Process modeling and simulation of plasma and HVOF sprayed cylinder liner coatings

Thermally sprayed ceramic and cermet coatings as cylinder surfaces are promising solutions in lightweight motor engineering. Properties, quality and lifetime of thermally sprayed coating systems strongly depend on the state of residual stresses. Different thermophysical properties of the coating and substrate materials and dynamic heat and mass transfer processes during the manufacturing process lead to different thermal expansions of coating and substrate. This induces temporary stresses, which result in residual thermal stresses at the end of deposition and cooling. By use of different simultaneous process cooling techniques, the residual stresses can be influenced and optimized in a wide range. In order to minimize experimental testing, numerical thermal stress analysis with the finite element method is applied to determine the influences of different process cooling fluids and designs. Numerical simulation enables the investigation of temporary stresses during coating deposition and therefore leads to a better understanding of residual stress formation mechanisms. By adapting the finite element model, the influence of other manufacturing parameters like composite materials properties, thermal coating energy or substrate pre-heating temperature can also be considered. Experimental residual stress measurements after the manufacturing process are used to validate the numerical analysis results.