A zirconium-based brazing filler metal for high-entropy carbide ceramic brazing and its use method

Abstract

A zirconium-based brazing filler metal for brazing high-entropy carbide ceramics and a method for using the same relate to a brazing filler metal for brazing high-entropy carbide ceramics and a method for using the same. The present invention aims to solve the technical problem that the current metal brazing of high-entropy ceramics uses a high-temperature, high-pressure, and long-term heat preservation method, which is energy-consuming and inefficient. The brazing filler metal provided by the present invention is a Zr-based brazing filler metal. In addition to the Zr element, the remaining elements are Ni or Cu. The brazing filler metal has excellent wettability and weldability to the parent material high-entropy carbide ceramic. The present invention realizes the connection of high-entropy ceramics by combining the interface reaction between the brazing filler metal and the ceramic parent material. The weld is dense, the mechanical properties are almost consistent with those of the ceramic parent material, and the filler metal has good high-temperature mechanical properties. The present invention can realize the reliable connection of high-entropy carbide ceramics, and provide technical support for their application in extreme high-temperature environments.

Description

Technical Field

[0001] The invention relates to a brazing filler metal for high-entropy carbide ceramic brazing and a use method thereof. Background Art

[0002] High-entropy ceramics (HECs) are a new class of ceramic materials characterized by rich lattice distortion, which distinguishes their properties from those of single-component ceramics. More specifically, HECs possess excellent mechanical properties, corrosion resistance, and radiation resistance, making them promising structural materials for the aerospace, nuclear power, and electronics industries. However, the fabrication of HECs is challenging, especially for large and complex components. To address this challenge, welding techniques can be employed to reliably join HECs and expand their engineering applications. Active metal brazing is a well-established method for joining ceramic-based materials, and the joint properties can be tailored by designing different brazing alloy systems. As with other ceramics, efficient liquid-phase brazing of active metals requires good wettability of the liquid brazing alloy. Research has shown that chemical reactions between active elements in the brazing alloy, such as Ti, Zr, and V, and the ceramic promote wetting. Therefore, the addition of active elements to the brazing alloy is crucial for improving wetting and metallurgical bonding between the ceramic matrix and the brazing material. Patent CN202111245353.4 reports a diffusion bonding method for high-entropy ceramics and metals, which achieves the connection by using high temperature, high pressure, and long-term heat preservation. Vacuum brazing technology can achieve the effect of no pressure and short-term heat preservation, which is more conducive to the formation of complex high-entropy ceramic structures. However, there are few reports on pressureless brazing of high-entropy ceramics under vacuum conditions. In view of this, it is necessary to develop an active metal brazing filler metal and brazing method suitable for high-entropy ceramics to meet the above needs. Summary of the Invention

[0003] The present invention aims to solve the technical problem that the current metal brazing of high entropy ceramics adopts high temperature, high pressure and long time insulation method, which is energy-consuming and inefficient, and provides a zirconium-based brazing filler metal for brazing high entropy carbide ceramics and its use method.

[0004] The main element of the zirconium-based brazing filler metal for high-entropy carbide ceramic brazing of the present invention is Zr, and the rest is Ni or Cu; the atomic percentage of the Zr element is 51% to 80%, and the rest is Ni or Cu.

[0005] The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing of the present invention is as follows:

[0006] Step 1: Weigh the corresponding pure metal powders according to the composition ratio of the two metal elements in the solder, and then mix them to obtain a mixed powder; low-energy ball mill the mixed powder for 12 hours to 13 hours to obtain a metal powder solder, or smelt the mixed powder into an alloy solder;

[0007] The main element of the solder is Zr, and the rest is Ni or Cu; wherein the atomic percentage of the Zr element is 51% to 80%;

[0008] Step 2: grinding, ultrasonic cleaning and drying the parts of the high entropy carbide ceramic to be connected in sequence;

[0009] Step 3: Place the solder prepared in step 1 between the two high-entropy ceramic parts to be welded prepared in step 2 as an intermediate connecting layer;

[0010] Step 4: First, heat the temperature from room temperature to 800℃~850℃ at a heating rate of 10℃ / min~20℃ / min, then heat it to the brazing temperature of 950℃~1150℃ at a heating rate of 5℃ / min~10℃ / min and keep it at that temperature for 5min~30min, then cool it down to 400℃~450℃ at a cooling rate of 5℃ / min~10℃ / min and then cool it naturally to room temperature in the furnace; the vacuum degree of the whole process is ≤1×10 -3 Pa.

