AgTiC-coated Ni electric contact material and preparation method thereof

Abstract

The invention belongs to the technical field of nickel-doped silver-based electric contact materials, and particularly relates to an AgTiC-Ni electric contact material and a preparation method thereof. The method comprises the following steps: (1) adding TiC powder into a nickel-containing chemical plating solution, carrying out stirring and heating reaction, and washing and drying to obtain TiC-coated Ni composite powder; (2) Ag powder and the TiC-coated Ni composite powder are added into a container, a solvent is added, ultrasonic mixing is conducted, and a mixture is obtained after drying; (3) pressing the mixed material into a blank, sintering for the first time in an inert atmosphere, and cooling to room temperature after sintering to obtain a prefabricated material; and (4) carrying out compression molding on the prefabricated material again, carrying out secondary sintering in an inert atmosphere, and cooling to room temperature after sintering to obtain the AgTiC-coated Ni electric contact material. According to the method, Ni is more uniformly distributed in AgTiC through chemical nickel plating, the conductivity and the hardness of the AgTiC-Ni electric contact material are remarkably improved, the arcing time and the arcing energy of arc erosion are more stable, the material transfer amount is minimum, and the material loss is less.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-doped silver-based electric contact materials, and in particular relates to an AgTiC@Ni electric contact material and a preparation method thereof. Background Art

[0002] Electrical contact materials are key components for achieving circuit switching in electrical equipment. They are responsible for establishing or interrupting current paths in contactors, relays, circuit breakers and switchgear. The performance standards of electrical contact materials, including their conductivity, wear resistance and resistance to welding, directly affect the stability, reliability and long-term operation sustainability of the entire electrical system. In actual operation, electrical contact materials will also suffer mechanical wear during frequent contact and separation, which will further reduce their electrical contact performance. The performance of electrical contact materials is closely related to their preparation process. The preparation method and process of the material will significantly affect the physical properties and electrical contact performance of the bulk material.

[0003] AgCdO electrical contact material has a wide range of applications in the field of electronics and electrical due to its excellent performance under high current conditions. However, CdO is toxic, seriously threatening the environment and human health, and is gradually banned worldwide. With the continuous advancement of science and technology and the development of new materials, some new, environmentally friendly and high-performance electrical contact materials have gradually emerged. Among them, the AgMeO electrical contact material has been studied more and widely used. However, there is a problem of poor interface wettability between MeO and Ag, resulting in weak interface bonding strength; at the same time, during arc erosion, an enriched layer of the reinforcing phase is easily formed, which increases its resistance, deteriorates its arc erosion resistance, and increases the instability and unreliability of the electrical system. Therefore, it is urgent to develop electrical contact materials with good conductivity, good wear resistance and good chemical stability to meet the requirements of use. Summary of the invention

[0004] The object of the present invention is to provide a AgTiC@Ni electrical contact material and a preparation method thereof.

[0005] The implementation process of the present invention is as follows:

[0006] A method for preparing an AgTiC@Ni electrical contact material comprises the following steps:

[0007] (1) adding TiC powder into a nickel-containing chemical plating solution, stirring and heating the solution for reaction, and obtaining a TiC@Ni composite powder after washing and drying;

[0008] (2) adding Ag powder and TiC@Ni composite powder into a container, adding a solvent, performing ultrasonic mixing, and drying to obtain a mixture;

[0009] (3) pressing the mixed material obtained in step (2) into a blank, sintering it for the first time under an inert atmosphere, and cooling it to room temperature after sintering to obtain a prefabricated material;

[0010] (4) The preform obtained in step (3) is pressed into shape again, sintered for a second time under an inert atmosphere, and cooled to room temperature after sintering to obtain an AgTiC@Ni electrical contact material.

[0011] Furthermore, in step (1), the nickel-containing chemical plating solution is composed of the following components: a nickel source NiSO4·6H2O, a reducing agent N2H4, a composite complexing agent of EDTA-2Na and lactic acid, a stabilizer thiourea and a pH adjuster NaOH solution, the concentration of the nickel source in the nickel-containing chemical plating solution is 11-13 g / L, the concentration of N2H4 is 90-110 mL / L, the concentration of EDTA-2Na is 20-30 g / L, the concentration of lactic acid is 10-20 g / L, the concentration of thiourea is 0.8-1.2 mg / L, and the pH value of the nickel-containing chemical plating solution is 9-11.

[0012] Furthermore, in step (1), the stirring and heating reaction temperature is 70 to 80° C., and the reaction time is 40 to 70 min.

[0013] Furthermore, in step (2), the solvent is ethanol or acetone.

[0014] Furthermore, in step (2), the mass ratio of Ag powder to TiC@Ni composite powder is (95-97):(3-5), and the ultrasonic mixing time is 15-30 min.

[0015] Furthermore, in step (3), the pressure for pressing the blank is 330-380 MPa, and the holding time is 4-6 min; the inert gas is nitrogen or argon; the temperature for the first sintering is 880-920° C., and the sintering time is 1.8-2.2 h.

[0016] Furthermore, in step (4), the pressure of the preform for pressing again is 1080-1120 MPa, and the holding time is 4-6 min; the inert gas is nitrogen or argon; the temperature of the second sintering is 780-820° C., and the sintering time is 1.8-2.2 h.

[0017] Further, in step (1), the pretreatment process of the TiC powder is

[0018] (S1.1) adding TiC powder to a NaOH solution for ultrasonic cleaning and then washing with deionized water to obtain a neutral TiC powder solution;

[0019] (S1.2) adding the neutral TiC powder solution into a roughening solution containing HF and HNO3 for etching, and obtaining a TiC powder solution having a concave-convex rough surface after washing;

[0020] (S1.3) adding the TiC powder solution with a rough surface to a sensitizing solution containing SnCl2·2H2O and HCl to perform ultrasonic treatment, and after the ultrasonic treatment, washing with deionized water to obtain a neutral TiC powder solution;

[0021] (S1.4) The neutral TiC powder solution obtained in step (S1.3) is activated by adding an activation solution containing PdCl2 and HCl, and the activated TiC powder is washed to neutrality and dried for later use.

