Friction surface cladding of AA1050 onto AA2024: parameter study and process window development

Friction surface cladding (FSC), a relatively new solid state surface modification technique, was developed to deposit thin metallic layers onto substrates to protect the substrates from chemical corrosion. The FSC process employs a specially designed rotating tool containing an opening as the supply channel of the clad material and a specific tool bottom to support the material flow. The objectives of the current thesis are to carry out a systematic analysis of the FSC process, to develop appropriate process models and to determine a FSC process window. The various series of experiments presented in this work show that defect free layers can be manufactured within a large range of process parameters. The heat input of the FSC process is estimated using a 3D thermal model. A 2D axisymmetric thermo-mechanical model indicates that the heat generation increases with the tool rotation rate and the clad layer width, whereas the clad layer thickness and the size of the tool opening have negligible influence. The normal force exerted on the substrate decreases for larger values of the clad layer thickness, the tool opening diameter and the tool rotation rate, but it increases with larger clad layer widths. These results confirm approximately the experimental trends observed and supply further understanding of the FSC process. A quantitative comparison of the experimental and model results shows that the thermo-mechanical model overestimates the estimated heat generation and it underestimates the measured normal force, mainly ascribed to the assumed full sticking conditions at the tool-clad layer interfaces. Better comparison was obtained if the sticking conditions vary from full sticking in a region close to the FSC tool opening to almost full slipping at the FSC tool edge. Additional experiments were performed to determine the FSC process window by adjusting the tool rotation rates in the cladding phase. It is found that continuous and defect free layers can be deposited with the substrate temperature between a lower and an upper bound of 317 ℃ and 407℃, respectively.