth passes are horizontal rolling, and even passes such as the second, fourth, sixth and eighth passes are vertical rolling. The reduction of the first pass for blooming horizontal rolling is 41%, and the reductions of the remaining horizontal rolling are respectively 22% for the third pass, 20% for the fifth pass, 18% for the seventh pass, 18% for the ninth pass, 17% for the eleventh pass, 16% for the thirteenth pass, 15% for the fifteenth pass, 14% for the seventeenth pass; the reductions of vertical rolling are respectively 19% for the second pass, 18% for the fourth pass, 18% for the sixth pass, 17% for the eighth pass, 14% for the tenth pass, 10% for the twelfth pass, 7% for the fourteenth pass, 7% for the sixteenth pass; the thickness of the copper-aluminum composite busbar after rolling is 10.40 mm, and the width is 31.10 mm;

[0074] 3. Process drawing and intermediate heat treatment

[0075] The incoming material continues to be drawn or coil-drawn. The reduction in thickness for the first pass is 31%, and the reduction in width is 0.25 mm. The reduction in thickness for the second pass is 25%, and the reduction in width is 0.15 mm. The reduction in thickness for the third pass is 25%, and the reduction in width is 0.10 mm. The reduction in thickness for the fourth pass is 24%, and the reduction in width is 0.10 mm. At this time, the thickness of the process drawing is 3.10 mm, and the width is 30.50 mm. The first intermediate heat treatment is carried out, with insulation at 190 °C for 1.5 h. Then continue with the fifth pass of drawing, with a reduction in thickness of 27% and a reduction in width of 0.15 mm. The reduction in thickness for the sixth pass is 25%, and the reduction in width is 0.12 mm. The reduction in thickness for the seventh pass is 23%, and the reduction in width is 0.11 mm. At this time, it is the last process drawing size before the finished product specification, with a thickness of 1.32 mm and a width of 30.12 mm, which is 0.32 mm larger than the final finished product thickness and 0.12 mm larger than the final finished product width. Then the second intermediate heat treatment is carried out, with insulation at 166 °C for 1.5 h.

[0076] 4. Finish drawing and finish heat treatment

[0077] The reduction in thickness for the finish drawing is 24%, and the reduction in width is 0.12 mm. At this time, the width of the product is 30 mm and the thickness is 1.0 mm. Finish heat treatment is carried out, with insulation at 235 °C for 1 h. The thickness of the finished product bonding layer is 0.20 - 0.90 μm, the shear bonding strength is 124 MPa, the copper volume ratio is 25%, the tensile strength is 231 MPa, the elongation rate is 29%, and the volume conductivity is ≥72.7% IACS.

[0078] 5. Surface treatment

[0079] Use a 230-mesh sand belt to perform surface grinding and wire drawing in 1 group. Each group of grinding includes two grindings. The angles between the sand belt and the length direction of the product for the two grindings are 50° and 140° respectively.

[0080] Comparative example 1

[0081] The difference from Example 1 is that the first intermediate heat treatment is not carried out, and problems such as orange peel on the product surface and even cracking of the copper layer occur during the fifth pass of drawing, and the product is scrapped and cannot be used continuously.

[0082] Comparative example 2

[0083] The difference from Example 2 is that the finish heat treatment temperature is 295 °C, with insulation for 2 h, and the tensile strength of the obtained product is 185 MPa, and the tensile strength performance is unqualified.

[0084] Comparative example 3

[0085] The difference from Example 3 is that after the electrolytic aluminum ingots are melted, alloying materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloying materials cerium, lanthanum, neodymium, and praseodymium are added in sequence. Silicon is 0.020%, iron is 0.250%, copper is 0.040%, magnesium is 0.030%, zinc is 0.040%, boron is 0.010%; the rare earth materials include elements in the following weight ratios: cerium is 0.020%, lanthanum is 0.008%, neodymium is 0.007%, and praseodymium is 0.005%. The tensile strength of the obtained product is 165 MPa, and the tensile strength performance is unqualified.

[0086] Comparative Example 4

[0087] The difference from Example 1 is that the aluminum liquid does not contain rare earth elements, that is, after the electrolytic aluminum ingots are melted, alloying materials silicon, iron, copper, magnesium, zinc, and boron are added in sequence, and the contents are: silicon 0.055%, iron 0.500%, copper 0.220%, magnesium 0.045%, zinc 0.045%, boron 0.015%. The volume conductivity of the obtained product is ≥70.3% IACS, and the volume conductivity performance is unqualified.

[0088] Comparative Example 5

[0089] The difference from Example 2 is that the finished product heat treatment temperature is 330 °C and the holding time is 5 h. The tensile strength of the obtained product is 165 MPa, the bonding layer thickness is 8 μm, and the interfacial bonding strength is 65 MPa. All of the above three indexes are unqualified.

