阅读说明：本技术 一种无氧铜和铬锆铜中低温直接扩散连接方法 (Oxygen-free copper and chromium zirconium copper medium and low temperature direct diffusion connection method ) 是由 黄远 赵璨 王祖敏 刘永长 于 2019-04-13 设计创作，主要内容包括：本发明公开一种无氧铜和铬锆铜中低温直接扩散连接方法,对无氧铜块体和铬锆铜块体待连接表面进行打磨、抛光、超声清洗等前处理；将经过前处理的无氧铜块体和铬锆铜块体的待连接面进行对接,加压固定；在氩气保护气氛中进行保温并连接。本发明的连接方法成功地实现了无氧铜和铬锆铜两种铜合金之间的扩散和界面上的冶金结合,获得了无氧铜/铬锆铜之间的高强度连接,最大剪切强度达到了136MPa左右,且退火后的铬锆铜的硬度符合ITER中铬锆铜布氏硬度HB≥120的要求。(The invention discloses a method for directly diffusion bonding oxygen-free copper and chromium zirconium copper at medium and low temperature, which comprises the steps of carrying out pretreatment such as grinding, polishing, ultrasonic cleaning and the like on surfaces to be bonded of an oxygen-free copper block and a chromium zirconium copper block; butting the surfaces to be connected of the oxygen-free copper block and the chromium zirconium copper block which are subjected to pretreatment, and pressurizing and fixing; and (5) preserving the temperature and connecting in an argon protective atmosphere. The connection method successfully realizes the diffusion between the two copper alloys of the oxygen-free copper and the chromium-zirconium-copper and the metallurgical bonding on the interface, obtains the high-strength connection between the oxygen-free copper and the chromium-zirconium-copper, has the maximum shearing strength of about 136MPa, and meets the requirement that the Brinell hardness HB of the chromium-zirconium-copper in ITER is more than or equal to 120.)

1. A method for directly diffusion bonding oxygen-free copper and chromium zirconium copper at medium and low temperature is characterized by comprising the following steps:

step 1, enabling surfaces to be connected of oxygen-free copper and chromium zirconium copper to be opposite and contacted, fixing the oxygen-free copper and the chromium zirconium copper and applying pressure in a direction vertical to the surfaces to be connected, wherein the applied pressure is 80-150 MPa;

And 2, under the condition of keeping the pressure, annealing the oxygen-free copper and the chromium-zirconium-copper in an inert protective atmosphere, wherein the annealing temperature is 445-475 ℃, the heat preservation time is 1-5 hours, and the oxygen-free copper and the chromium-zirconium-copper are cooled to room temperature along with the furnace, so that the connection of the oxygen-free copper and the chromium-zirconium-copper can be realized.

2. The process of claim 1, wherein the pressure applied in step 1 is in the range of 100 to 120 MPa.

3. The method for low temperature direct diffusion bonding between oxygen-free copper and chromium zirconium copper as claimed in claim 1, wherein in step 1, the oxygen-free copper is pre-treated as follows: the surfaces to be connected of the oxygen-free copper are polished, the polishing is carried out by adopting metallographic abrasive paper, and the specification of the metallographic abrasive paper is as follows: 400#, 800# and 1500#, the surfaces to be connected are polished by 1500# metallographic abrasive paper and then are polished with high precision, and the polishing is carried out by using 0.5 mu m diamond polishing agent; polishing the surface to be connected to a mirror surface state, wherein the roughness Ra of the mirror surface reaches 0.025-012 μm; and after polishing, ultrasonically cleaning in absolute ethyl alcohol for 15-20 min, and airing for later use.

