ADVANCED MATERIALS & PROCESSES | MARCH 2026 16 depending on the binder composition. These alternatives provide additional flexibility to meet various requirements in coating technology. Preforms are prefabricated solder materials in solid form that are applied to the components as needed, while slurries are liquid suspensions of the solder material that are applied to the component and then sintered. Furthermore, different coating architectures can be implemented, including monolayer, multilayer, top- layer, and bond-layer configurations, allowing functional tailoring to specific application requirements. Figure 5 illustrates these different types of coatings and shows their respective characteristics and areas of application. ADVANTAGES OF BRAZED COATINGS Brazing is primarily used to coat and repair components and parts in various industries. It offers numerous advantages that make it a preferred choice for many manufacturing processes. In brazing, the filler material is applied precisely and deliberately to the joint, achieving high accuracy. This carbide, nitride-bonded boron carbide, and iron-chromium carbide. Nickel is a very versatile material that is commonly used due to its good corrosion resistance and strength at high temperatures. Iron is highly available and is used in many industrial applications due to its stability and workability. Cobalt is known for its high temperature resistance and strength and is mainly used in high-stress applications. Copper offers excellent thermal conductivity and is often used in combination with other materials to optimize specific mechanical properties. Silver is an excellent heat conductor and is particularly used in applications requiring good thermal and electrical conductivity. Other materials, depending on the application, may also be considered, including tin, zinc, CuSn, and AlN. On the other hand, there are a number of hard materials frequently used in powder form to improve the hardness, wear resistance, and other mechanical properties of the final product (Figs. 3 and 4). These include tungsten carbide, titanium carbide, chromium carbide, nitride-bonded boron carbide, and iron-chromium carbide. The selection of the right combination of matrix and hard materials depends on the specific requirements of the brazing technology. It must optimize both the mechanical and thermal properties of the final product. Depending on the application, other hard metals and/or ceramics can be added to the matrix materials, such as BN, NbC, AlN, diamonds, or cubic boron nitride. BRAZING METHODS After the base powder is selected, it is used in various brazing technologies to ensure a stable connection between the components. One method of brazing is so-called tape technology, where the metallic powder is first mixed with a special binder that ensures the particles stay together. The mixture is then processed into a thin, flexible band, called a brazing tape. This brazing tape is then applied to the components to be coated and subsequently sintered at high temperatures. The sintering process causes the metal powder to transition into a solid, bonding structure, allowing for a permanent coating of the components. Another interesting feature of tape technology is that it does not require the use of flux, simplifying the process and reducing the need for additional materials. It is also possible to produce other forms such as preforms or slurries, Fig. 3 — Micrograph of an atmosphere brazed tungsten carbide coating on ductile cast iron. Fig. 4 — Micrograph of an atmosphere brazed Ni-coating (25 HRC) for sealing surfaces. Fig. 5 — Schematic representation of different coating systems.
RkJQdWJsaXNoZXIy MTYyMzk3NQ==