[0022] Furthermore, in step (S1.1), the concentration of the NaOH solution is 18 to 22 g / L; in step (S1.2), the volume concentration ratio of HF and HNO3 in the roughening solution is 1:2, and the volume concentration of HF in the roughening solution is 18 to 22 mL / L; in step (S1.3), the concentration of SnCl2·2H2O in the sensitizing solution is 8 to 12 g / L, and the volume concentration of HCl is 35 to 45 mL / L; in step (S1.4), the concentration of PdCl2 in the activation solution is 0.08 to 0.12 g / L, and the volume concentration of HCl is 55 to 65 mL / L.

[0023] AgTiC@Ni electrical contact material prepared by the above method.

[0024] Positive effects of the present invention:

[0025] (1) The present invention uses TiC as a reinforcing phase, and adopts powder metallurgy and chemical plating technology to prepare AgTiC@Ni electrical contact materials with high electrical conductivity and excellent arc erosion resistance. The doped metal Ni is beneficial to enhancing the arc erosion resistance of the AgTiC@Ni electrical contact material. The AgTiC@Ni electrical contact material is expected to become a substitute for the universal electrical contact material AgCdO.

[0026] (2) In the embodiment of the present invention, when the mass percentage of the TiC@Ni composite powder is 3.5wt.%, the electrical conductivity and microhardness performance of the AgTiC@Ni electrical contact material are optimal.

[0027] (3) In the present invention, chemical nickel plating makes Ni more evenly distributed in AgTiC, the electrical conductivity and hardness of the AgTiC@Ni electrical contact material are significantly improved, the arcing time and arcing energy of arc erosion are more stable, the material transfer amount is minimized, and the material loss is less. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1The SEM morphology and EDS images of TiC@Ni composite powder; (a) SEM morphology of Ni@TiC composite powder; (b) C element; (c) Ni element; (d) Ti element; (e) EDS analysis;

[0029] Figure 2 XPS spectrum of TiC@Ni composite powder; (a) full spectrum; (b) fine spectrum of Ti element; (c) Ni 2p3 / 2 XPS fine spectrum;

[0030] Figure 3 The SEM morphology of TiC powder before and after chemical Ni plating; (a) TiC powder; (b) TiC@Ni composite powder after chemical plating;

[0031] Figure 4 Phase analysis diagram of AgTiC electrical contact materials with Ni added by different methods; (a) AgTiC; (b) AgTiC@Ni; (c) AgTiC-Ni;

[0032] Figure 5 Microstructure diagrams of AgTiC electrical contact materials with Ni powder added by different methods; (a) and (a1) are AgTiC; (b) and (b1) are AgTiC-Ni; (c) and (c1) are AgTiC@Ni;

[0033] Figure 6 This is the effect of TiC@Ni composite powder and Ni powder addition on the physical properties of AgTiC material;

[0034] Figure 7 The erosion morphology of the anode and cathode of the AgTiC electrical contact material; (a) AgTiC anode; (b) AgTiC cathode;

[0035] Figure 8 The erosion morphology of the anode and cathode of the AgTiC-Ni electrical contact material; (a) AgTiC-Ni anode; (b) AgTiC-Ni cathode;

[0036] Fig. 9 The erosion morphology of the anode and cathode of the AgTiC@Ni electrical contact material; (a) AgTiC@Ni anode; (b) AgTiC@Ni cathode;

[0037] Fig.10 This is the quality diagram of TiC@Ni and directly added Ni electrical contact materials after testing;

[0038] Fig.11 The average arc closing time and arc energy diagram of AgTiC electrical contact materials obtained by adding Ni in different ways;

[0039] Fig.12 The arc energy and arc duration analysis diagrams of blank samples and electrical contact materials prepared by different addition methods; (a) the change of arc time with the number of contacts; (b) the change of arc energy with the number of contacts;

[0040] Fig.13 This is the stress-strain curve of the compression experiment of TiC@Ni composite powder and AgTiC electrical contact material prepared by adding Ni powder. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the embodiments.

[0042] In the method of the present invention, the purity of the silver powder used is 99.9% and the particle size is 1 μm, while the purity of the TiC powder is 99.9% and the particle size is 1 μm.

[0043] The present invention provides a method for preparing an AgTiC@Ni electrical contact material, comprising the following steps:

[0044] (1) Add TiC powder to a nickel-containing chemical plating solution, stir and heat the solution at 70-80°C for 40-70 minutes, and wash and dry to obtain TiC@Ni composite powder; the washing and drying process is taken as an example of "washing with deionized water to neutrality and drying in a 60°C drying oven for 4 hours". The present invention does not limit the washing and drying process, as long as neutrality can be achieved through washing, as long as powder is obtained through drying. In addition to this case, other temperatures can be selected, such as drying at 80°C for 2 hours, or drying at 90°C for 3 hours.

[0045] The nickel-containing chemical plating solution is composed of the following components: a nickel source NiSO4·6H2O, a reducing agent N2H4, a composite complexing agent of EDTA-2Na and lactic acid, a stabilizer of thiourea and a pH adjuster of NaOH solution. The concentration of the nickel source in the nickel-containing chemical plating solution is 11 to 13 g / L, the concentration of N2H4 is 90 to 110 mL / L, the concentration of EDTA-2Na is 20 to 30 g / L, the concentration of lactic acid is 10 to 20 g / L, the concentration of thiourea is 0.8 to 1.2 mg / L, and the pH value of the nickel-containing chemical plating solution is 9 to 11.

[0046] The TiC powder needs to be pretreated before chemical plating. The specific process is as follows:

[0047] (S1.1) adding TiC powder to a NaOH solution with a concentration of 18 to 22 g / L for ultrasonic cleaning and then washing with deionized water to obtain a neutral TiC powder solution; wherein, the ultrasonic cleaning time is not limited, and the solution is washed until the solution is neutral.

