Thermally Sprayed Coatings on Light Metal Substrates - Finite Element Analysis (FEA) of Residual Stress Formation during Manufacturing

摘要

Due to the substitution of steel and cast iron by light metals in automotive lightweight design and engineering, functional coatings are necessary to protect the surfaces of light metal components. An interesting example is the application of aluminum crankcases, where protective and functional coatings are deposited in the cylinder bores. These layer composites can be produced by thermal spraying. Different thermophysical properties of the composite materials and the intensive heat and mass transfer processes during coating deposition lead to thermal expansion gradients which result in quenching stresses and thermal stresses during cooling down after the manufacturing. The final state of residual stresses is the main factor taking influence on quality, performance, reliability and life time of thermally sprayed coatings on cylinder liner surfaces. Numerical thermal stress analysis is used to reduce the experimental measurement extent. The finite element model and the modeling of the thermal spray process are described. The influence of process heat and mass transfer on the stress formation is analyzed with regard to different simultaneous cooling techniques. The simulation results obtained by the idealized elastic material model are discussed with respect to real ceramic coating material behavior.