Preparation method of copper-nickel-tin alloy with improved oxidation resistance

Abstract

The application discloses a preparation method of copper-nickel-tin alloy capable of improving oxidation resistance, and relates to the technical field of copper-nickel-tin alloy; the method comprises the following steps: vacuum drying high-purity copper powder, nickel powder, tin powder, gallium powder and / or indium powder respectively, then placing the powders in a high-energy ball milling tank to perform ball milling under the protection of argon, and screening to obtain uniformly mixed composite powder; placing the composite powder in a graphite mold, pre-pressing through a cold isostatic pressing machine, densifying through discharge plasma sintering to obtain a blank; placing the blank in a vacuum furnace to perform heat treatment, then performing surface pre-oxidation treatment, uniformly and dispersedly adding low-melting-point metal gallium and / or indium through a powder metallurgy method, so that the low-melting-point metal is liquefied at high temperature and migrates to an oxidation crack, defects are filled, and a new oxidation film is formed, a liquid-phase self-repairing mechanism is introduced, and the oxidation resistance life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper-nickel-tin alloy, and particularly relates to a preparation method of copper-nickel-tin alloy capable of improving oxidation resistance. BACKGROUND

[0002] The copper-nickel-tin alloy has the advantages of wear resistance, corrosion resistance, high lubricity and good high-temperature stability, and is commonly used for manufacturing high-temperature heavy-load bearing base materials. In addition, compared with beryllium bronze, the copper-nickel-tin alloy has low production cost, no pollution, high strength and hardness, good corrosion resistance and excellent machinability, and can be used at a temperature of 300 DEG C or above, and is commonly used as a substitute material of beryllium bronze.

[0003] In the prior art, the oxidation resistance of the copper-nickel-tin alloy is mainly improved by a surface treatment process, but the traditional method has the following obvious defects:

[0004] Micro-arc oxidation: although a ceramic coating can be formed on the alloy surface, the high porosity (>10%) in the process leads to the easy invasion of the corrosion medium into the base body, and an additional sealing treatment (such as phosphating liquid post-treatment) is needed, which increases the process complexity;

[0005] Anodic oxidation: the conventional process has high energy consumption, and the uniformity and adhesion of the film layer are insufficient, and the film layer is easy to peel off under high temperature or mechanical stress, for example, the oxidation film formed by anodic oxidation of CuNi34 alloy has corrosion resistance, but the long-term stability is limited;

[0006] Electroplating / chemical plating: although the electroplated nickel or chromium layer can improve the corrosion resistance, the adhesion between the plating layer and the base body is weak, and environmental pollutants (such as hexavalent chromium) may be introduced. SUMMARY

[0007] The present application aims to provide a preparation method of copper-nickel-tin alloy capable of improving oxidation resistance, so as to at least partially solve the above problems.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of copper-nickel-tin alloy capable of improving oxidation resistance, comprising the following steps:

[0009] The high-purity copper powder, nickel powder, tin powder and gallium powder and / or indium powder are respectively vacuum-dried, then placed in a high-energy ball milling tank for ball milling under the action of argon protection, and then sieved to obtain a uniformly mixed composite powder;

[0010] The composite powder is placed in a graphite mold, pre-pressed by a cold isostatic pressing machine, and densified by a spark plasma sintering machine to obtain a billet;

[0011] The billet is placed in a vacuum furnace for heat treatment, and then subjected to surface pre-oxidation treatment.

[0012] Further, the heat treatment comprises low-temperature aging heat treatment and medium-temperature stabilization heat treatment.

[0013] During the low-temperature aging heat treatment, the temperature in the vacuum furnace is adjusted to 240-260℃, and the low-temperature aging treatment time is 2-8h.

[0014] During the medium-temperature stabilization heat treatment, the temperature in the vacuum furnace is adjusted to 440-450℃, and the medium-temperature stabilization treatment time is 2h.

