A pressureless sintered Cu / MoAlB composite material, its preparation method and application

Abstract

The present invention discloses a pressureless sintered Cu / MoAlB composite material, its preparation method, and application. The process involves ball-milling Cu / MoAlB powder and anhydrous ethanol until the mixture is completely uniform; pressing the uniformly mixed Cu / MoAlB powder into a block; and pressureless sintering the block to obtain a Cu / MoAlB composite material with a dense structure. The pressureless sintering process effectively reduces equipment requirements, expands production capacity, and produces a pantograph slide material with excellent electrical conductivity, wear resistance, and lubricity.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper-based composite material preparation, and in particular relates to a pressureless sintered Cu / MoAlB composite material and a preparation method and application thereof. Background Art

[0002] As a core component of rail transit, pantograph slides are crucial to the future development of related sectors. Technological limitations significantly impact both infrastructure and economic development. By the end of 2021, China's railway system had 13,900 electric locomotives and 4,153 standard EMU sets, resulting in a demand for over 100,000 slides, with an output value exceeding 300 million yuan. In terms of slide material, pure carbon and metal-impregnated carbon slides are the most common.

[0003] The metal-impregnated carbon slide plate, which is currently widely used, has good anti-friction lubrication properties and low resistivity, but its mechanical strength, especially shear strength and hardness, are difficult to meet the requirements of 350km / h high-speed railway pantograph slide plates. Copper and steel, the first generation of pantograph slide materials, offer excellent conductivity, high strength, and low production costs, but they are largely eliminated due to their high wear on power grid conductors. Copper- and steel-based powder metallurgy materials, the second generation of pantograph slide materials, incorporate lubricating phases such as MoS2 and graphite into the copper or steel matrix. While maintaining the excellent conductivity and strength of the first generation materials, they also reduce friction on copper conductors. However, they still cause significant damage, leading to high grid maintenance costs. Carbon slides and metal-impregnated carbon slides, the third generation of pantograph slide materials, utilize carbon-based slide materials. While maintaining some conductivity, they significantly reduce friction on the grid. However, carbon-based slides suffer from low strength, short lifespan, and high resistivity. Even with improved production processes, such as impregnation with binary or ternary copper alloys to enhance conductivity and strength, the performance gains are limited. Under high-speed train service conditions, significant room for improvement remains, as they cannot achieve a balance between conductivity, mechanical strength, slide life, and friction with copper conductors. Therefore, developing new slide materials that meet the demands of today's times is a crucial need. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a pressureless sintered Cu / MoAlB composite material and its preparation method and application. Cu / MoAlB composite materials with different compositions are prepared by the pressureless sintering method. By taking advantage of the controllable performance, the composite materials can play an excellent role in friction reduction, wear resistance and conductivity during service, and are used to solve the technical problems of defects and failures caused by traditional pantograph materials during service.

[0005] The present invention adopts the following technical solutions:

[0006] A method for preparing a pressureless sintered Cu / MoAlB composite material comprises the following steps:

[0007] S1. Ball-milling Cu / MoAlB powder and anhydrous ethanol until the powders are completely uniform;

[0008] S2, pressing the uniformly mixed Cu / MoAlB powder into a block;

[0009] S3. The block is pressurelessly sintered to obtain a Cu / MoAlB composite material with a dense structure.

[0010] Specifically, in step S1, in the Cu / MoAlB powder, Cu accounts for 20 Vol.% to 50 Vol.%, and MoAlB accounts for 50 Vol.% to 80 Vol.%.

[0011] Specifically, anhydrous ethanol accounts for 20% by mass of the Cu / MoAlB powder.

[0012] Specifically, in step S1, the ball-to-material ratio is 5:1, the ball milling speed is 300-400 r / min, and the ball milling time is 10-15 h.

[0013] Furthermore, the grinding balls are 5 mm, 7 mm, and 10 mm agate balls mixed in a ratio of 1:1:1.

[0014] Specifically, in step S2, the pressure for pressing the block is 100-200 MPa, and the holding time is 120-180 seconds.

[0015] Specifically, in step S3, the heating rate of the pressureless sintering is 10°C / min, the holding temperature is 1050-1200°C, and the holding time is 2h.

[0016] Furthermore, pressureless sintering was performed in an argon atmosphere.

[0017] Another technical solution of the present invention is a pressureless sintered Cu / MoAlB composite material.

