Abstract:
Ni-W-P based coatings offer promising properties such as superior hardness, wear resistance and high corrosion resistance. The emphasis of this evaluation has been put on improvement of mechanical and corrosion resistant properties of Ni-W-P by inclusion of the suitable BN and Al2O3 nanoparticles loading along with deposition. Ternary Ni-W-P alloy coating and both composite coatings (Ni-W-P/Al2O3 and Ni- W-P/BN) with particles concentration of (0.1g/L, 0.2g/L, 0.4g/L, and 0.8g/L) were successfully deposited on HSLA steel substrates via electrodeposition method. Their mechanical and corrosion resistant properties were studied using SEM, EDS, nano- indentation, optical profilometry, wear and corrosion tests and comparison was made. Addition of nano Al2O3 particles led to an enhancement in mechanical properties while addition of BN reduces the FC and wear rate of the coatings significantly. Corrosion rate when compared with HSLA steel decreased considerably but remained almost the same for BN and nano-alumina loadings. The hardness value of Ni-W-P (0.2g/L) alumina and Ni-W-P (0.8g/L) BN when compared to Ni-W-P alloy coatings increased from 8.84 to 11.60 GPa and 10.83 GPa respectively, the wear rate decreased from 1.834 × 10-7 to 1.946 × 10-8 (mm3/m) for (0.2g/L) alumina and for (0.8g/L) BN it decreased to 6.634× 10-10 (mm3/m). Corrosion rate also decreased from 2.82 to 1.54 and 1.46 mils/yr for alumina and BN loadings respectively. It is concluded that concentration of 0.2g/L of alumina in Ni- W-P composite coating displayed better mechanical and corrosion resistant properties while Ni-W-P/BN (0.8g/L) reported superior wear resistant properties.