[0015] Further, the surface pre-oxidation treatment comprises:

[0016] After the heat treatment, the embryo block is placed in an argon atmosphere with an oxygen content of 5-10%, heated at 600℃ for 1h, and then naturally cooled.

[0017] Further, the sintering temperature of the spark plasma sintering is 750-850℃, the sintering time is 5-10min, the pressure during sintering is 30-50MPa, and the vacuum degree is ≤10 -3 Pa.

[0018] Further, the ball-to-material ratio in the high-energy ball mill is 10:1, the rotation speed in the high-energy ball mill during ball milling is 300rpm, and the ball milling time is 19-21h.

[0019] After ball milling in the high-energy ball mill, the composite powder is passed through a 100-mesh sieve to obtain uniformly mixed composite powder.

[0020] Further, the drying temperature of the vacuum drying is 100-150℃, and the drying time is 2-3h.

[0021] Further, a batch is provided, which comprises the following raw materials in parts by weight:

[0022] 78-84 parts of copper, 12-15 parts of nickel, 4-6 parts of tin, 0.5-2 parts of gallium and / or indium.

[0023] Further, a batch is provided, which comprises the following raw materials in parts by weight:

[0024] 79-82 parts of copper, 13-14 parts of nickel, 4-6 parts of tin, 0.5-1.5 parts of gallium and / or indium.

[0025] Further, the present application also provides a copper-nickel-tin alloy with improved oxidation resistance, which is prepared according to the above preparation method.

[0026] Further, the present application also provides an application of the copper-nickel-tin alloy with improved oxidation resistance, which is prepared according to the above preparation method, in the fields of electronic components, automobile manufacturing, and aerospace materials.

[0027] Compared with the prior art, the present application has the beneficial effects that:

[0028] 1. The present application can make the low-melting-point metal liquefy and migrate to the oxidation crack at high temperature by uniformly adding low-melting-point metals gallium and / or indium through a powder metallurgy method, fill the defects and form a new oxidation film, achieve the purpose of introducing a liquid-phase self-repairing mechanism, and prolong the anti-oxidation life.

[0029] 2. The copper-nickel-tin alloy prepared in the present application is autonomously triggered in the repair process without external intervention, and the addition amount of gallium and / or indium is low, and the influence on the electrical conductivity and thermal conductivity of the substrate is small. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application are described clearly and completely, obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments.

[0031] The present application provides a technical solution: a preparation method of a copper-nickel-tin alloy capable of improving the anti-oxidation ability, comprising the following steps:

[0032] Vacuum dry high-purity copper powder, nickel powder, tin powder and gallium powder and / or indium powder, then put them in a high-energy ball mill pot and ball mill under the protection of argon to obtain uniformly mixed composite powder after screening.

[0033] Put the composite powder into a graphite mold, pre-press it by a cold isostatic pressing machine, and densify it by spark plasma sintering to obtain a billet.

[0034] Put the billet into a vacuum furnace for heat treatment, and then perform surface pre-oxidation treatment.

[0035] It should be noted that: high-purity copper, nickel and tin powder (for example, particle size ≤50 μm) is selected as the base material, and low-melting-point metal powder gallium and / or indium is added, the melting point of which is <30℃, the purity of which is ≥99.9%, and the powder is vacuum dried to remove surface adsorbed water; gallium and / or indium can be liquefied at high temperature (within the working temperature range of the alloy), and migrate to the oxidation crack by capillary action.

[0036] Put the copper, nickel, tin and gallium and / or indium powder into a high-energy ball mill pot, ball mill under the protection of argon, and obtain uniformly mixed composite powder by screening. The plastic deformation and cold welding effect during the ball milling process refines the powder particles, increases the interface bonding area, and the argon environment avoids the oxidation failure of gallium and / or indium during the ball milling process.

