CN-121972862-A - Solder for reducing brittleness of carbon-containing ceramic matrix composite-metal joint, preparation method thereof and connecting process using solder

Abstract

The invention relates to a solder for reducing brittleness of a carbon-containing ceramic matrix composite-metal joint, a preparation method and a connecting process thereof, belonging to the technical field of dissimilar material connection, wherein the solder is formed by mixing Ni-Cr-B alloy powder and Fe powder, wherein the Ni-Cr-B alloy powder contains 4-10% of Cr, 2-6% of B and the balance of Ni in percentage by mass; the addition amount of Fe powder is 15-40% of the total mass of the solder. The preparation method comprises smelting to prepare Ni-Cr-B alloy, atomizing into powder, and mixing with Fe powder uniformly. When the brazing filler metal is used for connection, the brazing filler metal is assembled after the surface of a part to be welded is pretreated, and the brazing is carried out under the vacuum environment at the temperature of 1000-1200 ℃ for 30-120 minutes. According to the invention, through the addition of Fe powder, the interface reaction layer is converted from continuous brittle carbide into a discontinuous composite structure, so that the interface brittleness is obviously reduced, the diffusion of the melting-reducing element B is promoted, and the high-temperature stability and heat resistance of the joint are enhanced while the room-temperature shear strength of the joint is greatly improved.

Inventors

• WANG YONGLEI
• LI CHENGDA
• HU HUAQING
• LIU TIANLI
• YIN DANQING
• Wu Zhiao
• HU KAITAO

Assignees

• 河南科技大学

Dates

Publication Date

20260505

Application Date

20260203

Claims (9)

1. 1. A brazing filler metal for reducing brittleness of a carbon-containing ceramic matrix composite-metal joint is characterized by being formed by mixing Ni-Cr-B alloy powder and Fe powder, wherein the Ni-Cr-B alloy powder comprises, by mass, 4% -10% of Cr, 2% -6% of B, and the balance of Ni and unavoidable impurities, and the mass percentage of the Fe powder in the brazing filler metal is 15% -40%.
2. 2. The brazing filler metal according to claim 1, wherein the Ni-Cr-B alloy powder is composed of, by mass, 6% Cr, 4% B, and the balance Ni and unavoidable impurities.
3. 3. Solder according to claim 1 or 2, characterized in that the mass percentage of Fe-powder in the solder is 20-25%.
4. 4. A method for producing the filler metal for reducing brittleness of a carbon-containing ceramic matrix composite-metal joint as defined in any one of claims 1 to 3, comprising the steps of: s1, weighing Ni, cr and B simple substance blocks according to design components of Ni-Cr-B alloy, preparing a Ni-Cr-B alloy bar by adopting vacuum induction magnetic levitation melting, and preparing the Ni-Cr-B alloy bar into Ni-Cr-B alloy powder by adopting an air atomization method; S2, adding Fe powder into the Ni-Cr-B alloy powder, and uniformly mixing to obtain mixed solder powder; And S3, adding an organic solvent into the mixed solder powder, and stirring to prepare the pasty solder.
5. 5. The method according to claim 4, wherein in step S3, the organic solvent is ethylene glycol.
6. 6. A process for joining a carbonaceous ceramic matrix composite material to a metal using the solder according to any one of claims 1 to 3, comprising the steps of: (1) Pretreating the surfaces to be connected of the metal base material and the carbon-containing ceramic matrix composite base material; (2) The brazing filler metal is pre-arranged between the carbon-containing ceramic matrix composite material base metal and the surface to be connected of the metal base metal to form a component to be welded; (3) And placing the components to be welded in a vacuum environment for braze welding, wherein the braze welding temperature is 1000-1200 ℃, and the heat preservation time is 30-120min.
7. 7. The joining process according to claim 6, wherein in the step (3), the vacuum degree of the vacuum atmosphere is not lower than 3 x 10 -3 Pa.
8. 8. The joining process according to claim 6, wherein in step (1), the pretreatment includes polishing and ultrasonic cleaning.
9. 9. The joining process according to claim 6, wherein the carbonaceous ceramic matrix composite is selected from the group consisting of C/C composite, C/SiC composite and SiC/SiC composite, and the metal is selected from the group consisting of nickel-based superalloy, cobalt-based superalloy, iron-based superalloy and stainless steel.