[0048] (S1.2) A neutral TiC powder solution is added to a roughening solution containing HF and HNO3 in a volume concentration ratio of 1:2 for etching, and a TiC powder solution with a rough surface is obtained after washing; wherein the volume concentration of HF in the roughening solution is 18-22 mL / L; wherein etching is not limited, as long as a TiC powder with a rough surface can be obtained. Here, the TiC powder obtains a rough surface to facilitate successful nickel plating on the TiC surface. The washing time is also not limited, and it is washed until neutral.

[0049] (S1.3) Add the TiC powder solution with a rough surface into a sensitizing solution containing 8-12 g / L SnCl2·2H2O and 35-45 mL / L HCl for ultrasonic treatment. After the ultrasonic treatment, wash the solution with deionized water to a neutral TiC powder solution. There is no limit on the ultrasonic treatment time. The purpose of the ultrasonic treatment is to improve the catalytic activity of the TiC surface.

[0050] (S1.4) The neutral TiC powder solution obtained in step (S1.3) is activated by adding an activation solution containing 0.08-0.12 g / L PdCl2 and 55-65 mL / L HCl, and the activated TiC powder is washed to neutrality and dried for use. Among them, the activation time is not limited, as long as a catalytically active Pd layer can be formed on the TiC surface. The drying process is taken as an example of "washing with deionized water to neutrality and drying in a drying oven at 60°C for 4 hours". The present invention does not limit the drying process, as long as the powder is dried. In addition to this case, other temperatures can be selected, such as drying at 80°C for 2 hours, or drying at 90°C for 3 hours.

[0051] (2) Adding Ag powder and TiC@Ni composite powder into a container, and adding a solvent, wherein the solvent is ethanol or acetone, ultrasonically mixing the materials for 15 to 30 minutes, and drying the mixture;

[0052] The mass ratio of Ag powder to TiC@Ni composite powder is (95-97): (3-5). The amount of the solvent is not limited, as long as it can submerge the material.

[0053] (3) The mixed material obtained in step (2) is pressed into a blank at a pressure of 330 to 380 MPa for a holding time of 4 to 6 minutes, and is first sintered in an inert atmosphere (including nitrogen or argon) at 880 to 920° C. for 1.8 to 2.2 hours. After the sintering is completed, the blank is cooled to room temperature to obtain a preform;

[0054] (4) The preform obtained in step (3) is pressed again at a pressure of 1080-1120 MPa for 4-6 min, and sintered for a second time at 780-820° C. for 1.8-2.2 h in an inert atmosphere (including nitrogen or argon). After sintering, it is cooled to room temperature to obtain an AgTiC@Ni electrical contact material.

[0055] The present invention also provides an AgTiC@Ni electrical contact material with higher electrical conductivity and better arc erosion resistance, wherein the doped metal Ni is beneficial to enhancing the arc erosion resistance of the AgTiC@Ni electrical contact material, and the AgTiC@Ni electrical contact material is expected to become a substitute material for the universal electrical contact material AgCdO.

[0056] The tablet press used in the present invention is a FYS-30F desktop powder tablet press produced by Tianjin Sichuang Jingshi Technology Development Co., Ltd. The sintering furnace used is a NBD-01200-50IT mini tube furnace produced by Henan Nuobadi Material Technology Co., Ltd.

[0057] The present invention takes AgTiC as the research object, continuously optimizes the composition ratio of TiC and Ag, improves the poor wettability between the reinforcement and the matrix by metal addition, uses chemical nickel plating to target the wetting interface and enhance the dispersion of Ni in the matrix, so as to improve the comprehensive performance of the AgTiC electrical contact material. In the Ag-based electrical contact material of the present invention, the purity of the silver powder used is 99.9% and the particle size is 1μm, while the purity of the TiC powder is 99.9% and the particle size is 1μm.

[0058] In the method of the present invention, chemical nickel plating is used to prepare TiC@Ni composite powder. Chemical nickel plating is a surface metallization technology based on heterogeneous catalytic reaction, which allows the deposition of a nickel layer on a catalytically inactive surface. Since the TiC surface lacks catalytic activity, a specific pretreatment step is required to activate the surface in preparation for chemical nickel plating. The TiC surface is first roughened with a mixed acid solution of nitric acid and hydrochloric acid. This step is intended to increase the surface roughness and provide more active sites for subsequent sensitization and activation reactions. The roughened TiC surface is then sensitized in a SnCl2 solution to allow Sn 2+ ions are deposited on the TiC surface. Subsequently, the sensitized surface is activated in a PdCl2 solution. 2+ Ion reduction of Pd 2+ Pd is a single substance, forming a Sn / Pd composite catalytic core, providing a catalytic center for chemical nickel plating. 2 +Under the action of the reducing agent, it is reduced to neutral nickel atoms and deposited to form nickel nanoparticles. When sodium hypophosphite is used as a reducing agent, phosphorus and nickel will co-precipitate, resulting in a nickel-phosphorus alloy coating, which often introduces impurities P into the coating. This paper uses hydrazine (N2H4·H2O) as a reducing agent, which undergoes two reactions at the same time. First, Ni 2+ and The cathode reaction is followed by the deposition of metallic Ni particles and the formation of N2.

[0059] Ni 2+ +2e - →Ni

[0060] N2H4 - 4e - +4OH - →N2↑+4H2O

[0061] The other is the ionization of hydrazine (N2H4·H2O) in aqueous solution, in which the reaction is:

[0062]

[0063] In this process, OH is produced - , so the solution is alkaline.

[0064] Example 1

[0065] A method for preparing an AgTiC@Ni electrical contact material comprises the following steps:

[0066] (1) TiC surface pretreatment and chemical plating

[0067] The TiC surface pretreatment process is:

[0068] (S1.1) The TiC powder is added to a NaOH solution with a concentration of 20 g / L to remove surface impurities, and ultrasonically cleaned for 20 min, and then cleaned with deionized water to a neutral TiC powder solution.

