Cucrti materials and methods of making cucrti materials

Abstract

The application provides a CuCrTi material and a method for manufacturing the CuCrTi material, the CuCrTi material contains 2-8 wt% of Ti, 44-53 wt% of Cu, and the balance of Cr, and in the microstructure of the CuCrTi material, a Ti phase is composed of Ti particles with an average particle size of 15-25 microns, and the Ti particles are surrounded around Cr particles. According to the application, the technical problems of too many internal pores, too poor compactness, too high oxygen content and too low hardness of the material are effectively solved, and the compactness is good, the oxygen content is low, and the application performance is good.

Description

CuCrTi materials and methods for manufacturing CuCrTi materials Technical Field

[0001] This invention relates to a CuCrTi material and a method for manufacturing the CuCrTi material. Background Technology

[0002] Powder metallurgy is a process that uses metal powders as raw materials to manufacture metal materials, composite materials, and various types of products through forming and sintering processes. Compared with traditional metallurgical processes, powder metallurgy has the highest material utilization rate (over 95%, compared to only 50% in traditional machining) and the lowest energy consumption (approximately 80% of raw materials come from recycled waste). It is an advanced, green, low-carbon metal forming process that aligns with the trend of high-quality development.

[0003] In powder metallurgy, CuCr alloy products manufactured using the commonly used CuCr powder metallurgy process have the following defects: The resulting products have numerous internal pores, leading to low density and severely reducing material performance and product lifespan. Furthermore, when these products with excessively low hardness are used in vacuum interrupters, their low mechanical strength often results in delamination or fracture, rendering them unusable. Other defects include poor density and excessively high oxygen content. Poor density leads to significant problems with material strength and brittleness, while excessive oxygen content prevents the maintenance of vacuum levels during vacuum circuit breaker operation, shortening the breaker's lifespan.

[0004] Therefore, it is evident that whether an improved material can be provided based on the shortcomings of existing technologies to effectively solve the technical problems of excessive internal porosity, poor density, excessive oxygen content, and low hardness has become a technical challenge that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an improved material and manufacturing method. According to the improved material and manufacturing method provided by this invention, the technical problems of excessive internal porosity, poor density, excessive oxygen content, and insufficient hardness in the material are solved.

[0007] Methods for solving problems

[0008] The first aspect of this invention relates to a CuCrTi material containing 2% to 8% by weight Ti, 42% to 54% by weight Cu, and the balance Cr.

[0009] In the microstructure of this CuCrTi material, the Ti phase consists of Ti particles with an average particle size of 15-25 micrometers, which surround the Cr particles.

[0010] Preferably, it contains 3% to 7% Ti.

[0011] Preferably, it contains 44% to 53% Cu by weight.

[0012] Preferably, it has a hardness of HV 170-210.

[0013] Preferably, it has a hardness of HV 200-205.

[0014] The second aspect of this invention relates to a method for manufacturing the CuCrTi material described in the first aspect of this invention, comprising the following steps:

[0015] The mixing step involves mixing Cu powder, Cr powder, and Ti powder.

[0016] The filling step involves filling the mixed powder into a graphite mold;

[0017] The pressing and sintering step involves pressing and sintering the filled powder to form a blank.

[0018] Preferably, the pressing and sintering step is achieved by performing spark plasma sintering on the powder.

[0019] Preferably, a double cone mixer is used in the mixing step, a protective gas is introduced, and steel balls are added for mixing.

[0020] Preferably, the graphite mold includes: a graphite gasket, a graphite casting mold, a graphite punch, and a thermocouple.

[0021] The effects of the invention

[0022] According to the CuCrTi material and the method for manufacturing CuCrTi material of the present invention, the technical problems of excessive internal pores, poor density, excessive oxygen content and low hardness are effectively solved, resulting in good density, low oxygen content and good application performance. Attached Figure Description

[0023] Figure 1 is a phase diagram of the CuCrTi material of the first aspect of the present invention.

[0024] Figure 2 is a magnified view of a portion of Figure 1.

[0025] Figure 3 is a magnified view of a portion of Figure 2.

[0026] Figure 4 shows the phase diagram of materials manufactured using existing technology.

[0027] Figure 5 is an electron image obtained by scanning electron microscopy using CuCrTi material according to the first aspect of the present invention.

[0028] Figure 6 shows the specific spectrum at point 1 in Figure 5.

[0029] Figure 7 shows the specific spectrum at point 2 in Figure 5.

[0030] Figure 8 is a schematic diagram of the graphite mold used in Embodiments 1 to 2 of the manufacturing method of the second aspect of the present invention.