[0011] The beneficial effects of the present invention are as follows:

[0012] The present invention uses a Zr-based alloy as an intermediate layer to connect high-entropy carbide ceramics and uses vacuum brazing to achieve the connection. The Zr-based alloy brazing filler metal exhibits excellent high-temperature resistance, good ductility and strength, and excellent wettability to the high-entropy carbide ceramic. During the high-temperature brazing process, the Zr element in the alloy plays a key role in reacting with the high-entropy carbide ceramic, forming a reaction layer between the high-entropy carbide ceramic and the brazing filler metal. This reaction layer is primarily composed of nanocrystalline ZrC, with small amounts of Ta and Nb dissolved therein, forming a 1μm to 3μm thick weld interface layer. This interface layer achieves chemical bonding between the base metal and the brazing filler metal, while forming metal and intermetallic compound phases such as Zr, Zr2Ni, and Zr2Cu in the brazing seam. These phases exhibit good plasticity and toughness, while also having a high melting point, resulting in excellent high-temperature resistance for the joint. The joint has a maximum room-temperature shear strength of approximately 73MPa and a high-temperature strength of 98MPa at 800°C.

[0013] The present invention adopts a Zr-based solder alloy as an intermediate layer for welding high-entropy carbide ceramics, which can achieve good wetting of the base material and interface bonding, thereby enabling the forming and manufacturing of complex structural parts of high-entropy carbide ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the first microstructure diagram of the joint in Example 3;

[0015] Figure 2 This is the second microstructure diagram of the joint in Example 3;

[0016] Figure 3 is a microstructure diagram of the joint in Example 6;

[0017] Figure 4 This is a diagram showing the element content of each element obtained by energy spectrum analysis of the element composition of the joint interface reaction layer in Example 6. DETAILED DESCRIPTION

[0018] Specific embodiment 1: This embodiment is a zirconium-based brazing filler metal for brazing high entropy carbide ceramics, wherein the main element is Zr, and the rest is Ni or Cu; wherein the atomic percentage of Zr element is 51% to 80%, and the rest is Ni or Cu.

[0019] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the solder is in the form of alloy powder, alloy foil or metal powder mixture. Other aspects are the same as specific embodiment 1.

[0020] Specific embodiment three: This embodiment is a method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing in specific embodiment one. The specific process is as follows:

[0021] Step 1: Weigh the corresponding pure metal powders according to the composition ratio of the two metal elements in the solder, and then mix them to obtain a mixed powder; low-energy ball mill the mixed powder to obtain a metal powder solder, or smelt the mixed powder into an alloy solder;

[0022] The main element of the solder is Zr, and the rest is Ni or Cu; wherein the atomic percentage of the Zr element is 51% to 80%;

[0023] Step 2: grinding, ultrasonic cleaning and drying the parts of the high entropy carbide ceramic to be connected in sequence;

[0024] Step 3: Place the solder prepared in step 1 between the two high-entropy ceramic parts to be welded prepared in step 2 as an intermediate connecting layer;

[0025] Step 4: First, heat the temperature from room temperature to 800℃~850℃ at a heating rate of 10℃ / min~20℃ / min, then heat it to the brazing temperature of 950℃~1150℃ at a heating rate of 5℃ / min~10℃ / min and keep it at that temperature for 5min~30min, then cool it down to 400℃~450℃ at a cooling rate of 5℃ / min~10℃ / min and then cool it naturally to room temperature in the furnace; the vacuum degree of the whole process is ≤1×10 -3 Pa.

