C. Lyphout, D. P. Nylén, University West, Trollhättan, Sweden
Thermally sprayed Inconel 718 coatings have been deposited by high velocity oxy-fuel (HVOF) spraying on Inconel 718 substrates. The aim of the on-going study is to understand and control the adhesion mechanisms and the residual stress state of the deposit/substrate system, in order to build up thick coatings for maintenance purposes. The coating adhesion strength was evaluated by a developed tensile test method, similar to the standard ASTM C633, but allowing higher adhesion strengths. Coating shear strength was evaluated by the recently developed prEN15340 Shear Test. A modified Layer Removal Method (MLRM) test was carried out to measure residual stresses. The relationship between process parameters and adhesion strength as well as residual stress distribution was evaluated.
Summary: In the present study, mechanical properties of HVOF thermally sprayed Inconel 718 coatings on Inconel 718 substrates have been investigated. Coating adhesion and residual stress distribution through the deposit/substrate system are strongly dependent on pre-treatment, process conditions during spraying and post-treatment. Better understanding of parameters controlling the adhesion and a better stability is needed to be able to improve the process control, to get reproductible results, and to be able to expand the application area of thermal sprayed products to aerospace repair applications.