[0031] Figure 9 shows an electron image of the CuCrTi material manufactured by the method of Comparative Example 1 obtained by scanning electron microscopy. Detailed Implementation

[0032] Hereinafter, the CuCrTi material involved in the first aspect of the present invention will be described in detail.

[0033] The CuCrTi material contains 2% to 8% Ti, 42% to 54% Cu, and the balance Cr. More preferably, the CuCrTi material contains 3% to 7% Ti and 44% to 53% Cu, which further improves density and application performance.

[0034] In addition, in the microstructure of this CuCrTi material, the Ti phase consists of Ti particles with an average particle size of 15-25 micrometers, surrounding the Cr particles. The average particle size of the Ti particles is further preferably 18-22 micrometers, and even more preferably 20 micrometers, as this average particle size further improves density and application performance. The average particle size of the Cr particles is 32-100 micrometers. During the opening process of a vacuum circuit breaker, arc ignition on the contact surface mainly relies on Cr particles. Filling this particle size distribution range with Ti particles smaller than 32 micrometers allows the small particles to embed around the larger Ti particles, increasing the density during the pressing and sintering process, while simultaneously igniting the arc and withstanding arc erosion together with the Cr particles. However, excessively small Ti particles reduce erosion resistance, while excessively large particles hinder the adhesion and growth of Ti and Cr particles. Therefore, it is preferable to use Ti particles of 15-25 micrometers in this material.

[0035] As shown in Figures 1-3, especially the circled areas in Figures 2 and 3, in this CuCrTi material, spongy Ti particles grow close to Cr particles and are tightly bonded together. As shown in Figures 5-7, in this CuCrTi material, there is a clear distribution of Ti at spectra 1 and 2.

[0036] Figure 4 shows the phase diagram of a material manufactured using existing technology. This material is CuCr, which does not contain Ti. Therefore, there are no Ti particles on this phase diagram. Compared with Figure 1, it can be seen that the CuCr material manufactured using this existing technology has many internal pores and poor compactness.

[0037] The CuCrTi material involved in the first aspect of the present invention preferably has a hardness of HV 170-210. More preferably, it has a hardness of HV 200-205. In contrast, the CuCr material manufactured using the prior art, as shown in FIG. 4, has a hardness of only about HV 85, which is far lower than that of the CuCrTi material involved in the first aspect of the present invention.

[0038] The CuCrTi material of the first aspect of this invention, obtained by sintering mixed Cu, Cr, and Ti powders, has a density of 7.6-7.8 g / cm³. 3 This density is higher than that of the material manufactured according to the prior art as shown in Figure 4, meaning that the material's density is superior to that of the prior art.

[0039] Meanwhile, the oxygen content inside the CuCrTi material involved in the first aspect of the present invention is below 300 ppm, while the oxygen content of the material manufactured according to the prior art, as shown in Figure 4, is between 400-600 ppm. Low oxygen content is very beneficial for maintaining the vacuum level during the operation of vacuum circuit breakers and is closely related to the insulation performance of the circuit breaker after arc interruption.

[0040] As described above, the CuCrTi material according to the first aspect of the present invention effectively solves the technical problems of excessive internal pores, poor density, excessive oxygen content, and low hardness, resulting in good density, low oxygen content, and good application performance.

[0041] The CuCrTi material of this invention is suitable for the following applications: For example, it can be used as a vacuum emission electrode. When a vacuum emission tube is operating, a strong electric arc is generated between the emission electrodes. Cr and Ti are both refractory metals. Cr has a melting point of 1907 degrees Celsius, and Ti has a melting point of 1668 degrees Celsius. These two refractory metals increase the material's resistance to arc erosion. The aforementioned density and hardness of the CuCrTi material of the first aspect of this invention further enhance this resistance. For example, it can also be used as a high-performance contact in a medium-voltage vacuum interrupter. When continuously interrupted at 20kV to 31.5kV, the high-load arc will erode the contact surface. The standard specification for CuCr contacts is 30 interruptions. Contacts made of the CuCrTi material of the first aspect of this invention will achieve more interruptions than contacts made of CuCr material in the prior art because the Ti-containing CuCr contacts have enhanced resistance to welding and are less prone to sticking together.

[0042] The following describes the manufacturing method of CuCrTi material according to the second aspect of the present invention.

[0043] The method for manufacturing CuCrTi material according to the second aspect of the present invention is characterized by comprising at least the following steps:

[0044] The mixing step involves mixing Cu powder, Cr powder, and Ti powder.

[0045] The filling step involves filling the mixed powder into a graphite mold;

[0046] The pressing and sintering step involves pressing and sintering the filled powder to form a blank.