[0026] Specific embodiment 4: This embodiment differs from specific embodiment 3 in that: in step 1, the mixed powder is subjected to low-energy ball milling for 12 hours to obtain the metal powder brazing material. Other aspects are the same as specific embodiment 3.

[0027] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that the high-entropy carbide ceramic base material to be joined in step 2 is composed of carbides formed by three or more of the refractory metal elements Ta, Zr, Nb, Ti, and Cr and carbon atoms. Otherwise, this embodiment is the same as specific embodiment 4.

[0028] Specific embodiment 6: This embodiment differs from specific embodiment 5 in that the high-entropy carbide ceramic to be connected in step 2 is a (ZrTiNbTa)C high-entropy ceramic. Other aspects are the same as specific embodiment 5.

[0029] Specific embodiment 7: This embodiment differs from specific embodiment 6 in that: in step 2, ultrasonic cleaning is performed for 5 to 10 minutes, followed by drying at 60° C. to 80° C. for 30 minutes. Other aspects are the same as specific embodiment 6.

[0030] Specific embodiment eight: This embodiment differs from specific embodiment seven in that the thickness of the solder in step three is 20 μm to 200 μm. Other aspects are the same as specific embodiment seven.

[0031] Specific embodiment 9: This embodiment differs from specific embodiment 8 in that in step 4, the temperature is first raised from room temperature to 800°C at a heating rate of 10°C / min, then raised to the brazing temperature of 950°C to 1150°C at a heating rate of 10°C / min and held at that temperature for 5 to 30 minutes. Other aspects are the same as specific embodiment 8.

[0032] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that in step 4, the temperature is lowered to 400°C at a cooling rate of 10°C / min and then naturally cooled to room temperature in the furnace. Other aspects are the same as specific embodiment 9.

[0033] The present invention is verified using the following 9 examples, and the specific process is as follows:

[0034] Step 1: Weigh the corresponding pure metal powders according to the composition ratio of the two metal elements in the solder, then mix them to obtain a mixed powder, and smelt the mixed powder into an alloy solder; the specific composition of the solder is shown in Table 1;

[0035] Step 2: grinding, ultrasonic cleaning for 10 minutes, and drying at 80° C. for 30 minutes on the part of the high-entropy carbide ceramic to be connected; the base material is (TiZrNbTa)C high-entropy ceramic;

[0036] Step 3: Place the solder prepared in step 1 between the two high-entropy ceramic parts to be welded prepared in step 2 as an intermediate connecting layer;

[0037] Step 4: First, heat the temperature from room temperature to 800℃ at a heating rate of 10℃ / min, then heat it to the brazing temperature at a heating rate of 10℃ / min and keep it warm, then cool it down to 400℃ at a cooling rate of 10℃ / min and then cool it naturally to room temperature in the furnace; the vacuum degree of the whole process is ≤1×10 -3 Pa; the specific brazing temperature, brazing time and room temperature shear strength of the joint are shown in Table 1.

[0038] Table 1

[0039]

[0040] The strength of the joint in Example 4 at 800°C is 98 MPa.

[0041] In step 1, the mixed powder is melted into an alloy solder by induction melting technology. The melting temperature of the ZrNi alloy is 1250°C, and the melting temperature of the ZrCu alloy is 1150°C. Both are repeatedly melted 7 times to homogenize the alloy composition, and finally the alloy solder is obtained.

[0042] Figure 1 This is the microstructure diagram of the joint in Example 3, 1 and 3 are (TiZrNbTa)C high-entropy ceramic base materials, 2 is the ZrNi brazing seam intermediate layer, wherein the brazing seam intermediate layer is composed of a eutectic structure composed of Zr2Ni and a Zr matrix, and elements such as Nb and Ta in the base material high-entropy ceramic diffuse out from the base material and dissolve into the brazing seam, and the joint is densely bonded and defect-free.