[0069] (S1.2) The neutral TiC powder solution is added to a roughening solution containing 20 mL / L HF and 40 mL / L HNO3 and etched for 20 minutes to obtain a rough surface to facilitate successful nickel plating on the TiC surface, and then washed with deionized water until neutral to obtain a TiC powder solution with a rough surface.

[0070] (S1.3) The TiC powder solution with a rough surface is added to a sensitizing solution containing 10 g / L SnCl2·2H2O and 40 mL / L HCl and ultrasonicated for 30 min to improve the catalytic activity of the TiC surface. After the ultrasonication is completed, the TiC powder solution is washed with deionized water to a neutral state.

[0071] (S1.4) The neutral TiC powder solution obtained in step (S1.3) is added to an activation solution containing 0.1 g / L PdCl2 and 60 mL / L HCl and activated for 30 min. The activated TiC powder is washed to neutrality and separated by accelerated sedimentation using a centrifuge. Finally, the powder is dried in a drying oven at 60°C for 4 h and set aside.

[0072] The surface of the pretreated TiC powder has catalytic activity and can be used for chemical nickel plating.

[0073] The powder loading of the electroless plating solution was 9 g / L.

[0074] The composition of the chemical plating solution is: nickel source: NiSO4·6H2O, with a concentration of 12 g / L; reducing agent: N2H4, with a concentration of 100 mL / L; complexing agent: EDTA-2Na and lactic acid, with concentrations of 25 g / L and 15 g / L respectively; stabilizer: thiourea, with a concentration of 1 mg / L; pH regulator: NaOH (4 g / L) solution, controlling the pH value to 10.

[0075] Chemical plating:

[0076] The pretreated TiC powder was poured into the chemical plating solution and stirred continuously for 60 min in a magnetic heating stirrer at 75 °C. After stirring, it was washed with deionized water until neutral and dried in a drying oven at 60 °C for 4 h to finally obtain TiC@Ni composite powder.

[0077] (2) Mixing

[0078] The material was weighed according to the mass ratio of Ag powder to TiC@Ni composite powder of 96:4, and placed in a 50 mL wide-mouth beaker, anhydrous ethanol was added to submerge the material, the powder was mixed in an ultrasonic cleaner for 20 minutes, and a magnet was added to continuously stir in a magnetic stirrer until the anhydrous ethanol was completely evaporated, and the mixture was placed in an oven for drying to obtain a mixed material.

[0079] (3) First pressing and first sintering

[0080] The mixture was slowly poured into a Φ10 mm tablet press mold, and pressed into a blank at a pressure of 350 MPa for 5 minutes. The pressed blank was placed into a crucible with tweezers and placed in a tubular sintering furnace. It was sintered for the first time at 900°C for 2 hours in an argon atmosphere. After sintering, it was cooled to room temperature to obtain a prefabricated material.

[0081] (4) Second pressing and second sintering

[0082] The oxide on the surface of the prefabricated material was removed by sandpaper polishing, and then loaded into a Φ10.5mm tablet press mold, and pressed again at a pressure of 1100MPa for 5 minutes; the pressed blank was placed in a crucible with tweezers and placed in a tubular sintering furnace, and sintered for a second time at 800°C in an argon atmosphere for 2 hours. After sintering, it was cooled to room temperature to obtain the AgTiC@Ni electrical contact material.

[0083] Comparative Example 1 AgTiC electrical contact material

[0084] The method for preparing the AgTiC electrical contact material described in this embodiment comprises the following steps:

[0085] (1) Mixing

[0086] The materials were weighed according to the mass ratio of Ag powder to TiC powder of 96.5:3.5, and placed in a 50 mL wide-mouth beaker. Anhydrous ethanol was added to submerge the materials. The powders were mixed in an ultrasonic cleaner for 20 min. A magnet was added and the mixture was continuously stirred in a magnetic stirrer until the anhydrous ethanol was completely evaporated. The mixture was placed in an oven for drying to obtain a mixed material.

[0087] (2) First pressing and first sintering

[0088] The mixture was slowly poured into a Φ10 mm tablet press mold, and pressed into a blank at a pressure of 350 MPa for 5 minutes. The pressed blank was placed into a crucible with tweezers and placed in a tubular sintering furnace. It was sintered for the first time at 900°C for 2 hours in an argon atmosphere. After sintering, it was cooled to room temperature to obtain a prefabricated material.

[0089] (3) Second pressing and second sintering

[0090] The oxide on the surface of the prefabricated material was removed by sandpaper polishing, and then loaded into a Φ10.5mm tablet press mold, and pressed again at a pressure of 1100MPa for 5 minutes; the pressed blank was placed in a crucible with tweezers, and placed in a tubular sintering furnace, and sintered for a second time at 800°C in an argon atmosphere for 2 hours. After sintering, it was cooled to room temperature to obtain AgTiC electrical contact material.

[0091] Comparative Example 2: Adding nickel to the electrical contact material in a manner different from that in Example 1

[0092] The preparation method of the AgTiC-Ni electrical contact material described in this comparative example comprises the following steps:

[0093] (1) Mixing

[0094] Weigh the materials according to the mass ratio of Ag powder, TiC powder and nickel powder of 96:3.5:0.5, put them into a 50 mL wide-mouth beaker, add anhydrous ethanol to submerge the materials, mix the powder in an ultrasonic cleaner for 20 minutes, add a magnet and continue stirring in a magnetic stirrer until the anhydrous ethanol is completely evaporated, and put them into an oven for drying to obtain a mixture.

[0095] (2) First pressing and first sintering

[0096] The mixture was slowly poured into a Φ10 mm tablet press mold, and pressed into a blank at a pressure of 350 MPa for 5 minutes. The pressed blank was placed into a crucible with tweezers and placed in a tubular sintering furnace. It was sintered for the first time at 900°C for 2 hours in an argon atmosphere. After sintering, it was cooled to room temperature to obtain a prefabricated material.