Description

Solder for reducing brittleness of carbon-containing ceramic matrix composite-metal joint, preparation method thereof and connecting process using solder Technical Field The invention belongs to the technical field of dissimilar material connection, and particularly relates to a brazing filler metal for reducing brittleness of a carbon-containing ceramic matrix composite material-metal joint, a preparation method thereof and a connection process using the brazing filler metal. Background Ceramic matrix composites (Ceramic Matrix Composites, CMCs), such as C/C (carbon fiber reinforced carbon matrix composites), C/SiC (carbon fiber reinforced silicon carbide matrix composites) and SiC/SiC (silicon carbide fiber reinforced silicon carbide matrix composites), have become critical high temperature structural materials in the aerospace, military equipment, nuclear energy systems, etc. fields by virtue of their low density, low coefficient of thermal expansion, excellent high temperature stability and thermal shock resistance. On the other hand, the nickel-based superalloy, cobalt-based superalloy, stainless steel and other metal materials have excellent high-temperature strength, plasticity, toughness and processability. The reliable connection of ceramic matrix composite materials and metals to form composite components with the advantages of both are urgent needs for the development of the high-end technical field. The brazing technology is a mainstream method for realizing the connection of the ceramic matrix composite material and the metal at present because of the advantages of relatively simple process, strong applicability, no need of external pressure and the like. Wherein, the active brazing is realized by using brazing filler metal containing active elements such as Ti, cr, zr and the like, so that the brazing filler metal and a ceramic matrix are subjected to chemical reaction in the brazing process, thereby realizing metallurgical bonding and being most widely applied. However, when the existing active brazing technology is used for connecting a ceramic matrix composite material and a metal, two significant technical bottlenecks still exist, namely first, the joint brittleness is large. Reactive elements (e.g., ti, cr) tend to form a continuous, dense and thick brittle intermetallic or carbide reaction layer at the ceramic matrix composite/braze interface. The continuous brittle layer becomes a weak link of the joint, and cracks are easy to initiate and rapidly expand under service stress, so that the joint is subjected to low-stress brittle fracture, and the mechanical properties (especially room temperature strength) are seriously insufficient. Second, the joint is poor in heat resistance. To increase the high temperature service capacity of the joint, a high melting point braze is required, but this generally means a higher braze temperature. The higher temperature can introduce larger residual thermal stress between the two materials with large thermal expansion coefficients of ceramic and metal on one hand, so as to aggravate the cracking tendency of the joint, and on the other hand, the microstructure and the performance of the ceramic matrix composite material or the metal base metal can be damaged thermally. In view of the above problems, although there have been many studies in the industry on the design of solder components (e.g., developing a multi-element alloy system), process optimization (e.g., using a gradient interlayer, applying external field assistance), etc., it is often difficult to reduce the brittleness of joints while simultaneously compromising the high temperature properties, i.e., the contradiction between "brittleness" and "heat resistance". Therefore, a novel solder system and a matched process capable of fundamentally optimizing interface reaction, synchronously reducing joint brittleness and improving heat resistance of the joint are developed, and the novel solder system has important scientific and engineering significance. Disclosure of Invention 1. Object of the invention The primary aim of the invention is to overcome the defects in the prior art and provide a novel solder which can obviously reduce the interfacial brittleness of carbon-containing ceramic matrix composite materials (such as C/C, C/SiC and SiC/SiC) and metal soldered joints and improve the heat resistance of the joints. Another object of the present invention is to provide a method for producing the above solder. It is a further object of the present invention to provide a process for joining a carbonaceous ceramic matrix composite to a metal using the above braze. 2. Technical proposal In order to achieve the above purpose, the invention adopts the following specific scheme: In a first aspect, the invention provides a solder for reducing brittleness of a carbon-containing ceramic matrix composite-metal joint, which is formed by mixing Ni-Cr-B alloy powder and Fe powder, wherein the Ni-Cr-B alloy p