[0043] Figure 2 This is the microstructure diagram of the joint in Example 3, where 1 is the base material (TiZrNbTa)C high-entropy ceramic, 2 is the interface nano-ZrC reaction layer, and 3 is the ZrNi brazing seam intermediate layer. It can be seen that the thickness of the interface nano-ZrC reaction layer is about 1.5 μm, which is formed by the interaction between the Zr element in the brazing material and the high-entropy ceramic. The dense interface bonding is achieved through the reaction between the Zr element in the brazing alloy and the high-entropy ceramic.

[0044] Figure 3 This is the microstructure diagram of the joint in Example 6, where 1 and 4 are the base material (TiZrNbTa)C high-entropy ceramics, 2 is the interface nano-ZrC reaction layer, and 3 is the ZrCu brazing seam intermediate layer. It can be seen that the thickness of the interface nano-ZrC reaction layer is about 2 μm, and it is composed of a large number of ZrC nanocrystals. The active element Zr provided by the liquid brazing material reacts with the C in the high-entropy ceramic to form this reaction layer, while achieving a reliable connection.

[0045] Figure 4 is the joint interface reaction layer in Example 6 ( Figure 32) The element composition energy spectrum point analysis of each element content diagram is shown in Table 2, and the analysis data is as follows. From the composition, it can be determined that the joint interface reaction layer is ZrC.

[0046] Table 2

[0047] element at% C 64.8 Ti 0.19 Cu 1.68 Zr 31.48 Nb 0.81 Ta 1.03 Total amount: 100

Claims

1. A method for using a zirconium-based brazing filler metal for brazing high entropy carbide ceramics, characterized in that The process of using zirconium-based brazing filler metal for high entropy carbide ceramic brazing is as follows: Step 1: Weigh the corresponding pure metal powders according to the composition ratio of the two metal elements in the solder, and then mix them to obtain a mixed powder; low-energy ball mill the mixed powder to obtain a metal powder solder, or smelt the mixed powder into an alloy solder; The main element of the solder is Zr, and the rest is Ni or Cu; wherein the atomic percentage of the Zr element is 51% to 80%; Step 2: grinding, ultrasonically cleaning, and drying the welded parts of the high-entropy carbide ceramic of the parent material to be connected; the high-entropy carbide ceramic of the parent material to be connected is (ZrTiNbTa)C high-entropy ceramic; Step 3: Place the solder prepared in step 1 between the two high-entropy ceramic parts to be welded prepared in step 2 as an intermediate connecting layer; Step 4: First, heat the temperature from room temperature to 800℃~850℃ at a heating rate of 10℃ / min~20℃ / min, then heat it to the brazing temperature of 950℃~1150℃ at a heating rate of 5℃ / min~10℃ / min and keep it at that temperature for 5min~30min, then cool it down to 400℃~450℃ at a cooling rate of 5℃ / min~10℃ / min and then cool it naturally to room temperature in the furnace; the vacuum degree of the whole process is ≤1×10 -3 Pa.

2. The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing according to claim 1, characterized in that In step 1, the mixed powder is subjected to low-energy ball milling for 12 hours to obtain metal powder solder.

3. The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing according to claim 1, characterized in that In step 2, ultrasonic cleaning is performed for 5 to 10 minutes, and then drying is performed at 60 to 80° C. for 30 minutes.

4. The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing according to claim 1, characterized in that The thickness of the solder in step 3 is 20 μm to 200 μm.

5. The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing according to claim 1, characterized in that In step 4, the temperature is first increased from room temperature to 800°C at a heating rate of 10°C / min, and then increased to the brazing temperature of 950°C to 1150°C at a heating rate of 10°C / min and kept at this temperature for 5min to 30min.

6. The method for using the zirconium-based brazing filler metal for high entropy carbide ceramic brazing according to claim 1, characterized in that In step 4, the temperature was lowered to 400°C at a cooling rate of 10°C / min and then naturally cooled to room temperature in the furnace.

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