4. The method for oxygen-free copper and chromium zirconium copper medium and low temperature direct diffusion bonding according to claim 1, wherein in step 1, chromium zirconium copper is pretreated as follows: the chromium-zirconium-copper connecting surface to be connected is polished by adopting metallographic abrasive paper, and the specification of the metallographic abrasive paper is as follows: 400#, 800#, and 1500 #; polishing the surfaces to be connected by using 1500# metallographic abrasive paper, and then polishing with high precision by using a 0.5 micron diamond polishing agent; polishing the surface to be connected to a mirror surface state, wherein the roughness Ra of the mirror surface reaches 0.025-012 μm; and after polishing, ultrasonically cleaning in absolute ethyl alcohol for 15-20 min, and airing for later use.

5. the method for low temperature direct diffusion bonding in oxygen free copper and chromium zirconium copper as claimed in claim 1 wherein in step 2 the inert protective atmosphere is nitrogen, helium or argon.

6. The method of claim 1, wherein in step 2, the annealing temperature is 450-470 ℃ and the holding time is 2.5-3.5 hours.

7. The method of claim 1, wherein in step 2, annealing is performed by using an annealing furnace, and the temperature is raised from room temperature (20-35 ℃) to 100 ℃ below the annealing temperature at a rate of 10 ℃ per minute, and then raised to the annealing temperature at a rate of 5 ℃ per minute to perform heat preservation treatment.

8. Oxygen-free copper/chromium zirconium copper joint obtained by a process for the low temperature direct diffusion joining of oxygen-free copper and chromium zirconium copper as claimed in any one of claims 1 to 7.

9. The oxygen-free copper/chromium zirconium copper joint as claimed in claim 8, wherein the shear strength is 120-136 MPa and the Brinell hardness HB is not less than 120.

Technical Field

The invention belongs to a metal connection technology, and particularly relates to a metal direct connection process for realizing metallurgical bonding under the conditions of lower connection temperature and non-vacuum pressure, in particular to a medium-low temperature direct diffusion connection process of an oxygen-free copper block and a chromium-zirconium-copper block.

Background

The ITER device being a device capable of generatingSuperconducting tokomak for large-scale nuclear fusion reactions, commonly known as "artificial sun". The controlled thermonuclear fusion energy is expected to become one of the main energy sources in the new century, wherein a plasma-oriented element is a key part of nuclear fusion engineering. Plasma-facing components require materials that are both temperature resistant and highly thermally conductive, while also having a relatively low ion beam sputtering rate. Tungsten is a rare high melting point metal (3410 ℃), is relatively stable in chemical properties, has the characteristics of high thermal conductivity, high sputtering threshold and low tritium retention, and is therefore determined to be one of the materials of choice for plasma-oriented components. When the tungsten is used as a plasma-facing material, the heat flux of the surface of the tungsten is up to 10-20 MW/m²Rapid heat dissipation is required, and chromium zirconium copper has excellent heat conductivity and good comprehensive mechanical properties and is often used as a heat sink material, so that tungsten and chromium zirconium copper are required to be connected to facilitate rapid heat dissipation for plasma-oriented components. During the connection of tungsten and chromium zirconium copper in engineering, a layer of oxygen-free copper is generally cast on the surface of tungsten, and then the oxygen-free copper and the chromium zirconium copper are connected through other technologies, such as an HIP (hot stamping) technology, at 600-750 ℃, so that the connection of the tungsten and the chromium zirconium copper is finally realized. The reason for using the oxygen-free copper is that the oxygen-free copper has creep relaxation property, can effectively relieve the thermal stress between tungsten and chromium zirconium copper, and can obtain a connecting piece with higher thermal cycle resistance. It is clear that the joining of oxygen-free copper with chromium zirconium copper is a key technology for the production of tungsten/chromium zirconium copper joints.

