Complex phase ceramic vacuum brazing

Multiphase ceramics are ceramic matrix composite materials prepared by uniformly mixing one ceramic material as the matrix phase and one or more ceramic or non-ceramic materials as the additive phase. Currently, the most widely used composite phase ceramics include SiO2-BN (SiO2+h-BN), ZS ceramics (ZrC +SiC) and ZSC ceramics (ZrB2+ SiC + C). While maintaining the high temperature resistance of ceramic materials, they also improve It improves the thermal shock resistance of the material. The operating temperature can reach 2000C. Part of the multi-phase ceramics that are commonly used in aerospace engine thrust chambers and aircraft thermal protective coatings combine the characteristics of the matrix phase and the additive phase, and have good wave transmission and Dielectric properties.

Compared with single-phase ceramics, the material used in vacuum brazing of multi-phase ceramics needs to react with the matrix phase and the additive phase at the same time to achieve better wetting and spreading. Ti is included in the vacuum brazing connection of ceramics and metal materials. , Active solder materials with active elements such as Zr, Cr, and V are widely used. For multi-phase ceramics, researchers often adjust the component ratio of materials and increase the content of active elements to enhance the interface reaction between solder materials and multi-phase ceramics. Thereby improving the wettability of the solder on its surface, forming a continuous dense reaction layer at the interface, and achieving effective combination of the multi-phase ceramic side interface. However, too many active elements will also enhance the interface reaction on the metal base metal side, resulting in The metal base material excessively dissolves a large amount of Fe.Ti, Ni.Cu and other elements into the liquid fiber material and enters the brazing seam, forming a massive brittle compound phase or a continuous brittle layer at the joint interface.
With the continuous progress and development of human society, more and more advanced functional materials have been developed to meet the needs of production, manufacturing and application. Materials such as composite-phase ceramics, fiber-reinforced ceramic matrix composites and thermoelectric materials have their wide range of uses. Application scenarios and huge application potential have attracted much attention.

For composite-phase ceramics and fiber-reinforced ceramic matrix composites, improving the wettability of the needle material, increasing the interface bonding strength, and alleviating the residual stress of the joint are the main research directions. Existing research basically focuses on adding active elements to the solder, and the surface of the base metal. Modification, adding intermediate layers to brazing seams, and strengthening are carried out, but most of the results are only applicable when the size of the components and the area to be welded are small. How to further promote the advanced connection technology and apply it to actual production is the top priority to achieve the transformation of industry, academia and research. Heavy. With the specific application requirements, higher requirements have been put forward for joint assembly and vacuum brazing process. On the one hand, the pre-welding processing steps should be simplified as much as possible to avoid mechanical damage to the base metal and excessive thickness of the brazing seam, while ensuring Improve assembly accuracy and reduce production costs on the premise of joint mechanical properties and functionality; on the other hand, the preparation technology and process of advanced functional materials also have a huge impact on the realization of high-quality joints, and the part of surface modification before welding is advanced to the material During the preparation process, special treatment of the material surfaces to be connected is carried out in advance, which is of great significance to simplifying the component preparation process and improving the integration of the production process.

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