SURFACE MODIFICATION BY COATINGS HAS BECOME AN ESSENTIAL STEP TO IMPROVE THE SURFACE PROPERTIES SUCH AS WEAR, CORROSION AND OXIDATION. VARIOUS CONVENTIONAL TECHNIQUES ARE UTILIZED FOR DEPOSITING THE DESIRED MATERIALS ON TO THE SUBSTRATE TO ACHIEVE THE SURFACE MODIFICATION. HERE, A LAYER OF CHROMIUM COATING WAS COMPARED WITH A LAYER OF THE CHROMIUM OXIDE COATING IN WHICH THE LAYERS WERE PRODUCED BY ELECTRODE POSITION TECHNIQUE. THE ELECTRODE POSITION OF METALLIC CHROMIUM WAS CARRIED OUT USING CYCLIC POTENTIAL (20 SCANS BETWEEN 0 AND -1.0V AT ASCAN RATE OF 50MVS-1) IN 0.1 MOLL-1 H2SO4 SOLUTION, IN A SOLUTION CONTAINING 0.5 MOLL-1 CHROMIUM (III) CHLORIDE. THE POTENTIAL WAS REPETITIVELY CYCLED (30 SCANS) FROM 0 TO 1.2 V AT A SCAN RATE OF 100MVS-1 IN FRESH PHOSPHATE SOLUTION FOR THE PASSIVATION OF A CHROMIUM OXIDE LAYER AT A CARBON STEEL SPECIMEN. IN INVESTIGATING OF COATING SURFACES BY SCANNING ELECTRON MICROSCOPE (SEM), THE RESULTS SHOWED THAT THE MORPHOLOGY OF THE COATING SURFACE WAS CHANGED BY CONVERTING CHROMIUM TO THE CHROMIUM OXIDE. THE CORROSION BEHAVIOR OF THE COATINGS WAS ASSESSED BY POLARIZATION TECHNIQUE IN SEAWATER AND 3.5% NACL SOLUTION. THE RESULTS SHOWED THAT CHROMIUM OXIDE COATING REDUCE CORROSION CURRENT AND CORROSION RATE MORE THAN CHROMIUM COATING.

IN INDUSTRY, THE PLATING OF MILD STEEL AND IRON BY METALS LIKE NICKEL, CHROME, ZINC HAS BEEN WIDELY USED TO PROTECT THEM AGAINST CORROSION, FOR MANY YEARS [1-3] AND THIN TOP COAT PHOSPHATATION AND CHROMATATION ON ELECTRODEPOSITED METAL COATINGS HAVE IMPROVED THE CORROSION RESISTANCE OF THE SUBSTRATES. THE NICKEL PLATING ON MILD STEEL HAS BEEN GENERALLY APPLIED FOR LONGER PERIODS, WHICH EXCEED THE CAR LIFETIME IN AUTOMOBILE INDUSTRY AND FOR THE FABRICATED PARTS SUCH AS NAILS AND BOLTS. IN THIS WORK, A LAYER OF NICKEL COATING WAS COMPARED WITH A LAYER OF THE NICKEL OXIDE COATING IN WHICH THE LAYERS WERE PRODUCED BY ELECTRODE POSITION TECHNIQUE. THE ELECTRODE POSITION OF METALLIC NICKEL WAS CARRIED OUT USING CYCLIC POTENTIAL (20 SCANS BETWEEN 0 AND -1.0V AT ASCAN RATE OF 50MVS-1) IN 0.1 MOLL-1 H2SO4 SOLUTION, IN A SOLUTION CONTAINING 0.5 MOLL-1 NICKELNITRATE. THE POTENTIAL WAS REPETITIVELY CYCLED (30 SCANS) FROM 0 TO 1.2 V AT A SCAN RATE OF 100MVS-1 IN FRESH PHOSPHATE SOLUTION FOR THE PASSIVATION OF A NICKEL OXIDE LAYER AT A CARBON STEEL (CS) SPECIMEN. ANODIC POLARIZATION CURVES WERE USED TO EVALUATE THE CORROSION PERFORMANCE OF NI COATED AND NIO COATED ELECTRODES IN SEAWATER AND 3.5% NACL. IT WAS OBSERVED THAT NI ELECTROPLATING REDUCED DRASTICALLY THE CORROSION RATE OF CARBON STEEL AND EXHIBITED AN EFFICIENT BARRIER PROPERTY ON CS. HOWEVER, THE POROSITY OF NI ELECTROPLATING INCREASED FOR LONGER PERIODS. IT WAS FOUND THAT THE POROSITY OF NIO COATING WAS LOWERED DUE TO THE MORE PASSIVATION EFFECT OF THIS LAYER AND NIO COATING COULD PROVIDE SIGNIFICANT PROTECTION EFFICIENCY TO CS ELECTRODE. THE RESULTS SHOWED THAT NICKEL OXIDE COATING REDUCE CORROSION CURRENT AND CORROSION RATE MORE THAN NICKEL COATING.