High-strength silver-copper alloy and method of making

Abstract

The application relates to the alloy technical field and discloses a high-strength silver-copper alloy and a preparation method. Acidified carbon nanotubes are functionally modified, -NCO groups are introduced by reacting toluene-2,4-diisocyanate with surface active groups, and a plurality of carboxyl groups are grafted on the surface of the carbon nanotubes by reacting the -NCO groups with the hydroxyl groups of 4-hydroxyphthalic acid. The carboxyl groups can firmly adsorb lanthanum nitrate through coordination, avoid the separation of rare earth elements in the ball milling process with raw materials, ensure the uniform distribution, reduce the carbon nanotube agglomeration tendency, and improve the dispersity of the carbon nanotubes in the silver-copper alloy. The carbon nanotubes have extremely high axial strength and excellent conductivity, the load transmission and the conductive network effect can enhance the mechanical and electrical properties of the alloy material, the rare earth lanthanum is segregated at the grain boundary to form a pinning effect to refine the grains, the alloy strength is further improved, and the strength and the conductivity of the silver-copper alloy are synergistically improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloys, in particular to a high-strength silver-copper alloy and a preparation method. BACKGROUND

[0002] For some high-end fields with high requirements on strength, electrical conductivity, heat resistance and ductility, such as industrial robot arms, unmanned aerial vehicles, motor rotors, etc., the existing high-strength and high-conductivity materials do not meet the corresponding performance requirements, while silver-copper alloys have shown great advantages in these aspects. Silver-copper alloy is a binary alloy, which has good electrical conductivity, flowability and wettability, good mechanical properties, high hardness, wear resistance and resistance to melting and welding.

[0003] As quasi-one-dimensional nanomaterials, carbon nanotubes (CNTs) have extremely high strength and excellent electrical conductivity, and are considered as one of the most ideal reinforcing bodies in metal matrix composites. Therefore, the combination of CNTs and Cu is expected to further improve the mechanical properties while retaining or even improving the excellent thermal and electrical properties of Cu itself, thereby promoting the integration of materials in terms of structure and function. Carbon nanotube-reinforced copper matrix composites are widely concerned and applied in new energy transportation, national defense and military industry, and electronic information due to their excellent mechanical properties, outstanding thermal and electrical properties. However, the weak interface bonding caused by poor interface wettability and easy agglomeration of CNTs reduces the strengthening efficiency of CNTs and limits the full play of their intrinsic excellent properties, which seriously limits the practical application of such composites. Therefore, interface design and regulation of CNTs / Cu composites is an important means to achieve the synergistic improvement of their comprehensive properties. The patent with the authorization announcement number CN109126822B discloses a carbon nanotube-gold-copper alloy composite material and its preparation method and application, which melts and blends carbon nanotubes, gold and copper to obtain an alloy material. However, this patent only improves the ablation resistance of the alloy, but does not improve the tensile strength and electrical conductivity of the alloy.

[0004] Rare earth elements (such as lanthanum) further empower through unique electronic structure and chemical activity: they segregate at grain boundaries to form pinning effect to refine grains, improve alloy strength and toughness; form stable compounds with impurities to increase recrystallization temperature, enhance alloy heat resistance to adapt to high temperature working conditions; can also act as heterogeneous nucleation core for precipitated phase to promote its uniform distribution and reduce the adverse effects on the electrical conductivity of the alloy. This silver-copper-rare earth alloy has significantly improved adaptability in application, but still faces challenges such as cost control of silver and rare earth, uniformity of rare earth addition, etc. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a high-strength silver-copper alloy and a preparation method, which solves the problem of insufficient strength of traditional silver-copper alloys.

[0006] The present application provides a method for preparing high-strength silver-copper alloy, comprising the following steps:

[0007] Step (1), adding toluene, acidified carbon nanotubes, ultrasonic dispersion, adding toluene-2,4-diisocyanate and dibutyltin dilaurate, stirring at 60-75℃ for 7-10h, then adding 4-hydroxyphthalic acid, stirring for 4-8h, suction filtration, washing with ethanol, drying to obtain phthalic acid modified carbon nanotubes.