at present, the connection method of oxygen-free copper and chromium zirconium copper mainly comprises the following types: the first type is brazing, the brazing filler metal is mainly Cu-based brazing filler metal, for example, the brazing connection of oxygen-free copper and chromium zirconium copper by using Cu-37Mn-9Ni brazing filler metal can obtain the interlaminar (interface) shear strength of 108-116 MPa; the second category is the hiping method, which typically uses a metallic interlayer, such as oxygen-free copper and chromium zirconium copper, to achieve an interlayer (interface) shear strength of 128MPa for hipping with an interlayer of Ni. The above methods all require the introduction of an intermediate material which reduces the thermal conductivity of the overall connection. Meanwhile, the connection temperature of the two methods is higher than 475 ℃, and when the annealing temperature is higher than 475 ℃ (the optimal aging temperature of the chromium-zirconium-copper), because the second phase in the chromium-zirconium-copper can be re-dissolved into the copper matrix, the mechanical property of the second-phase dispersion-strengthened chromium-zirconium-copper is reduced, so that the chromium-zirconium-copper is required to be subjected to secondary quenching and aging, the manufacturing period is greatly prolonged, and the manufacturing cost is increased. In addition to the above two methods, the connection of oxygen-free copper and chromium zirconium copper is also performed by electron beam welding, laser welding, etc., which have the defects of difficult parameter control, high manufacturing cost, inability of large-scale use, etc.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a method for directly diffusion bonding between oxygen-free copper and chromium-zirconium-copper at a low temperature, which can realize diffusion between the oxygen-free copper and the chromium-zirconium-copper and metallurgical bonding on an interface under the conditions of a low temperature and a non-vacuum pressure, so that high-strength bonding between the oxygen-free copper and the chromium-zirconium-copper is obtained, and the maximum shear strength reaches 120-136 MPa. The connection process does not involve the use of corrosive and dangerous chemicals, is safe and pollution-free, and has the advantages of convenient operation, low cost and the like

The technical purpose of the invention is realized by the following technical scheme.

A method for directly diffusion bonding oxygen-free copper and chromium zirconium copper at medium and low temperature comprises the following steps:

step 1, enabling surfaces to be connected of oxygen-free copper and chromium zirconium copper to be opposite and contacted, fixing the oxygen-free copper and the chromium zirconium copper and applying pressure in a direction vertical to the surfaces to be connected;

In step 1, the applied pressure is from 80 to 150MPa, preferably from 100 to 120 MPa.

In step 1, the oxygen-free copper is pretreated as follows: the surfaces to be connected of the oxygen-free copper are polished, the polishing is carried out by adopting metallographic abrasive paper, and the specification of the metallographic abrasive paper is as follows: 400#, 800# and 1500#, the surfaces to be connected are polished by 1500# metallographic abrasive paper and then are polished with high precision, and the polishing is carried out by using 0.5 mu m diamond polishing agent; polishing the surface to be connected to a mirror surface state, wherein the roughness Ra of the mirror surface reaches 0.025-012 μm; and after polishing, ultrasonically cleaning in absolute ethyl alcohol for 15-20 min, and airing for later use.

In step 1, the chromium zirconium copper is pretreated as follows: the chromium-zirconium-copper connecting surface to be connected is polished by adopting metallographic abrasive paper, and the specification of the metallographic abrasive paper is as follows: 400#, 800#, and 1500 #; polishing the surfaces to be connected by using 1500# metallographic abrasive paper, and then polishing with high precision by using a 0.5 micron diamond polishing agent; the surface to be connected is polished to a mirror surface state, and the roughness Ra of the mirror surface reaches 0.025-012 μm. And after polishing, ultrasonically cleaning in absolute ethyl alcohol for 15-20 min, and airing for later use.

In step 1, oxygen-free copper and chromium zirconium copper are fixed using a jig and a vertical pressure is applied in a direction perpendicular to the surface to be joined.

And 2, under the condition of keeping the pressure, annealing the oxygen-free copper and the chromium-zirconium-copper in an inert protective atmosphere, wherein the annealing temperature is 445-475 ℃, the heat preservation time is 1-5 hours, and the oxygen-free copper and the chromium-zirconium-copper are cooled to room temperature along with the furnace, so that the connection of the oxygen-free copper and the chromium-zirconium-copper can be realized.