[0037] By high-energy ball milling, the nanoscale mixing of raw materials is realized, the agglomeration of gallium and / or indium is avoided, and by heat treatment, the gallium and / or indium is induced to segregate to the grain boundary to form a uniform "storage network" to ensure that when an oxidation crack occurs, the liquid gallium and / or indium can quickly migrate to the damage area through the grain boundary to avoid the occurrence of the case that the local gallium and / or indium is depleted due to uneven distribution, resulting in repair failure or the enrichment of gallium and / or indium, leading to intergranular corrosion.

[0038] In a further embodiment of the present embodiment, the heat treatment includes a low-temperature aging heat treatment and a medium-temperature stabilization heat treatment.

[0039] During the low-temperature aging heat treatment, the temperature in the vacuum furnace is adjusted to 240-260℃, and the low-temperature aging treatment time is 2-8h.

[0040] During the medium-temperature stabilization heat treatment, the temperature in the vacuum furnace is adjusted to 440-450℃, and the medium-temperature stabilization treatment time is 2h.

[0041] It should be noted that the sintered blank is subjected to two-stage heat treatment in the vacuum furnace, low-temperature aging: 240-260℃×2-8h, promoting the segregation of gallium and / or indium elements to the grain boundary, medium-temperature stabilization: 440-450℃×2h, inducing the copper-nickel-tin matrix to form a uniform solid solution, the low-temperature aging makes the gallium and / or indium enriched in the grain boundary, providing a "storage pool" for subsequent oxidation crack repair, and the medium-temperature treatment eliminates internal stress, while avoiding the loss of a large amount of gallium and / or indium diffusion.

[0042] In a further embodiment of the present embodiment, the surface pre-oxidation treatment includes:

[0043] After the heat treatment, the embryo block is placed in an argon atmosphere containing 5-10% oxygen, heated at 600℃ for 1h, and then naturally cooled to form a pre-oxidation film as an initial protective layer to delay further oxidation during subsequent service. The microcracks in the pre-oxidation film can serve as preferential channels for the liquid phase migration of gallium and / or indium, and the low oxygen partial pressure can avoid the consumption of a large amount of gallium and / or indium during the pre-oxidation stage.

[0044] In a further embodiment of the present embodiment, the sintering temperature of the spark plasma sintering is 750-850℃, the sintering time is 5-10min, the pressure during sintering is 30-50MPa, and the vacuum degree is ≤10 -3 Pa, densification is carried out by spark plasma sintering, the pulse current of spark plasma sintering generates local joule heat, shortens the sintering time, avoids the premature volatilization of gallium and / or indium, and the temperature that is too low will lead to insufficient powder diffusion and increased porosity, and the temperature that is too high will lead to tin segregation or local liquid phase generation.

[0045] In a further embodiment of the present embodiment, the ball-to-material ratio in the high-energy ball mill is 10:1, the rotation speed in the high-energy ball mill during the ball milling is 300 rpm, and the ball milling time is 19-21 h.

[0046] After the ball milling in the high-energy ball mill, the composite powder is sieved through a 100-mesh sieve to obtain a uniformly mixed composite powder.

[0047] In a further embodiment of the present embodiment, the drying temperature of the vacuum drying is 100-150℃, and the drying time is 2-3 h.

[0048] In a further embodiment of the present embodiment, a batch is provided, which comprises the following raw materials in parts by weight:

[0049] 78-84 parts of copper, 12-15 parts of nickel, 4-6 parts of tin, and 0.5-2 parts of gallium and / or indium.

[0050] In a further embodiment of the present embodiment, a batch is provided, which comprises the following raw materials in parts by weight:

[0051] 79-82 parts of copper, 13-14 parts of nickel, 4-6 parts of tin, and 0.5-1.5 parts of gallium and / or indium.

[0052] It should be noted that: the copper in each raw material ensures the electrical conductivity / thermal conductivity of the alloy, the nickel improves the high-temperature strength and oxidation resistance, promotes the formation of a nickel oxide protective layer, the tin enhances the corrosion resistance and cooperates with the nickel to form a dense tin oxide film, and the gallium and / or indium ensures the continuity of the repair liquid phase, and too low a content will lead to the occurrence of a repair blind area, and too high a content will lead to a decrease in the mechanical properties of the matrix.