[0097] (3) Second pressing and second sintering

[0098] The oxide on the surface of the prefabricated material was removed by sandpaper polishing, and then loaded into a Φ10.5mm tablet press mold, and pressed again at a pressure of 1100MPa for 5 minutes; the pressed blank was placed in a crucible with tweezers, and placed in a tubular sintering furnace, and sintered for a second time at 800°C in an argon atmosphere for 2 hours. After sintering, it was cooled to room temperature to obtain AgTiC-Ni electrical contact material.

[0099] Performance Testing:

[0100] (1) Characterization of TiC@Ni composite powders

[0101] Figure 1 SEM morphology and EDS analysis of TiC@Ni composite powder. Figure 1 (a) shows the SEM morphology of TiC@Ni composite powder. The matrix is ​​TiC particles, and a large number of white dot-like nanoparticles are evenly distributed on the particles. EDS surface scanning analysis of this area shows the results. Figure 1 As shown in (b)-(d). Figure 1 (b) and Figure 1 (d) shows the uniform distribution of Ti and C elements, indicating that the matrix is ​​TiC ceramic. Figure 1 (c) Ni is distributed in the green area, which is exactly the same as Figure 1 The TiC particle area in (a) is consistent, indicating that Ni is distributed on the surface of TiC particles. However, from the SEM image, although the Ni element is distributed more evenly on the surface of TiC particles, slight agglomeration can still be observed, which may affect the comprehensive performance of the final material. Figure 1 (a) The element content results after regional EDS surface scanning are as follows Figure 1(e), the content of Ni element is 0.49%, indicating that the amount of Ni coated on the TiC surface is relatively small. The successful coating of Ni element on the surface of TiC particles was confirmed by SEM and EDS analysis. Although the content of Ni is not high, its uniform distribution has a positive effect on improving the interfacial wettability and bonding strength of AgTiC@Ni electrical contact materials. However, the existence of agglomeration indicates that the preparation process needs to be further optimized during the preparation process to ensure that the composite powder has good composition uniformity.

[0102] Figure 2 XPS analysis of the elemental composition and chemical valence state of the surface coating of TiC@Ni composite powder. Figure 2 (a) is the full XPS spectrum of the TiC@Ni composite powder coating. The presence of Ni, Ti, C and O elements were detected in the figure, indicating that these elements constitute the main components of the coating. In order to accurately analyze the chemical valence state of the elements on the surface of the TiC@Ni composite powder, the binding energy of C1s (284.80eV) was used as a reference for calibration, and a peak fitting analysis was performed. The analysis results show the characteristic peaks of Ni2p, C1s and O1s. The presence of these characteristic peaks confirms the deposition of Ni elements on the surface of the TiC matrix. By using peak fitting software, the Ni 2p peak is decomposed into multiple components, such as Figure 2 (c), these components correspond to different chemical states or coordination environments. By comparing the Ni 2p peak position of the sample with the peak position of the standard reference material, it can be determined that the valence state of Ni is +2, and the Ni2p3 / 2 binding energy corresponding to metallic nickel in the spectrum is 852.4eV, which is consistent with the previous energy spectrum analysis results, indicating that the coating does contain metallic nickel. Due to the low nickel content on the surface of the coating, the nickel metal characteristic peak of Ni2p3 / 2 is not obvious enough. This observation is consistent with the EDS analysis results. The Ni element was successfully deposited on the surface of the TiC substrate, forming the expected TiC@Ni composite structure.

[0103] SEM morphology of TiC powder before and after chemical Ni plating Figure 3 shown. Figure 3 (a) is the original SEM morphology of TiC powder, from which it can be seen that the surface of TiC powder is flat. Figure 3 As shown in (b), small pits appeared on the surface of TiC powder, and the particles that appeared were Ni metal. The roughening treatment can effectively remove the dirt on the surface of TiC powder. The mixed acid solution can smoothly etch the surface of TiC powder, making the surface of TiC particles uneven. The appearance of the grooves increases the surface roughness and enhances the adhesion of chemical nickel. Secondly, the surface of TiC particles is activated by Pd 2+ Sn 2+It is reduced to metal Pd and deposited on the TiC surface, making it catalytically active and allowing for better chemical plating. From the picture, it can be observed that after chemical Ni plating, the TiC powder surface is coated, and Ni metal particles are wrapped on the surface of TiC particles. Due to the Ni content of 0.5%, the Ni particles are not evenly coated.

[0104] (2) Comparative analysis of the electrical contact materials of Example 1 and Comparative Examples 1-2

[0105] Figure 4 The XRD results of three electrical contact materials, AgTiC, AgTiC@Ni, and AgTiC-Ni. All samples show characteristic diffraction peaks of Ag and TiC. The diffraction peaks at 2θ of 35.9°, 41.7°, 60.4°, 72.4°, and 76.1° correspond to the (111), (200), (220), (311), and (222) crystal planes of the standard spectrum of cubic TiC (JCPDS No.03-065-8417). The diffraction peaks of Ag in the obtained composition are basically consistent with the material components, indicating that the components are relatively stable and no reaction occurs to produce other impurity peaks.

[0106] Figure 5 Microstructure of AgTiC electrical contact materials prepared by adding Ni by different methods. Figure 5 (a) shows that without adding the third phase, the TiC reinforcement phase is mainly distributed around the particles of the Ag matrix, and the distribution between the particles is relatively loose, but the overall uniformity is maintained. Figure 5 (b) reveals the effect of Ni addition on the microstructure of the composite material. The addition of nickel makes the composite powder more evenly distributed in the Ag matrix, and the microstructure is more compact than when Ni is not added. Figure 5 (c) is the microstructure of AgTiC@Ni electrical contact material prepared from TiC@Ni composite powder. It can be seen that TiC particles are dispersed and coated with Ni, indicating that chemical Ni plating improves the dispersion of TiC in the Ag matrix.

[0107] (3) Comparative analysis of the performance of the electrical contact materials of Example 1 and Comparative Examples 1-2

[0108] Figure 6 Density, hardness and conductivity analysis results of blank sample and AgTiC electrical contact material obtained by adding Ni in different ways. Figure 6It can be seen that the mechanical properties of AgTiC electrical contact materials prepared by adding Ni by different methods are much improved compared with the blank samples. Compared with the direct addition of Ni, the electrical conductivity of the electrical contact material prepared by TiC@Ni composite powder prepared by chemical plating increased by 3.56% and the Vickers hardness increased by 6.11%. It is proved that chemical nickel plating can effectively improve the physical properties of AgTiC@Ni electrical contact materials.

