Effects of Furnace Atmosphere on the Post-Annealing Adhesion Capability of Insulation Coating to Electrical Steel Substrates

摘要

Electrical steels (ES) are the core of electrical motors, power generators, etc. To restore the electromagnetic properties of ES after stamping, stress-relieving annealing is often adopted. However, annealing can be very destructive to the insulation coating on ES. Inappropriate annealing usually results in coating adhesion failure, which greatly affects the performance of ES facilities. In this paper, effects of furnace atmosphere on the postannealing adhesion capability of ES coating were investigated to reveal the individual influence of O2, CO2, H2, and H2O, respectively. The presence of CO2 has little effect while both O2 and H2O can deteriorate the postannealing adhesion capability. Contrarily, H2 has protecting effects so that good post-annealing adhesion capability of coating can be fulfilled. Therefore, to ensure good post-annealing adhesion capability to the coating, low contents of oxygen & humidity (dew point) in the furnace atmosphere is required and the presence of some hydrogen in the furnace atmosphere can further help.