[0008] Step (2), adding phthalic acid modified carbon nanotubes and lanthanum nitrate to water, stirring at 20-35℃ for 4-6h, then suction filtration, washing with water, and then placing the product in a muffle furnace, calcining at 250-300℃ for 1-2h, cooling to obtain carbon nanotube supported lanthanum oxide.

[0009] Step (3), placing carbon nanotube supported lanthanum oxide, elemental silver and elemental copper in a planetary ball mill, ball milling and mixing in an argon atmosphere, placing in a hot-type horizontal continuous casting device, covering with a layer of calcined charcoal, introducing argon, and smelting at 1100-1250℃, cooling to form a high-strength silver-copper alloy.

[0010] Further, in step (1), the amount of acidified carbon nanotubes is 100 parts by weight, the amount of toluene-2,4-diisocyanate is 800-1500 parts by weight, the amount of dibutyltin dilaurate is 6-12 parts by weight, and the amount of 4-hydroxyphthalic acid is 850-1800 parts by weight.

[0011] Further, in step (2), the amount of phthalic acid modified carbon nanotubes is 100 parts by weight, and the amount of lanthanum nitrate is 20-60 parts by weight.

[0012] Further, in step (3), the amount of carbon nanotube supported lanthanum oxide is 0.3-1 parts by weight, the amount of elemental copper is 100 parts by weight, and the amount of elemental silver is 3-4 parts by weight.

[0013] The present application provides a high-strength silver-copper alloy obtained by the above-mentioned preparation method.

[0014] Beneficial technical effect: the acidified carbon nanotubes are functionally modified, -NCO groups are introduced by reacting toluene-2, 4-diisocyanate with the surface active groups, and then the -NCO groups are reacted with the hydroxyl groups of 4-hydroxy phthalic acid to graft multiple carboxyl groups on the surface of the carbon nanotubes; the carboxyl groups can firmly adsorb lanthanum nitrate through strong polarity or coordination, avoid the separation of rare earth elements in the raw material ball milling process, ensure uniform distribution, and on the other hand, can reduce the agglomeration tendency of the carbon nanotubes and improve the dispersibility of the carbon nanotubes in the silver-copper alloy; the carbon nanotubes have extremely high axial strength and excellent electrical conductivity, and can enhance the mechanical and electrical properties of the alloy material through load transmission and conductive network effect, which is beneficial to improve the mechanical strength and electrical conductivity of the alloy; the rare earth lanthanum is segregated at the grain boundaries to form a pinning effect to refine the grains, further improve the strength of the alloy and improve the toughness, and finally realize the synergistic improvement of the strength, toughness and electrical conductivity of the silver-copper alloy. DETAILED DESCRIPTION

[0015] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0016] 2g carbon nanotubes were placed in a mixed solution of 120mL concentrated sulfuric acid and 40mL concentrated nitric acid HNO3, heated to 70℃, stirred and refluxed for 8h, washed with pure water after filtration, and dried to obtain acidified carbon nanotubes.

[0017] Example 1: a preparation method of high-strength silver-copper alloy, comprising the following steps:

[0018] (1) 300mL of toluene, 5g of acidified carbon nanotubes were added to a flask, ultrasonic dispersion, 75g of toluene-2, 4-diisocyanate and 0.3g of dibutyltin dilaurate were added, and the reaction was stirred at 75℃ for 7h, then 42.5g of 4-hydroxy phthalic acid was added, and the reaction was stirred for 8h, then filtered, washed with ethanol, and dried to obtain phthalic acid modified carbon nanotubes;

[0019] (2) 10g of phthalic acid modified carbon nanotubes and 5g of lanthanum nitrate were added to 3L of water, stirred at 30℃ for 6h, then filtered, washed with water, and the product was placed in a muffle furnace and calcined at 260℃ for 1h, then cooled to obtain carbon nanotube supported lanthanum oxide;

[0020] (3), 6g carbon nanotube loaded lanthanum oxide, 2kg elemental copper, 60g elemental silver are placed in a planetary ball mill, ball milling mixing is carried out in an argon atmosphere, placed in a hot type horizontal continuous casting equipment, and covered with a layer of calcined charcoal, argon is introduced, and smelting is carried out at 1250 DEG C, and cooling is formed, to obtain a high-strength silver-copper alloy.