[0109] (4) Comparative analysis of electrical contact tests of the electrical contact materials of Example 1 and Comparative Examples 1-2

[0110] (4.1) Arc erosion morphology analysis

[0111] Figure 7 The erosion morphology of the anode and cathode of the AgTiC electrical contact material in comparative example 1. From the figure, we can observe the granular shape of silver balls, which indicates that there is poor interfacial wettability between Ag and TiC, resulting in a large number of splashed Ag beads distributed on the contact surface. Figure 7 As can be seen in (a), in areas with severe arc erosion, a large number of pores exist on the surfaces of the anode and cathode, which may be due to the fact that Ag is easy to evaporate or migrate at high temperatures, resulting in the formation of pores on the surface. The pores in the anode area are accompanied by larger cracks, which may be due to the internal stress concentration and structural damage of the material caused by the increase in temperature. The temperature increase under the action of the arc may aggravate the thermal stress inside the material, thereby promoting the expansion of cracks and the formation of pores, which may further affect the electrical contact performance and mechanical strength of the material. Arc erosion morphology analysis reveals the interface wettability problems and structural damage risks that AgTiC electrical contact materials without the addition of Ni powder may face under the action of the arc. These problems may affect the long-term stability and reliability of the material and need to be solved through material design and process optimization.

[0112] Figure 8 (a)- Figure 8 (b) is the corrosion morphology of AgTiC electrical contact material with Ni powder added. Figure 8 In the eroded area of ​​(a), the traces produced by melting do not appear on the material surface in the shape of pits, indicating that TiC is relatively dispersed in the material without obvious aggregation. Figure 8 (a)- Figure 8 (b) shows that the presence of pores and cracks is significantly reduced in areas with severe anode and cathode erosion, which may be due to the fact that the addition of Ni improves the structural integrity of the material and reduces the formation of pores and cracks under the action of the arc, thereby improving the electrical contact performance and durability of the material.

[0113] Fig. 9 Arc erosion morphology of AgTiC@Ni electrical contact material prepared by adding TiC@Ni composite powder. Fig. 9(a) In the eroded area, compared with the case of no addition and direct addition of Ni powder, the Ag solidified in the form of spheres on the surface of the AgTiC@Ni electrical contact material anode prepared by adding TiC@Ni composite powder is significantly reduced. However, a small amount of TiC segregation is observed, which may be due to incomplete Ni coating, resulting in the failure of uniform dispersion of TiC in the area. Fig. 9 (b) shows that there are no pores in the cathode erosion area, which indicates that the addition of TiC@Ni composite powder improves the density and corrosion resistance of the material. Comprehensive analysis shows that compared with the direct addition of Ni powder, TiC@Ni composite powder can more effectively improve the arc resistance of AgTiC@Ni electrical contact materials. The uniform dispersion of TiC reinforcement helps to significantly improve the stability and reliability of AgTiC@Ni electrical contact materials, which is of great significance for the optimization of electrical contact material performance.

[0114] (4.2) Material transfer analysis

[0115] Fig.10 It is the mass change of the blank sample, Ni powder and the electrical contact material prepared by adding TiC@Ni composite powder. It shows that the anode mass loss of AgTiC@Ni electrical contact material prepared by TiC@Ni composite powder is 0.2μɡ lower than that of AgTiC-Ni electrical contact material prepared by directly adding Ni powder, and the mass added by the cathode has not changed.

[0116] (4.3) Analysis of closing arc characteristics

[0117] Fig.11 The figure shows the average closed arc time and arc energy of AgTiC electrical contact materials obtained by adding Ni in different ways. As can be seen from the figure, the arc energy of AgTiC electrical contact materials is between 0.75J and 0.15J, and the arc time is between 1.5ms and 2.5ms, and the arc time of both is related to the arc energy. As can be seen from the figure, Ni increases the closed arc energy and arc time of AgTiC electrical contact materials, but compared with the direct addition of Ni, the AgTiC@Ni electrical contact material prepared by TiC@Ni composite powder synthesized by chemical plating has lower average arc energy and average arc time, and smaller arc energy fluctuation. The addition of Ni by chemical plating effectively improves the arc stability of AgTiC@Ni electrical contact materials.

[0118] Fig.12 This is an analysis of the arcing energy and arcing duration of the blank sample and the electrical contact materials prepared by different addition methods. As can be seen from the figure, compared with the Ni-added AgTiC-Ni and AgTiC@Ni electrical contact materials, the latter exhibits lower arcing energy and arcing duration, which indicates that the chemical Ni plating method has obvious advantages in reducing arcing performance and can effectively improve the reliability and service life of electrical contact materials.

[0119] (4.4) Compression performance analysis

[0120] Fig.13 The stress-strain curves of electrical contact materials prepared by adding Ni in different ways. The results show that the AgTiC@Ni electrical contact materials prepared by TiC@Ni composite powders have significantly improved compressive strength and elongation. Compared with AgTiC electrical contact materials with direct addition of Ni powder and without any additives, the AgTiC@Ni electrical contact materials prepared by TiC@Ni composite powders have higher compressive strength and better elongation.

[0121] Example 2

[0122] A method for preparing an AgTiC@Ni electrical contact material comprises the following steps:

[0123] (1) TiC surface pretreatment and chemical plating

[0124] The TiC surface pretreatment process is:

[0125] (S1.1) The TiC powder is added to a NaOH solution with a concentration of 18 g / L to remove surface impurities, and ultrasonically cleaned for 20 min, and then cleaned with deionized water to a neutral TiC powder solution.

[0126] (S1.2) The neutral TiC powder solution is added to a roughening solution containing 18 mL / L HF and 36 mL / L HNO3 and etched for 20 minutes to obtain a rough surface to facilitate successful nickel plating on the TiC surface, and then washed with deionized water until neutral to obtain a TiC powder solution with a rough surface.

