What are the characteristics of composite powder materials

       Since the composite powder has two or more material components with different properties, it can give full play to the advantages of each independent component material, and can obtain a coating with superior comprehensive properties that cannot be compared with a single material. Its characteristics:



     1) According to the needs, different manufacturing methods can be used to prepare coatings with different comprehensive properties, especially the composite powder coatings made of metals or alloys and non-metallic ceramics, which are difficult to achieve by other processing methods.



     2) Unification of the heterogeneity of a single particle and the homogeneity of the powder as a whole. As far as each particle is concerned, it is composed of two or more solid phases, each component has different physical and chemical properties, and there is an obvious phase interface, so it is heterogeneous, but for the powder as a whole In other words, the composite powders in the same particle size range have the same characteristics such as bulk density, fluidity and spraying process performance, and the obtained surface coating has uniform comprehensive physical and chemical properties. Therefore, in the process of storage, transportation and use, there will be no tendency of component segregation, so as to avoid the defect of uneven coating quality caused thereby. This is unmatched by mixed powder coating materials.

     3) The core material is protected by the coating layer or coating powder, which can avoid or reduce the oxidation burning loss, carbon loss, volatilization and other phenomena of some elements caused by the action of the high temperature flame during the thermal spraying process, so as to obtain high performance. coating. Compared with the coating made of mixed powder, the carbon loss of carbide is significantly reduced, the hardness of the coating is improved, and the wear resistance is enhanced.

     4) Select the appropriate components to configure the composite powder, so that at the flame temperature of thermal spraying, chemical reactions can occur between the powder components to generate intermetallic compounds with a melting point higher than that of each component of the powder, accompanied by the release of a large amount of powder. Heat, auxiliary heating of the powder particles and the surface of the substrate, so that a microscopic molten thin layer appears in the substrate. When the molten particles hit the surface of the substrate at a high speed, the powder and the surface of the substrate form a firm "pseudo-metallurgical" bond, and the powder particles in the coating are between the powder particles. Welding to each other can obtain a dense coating, and the well-known nickel-aluminum composite powder is a typical example.

     There are many components that can undergo exothermic reaction and generate intermetallic compounds during thermal spraying. Different methods can be used to make composite powder or composite metal wire. However, Ni/Al composite powder or composite metal wire is the most widely used self-fluxing alloy in industry.

     5) Compared with spraying mixed powder, spraying composite powder not only has excellent coating performance, but also has much higher spraying rate and deposition efficiency, which can improve labor productivity.

     6) It conforms to the powder production process, which is simpler than the traditional powder manufacturing process, the components and proportions are easy to adjust, the performance is relatively easy to control, and the equipment used is less, which can be mass-produced and can be trial-produced in small quantities in the laboratory.