[0090] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-performance copper-aluminum composite row with a large width-thickness ratio, characterized in that, The following steps are involved: (1) Continuous casting composite The electrolytic copper plate is melted into copper liquid and kept at 1150~1250℃ for 3~6 hours; After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence, the mixture is kept at 750-850° C., and degassing and slagging are performed twice to obtain aluminum liquid. The mass fractions of silicon, iron, copper, magnesium, zinc and boron in aluminum are as follows: silicon 0.03%-0.07%, iron 0.40%-0.60%, copper 0.20%-0.40%, magnesium 0.04%-0.10%, zinc 0.04%-0.10%, and boron 0.01%-0.02%. The mass fractions of cerium, lanthanum, neodymium and praseodymium in aluminum are as follows: cerium 0.06%-0.09%, lanthanum 0.01%-0.03%, neodymium 0.01%-0.03%, and praseodymium 0.007%-0.015%. The copper liquid and aluminum liquid are respectively charged into the composite furnace through different channels, and the copper-aluminum continuous casting is directly composited to prepare the copper-aluminum composite rod billet, and the thickness of the rod billet bonding layer is 5-15μm; (2) Rolling copper-aluminum composite bar billets Through a two-roll reversible rolling mill, the groove is reciprocated and flat rolling and vertical rolling are performed alternately. The thickness of the copper-aluminum composite bar after rolling is 10~14mm, and the width after rolling is 0.5~2.5mm larger than the width of the final product; (3) Process drawing and intermediate heat treatment Drawing is performed, with the thickness reduction of the first drawing pass being 20% to 35%, and the thickness reduction of subsequent drawing passes being 10% to 30%; the width reduction per pass is 0.05 to 1.0 mm, and the process drawing is performed to a thickness of 3.0 to 5.5 mm; then the first intermediate heat treatment is performed; multiple drawing passes are continued to the last process drawing size before the finished product specification, and the process drawing size is 0.2 to 0.8 mm larger than the thickness of the final product and 0.05 to 0.3 mm larger than the width of the final product; then the second intermediate heat treatment is performed; (4) Finished product drawing and finished product heat treatment Finished product drawing: when the product width is ≥80mm, the minimum thickness can reach 2mm; when the product width is 50-60mm, the minimum thickness can reach 1.5mm; when the product width is ≤40mm, the minimum thickness can reach 1mm; finished product heat treatment: the finished product heat treatment process is 230-255℃, heat preservation 0.5-1.5h, and the finished product bonding layer thickness is less than 3μm; (5) Surface treatment Use the sanding belt to perform 1~2 sets of surface grinding and brushing, and each set of grinding includes two grindings.

2. The preparation method of the high-performance copper-aluminum composite row with large width-thickness ratio according to claim 1, characterized in that, In step (2), the thickness reduction of the first flat rolling is 35% to 60%, the thickness reduction of the remaining flat rolling is controlled between 10% and 35%, and the thickness reduction of the vertical rolling is controlled between 3% and 20%.

3. A high-performance copper-aluminum composite bar with a large width-to-thickness ratio, prepared according to the method for preparing a high-performance copper-aluminum composite bar with a large width-to-thickness ratio according to claim 1 or 2, characterized in that: The high-performance, high-width-to-thickness-ratio copper-aluminum composite bar comprises a cladding copper layer and an aluminum core substrate, wherein a bonding layer is formed between the cladding copper layer and the aluminum core substrate, and the thickness of the bonding layer is less than 3 μm. When the width of the high-performance, high-width-to-thickness-ratio copper-aluminum composite bar is ≥80 mm, the width-to-thickness ratio is 20-60; when the width is 50-60 mm, the width-to-thickness ratio is 20-40; when the width is ≤40 mm, the width-to-thickness ratio is 10-40.

4. The high-performance copper-aluminum composite row with large width-thickness ratio according to claim 3, wherein The aluminum core matrix includes aluminum, silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials, and the rare earth alloy materials include cerium, lanthanum, neodymium, and praseodymium.

5. The high-performance copper-aluminum composite row with a large width-thickness ratio according to claim 3, characterized in that The mass fractions of silicon, iron, copper, magnesium, zinc, and boron in aluminum are respectively: silicon 0.03% - 0.07%, iron 0.40% - 0.60%, copper 0.20% - 0.40%, magnesium 0.04% - 0.10%, zinc 0.04% - 0.10%, boron 0.01% - 0.02%; the mass fractions of cerium, lanthanum, neodymium, and praseodymium in aluminum are respectively: cerium 0.06% - 0.09%, lanthanum 0.01% - 0.03%, neodymium 0.01% - 0.03%, praseodymium 0.007% - 0.015%.