진공 저온 분사 공정을 통해 형성된 Fe계 비정질 재료의적층거동 및 미세구조 변화 관찰

Abstract

Fe-based amorphous coatings were fabricated on a soda-lime glass substrate by the vacuum kinetic spray method. The effect of the gas flow rate, which determines particle velocity, on the deposition behavior of the particle and microstructureof the resultant films was investigated. The as-fabricated microstructure of the film was studied by field emission scanningelectron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Although the activationenergy for transformation from the amorphous phase to crystalline phase was lowered by severe plastic deformation and particlefracturing under a high strain rate, the crystalline phases could not be found in the coating layer. Incompletely fractured andsmall fragments 100~300 nm in size, which are smaller than initial feedstock material, were found on the coating surface andinside of the coating. Also, some pores and voids occurred between particle-particle interfaces. In the case of brittle Fe-basedamorphous alloy, particles fail in fragmentation fracture mode through initiation and propagation of the numerous small cracksrather than shear fracture mode under compressive stress. It could be deduced that amorphous alloy underwent particle fracturingin a vacuum kinetic spray process. Also, it is considered that surface energy caused by the formation of new surfaces andfriction energy contributed to the bonding of fragments.