[0021] Example 2: a method for preparing a high-strength silver-copper alloy, comprising the following steps:

[0022] (1), 350mL of toluene, 5g of acidified carbon nanotubes are added to a flask, ultrasonic dispersion, 40g of toluene-2, 4-diisocyanate and 0.6g of dibutyltin dilaurate are added, stirring at 60 DEG C for 10h, then 80g of 4-hydroxyphthalic acid is added, stirring for 4h, suction filtration, washed with ethanol, and dried to obtain phthalic acid modified carbon nanotubes;

[0023] (2), 10g of phthalic acid modified carbon nanotubes, 4g of lanthanum nitrate are added to 4L of water, stirred at 25 DEG C for 5h, then suction filtered, washed with water, and the product is placed in a muffle furnace, calcined at 275 DEG C for 2h, and cooled to obtain carbon nanotube loaded lanthanum oxide;

[0024] (3), 10g of carbon nanotube loaded lanthanum oxide, 2kg of elemental copper, 80g of elemental silver are placed in a planetary ball mill, ball milling mixing is carried out in an argon atmosphere, placed in a hot type horizontal continuous casting equipment, and covered with a layer of calcined charcoal, argon is introduced, and smelting is carried out at 1100 DEG C, and cooling is formed, to obtain a high-strength silver-copper alloy.

[0025] Example 3: a method for preparing a high-strength silver-copper alloy, comprising the following steps:

[0026] (1), 320mL of toluene, 5g of acidified carbon nanotubes are added to a flask, ultrasonic dispersion, 50g of toluene-2, 4-diisocyanate and 0.4g of dibutyltin dilaurate are added, stirring at 65 DEG C for 8h, then 60g of 4-hydroxyphthalic acid is added, stirring for 5h, suction filtration, washed with ethanol, and dried to obtain phthalic acid modified carbon nanotubes;

[0027] (2), 10g of phthalic acid modified carbon nanotubes, 2g of lanthanum nitrate are added to 4L of water, stirred at 20 DEG C for 6h, then suction filtered, washed with water, and the product is placed in a muffle furnace, calcined at 250 DEG C for 2h, and cooled to obtain carbon nanotube loaded lanthanum oxide;

[0028] (3), 15g of carbon nanotube loaded lanthanum oxide, 2kg of elemental copper, 100g of elemental silver are placed in a planetary ball mill, ball milling mixing is carried out in an argon atmosphere, placed in a hot type horizontal continuous casting equipment, and covered with a layer of calcined charcoal, argon is introduced, and smelting is carried out at 1150 DEG C, and cooling is formed, to obtain a high-strength silver-copper alloy.

[0029] Example 4: A method for preparing high-strength silver-copper alloy, comprising the following steps:

[0030] (1) 330 mL of toluene, 5 g of acidified carbon nanotubes were added to a flask, ultrasonic dispersion, 65 g of toluene-2, 4-diisocyanate and 0.5 g of dibutyltin dilaurate were added, and the reaction was stirred at 70°C for 9 h, then 75 g of 4-hydroxyphthalic acid was added, and the reaction was stirred for 7 h, then filtered, washed with ethanol, and dried to obtain phthalic acid modified carbon nanotubes;

[0031] (2) 10 g of phthalic acid modified carbon nanotubes and 6 g of lanthanum nitrate were added to 3 L of water, stirred at 35°C for 4 h, then filtered, washed with water, and then placed in a muffle furnace and calcined at 300°C for 1 h, then cooled to obtain carbon nanotube supported lanthanum oxide;

[0032] (3) 20 g of carbon nanotube supported lanthanum oxide, 2 kg of elemental copper, and 200 g of elemental silver were placed in a planetary ball mill and ball-mixed in an argon atmosphere, then placed in a hot-type horizontal continuous casting device and covered with a layer of calcined charcoal, then argon was introduced and smelted at 1200°C, then cooled to form a high-strength silver-copper alloy.

