Recent Developments in Thermal Spray Materials

       Materials for thermal spraying have developed with the development of thermal spraying technology, such as the use of white spreading synthesis technology to prepare new spraying powders. Ceramic powder materials such as TiC, TiB2, ZrB2 have been synthesized; in order to meet the needs of biomedicine, thermal spray materials with good biocompatibility such as hydroxyapatite and fluorohydroxyapatite have been developed. Nano-coating materials have also begun to be applied, but in order to adapt to the thermal spraying process, nano-powders are generally agglomerated into powders with slightly larger particle sizes that can be used for thermal spraying. In addition, a series of amorphous coating materials have been developed by utilizing the rapid solidification characteristics of thermal spraying technology. In order to solve the fluidity problem of thermal spray powder, the plasma spheroidization technology was invented to prepare spherical powder.



    There are more and more studies on composite coating materials. Composite coatings not only have the properties of a single structural coating, but also can obtain coatings with special properties or multi-functions. At present, the types of composite coatings obtained by compounding various materials mainly include metal-based ceramic composite coatings, ceramic composite coatings, multi-layer composite coatings, and gradient functional composite coatings. For example, Al is a coating material with good corrosion resistance, but pure Al coating has poor wear resistance. The metal matrix composite coating is obtained by adding hard ceramic phases A1N, A12O3, SiC, TiC, etc. to Al, which can significantly improve its wear resistance. Metal matrix composite coatings can be obtained by plasma spraying composite powder or arc spraying powder core wire. A new type of spray material developed in the past few years is the crystal-like material. Metastable and stable-like structures are obtained by quenching or spin-melting and dispersion and mechanical alloying. Crystalline materials have special properties, such as high hardness, low surface energy and low coefficient of friction, and are relatively brittle. Crystalline materials can be used as non-stick coatings on pots or other cookware,

    In order to meet the new development requirements for multi-functional and high-performance materials. The use of composite materials, nanomaterials, new alloys or amorphous materials has become the main trend in the development of thermal spray materials. In recent years, thermal sprayed amorphous materials have become a focus of attention. Certain amorphous metal alloys have much higher wear and corrosion resistance than crystalline alloys of similar composition. Compared with their corresponding micro-scale materials, nano-materials have many excellent properties. Significant progress has been made in the preparation of high-quality nano-powders, and some methods have been applied in industry. However, how to make full use of these materials and how to exert the excellent properties of nanomaterials is an urgent problem to be solved. The main advantages of thermal spraying to prepare nanoscale grained coatings are flexibility and cost feasibility, which may soon lead to the realization of industrial applications of nanoscale grained materials.

    The working conditions of machinery and equipment in all walks of life vary widely, even if the working conditions of different working parts of the same machinery and equipment are different. In order to make the machinery and equipment operate normally and fully utilize the potential of the coating material, the coating material must be specialized. Along with specialization, the coating material must be serialized. The quality of the coating material needs to be guaranteed in terms of performance and spraying process performance, and it should be continuously improved.