[0127] (S1.3) The TiC powder solution with a rough surface is added to a sensitizing solution containing 8 g / L SnCl2·2H2O and 35 mL / L HCl and ultrasonicated for 20 min to improve the catalytic activity of the TiC surface. After the ultrasonication is completed, the TiC powder solution is washed with deionized water to a neutral state.

[0128] (S1.4) The neutral TiC powder solution obtained in step (S1.3) is added to an activation solution containing 0.08 g / L PdCl2 and 55 mL / L HCl and activated for 20 min. The activated TiC powder is washed to neutrality and separated by accelerated sedimentation using a centrifuge. Finally, the powder is dried in a drying oven at 80°C for 3 h and set aside.

[0129] The surface of the pretreated TiC powder has catalytic activity and can be used for chemical nickel plating.

[0130] The powder loading of the electroless plating solution was 9 g / L.

[0131] The composition of the chemical plating solution is: nickel source: NiSO4·6H2O, with a concentration of 11 g / L; reducing agent: N2H4, with a concentration of 90 mL / L; complexing agent: EDTA-2Na and lactic acid, with concentrations of 20 g / L and 10 g / L respectively; stabilizer: thiourea, with a concentration of 0.8 mg / L; pH regulator: NaOH (4 g / L) solution, controlling the pH value to 9.

[0132] Chemical plating:

[0133] The pretreated TiC powder was poured into the chemical plating solution and stirred continuously for 70 min in a magnetic heating stirrer at 70 °C. After stirring, it was washed with deionized water until neutral and dried in a drying oven at 80 °C for 2 h to finally obtain TiC@Ni composite powder.

[0134] (2) Mixing

[0135] The material was weighed according to the mass ratio of Ag powder to TiC@Ni composite powder of 95:5, and placed in a 50 mL wide-mouth beaker. Acetone was added to submerge the material, and the powder was mixed in an ultrasonic cleaner for 15 minutes. A magnet was then added to continuously stir in a magnetic stirrer until the acetone was completely evaporated. The mixture was placed in an oven for drying to obtain a mixed material.

[0136] (3) First pressing and first sintering

[0137] The mixture was slowly poured into a Φ10 mm tablet press mold, and pressed into a blank at a pressure of 330 MPa for 6 minutes. The pressed blank was placed into a crucible with tweezers and placed in a tubular sintering furnace. The blank was sintered for the first time at 880°C in an argon atmosphere for 2.2 hours. After sintering, it was cooled to room temperature to obtain a prefabricated material.

[0138] (4) Second pressing and second sintering

[0139] The oxide on the surface of the prefabricated material was removed by sandpaper polishing, and then loaded into a Φ10.5mm tablet press mold, and pressed again at a pressure of 1080MPa for 6 minutes; the pressed blank was placed in a crucible with tweezers and placed in a tubular sintering furnace, and sintered for a second time at 780°C in an argon atmosphere for 2.2 hours. After sintering, it was cooled to room temperature to obtain AgTiC@Ni electrical contact material.

[0140] Example 3

[0141] A method for preparing an AgTiC@Ni electrical contact material comprises the following steps:

[0142] (1) TiC surface pretreatment and chemical plating

[0143] The TiC surface pretreatment process is:

[0144] (S1.1) The TiC powder is added to a NaOH solution with a concentration of 22 g / L to remove surface impurities, and ultrasonically cleaned for 20 min, and then cleaned with deionized water to a neutral TiC powder solution.

[0145] (S1.2) The neutral TiC powder solution is added to a roughening solution containing 22 mL / L HF and 44 mL / L HNO3 and etched for 20 minutes to obtain a rough surface to facilitate successful nickel plating on the TiC surface, and then washed with deionized water until neutral to obtain a TiC powder solution with a rough surface.

[0146] (S1.3) The TiC powder solution with a rough surface is added to a sensitizing solution containing 12 g / L SnCl2·2H2O and 45 mL / L HCl and ultrasonicated for 40 min to improve the catalytic activity of the TiC surface. After the ultrasonication is completed, the TiC powder solution is washed with deionized water to a neutral state.

[0147] (S1.4) The neutral TiC powder solution obtained in step (S1.3) is added to an activation solution containing 0.12 g / L PdCl2 and 65 mL / L HCl and activated for 40 min. The activated TiC powder is washed to neutrality and separated by accelerated sedimentation using a centrifuge. Finally, the powder is dried in a drying oven at 70°C for 4 h and set aside.

[0148] The surface of the pretreated TiC powder has catalytic activity and can be used for chemical nickel plating.

[0149] The powder loading of the electroless plating solution was 9 g / L.

[0150] The composition of the chemical plating solution is: nickel source: NiSO4·6H2O, with a concentration of 13 g / L; reducing agent: N2H4, with a concentration of 110 mL / L; complexing agent: EDTA-2Na and lactic acid, with concentrations of 30 g / L and 20 g / L respectively; stabilizer: thiourea, with a concentration of 1.2 mg / L; pH regulator: NaOH (4 g / L) solution, controlling the pH value to 11.

[0151] Chemical plating:

[0152] The pretreated TiC powder was poured into the chemical plating solution and stirred continuously in a magnetic heating stirrer at 80°C for 40 min. After stirring, it was washed with deionized water until neutral and dried in a drying oven at 70°C for 4 h to finally obtain TiC@Ni composite powder.

[0153] (2) Mixing

[0154] The material was weighed according to the mass ratio of Ag powder to TiC@Ni composite powder of 97:3, and placed in a 50 mL wide-mouth beaker, anhydrous ethanol was added to submerge the material, the powder was mixed in an ultrasonic cleaner for 30 minutes, and a magnet was added to continuously stir in a magnetic stirrer until the anhydrous ethanol was completely evaporated, and the mixture was placed in an oven for drying to obtain a mixed material.