[0033] Comparative Example 1: A method for preparing silver-copper alloy, comprising the following steps:

[0034] (1) 2 kg of elemental copper and 60 g of elemental silver were placed in a planetary ball mill and ball-mixed in an argon atmosphere, then placed in a hot-type horizontal continuous casting device and covered with a layer of calcined charcoal, then argon was introduced and smelted at 1250°C, then cooled to form a silver-copper alloy.

[0035] Comparative Example 2: A method for preparing silver-copper alloy, comprising the following steps:

[0036] (1) 6 g of acidified carbon nanotubes, 2 kg of elemental copper, and 60 g of elemental silver were placed in a planetary ball mill and ball-mixed in an argon atmosphere, then placed in a hot-type horizontal continuous casting device and covered with a layer of calcined charcoal, then argon was introduced and smelted at 1250°C, then cooled to form a silver-copper alloy.

[0037] Comparative Example 3: A method for preparing silver-copper alloy, comprising the following steps:

[0038] (1) 10 g of acidified carbon nanotubes and 5 g of lanthanum nitrate were added to 3 L of water, stirred at 30°C for 6 h, then filtered, washed with water, and then placed in a muffle furnace and calcined at 260°C for 1 h, then cooled to obtain carbon nanotube supported lanthanum oxide;

[0039] (2), 6 g of carbon nanotube loaded lanthanum oxide, 2 kg of elemental copper, and 60 g of elemental silver were placed in a planetary ball mill, ball-mixed in an argon atmosphere, placed in a hot-type horizontal continuous casting device, covered with a layer of calcined charcoal, and argon was introduced to carry out smelting at 1250°C. After cooling, a silver-copper alloy was obtained.

[0040] Comparative Example 4: A method for preparing a silver-copper alloy, comprising the following steps:

[0041] (1), 300 mL of toluene, 5 g of acidified carbon nanotubes, 75 g of toluene-2,4-diisocyanate, and 0.3 g of dibutyltin dilaurate were added to a flask and ultrasonically dispersed. The mixture was stirred at 75°C for 7 h, then 42.5 g of p-hydroxybenzoic acid was added and stirred for 8 h. After filtration and washing with ethanol, the product was dried to obtain p-benzoic acid modified carbon nanotubes;

[0042] (2), 10 g of p-benzoic acid modified carbon nanotubes and 5 g of lanthanum nitrate were added to 3 L of water and stirred at 30°C for 6 h. After filtration and washing with water, the product was placed in a muffle furnace and calcined at 260°C for 1 h. After cooling, carbon nanotube loaded lanthanum oxide was obtained;

[0043] (3), 6 g of carbon nanotube loaded lanthanum oxide, 2 kg of elemental copper, and 60 g of elemental silver were placed in a planetary ball mill, ball-mixed in an argon atmosphere, placed in a hot-type horizontal continuous casting device, covered with a layer of calcined charcoal, and argon was introduced to carry out smelting at 1250°C. After cooling, a silver-copper alloy was obtained.

[0044] Test of alloy conductivity: The test was carried out according to the national standard GB / T 32791-2016 "Copper and copper alloy conductivity eddy current test method".

[0045] Test of tensile strength and elongation: The test was carried out according to the national standard GB / T 228.1-2021 "Metal material tensile test Part 1: Room temperature test method".

[0046] The test results of each example and comparative example obtained by the above test methods are shown in Table 1 as follows:

[0047] Table 1: Performance test results of silver-copper alloy prepared in each example and comparative example

[0048]

[0049] As can be seen from Table 1, the acidized carbon nanotubes in Examples 1-4 are functionally modified, -NCO groups are introduced by reacting toluene-2,4-diisocyanate with the surface active groups, and then multiple carboxyl groups are grafted on the surface of the carbon nanotubes by the reaction of -NCO with the hydroxyl groups of 4-hydroxyphthalic acid; these carboxyl groups can firmly adsorb lanthanum nitrate through strong polarity or coordination, avoiding the separation of rare earth elements during the raw material ball milling process, ensuring uniform distribution, on the one hand, and reducing the tendency of carbon nanotube agglomeration and improving its dispersibility in silver-copper alloy, on the other hand; as quasi-one-dimensional nanomaterials, carbon nanotubes can enhance the mechanical and electrical properties of the composite material through load transmission and conductive network effect due to their high axial strength and excellent electrical conductivity, and rare earth lanthanum can form pinning effect to refine the grain size, further improving the strength and toughness of the alloy, and finally realizing the synergistic improvement of the strength, toughness and electrical conductivity of the silver-copper alloy.