[0018] Another technical solution of the present invention is the application of the pressureless sintered Cu / MoAlB composite material in the field of pantograph slides.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] A method for preparing a pressureless sintered Cu / MoAlB composite material adopts a pressureless sintering preparation process, which can effectively reduce equipment requirements and expand production capacity. At the same time, a pantograph slide material with excellent electrical conductivity, wear resistance, and lubricity is prepared, ensuring friction reduction performance. The sample is free of defects such as component segregation, cracks, pores, inclusions, and oxides, and has high strength and hardness, which can effectively reduce equipment requirements and is easy to automate.

[0021] Furthermore, the composition ratio of the Cu / MoAlB powder is: Cu is 20 Vol.% to 50 Vol.%, and MoAlB is 50 Vol.% to 80 Vol.%, which can ensure that the composite material has good electrical conductivity and lubricity and meets the required service conditions.

[0022] Furthermore, the proportion of anhydrous ethanol is about 20% of the added powder, which can accurately control the mixing degree between the powders and ensure the uniformity of the composite material structure.

[0023] Furthermore, the ball milling speed is 300-400 r / min and the ball milling time is 10-15 h, which can accurately control the mixing degree between the powders and ensure the uniformity of the composite material structure.

[0024] Furthermore, the grinding balls are a 1:1:1 mixture of 5mm, 7mm and 10mm agate balls, which can completely crush the composite material while ensuring that the fine materials are ground finely.

[0025] Furthermore, the green compact pressure is 100-200 MPa, and the holding time is 120s-180s, which can avoid the powder cracking problem due to the pressure and holding time, ensure the green compact quality, and facilitate the sintering process.

[0026] Furthermore, the heating rate is 10℃ / min, the sample is kept at 1000-1200℃ for 2h, which can ensure that the sample is free of oxidation, has dense structure, excellent electrical conductivity, and anti-friction performance. The sample has no defects such as component segregation, cracks, pores, inclusions, oxides, etc., and has high strength and hardness. The pressureless sintering process can improve production capacity and is conducive to automation.

[0027] Furthermore, pressureless sintering is performed in an argon atmosphere, providing a clean, oxygen-free environment to prevent the composite material from being affected by oxidation or other chemical reactions.

[0028] In summary, the composite material prepared by the present invention has the advantages of dense structure and excellent electrical conductivity, and can expand production capacity. At the same time, a pantograph slide material with excellent electrical conductivity, wear resistance and lubricity can be prepared.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the SEM photo of the example sample;

[0031] Figure 2 This is a metallographic photograph of the example sample;

[0032] Figure 3 Schematic diagram of friction changing with time. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0035] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0036] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0037] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0038] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0039] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0040] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0041] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0042] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0043] MoAlB has excellent mechanical properties, high-temperature oxidation resistance and electrical conductivity. As a typical machinable material, the tribological properties of copper-based composites reinforced with it are expected to be significantly improved. It has the application prospect of replacing traditional pantograph slide materials, which is expected to solve the above problems and meet the needs of railway development.

[0044] The present invention provides a pressureless sintered Cu / MoAlB composite material and a preparation method thereof, which has dense structure, excellent electrical conductivity, guaranteed anti-friction performance, and the sample is free of defects such as component segregation, cracks, pores, inclusions, oxides, etc., and has high strength and hardness. By adopting a pressureless sintering preparation process, it can effectively reduce equipment requirements, expand production capacity, and easily realize automation, providing a feasible preparation method for the large-scale promotion of this material in the field of pantograph slides.

[0045] The present invention provides a pressureless sintered Cu / MoAlB composite material and a preparation method thereof, comprising the following steps:

[0046] S1. Place Cu / MoAlB powder weighed in different proportions into a ball mill, add an appropriate proportion of anhydrous ethanol into the ball mill, and ball mill the mixed powders until they are completely uniform.

[0047] The composition ratio of the Cu / MoAlB powder is: 20% to 50% Cu by volume, 50% to 80% MoAlB by volume. The specific gravity of anhydrous ethanol is 20% of the total powder. The ball mill is a corundum mill, and the grinding balls are a 1:1:1 mixture of 5 mm, 7 mm, and 10 mm agate balls. The ball-to-material ratio is 5:1. The mill speed is 300 to 400 rpm, and the milling time is 10 to 15 hours.

[0048] S2. Take the uniformly mixed Cu / MoAlB powder and put it into a stainless steel mold and press it into a block;

[0049] The mold size is a stainless steel mold with a diameter of 25 mm. A release agent is used inside the mold to reduce the difficulty of sampling. The pressing pressure is 100 to 200 MPa, and the holding time is 120 to 180 s.

[0050] S3. The pressed block is placed in a tubular furnace for pressureless sintering to obtain a Cu / MoAlB composite material with a dense structure.

[0051] The tubular furnace was filled with argon atmosphere, the heating rate was 10°C / min, and the sample was kept at 1050-1200°C for 2 h.