[0155] (3) First pressing and first sintering

[0156] The mixed material was slowly poured into a Φ10 mm tablet press mold, and pressed into a blank at a pressure of 380 MPa for 4 minutes. The pressed blank was placed into a crucible with tweezers and placed in a tubular sintering furnace. The blank was sintered for the first time at 920°C in an argon atmosphere for 1.8 hours. After sintering, it was cooled to room temperature to obtain a prefabricated material.

[0157] (4) Second pressing and second sintering

[0158] The oxide on the surface of the prefabricated material was removed by sandpaper polishing, and then loaded into a Φ10.5mm tablet press mold, and pressed again at a pressure of 1120MPa for 4 minutes; the pressed blank was placed in a crucible with tweezers and placed in a tubular sintering furnace, and sintered for a second time at 820°C in an argon atmosphere for 1.8 hours. After sintering, it was cooled to room temperature to obtain AgTiC@Ni electrical contact material.

[0159] The present invention uses TiC as the reinforcement phase, adopts powder metallurgy and chemical plating technology, and studies the effects of the reinforcement addition amount, different metal elements and Ni element microdistribution on the organizational structure, physical properties and arc characteristics of AgTiC electrical contact materials. The final conclusion is:

[0160] (1) When the content of conductive ceramic TiC is 3.5wt.%, the AgTiC electrical contact material has higher conductivity and microhardness.

[0161] (2) Through the analysis of the microstructure, physical and electrical properties of AgTiC electrical contact materials, the addition of 0.5wt.% Ni significantly improved the physical properties and arc characteristics of AgTiC electrical contact materials.

[0162] (3) Chemical nickel plating makes Ni more evenly distributed in AgTiC, and the electrical conductivity and hardness of the AgTiC@Ni electrical contact material are significantly improved. The arcing time and arcing energy of arc erosion are more stable, the material transfer amount is minimized, and the material loss is less.

[0163] AgTiC@Ni electrical contact material has high electrical conductivity and excellent arc erosion resistance. Metal Ni is beneficial to enhancing the arc erosion resistance of AgTiC@Ni electrical contact material. AgTiC@Ni electrical contact material is expected to become a substitute for universal contact material AgCdO.

[0164] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and the specific implementation of the present invention cannot be limited to these descriptions. For ordinary technicians in the field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for preparing an AgTiC@Ni electrical contact material, characterized in that: The steps include: (1) adding TiC powder into a nickel-containing chemical plating solution, stirring and heating the solution for reaction, and obtaining a TiC@Ni composite powder after washing and drying; (2) adding Ag powder and TiC@Ni composite powder into a container, adding a solvent, performing ultrasonic mixing, and drying to obtain a mixture; (3) pressing the mixed material obtained in step (2) into a blank, sintering it for the first time under an inert atmosphere, and cooling it to room temperature after sintering to obtain a prefabricated material; (4) The preform obtained in step (3) is pressed into shape again, sintered for a second time under an inert atmosphere, and cooled to room temperature after sintering to obtain an AgTiC@Ni electrical contact material.

2. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (1), the nickel-containing chemical plating solution is composed of the following components: The invention comprises: a nickel source NiSO4·6H2O, a reducing agent N2H4, a composite complexing agent of EDTA-2Na and lactic acid, a stabilizer of thiourea and a pH value adjusting agent of NaOH solution. The concentration of the nickel source in the nickel-containing chemical plating solution is 11-13 g / L, the concentration of N2H4 is 90-110 mL / L, the concentration of EDTA-2Na is 20-30 g / L, the concentration of lactic acid is 10-20 g / L, the concentration of thiourea is 0.8-1.2 mg / L, and the pH value of the nickel-containing chemical plating solution is 9-11.

3. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (1), the stirring and heating reaction temperature is 70 to 80° C., and the reaction time is 40 to 70 min.

4. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (2), the solvent is ethanol or acetone.

5. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (2), the mass ratio of Ag powder to TiC@Ni composite powder is (95-97):(3-5), and the ultrasonic mixing time is 15-30 minutes.

6. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (3), the pressure for pressing the blank is 330-380 MPa, and the holding time is 4-6 min; the inert gas is nitrogen or argon; the temperature for the first sintering is 880-920° C., and the sintering time is 1.8-2.2 h.

7. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (4), the pressure of the preform for pressing again is 1080-1120 MPa, and the holding time is 4-6 min; the inert gas is nitrogen or argon; the temperature of the second sintering is 780-820° C., and the sintering time is 1.8-2.2 h.

8. The method for preparing the AgTiC@Ni electrical contact material according to claim 1, characterized in that: In step (1), the pretreatment process of the TiC powder is (S1.1) adding TiC powder to a NaOH solution for ultrasonic cleaning and then washing with deionized water to obtain a neutral TiC powder solution; (S1.2) adding the neutral TiC powder solution into a roughening solution containing HF and HNO3 for etching, and obtaining a TiC powder solution having a concave-convex rough surface after washing; (S1.3) adding the TiC powder solution with a rough surface to a sensitizing solution containing SnCl2·2H2O and HCl for ultrasonic treatment, and after the ultrasonic treatment, washing with deionized water to a neutral TiC powder solution; (S1.4) The neutral TiC powder solution obtained in step (S1.3) is activated by adding an activation solution containing PdCl2 and HCl, and the activated TiC powder is washed to neutrality and dried for later use.

9. The method for preparing the AgTiC@Ni electrical contact material according to claim 8, characterized in that: In step (S1.1), the concentration of the NaOH solution is 18-22 g / L; in step (S1.2), the volume concentration ratio of HF and HNO3 in the roughening solution is 1:2, and the volume concentration of HF in the roughening solution is 18-22 mL / L; in step (S1.3), the concentration of SnCl2·2H2O in the sensitizing solution is 8-12 g / L, and the volume concentration of HCl is 35-45 mL / L; in step (S1.4), the concentration of PdCl2 in the activation solution is 0.08-0.12 g / L, and the volume concentration of HCl is 55-65 mL / L.

10. AgTiC@Ni electrical contact material prepared by the method according to any one of claims 1 to 9.

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