[0050] Compared with the examples, no carbon nanotube loaded lanthanum oxide is added in Comparative Example 1, and the obtained silver-copper alloy has insufficient strength, which is difficult to meet the demand of large-scale application; only acidized carbon nanotubes are added in Comparative Example 2, and its strengthening effect is far less than that of the carbon nanotube loaded lanthanum oxide system, and its improvement effect on the performance of the silver-copper alloy is limited; in Comparative Example 3, the acidized carbon nanotubes are not modified, resulting in weak adsorption capacity of lanthanum nitrate, easy separation in subsequent ball milling, and then affecting the dispersibility of carbon nanotubes in the alloy, and finally reducing the strength of the alloy; in Comparative Example 4, toluene-2,4-diisocyanate is used to modify the acidized carbon nanotubes with p-hydroxybenzoic acid, compared with the modification system of 4-hydroxyphthalic acid, the number of carboxyl groups introduced on the surface of the carbon nanotubes is less, the adsorption capacity of lanthanum nitrate is reduced, but the adverse effect on the strength of the alloy is relatively reduced due to the retention of the carboxyl structure.

[0051] The above examples are only used to illustrate the technical method of the present application but not limit the present application, although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical method of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical method of the present application.

Claims

1. A method for producing a high-strength silver-copper alloy, characterized by, The preparation method comprises the following steps: Step (1), adding toluene, acidified carbon nanotubes, ultrasonic dispersion, adding toluene-2, 4-diisocyanate and dibutyl tin dilaurate, stirring and reacting, then adding 4-hydroxy phthalic acid, stirring and reacting, suction filtration, washing with ethanol, drying, and obtaining phthalic acid modified carbon nanotubes; Step (2), adding the phthalic acid modified carbon nanotubes and lanthanum nitrate to water, stirring, suction filtration, washing with water, and then placing the product in a muffle furnace, calcining at 250-300℃ for 1-2h, cooling, and obtaining carbon nanotube supported lanthanum oxide; Step (3), placing the carbon nanotube supported lanthanum oxide, elemental silver and elemental copper in a planetary ball mill, ball milling and mixing in an argon atmosphere, placing in a hot type horizontal continuous casting device, covering with a layer of calcined charcoal, introducing argon, melting, cooling and forming, and obtaining a high-strength silver copper alloy; In the step (3), the amount of the carbon nanotube supported lanthanum oxide is 0.3-1 parts by weight, the amount of the elemental copper is 100 parts by weight, and the amount of the elemental silver is 3-4 parts by weight.

2. The method of producing a high-strength silver-copper alloy according to claim 1, characterized by, In the step (1), the amount of the acidified carbon nanotubes is 100 parts by weight, the amount of toluene-2, 4-diisocyanate is 800-1500 parts by weight, the amount of dibutyl tin dilaurate is 6-12 parts by weight, and the amount of 4-hydroxy phthalic acid is 850-1800 parts by weight.

3. The method of producing a high-strength silver-copper alloy according to claim 1, characterized by, In the step (1), the temperature of the first reaction is 60-75℃, and the time is 7-10h; the time of the second reaction is 4-8h.

4. The method of producing a high-strength silver-copper alloy according to claim 1, characterized by, In the step (2), the amount of the phthalic acid modified carbon nanotubes is 100 parts by weight, and the amount of the lanthanum nitrate is 20-60 parts by weight.

5. The method of producing a high-strength silver-copper alloy according to claim 1, characterized by, In the step (2), the temperature of the stirring is 20-35℃, and the time is 4-6h.

6. The method of producing a high-strength silver-copper alloy according to claim 1, characterized by, In the step (3), the temperature of the melting is 1100-1250℃.

7. The high-strength silver copper alloy obtained by the preparation method according to any one of claims 1-6.

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