[0047] As shown in Figure 8, the graphite mold preferably includes: a graphite gasket, a graphite casting mold, a graphite punch, and a thermocouple. The graphite gasket, graphite casting mold, and graphite punch are all made of the same conductive material, preferably high-strength, high-density graphite. The thermocouple is used to detect the temperature inside the graphite mold. A powder mixer, preferably a double-cone powder mixer, is used to mix Cu powder, Cr powder, and Ti powder. Since Cu is a low-melting-point metal, a high Cu proportion makes the material prone to fusion and adhesion when subjected to high-temperature arc erosion during application. Since Cr is a high-melting-point metal, Cr is the main component resisting arc erosion, and the addition of Ti significantly improves the resistance to arc erosion. The mixed powder is then filled into the graphite mold shown in Figure 8, and finally the filled powder is pressed and sintered to form a blank. Preferably, sintering is achieved by spark plasma sintering of the powder.

[0048] The following describes a method for manufacturing CuCrTi materials according to the second aspect of the present invention with the aid of examples and comparative examples.

[0049] Example

[0050] Example 1:

[0051] Ti powder, Cr powder, and Cu powder were used as raw materials. They were mixed in a double cone mixer at a ratio of 5% by weight Ti, 45% by weight Cr, and 50% by weight Cu, under nitrogen protection and mixed with steel balls for 140-160 minutes to obtain a uniformly mixed powder.

[0052] The mixed powder is filled into a high-strength graphite mold. The vacuum level inside the furnace is then reduced to 10. -1 —10 -2 After applying a pressure of 5-10 MPa to the graphite mold, an electric current is passed through the powder to begin discharge plasma sintering.

[0053] Within approximately 10 minutes of the start of sintering, the temperature is raised to 400-500 degrees Celsius, held at this temperature for 3-5 minutes, and then the temperature is further increased to 850-950 degrees Celsius after about 10 minutes, held for 10-20 minutes. Then, a rapid cooling process is used to lower the temperature to room temperature within 30-60 minutes to obtain the green body. The green body obtained after sintering has a hardness of HV170-210 and is internally dense.

[0054] As can be seen, the hardness of the green blank, i.e. CuCrTi material, manufactured in Example 1 reached HV170-210, which is a hardness that cannot be achieved by materials manufactured according to the prior art as shown in Figure 4. It also reduces costs. Moreover, the green blank manufactured in Example 1 is dense inside, which enhances the material's resistance to arc erosion.

[0055] Example 2:

[0056] Ti powder, Cr powder, and Cu powder were used as raw materials. The mixtures were prepared in a double cone mixer at a ratio of 2.5 wt% Ti, 45.5 wt% Cr, and 52 wt% Cu, under nitrogen protection and mixed with steel balls for 140-160 minutes to obtain a uniformly mixed powder.

[0057] The mixed powder is filled into a high-strength graphite mold. The vacuum level inside the furnace is then reduced to 10. -1 —10 -2 After applying a pressure of 5-10 MPa to the graphite mold, an electric current is passed through the powder to begin discharge plasma sintering.

[0058] Within approximately 10 minutes of the start of sintering, the temperature is raised to 400-500 degrees Celsius, held at this temperature for 3-5 minutes, and then the temperature is further increased to 850-950 degrees Celsius after about 10 minutes, held for 10-20 minutes. Then, a rapid cooling process is used to lower the temperature to room temperature within 30-60 minutes to obtain the green body. The green body obtained after sintering achieves a hardness of HV160-200 and is internally dense.

[0059] As can be seen, the hardness of the green blank, i.e. CuCrTi material, manufactured in Example 2 reached HV160-200, which is a hardness that cannot be achieved by the material manufactured according to the prior art shown in Figure 4. It also reduces the cost. Moreover, the green blank manufactured in Example 2 is dense inside, which enhances the material's resistance to arc erosion.

[0060] Comparative Example

[0061] In contrast, the material was manufactured using the same method, but with more than 8% Ti. After the material was manufactured and measured, it was found that if the Ti content was higher than 8% Ti, the material density would decrease significantly and become less dense.

[0062] Comparative Example 1:

[0063] Ti powder, Cr powder, and Cu powder were used as raw materials. They were mixed in a double cone mixer at a ratio of 10% by weight Ti, 40% by weight Cr, and 50% by weight Cu, under nitrogen protection and with steel balls for 140-160 minutes to obtain a uniformly mixed powder.

[0064] The mixed powder is filled into a high-strength graphite mold. The vacuum level inside the furnace is then reduced to 10. -1 —10 -2 After applying a pressure of 5-10 MPa to the graphite mold, an electric current is passed through the powder to begin discharge plasma sintering.

[0065] Within approximately 10 minutes of the start of sintering, the temperature is raised to 400-500 degrees Celsius. After holding at this temperature for 3-5 minutes, the temperature is raised further, reaching 850-950 degrees Celsius after another 10 minutes, and held for 10-20 minutes. Then, the temperature is rapidly cooled to room temperature within 30-60 minutes to obtain the green body.

