A new Fe-Cr-Mo-B-C amorphous alloy is designed, which offers high mechanical strength, corrosion resistance as well as high glass-forming ability and its gas-atomized amorphous powder is deposited on an ASTM A213-T91 steel substrate using the high-velocity oxygen fuel (HVOF) process. The hybrid coating layer, consisting of nanocrystalline and amorphous phases, exhibits strong bonding features with the substrate, without revealing significant pore formation. By the coating process, it is possible to obtain a dense structure in which pores are hardly observed not only inside the coating layer but also at the interface between the coating layer and the substrate. The coating layer exhibits good adhesive strength as well as good wear resistance, making it suitable for coating layers for biomass applications.
Innovative SMC with low iron loss was made from iron powders with evaporated MgO insulation coating. The coating had greater heat-resistance than conventional phosphatic insulation coating, which enabled stress relieving annealing at higher temperature. Magnetic properties of toroidal samples (OD35mm,ID25mm, t5) were examined. The iron loss at 50Hz for Bm = 1.5T was lower 50% of conventional SMC and was almost the same with silicon iron laminations(t0.35). It became clear that MgO insulation coating has enough heat resistance and adhesiveness to powdersurface to obtain innovative SMC with low iron loss.
Seasonal changes have been recognized in particle characteristics and forming characteristics of iron powder with insulated coating for a compacted magnetic core because of its high hygroscopicity, due to its phosphate coating and resin binder additives. For this reason, particle characteristics and molding characteristics of the powder with diverse water absorbtivity have been studied. The result shows that the higher the volume of absorbed water, the worse the fluidity becomes, resulting in the reduction in both springback during the molding process and expansion reduction after the heat treatment. The requirement on dimension accuracy for the finished product can be satisfied with an additional drying process on the material powder, which contributes to maintain its water volume constant.