[0053] Further, the present application also provides a copper-nickel-tin alloy capable of improving oxidation resistance, which is prepared according to the above preparation method, can achieve a high-temperature oxidation rate reduction of more than 55%, a self-repair response time of less than 1 minute, and an oxidation film life extension of 3-5 times.

[0054] Example 1

[0055] The raw materials are weighed: 78 parts of copper powder, 12 parts of nickel powder, 4 parts of tin powder, and 0.5 parts of gallium powder.

[0056] The high-purity copper powder, nickel powder, tin powder, and gallium powder are vacuum dried at 150℃ for 2 h to remove the surface adsorbed water, and then are loaded into a high-energy ball mill for ball milling under argon protection at a ball-to-material ratio of 10:1, a rotation speed in the high-energy ball mill of 300 rpm, and a ball milling time of 19 h. After the ball milling, the composite powder is sieved through a 100-mesh sieve to obtain a uniformly mixed composite powder.

[0057] The composite powder is loaded into a graphite mold, pre-pressed in a cold isostatic pressing machine at a pressure of 200 MPa for 5 min, and then densification sintering is performed by a spark plasma sintering (SPS) technique at a temperature of 750 ℃, a sintering time of 5 min, a pressure of 50 MPa, and a vacuum degree of ≤10 -3 Pa to obtain a blank.

[0058] The blank is placed in a vacuum furnace, first subjected to low-temperature aging treatment at 240 ℃ for 2 h, and then subjected to medium-temperature stabilization treatment at 440 ℃ for 2 h to form a uniform solid solution.

[0059] The solid solution is heated to 600 ℃ in an argon atmosphere with an oxygen content of 5% for 1 h to perform pre-oxidation, and then naturally cooled to room temperature to form a NiO-SnO2 mixed oxide film with a thickness of 1-2 μm on the surface, thereby obtaining a copper-nickel-tin alloy with improved oxidation resistance.

[0060] Example 2

[0061] The difference from Example 1 is that the raw materials are weighed as follows: 79 parts of copper powder, 15 parts of nickel powder, 5 parts of tin powder, and 1 part of gallium powder.

[0062] Example 3

[0063] The difference from Example 1 is that the raw materials are weighed as follows: 80.5 parts of copper powder, 12 parts of nickel powder, 6 parts of tin powder, and 1.5 parts of indium powder.

[0064] Example 4

[0065] The difference from Example 1 is that the raw materials are weighed as follows: 84 parts of copper powder, 15 parts of nickel powder, 6 parts of tin powder, and 2 parts of indium powder.

[0066] Example 5

[0067] The difference from Example 2 is that the ball milling time is 20 h.

[0068] Example 6

[0069] The difference from Example 2 is that the ball milling time is 21 h.

[0070] Example 7

[0071] The difference from Example 5 is that the spark plasma sintering temperature is 800 ℃.

[0072] Example 8

[0073] The difference from Example 2 is that the spark plasma sintering temperature is 850 ℃.

[0074] Example 9

[0075] The difference from Example 7 is that the solid solution is heated to 600℃ in an argon atmosphere with 8% oxygen content for pre-oxidation for 1h.

[0076] Example 10

[0077] The difference from Example 7 is that the solid solution is heated to 600℃ in an argon atmosphere with 10% oxygen content for pre-oxidation for 1h.

[0078] Comparative Example 1

[0079] The difference from Example 3 is that the raw materials are weighed: 80.5 parts of copper powder, 12 parts of nickel powder, and 6 parts of tin powder.

[0080] Comparative Example 2

[0081] The difference from Example 2 is that the ball milling time is 15h.

[0082] Comparative Example 3

[0083] The difference from Example 2 is that the ball milling time is 25h.

[0084] Comparative Example 4

[0085] The difference from Example 5 is that the spark plasma sintering temperature is 700℃.

