Effect of corrosion inhibitor-based pre-treatment layers on the mechanical properties of electrical steel stacks
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
Adhesion 2024
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
Epoxy varnishes for stacked electrical steel are essential for further development of renewable energy (e.g., wind power) and electric mobility technologies. To enhance the efficiency of the stator, direct cooling solutions are under development. Therefore, good adherence of the epoxy isolation layer on the metal oxidic passivation layer has to be ensured. The main objective of this study was to assess the effect of silane- and corrosion inhibitor-based pre treatment layers as to the corrosion and mechanical performance of full-surface bonded electrical steel laminates. Low molar mass silanes with a glycidyl group (GS) or an amine functionality (AS) were considered for the pre-treatment varnish. Four corrosion inhibitors, including bisphosphate, benzotriazole, benzimidazole, and Cer(III)nitrate were investigated.
To evaluate the corrosion performance, an industrial condensation climate with alternating humidity and air temperature (AHT) and cyclovoltammetry were employed. Monotonic and cyclic fatigue mechanical tests were carried out to deduce the roll peel strength (RPS) and the fatigue crack growth (FCG) kinetics.
The corrosion tests revealed a superior performance of the AS based pre-treatment. As to the corrosion inhibitors, the bisphosphate and the benzimidazole allowed for slight improvement of the AHT performance. However, the AS based pre-treatment had a negative effect on roll peel strength (4.5 vs. 6.5 N/mm). The corrosion inhibitors added to GS did not lower the RPS performance compared to the laminate without pre-treatment. A similar ranking was achieved by fatigue fracture mechanics testing. However, the fatigue crack growth kinetics was much more sensitive to the effect of pre-treatment than the roll peel strength values.
Forschungs-