[0052] Compared with traditional copper-based pantograph slide materials, the Cu / MoAlB composite material prepared by pressureless sintering has excellent high-temperature compressive strength, elongation and conductivity, and forms an in-situ self-generated lubricating film in a friction environment, with self-lubricating properties. The tribological properties of the copper-based composite material reinforced with it are expected to be significantly improved. It has a dense structure, increased strength, extended service life, and a protective effect on the conductor. It is free of defects such as component segregation, cracks, pores, inclusions, and oxides.

[0053] A pressureless sintered Cu / MoAlB composite material, with a MoAlB lubricating phase added to the Cu matrix, exhibits excellent friction properties. Average friction coefficient testing of the composite material revealed a minimum friction coefficient of 0.10973, a maximum of 0.27954, and an average friction coefficient of 0.17674. Throughout the testing, the average friction coefficient of the composite remained below 0.2.

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] Example 1

[0056] 1) Weighed Cu / MoAlB powders of varying proportions were placed in a ball mill. Anhydrous ethanol was added in an appropriate proportion and the mixture was ball-milled until completely homogeneous. The composition ratio of the Cu / MoAlB powders was 20% by volume of Cu and 80% by volume of MoAlB. The specific gravity of the anhydrous ethanol was approximately 20% of the total powder content. The mill was a corundum mill, and the grinding balls were a 1:1:1 mixture of 5 mm, 7 mm, and 10 mm agate balls. The ball-to-material ratio was 5:1, and the milling speed was 400 rpm for 10 hours.

[0057] 2) The uniformly mixed Cu / MoAlB powder was placed in a stainless steel mold and pressed into a block; the mold size was a stainless steel mold with a diameter of 25 mm. A release agent was used inside the mold to reduce the difficulty of sampling. The pressing pressure was 200 MPa and the holding time was 120 s.

[0058] 3) The pressed block was placed in a tube furnace for pressureless sintering to obtain a Cu / MoAlB composite with a dense microstructure. The tube furnace was filled with argon gas and heated at a rate of 10°C / min. The sample was held at 1200°C for 2 hours.

[0059] Through Example 1, the following conclusions are obtained:

[0060] Using 20% Cu / 80% MoAlB powder as raw material, sintering was carried out at 1200℃ (keeping temperature for 2h) to generate a composite material with Cu-MoAlB as the main phase; the structure in the sample is relatively dense and has good friction performance.

[0061] Example 2

[0062] 1) Weighed Cu / MoAlB powders of varying proportions were placed in a ball mill. Anhydrous ethanol was added in an appropriate proportion and the mixture was ball-milled until completely homogeneous. The composition ratio of the Cu / MoAlB powders was 30% by volume of Cu and 70% by volume of MoAlB. The specific gravity of the anhydrous ethanol was approximately 20% of the total powder content. The mill was a corundum mill, and the grinding balls were a 1:1:1 mixture of 5 mm, 7 mm, and 10 mm agate balls. The ball-to-material ratio was 5:1, and the milling speed was 400 rpm for 10 hours.

[0063] 2) The uniformly mixed Cu / MoAlB powder was placed in a stainless steel mold and pressed into a block; the mold size was a stainless steel mold with a diameter of 25 mm. A release agent was used inside the mold to reduce the difficulty of sampling. The pressing pressure was 200 MPa and the holding time was 120 s.

[0064] 3) The pressed block was placed in a tube furnace for pressureless sintering to obtain a Cu / MoAlB composite with a dense microstructure. The tube furnace was filled with argon and heated at a rate of 10°C / min. The sample was held at 1150°C for 2 hours.

[0065] Through Example 2, the following conclusions are obtained:

[0066] Using 30% Cu / 70% MoAlB powder as raw materials, sintering at 1150℃ (holding temperature for 2h) produced a composite material with Cu-MoAlB as the main phase. The structure of the sample is relatively dense and has good electrical conductivity.

[0067] Example 3

[0068] 1) Weighed Cu / MoAlB powders of varying proportions were placed in a ball mill. Anhydrous ethanol was added to the mill in an appropriate proportion and the mixture was ball-milled until completely homogeneous. The composition ratio of the Cu / MoAlB powders was 40% by volume Cu and 60% by volume MoAlB. The specific gravity of the anhydrous ethanol was approximately 20% of the total powder content. The mill was a corundum mill, and the grinding balls were a 1:1:1 mixture of 5 mm, 7 mm, and 10 mm agate balls. The ball-to-material ratio was 5:1. The mill speed was 300 rpm and the milling time was 15 hours.