[0086] Comparative Example 5

[0087] The difference from Example 5 is that the spark plasma sintering temperature is 900℃.

[0088] Comparative Example 6

[0089] The difference from Example 7 is that the solid solution is heated to 600℃ in an argon atmosphere with 12% oxygen content for pre-oxidation for 1h.

[0090] The copper-nickel-tin alloys prepared in Examples 1-9 and Comparative Examples 2-6 are respectively subjected to atom probe tomography analysis of grain boundary segregation. A needle-shaped sample is prepared using a focused ion beam (FIB) with a tip curvature radius <50nm, a pulse voltage is applied, the pulse frequency is 200kHz, the temperature is 50K, the atoms are peeled off layer by layer and detected, the three-dimensional atomic distribution is reconstructed, the gallium and / or indium concentration at the grain boundary is counted, and the continuous network coverage rate is obtained, as shown in Tables 1-4 below.

[0091] The copper-nickel-tin alloys prepared in Examples 1-9 and Comparative Examples 2-6 are respectively subjected to high-temperature tensile testing. The sample is heated to 600℃ in a high-temperature furnace and kept for 30min, and then stretched at the same strain rate of 1×10 -3 s -1 The tensile test is performed, and the high-temperature yield strength is obtained as shown in Tables 1-4 below.

[0092] The weight gain of the copper-nickel-tin alloy prepared in Example 1-Example 9 and Comparative Example 1-Comparative Example 6 after oxidation at 800℃ for 100h is shown in Table 1-Table 4.

[0093] Table 1

[0094]

[0095] As shown in Table 1, the weight gain of the copper-nickel-tin alloy prepared in Example 1-4 after oxidation at high temperature is low, and the addition of gallium and / or indium in the alloy can effectively increase the high-temperature oxidation resistance of the copper-nickel-tin alloy, wherein the high-temperature oxidation resistance of Example 2 and Example 3 is better, and the high mass fraction of gallium and / or indium added in Example 4 can cause the mechanical properties of the alloy matrix to decrease.

[0096] Table 2

[0097]

[0098] As shown in Table 2, the ball milling time of 19-20h can effectively achieve uniform distribution of gallium and / or indium, while too low ball milling time can cause uneven mixing of the powder, and gallium and / or indium can easily agglomerate to form micron-sized particles. On the other hand, too long ball milling time can cause excessive cold welding, leading to powder caking, which can in turn cause a decrease in uniformity, resulting in a decrease in the continuous network coverage of gallium and / or indium, and a decrease in the high-temperature oxidation resistance of the alloy. As shown in Example 5, the ball milling time of 20h is the best, with the highest uniformity and the best high-temperature oxidation resistance.

[0099] Table 3

[0100]

[0101] As shown in Table 3, the temperature of spark plasma sintering in the range of 750-850℃ can effectively achieve rapid sintering through plastic flow, and short-time sintering can reduce the volatilization loss of gallium and / or indium, thereby increasing the continuous network coverage of gallium and / or indium, and achieving the purpose of increasing the high-temperature oxidation resistance of the alloy. Too low sintering temperature can cause insufficient diffusion of the powder, increasing the porosity of the alloy and thus decreasing the coverage, affecting the oxidation resistance. On the other hand, too high sintering temperature can cause segregation of tin or formation of local liquid phase, also causing a decrease in the oxidation resistance. As shown in Example 7, the high-temperature oxidation resistance of the alloy produced at a spark plasma sintering temperature of 800℃ is the best.

[0102] Table 4

[0103]

[0104] As shown in Table 4, the solid solution is placed in an argon atmosphere with an oxygen content of 5-10% and heated to 600°C for pre-oxidation for 1h, which can avoid the consumption of gallium and / or indium in the pre-oxidation stage, and generate a 1-2μm thick NiO-SnO2 mixed oxide film as an initial protective layer during the pre-oxidation process. The micro-cracks in the pre-oxidation film provide preferential channels for the subsequent migration of gallium and / or indium, accelerating dynamic repair. However, too high an oxygen content will cause a large amount of gallium and / or indium to be consumed in the pre-oxidation stage, thereby reducing the high-temperature oxidation resistance of the alloy.

