Optimizing the defensive characteristics of mild steel via the electrodeposition of Zn Si3N4 reinforcing particles

Abstract

The effect of ZneSi3N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of load. The experiment was conducted varying the mass concentration of silicon nitride (Si3N4) between 7 and 13 g at cell voltage of 0.3 and 0.5 V, at constant temperature of 45 �C. The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope (SEM) revealing that the particles of the ZneSi3N4 were homogeneously dispersed. The corrosion behaviour was studied using potentiodynamic polarization technique in 3.65% NaCl solution and the microhardness was examined using Brinell hardness testing technique. The result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year, maximum coating efficiency of 98.9%, maximum polarization resistance of 1555.3 U and a very low current density of 9.33 � 10�6 A/cm2. The negative shift in the Ecorr revealed the cathodic protective nature of the coating. The microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the 0.5Zne13Si3N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3N4 particles