Limitations of Thermal Spray Technology

       Limitations of Thermal Spray Technology

    (1) The bonding strength of the coating is not too high. The bonding between the thermal spray coating and the substrate is mainly physical bonding and mechanical bonding, the bonding strength is not too high, and the coating has poor resistance to high stress, impact and heavy load. However, with the development of thermal spraying technology, explosive spraying, supersonic flame spraying, supersonic plasma spraying, cold spraying, etc. have greatly improved the bonding strength of thermal spraying coatings.

    (2) The thermal spray coating contains different degrees of pores and inclusions, and the lamellar coating structure leads to the anisotropy of the coating, which makes the mechanical properties, corrosion resistance, oxidation resistance, insulation and other properties of the coating better than those of the dense solid. The same material is worse.

Of course, any technology needs to be analyzed and judged from a dialectical point of view. For example, the porosity problem of thermal spray coatings is a defect for applications such as anti-corrosion, insulation, high temperature resistance, etc., but for coatings such as gas sensing components (such as oxygen detectors), abradable seals, catalysis, biological functions, etc. Get unexpected results. Under oil-lubricated conditions, the pores play a good oil storage function, which makes the coating have better anti-friction lubricating properties.

    (3) The utilization rate of thermal energy is relatively low. Plasma spraying, which is the mainstay of thermal spraying technology, only has 10%~40% of the thermal energy used to melt the coating material; while the deposition effect of plasma sprayed ceramic coating varies from 30%~80% depending on the spraying material. , especially when spraying small parts, the deposition efficiency is low. These all make the cost of thermal spray coatings relatively high. Efforts to reduce costs on the premise of ensuring the quality of the coating are always the goal of thermal sprayers.

    (4) Thermal spray particles have the characteristics of linear flight, and it is difficult to prepare qualified coatings in sheltered cavities, complex surfaces, slender inner holes, blind holes and other parts.

    (5) The working environment of thermal spraying has problems such as noise, dust, heat and arc radiation. During manual operation on site, corresponding labor protection and environmental protection measures must be taken. However, with the application of advanced technologies such as computer control technology and robotics, these problems have been reduced.