[0105] In summary, by adding low-melting-point metals gallium and / or indium uniformly through powder metallurgy, the low-melting-point metals can be liquefied and migrate to the oxidation cracks at high temperatures to fill defects and form new oxide films, achieving the purpose of introducing a liquid-phase self-repairing mechanism and prolonging the oxidation resistance life. The copper-nickel-tin alloy triggers self-repairing in the process without external intervention, and the addition of gallium and / or indium has little effect on the electrical and thermal conductivity of the substrate.

[0106] It will be obvious to a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the application is defined by the appended claims rather than the above description, and it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims.

Claims

1. A method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance, characterized in that: The method comprises the following steps: The high-purity copper powder, nickel powder, tin powder, gallium powder and / or indium powder are vacuum dried respectively, and then placed in a high-energy ball mill tank for ball milling under the protection of argon, and then screened to obtain a uniformly mixed composite powder; The composite powder is placed in a graphite mold, pre-pressed by a cold isostatic pressing machine, and densified by spark plasma sintering to obtain a blank; The blank is placed in a vacuum furnace for heat treatment, and then subjected to surface pre-oxidation treatment; The method further comprises providing a batch consisting of the following raw materials by weight: 78-84 parts of copper, 12-15 parts of nickel, 4-6 parts of tin, 0.5-2 parts of gallium and / or indium.

2. The method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance according to claim 1, wherein: The heat treatment comprises low-temperature aging heat treatment and medium-temperature stabilization heat treatment: During the low-temperature aging heat treatment, the temperature in the vacuum furnace is adjusted to 240-260℃, and the low-temperature aging treatment time is 2-8h; During the medium-temperature stabilization heat treatment, the temperature in the vacuum furnace is adjusted to 440-450℃, and the medium-temperature stabilization treatment time is 2h.

3. The method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance according to claim 1, wherein: The surface pre-oxidation treatment comprises: The heat-treated blank is placed in an argon atmosphere containing 5-10% oxygen, heated at 600℃ for 1h, and then naturally cooled.

4. The method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance according to claim 1, wherein: The sintering temperature of the discharge plasma sintering is 750-850℃, the sintering time is 5-10min, the pressure during sintering is 30-50MPa, and the vacuum degree is ≤10 -3 Pa.

5. The method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance according to claim 1, wherein: The ball-to-material ratio in the high-energy ball mill tank is 10:1, the rotation speed in the high-energy ball mill tank during ball milling is 300rpm, and the ball milling time is 19-21h; After ball milling in the high-energy ball mill tank, the composite powder is screened through a 100-mesh sieve to obtain a uniformly mixed composite powder.

6. The method of claim 1, wherein the copper-nickel-tin alloy having improved oxidation resistance is prepared by the steps of: preparing a copper-nickel-tin alloy; and heat-treating the copper-nickel-tin alloy at a temperature of 400 to 600°C for 1 to 100 hours. The drying temperature of the vacuum drying is 100-150℃, and the drying time is 2-3h.

7. The method for preparing a copper-nickel-tin alloy capable of improving oxidation resistance according to claim 1, wherein: The method further comprises providing a batch consisting of the following raw materials by weight: 79-82 parts of copper, 13-14 parts of nickel, 4-6 parts of tin, 0.5-1.5 parts of gallium and / or indium.

8. A copper-nickel-tin alloy capable of improving antioxidant ability, characterized by comprising, in mass %, The copper-nickel-tin alloy prepared according to any one of the preparation methods of claims 1-7.

9. Use of a copper-nickel-tin alloy capable of improving the oxidation resistance, characterized in that, The copper-nickel-tin alloy prepared according to any one of the preparation methods of claims 1-7 is applied in the fields of electronic components, automobile manufacturing and aerospace materials.

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