In step 2, the inert protective atmosphere is nitrogen, helium or argon.

In step 2, the annealing temperature is 450-470 ℃, and the heat preservation time is 2.5-3.5 hours.

In the step 2, annealing is performed by using an annealing furnace, the temperature is raised from room temperature (20-35 ℃) to 100 ℃ below the annealing temperature at a speed of 10 ℃ per minute, and then the temperature is raised to the annealing temperature at a speed of 5 ℃ per minute to perform heat preservation treatment.

Compared with the prior art, the invention has the following beneficial effects: (1) the invention provides a medium-low temperature direct diffusion bonding process of oxygen-free copper and chromium zirconium copper, which is characterized in that the surfaces to be bonded of an oxygen-free copper block and a chromium zirconium copper block are pretreated to be in a mirror surface state, so that the scratch defect is avoided, and simultaneously, the proper pressure, heat preservation time and annealing temperature are selected to carry out annealing under the argon protective atmosphere, so that the diffusion between the oxygen-free copper and the chromium zirconium copper and the metallurgical bonding on the interface are realized, and the high-strength bonding between the oxygen-free copper and the chromium zirconium copper is successfully obtained. (2) The invention avoids the influence of introducing third-party elements on the material performance, and does not change the actual components of the connecting piece and generate additional performance. In addition, the high-strength connection of the oxygen-free copper and the chromium-zirconium-copper can be directly realized only by a simple pressure annealing process, the connection efficiency is higher, the operability is good, the safety and the pollution are realized, the secondary quenching and aging of the chromium-zirconium-copper are avoided, and the problems of the traditional method for connecting the oxygen-free copper and the chromium-zirconium-copper are solved. The performance test results show that the maximum interlayer (interface) shear strength of the oxygen-free copper/chromium zirconium copper connecting piece can reach about 120-136 MPa.

drawings

FIG. 1 is a schematic view showing the pressing and fixing of a sample according to the present invention, wherein 1-an upper press plate (made of molybdenum), 2-a lower press plate (made of molybdenum), 3-a pressing bolt (specification M8) made of molybdenum, 4-Al2O3 ceramic plate, 5-oxygen-free copper, and 6-chromium zirconium copper.

FIG. 2 is a diagram of an interlaminar (interfacial) shear test apparatus for samples according to the present invention, in which 1-chromium zirconium copper block, 2-oxygen-free copper block, and 3-shear test fixture are shown.

FIG. 3(a) is a graph of the interlaminar shear strength test for oxygen free copper/chromium zirconium copper connectors of example 1.

FIG. 3(b) is a graph of the interlaminar shear strength test for oxygen free copper/chromium zirconium copper connectors of example 2.

FIG. 3(c) is a graph of the interlaminar shear strength test for the oxygen free copper/chromium zirconium copper joint of example 3.

FIG. 4 is a Scanning Electron Microscope (SEM) micrograph of the morphology of the chromium zirconium copper side of the shear fracture of the oxygen-free copper/chromium zirconium copper joint of example 1.

FIG. 5 is an EDS spectrum of the composition on the shear fracture chromium zirconium copper side of the oxygen free copper/chromium zirconium copper joint of example 1.

FIG. 6(a) is a high Scanning Electron Microscope (SEM) photograph of the morphology of the sheared off chromium zirconium copper side of the oxygen free copper/chromium zirconium copper joint of example 1.

FIG. 6(b) is a high Scanning Electron Microscope (SEM) photograph of the morphology of the sheared fracture chromium zirconium copper side of the oxygen-free copper/chromium zirconium copper joint of example 2.

FIG. 6(c) is a high Scanning Electron Microscope (SEM) photograph of the morphology of the sheared fracture chromium zirconium copper side of the oxygen-free copper/chromium zirconium copper joint of example 3.

Detailed Description

The technical solutions of the present invention are further described in detail with reference to the accompanying drawings and specific embodiments, which are only illustrative of the present invention and are not intended to limit the present invention.