Engineers from Fluxtrol Inc., Auburn Hills, Mich., discussed results of a study of ceramic coatings on soft magnetic composites at the ASM International Heat Treat 2019 conference in Detroit.
Soft magnetic composites (SMCs) are widely used for induction heat treating applications to increase system efficiency, improve heat pattern control, and prevent heating of adjacent areas of the workpiece or machine components. In most induction heat treating applications, the expected lifetime of the inductor is limited by the fatigue life of the copper.
In some of the most severe cases, the lifetime of the inductor is limited by the lifetime of the magnetic flux controller. In these applications, corrosion is a typical failure mode of the magnetic flux controller. Corrosion of the soft magnetic particles in the composite is caused by a combination of elevated temperatures and exposure to oxidizing agents (quenchants, air, etc.). Coating SMCs can significantly enhance their corrosion resistance, improving their durability.
In this study, four commercially available SMCs, Ferrotron 559H, Fluxtrol 100, Fluxtrol 50, and Fluxtrol A, were coated with three different types of high performance ceramic polymer-based coating materials. ASTM D1735 humidity tests were carried out for 48, 96, and 168 hours on all the samples. The researchers presented results of the corrosion testing, including a comparative analysis of three types of coatings. They also discussed the potential impact on inductor lifetime.
Title: Improving Corrosion Resistance of Soft Magnetic Composites for Induction Heat Treating Applications
Authors: Dr. Prem Vaishnava, R. Mitchel Madeira, Doug Whittaker, Robert C. Goldstein, Fluxtrol Inc., Auburn Hills, Michigan.
