Electrodeposition parameters optimization for enhanced the performance of nickel and Ni-TiO2 coatings

Nickel and Ni-TiO2 coatings were synthesized through electrodeposition from watts bath on copper substrate. Ni coat from additive-free watts bath revealed good corrosion resistance but poor mechanical properties and rough surface. Watts bath has been modified with different amounts of sodium saccharin to decrease the grain size and improve micro-hardness and wear resistance of the coating. The grain size decreased from 25nm to 12nm which caused very smooth and uniform surface. The micro-hardness of the coating increased from 170 HV50 for simple Ni to 500 HV50 for modified Nickel. The effects of current density, temperature and additives on the properties of nickel coating was studied. Ni-TiO2 coat was electroplated by adding different amounts of TiO2 sol-gel into the watts bath, to study the effect of TiO2 sol concentration on the corrosion and mechanical behavior of the coating. Titanium (IV) butoxide was used as the source of Titanium. Effect of sulfur amount on X-ray diffraction and corrosion behavior of nickel coat has studied. Surface morphology, surface roughness, chemical and phase compositions of the coatings were also investigated by XRD, SEM and electrochemical techniques.

Keywords:

Electroplating , Composite coating , Ni-TiO2 , TiO2 Sol , Corrosion resistance , Microhardness.