Effect of Current Density on Composition and Microstructure of Boronized Layer by Electrodeposition

Boronized layer was prepared on silicon steel substrate by pulse electrodeposition in KCl-NaCl-NaF-Na2B4O7 molten salts with different current density. The effect of current density on composition and microstructure of boronized layer was studied. The phase, the cross-sectional morphology and the compositional depth profile of the layer were studied by X-ray diffraction analysis (XRD), optical microscopy (OM) and glow discharge spectrometry (GDS). The presence of FeB on the surface of the boronizied steel was confirmed by XRD analysis. Cross sectional observation revealed that the boronized layer consisted of the outer layer FeB and the sublayer Fe2B. In addition, the low current density produced more proportion of Fe2B and bigger saw-tooth grains.

Effect of Borax Content on Composition and Microstructure of Boride Layer by Electrodeposition

Boronizing of silicon steel is performed by electrodeposition in KCl-NaCl-NaF-Na2B4O710H2O molten salts with different amounts of borax. The effect of borax content on composition and microstructure of boride layer is studied. The compositional depth profile of boride layer is measured using the glow discharge spectrometry (GDS) and the depth from the surface to the substrate is taken as the layer thickness. The surface morphology is studied by atomic force microscopy (AFM). It is found that the thickness of the boride layer reached maximum values when the borax content is 0.05mol. The roughness decreases with raising borax content from 0.01 to 0.05mol while the further increase of borax content from 0.05 to 0.1mol results in increase of roughness. The boride layer formed at borax content 0.05 mol shows smallest values of surface roughness.

Process Optimization and Structural Characterization of Fe3Si Layer by Pulse Electrodeposition

Fe3Si layer was prepared by pulse eletrodeposition of Si on the surface of non-oriented steel in molten salts. With an orthogonal test the optimal process parameters were determined: the formulation of salts was NaCl:KCl:NaF:SiO2=1:1:3:0.3(mole ratio), current density of 60 mA/ cm2, duty cycle of 30%, pulse period of 1000 s and a deposition time of 50 min, respectively. The compositional depth profile, the structure, the surface morphology and cross sectional micrograph of the layer were studied by glow discharge spectrometry (GDS), X ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscope (OM). The results showed that Si in the layer existed in the form of the gradient distribution. The phase structure of the layer was composed of the single-phase Fe3Si. The layer composed of equiaxed grains. The surface appeared smooth and dense, and with uniform thickness.