[0066] Measurements of the green compact, as shown in the figure, revealed that the interior was not completely dense and contained a small number of pores. This is because the high Ti content prevents the formation of a solid solution with chromium, resulting in porosity.

[0067] It is evident that the green blank produced in Comparative Example 1, i.e., CuCrTi material, has a high Ti content and is not completely dense internally, resulting in a less effective product compared to Examples 1 and 2.

[0068] As another comparison, the material was manufactured in the same way, but with less than 2% by weight of Ti. After the material was manufactured and measured, it was found that if Ti was less than 2% by weight, the enhancement of the material's resistance to arc erosion was not significant.

[0069] Comparative Example 2:

[0070] Ti powder, Cr powder, and Cu powder were used as raw materials. The mixtures were prepared in a double cone mixer at a ratio of 0.5 wt% Ti, 44.5 wt% Cr, and 55 wt% Cu, under nitrogen protection and mixed with steel balls for 140-160 minutes to obtain a uniformly mixed powder.

[0071] The mixed powder is filled into a high-strength graphite mold. The vacuum level inside the furnace is then reduced to 10. -1 —10 -2 After applying a pressure of 5-10 MPa to the graphite mold, an electric current is passed through the powder to begin discharge plasma sintering.

[0072] Within approximately 10 minutes of the start of sintering, the temperature is raised to 400-500 degrees Celsius. After holding at this temperature for 3-5 minutes, the temperature is raised further, reaching 850-950 degrees Celsius after another 10 minutes, and held for 10-20 minutes. Then, the temperature is rapidly cooled to room temperature within 30-60 minutes to obtain the green body.

[0073] Measurements of the green body revealed that its hardness was not significantly different from that of materials manufactured using existing techniques. This is because the trace amounts of Ti added were insufficient to affect the material's hardness.

[0074] It is evident that the green blank manufactured in Comparative Example 2, i.e., CuCrTi material, has a low Ti content, resulting in only a slight increase in its resistance to arc erosion. Compared with Examples 1 and 2, the effect is not as good.

[0075] The data of Examples 1 and 2, Comparative Examples 1 and 2, and ordinary CuCr powder metallurgy contacts were compared and the following table was obtained.

[0076]

[0077] As shown in the table above, the materials manufactured using Examples 1 and 2 of the present invention have good ablation resistance, and also have high density, high hardness, and low oxygen content.

[0078] In contrast, the ablation resistance of Comparative Examples 1 and 2 and ordinary CuCr powder metallurgy contacts was worse than that of ordinary ones, and they also had low density, low hardness, and high oxygen content.

[0079] In summary, the method for manufacturing CuCrTi material according to the second aspect of the present invention effectively solves the technical problems of excessive internal porosity, poor density, excessive oxygen content, and low hardness of the material, resulting in good density, low oxygen content, and good application performance.

[0080] Industrial application

[0081] According to the CuCrTi material and the method for manufacturing CuCrTi material of the present invention, the technical problems of excessive internal pores, poor density, excessive oxygen content and low hardness are effectively solved, resulting in good density, low oxygen content and good application performance.

[0082] Although the invention has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A CuCrTi material, characterized in that, The material contains 2% to 8% by weight Ti, 42% to 54% by weight Cu, and the balance Cr. In the microstructure of this CuCrTi material, the Ti phase consists of Ti particles with an average particle size of 15-25 micrometers, which surround Cr particles with an average particle size of 32-100 micrometers.

2. The CuCrTi material according to claim 1, characterized in that, Contains 3% to 7% Ti.

3. The CuCrTi material according to claim 2, characterized in that, It contains 44% to 53% Cu by weight.

4. The CuCrTi material according to claim 1, characterized in that, It has a hardness of HV 170-210.

5. The CuCrTi material according to claim 4, characterized in that, It has a hardness of HV 200-205.

6. A method for manufacturing the CuCrTi material according to any one of claims 1 to 5, characterized in that, The process includes the following steps: a mixing step, in which Cu powder, Cr powder, and Ti powder are mixed; a filling step, in which the mixed powder is filled into a graphite mold; and a pressing and sintering step, in which the filled powder is pressed and sintered to form a blank.

7. The method according to claim 6, characterized in that, The pressing and sintering step is achieved by performing spark plasma sintering on the powder.

8. The method according to claim 6, characterized in that, In the mixing step, a double cone mixer is used, a protective gas is introduced, and steel balls are added for mixing.

9. The method according to claim 6, characterized in that, The graphite mold includes: a graphite gasket, a graphite casting mold, a graphite punch, and a thermocouple.

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