[0069] 2) The uniformly mixed Cu / MoAlB powder was placed in a stainless steel mold and pressed into a block; the mold size was a stainless steel mold with a diameter of 25 mm. A release agent was used inside the mold to reduce the difficulty of sampling. The pressing pressure was 100 MPa and the holding time was 180 s.

[0070] 3) The pressed block was placed in a tube furnace for pressureless sintering to obtain a Cu / MoAlB composite with a dense microstructure. The tube furnace was filled with argon and heated at a rate of 10°C / min. The sample was held at 1100°C for 2 hours.

[0071] Through Example 3, the following conclusions are obtained:

[0072] Using 40% Cu / 60% MoAlB powder as raw materials, sintering at 1100℃ (holding temperature for 2h) produced a composite material with Cu-MoAlB as the main phase. The structure of the sample is relatively dense and has good interface bonding effect.

[0073] Example 4

[0074] 1) Weighed Cu / MoAlB powders of varying proportions were placed in a ball mill. Anhydrous ethanol was added to the mill in an appropriate proportion and the mixture was ball-milled until completely homogeneous. The composition ratio of the Cu / MoAlB powders was 50% by volume Cu and 50% by volume MoAlB. The specific gravity of the anhydrous ethanol was approximately 20% of the total powder content. The mill was a corundum mill, and the grinding balls were a 1:1:1 mixture of 5 mm, 7 mm, and 10 mm agate balls. The ball-to-material ratio was 5:1. The mill speed was 300 rpm and the milling time was 15 hours.

[0075] 2) The uniformly mixed Cu / MoAlB powder was placed in a stainless steel mold and pressed into a block; the mold size was a stainless steel mold with a diameter of 25 mm. A release agent was used inside the mold to reduce the difficulty of sampling. The pressing pressure was 100 MPa and the holding time was 180 s.

[0076] 3) The pressed block was placed in a tube furnace for pressureless sintering to obtain a Cu / MoAlB composite with a dense microstructure. The tube furnace was filled with argon gas and heated at a rate of 10°C / min. The sample was held at 1050°C for 2 hours.

[0077] Through Example 4, the following conclusions are obtained:

[0078] Using 50% Cu / 50% MoAlB powder as raw materials, sintering at 1100℃ (holding temperature for 2h) produced a composite material with Cu-MoAlB as the main phase. The structure of the sample is relatively dense and has good matrix strength.

[0079] See also Figure 1 The figure shows a 2000x SEM photo of the composite material, in which the original Cu and MoAlB lamellar structures appear mixed.

[0080] See also Figure 2 ,As can be seen from the figure, the light colored part is Cu and the dark ,part is MoAlB, which are evenly mixed by ball milling and exhibit a continuous ,clustered structure.

[0081] See also Figure 3 As time goes by, the friction coefficient shows a trend of first decreasing and then stabilizing. The average friction coefficient is 0.17674, which is basically stable and remains below 0.2.

[0082] In summary, the present invention provides a pressureless sintered Cu / MoAlB composite material and a preparation method thereof. The prepared sample itself has no defects such as component segregation, cracks, pores, inclusions, oxides, etc., and has sufficiently high strength and hardness. While having the advantages of dense organization, it also ensures excellent electrical conductivity and friction reduction properties; and it can effectively reduce equipment requirements during the preparation process, can effectively reduce equipment requirements, expand production capacity, and at the same time prepare a pantograph slide material with excellent electrical conductivity, wear resistance, and lubrication properties, and is easy to automate.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a pressureless sintered Cu / MoAlB composite material, characterized in that: The following steps are involved: S1. Ball-mill Cu / MoAlB powder and anhydrous ethanol until the mixture is completely uniform. The anhydrous ethanol accounts for 20% of the mass of the Cu / MoAlB powder. In the Cu / MoAlB powder, Cu accounts for 20 Vol.%-50 Vol.%, MoAlB accounts for 50 Vol.%-80 Vol.%, and the ball-to-material ratio is 5:

1. The ball milling speed is 300-400 r / min, the ball milling time is 10-15 h, and the grinding balls are 5 mm, 7 mm, and 10 mm agate balls mixed in a ratio of 1:1:

1. S2. Pressing the uniformly mixed Cu / MoAlB powder into a block at a pressure of 100-200 MPa and a holding time of 120-180 s. S3. The block is pressurelessly sintered in an argon atmosphere with a heating rate of 10°C / min, a holding temperature of 1050-1200°C, and a holding time of 2h to obtain a Cu / MoAlB composite material with a dense structure.

2. A pressureless sintered Cu / MoAlB composite material, characterized in that: Prepared according to the method of claim 1.

3. Application of the pressureless sintered Cu / MoAlB composite material according to claim 2 in the field of pantograph slides.

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