Experimental study on spray parameters and properties of HVOF sprayed Fe-based amorphous nanocrystalline coating

This study demonstrates the benefits of high-quality and high-efficiency supersonic flame spraying, aids smart decision-making, and lays a theoretical basis for the practical application of iron-based amorphous coatings. By implementing an artificial neural network, a comprehensive design study that considers several factors and levels may effectively direct the optimization of process parameters, improve product surface performance, minimize expenses, and boost efficiency. This enables the raw materials to attain maximum efficiency in real-world applications. This work examined the technological parameters and properties of Fe-based amorphous nanocrystalline coating using supersonic flame spraying technology, utilizing a multi-factor and multi-level design analysis approach to conduct experimental parameter design. A BP neural network model was developed to investigate the impact of coal oil quantity, oxygen quantity, powder feeding rate and spraying distance on the porosity, hardness, bonding strength, and deposition efficiency of the coating. The powder and coating’s microstructures were analyzed using scanning electron microscopy and transmission electron microscopy. In addition, X-ray diffraction, synchronous thermal analysis, and other techniques were employed to observe and analyze the phase constitution and amorphous content of both the powder and the coating that was created. The computer simulation results were validated while optimizing the process parameters. The measurement of the ideal spraying process parameter range further improved the coating performance. The text discusses the mechanism of pore development at a microscopic level during spraying, as well as the connection between the formation principle of amorphous nanocrystalline and the coating performance. The results revealed that several components have mutual influence on the coating. Theoretically, the most favorable spray parameters for achieving optimal coating are as follows: a diesel flow rate of 23 L·h⁻¹, oxygen flow rate of 51 L·h⁻¹, a powder feeding rate of 72 g·min⁻¹, and a spraying distance of 280 mm. To develop a high quality coating of Fe-based amorphous alloy that improves material surface performance, one must carefully select a suitable spraying material and employ the proper thermal spraying procedure. The coating yielded the following results: a thickness of 270 μm, a porosity of 1.3%, a binding strength of 80 MPa, and a hardness of 1110 HV_0.3. The amorphousness degree of the coating was exhibited around 80%, with a nanocrystalline diameter was ranging from 3–5 nm. Crystallization of the coating is only possible above 600 ℃.