Fluidized Processing of Surface Engineering of Metallic Components: Problems Encountered and Effects on Design

Surface engineering techniques provide an effective way to improve surface properties of metals and alloys such as wear resistance, hardness, and corrosion resistance. Fluidized processing offers advantages such as excellent heat and mass transfer and intimate gas-solid contact. Such processing suffers from some technical problems. This paper critically reviews the main practical problems of particle attrition, particle agglomeration, heat and mass transfer, and distortion of complicated geometries. These problems are interrelated. The surface engineering processes require an in-depth quantitative investigation to develop a reliable control strategy. In addition, modeling and simulation are basic to achieve process control. Future research trends should focus on measures to avoid the inhibiting effects of these critical problems. The design problem of distortion control in heat treatment processes needs thorough investigation. The quenching power of fluidized beds is flexible and very effective. Designers and operators should carefully consider the design implications regarding the related problems. This review showed clearly how critical these problems are to surface engineering processes.