Swaminatha P. Kumaraguru

Corrosion Protection of Steel Using Nonanomalous Ni-Zn-P Coatings

A novel technique for obtaining nonanomalous Ni-Zn-P coatings with high Ni content ~74 wt % as compared to 15-20 wt % in the conventional plating method! has been developed. These coatings show promise as a replacement for Cd in sacrificially protecting steel. Ni-Zn-P coatings were deposited using an electroless method from a solution containing NiSO4 , complexing agent and ammonium chloride. Varying the concentration of ZnSO4 in the bath controls the final amount of Zn in the deposit. The Zn content in the coating was optimized based on the corrosion resistance of the final deposit. Coatings with 16.2 wt % Zn were found to display a potential of 20.652 V vs. SCE that is more electronegative to steel and hence can be used as a sacrificial coating for the protection of steel. Deposition parameters like pH and temperature have been optimized based on composition of the coating and the surface morphology. Corrosion studies in corroding media show that Ni-Zn-P coatings obtained using the electroless method show a higher barrier resistance and better stability as compared to cadmium coatings.

Development of an Electroless Method to Deposit Corrosion-Resistant Silicate Layers on Metallic Substrates

A novel electroless method for depositing corrosion-resistant silicate layers on metallic substrates from aqueous solutions has been developed. The silicate layer was deposited from an aqueous solution of sodium silicate 3.22 weight ratio sodium silicate, 37.5% solution in water from PQ Corporation and sodium borohydride. The technique is demonstrated by forming a passive film on galvanized steel. Deposition parameters such as concentration of the bath, temperature, and pH have been optimized based on the corrosion characteristics of the final coating. Studies on the coating reveal the formation of a very thin 5n m zinc disilicate layer followed by a much thicker 500 nm silica layer. Accelerated corrosion tests showed that the silicate coatings have higher corrosion resistance and better stability when compared to chrome passivates. Silica coatings developed by this method show promise as an alternative to chrome passivation for corrosion protection.

Highly Active Carbon Composite Electrocatalysts for PEM Fuel Cells

Highly active carbon composite catalysts were developed using a carbon based metal-free catalyst developed at USC as a support through catalyzed pyrolysis followed by chemical post-treatments. Materials characterization studies indicated that the nature of nitrogen functional groups on the carbon surface and the carbon nanostructures play a critical role in the activity and stability. The catalytic activity as high as 2.0 A cm at 0.2 V was obtained for the carbon composite catalyst in the fuel cell, and no irreversible activity loss was observed during stability test.

Cathodic Protection of Pipelines

Publisher Summary This chapter focuses on cathodic protection (CP) of pipelines, as pipelines are exposed to aggressive soil, varying climatic conditions, micro-organism, and stray currents that initiate corrosion processes. Cathodic protection is defined as reduction or elimination of corrosion by making the metal a cathode by means of an impressed current or attachment to a sacrificial anode. This is an electrochemical method that uses cathodic polarization to control the kinetics of the electrode processes occurring on the metal/electrolyte interface. The chapter categorizes CP systems into two types based on the type of the polarization used to protect the structure: sacrificial anode and impressed current systems. The criteria for CP are documented by National Association of Corrosion Engineers (NACE). The successful application of CP depends upon the selection, design, installation, and maintenance of the system. Before designing cathodic protection, adequate field data must be collected, analyzed, and evaluated. It discusses that the effectiveness of the CP can be determined by monitoring the pipeline potential using the close interval potential survey (CIPS) method or by using direct current voltage gradient (DCVG) or IR coupons techniques.

Chapter 24 – Cathodic protection of pipelines

Publisher Summary This chapter focuses on cathodic protection (CP) of pipelines, as pipelines are exposed to aggressive soil, varying climatic conditions, micro-organism, and stray currents that initiate corrosion processes. Cathodic protection is defined as reduction or elimination of corrosion by making the metal a cathode by means of an impressed current or attachment to a sacrificial anode. This is an electrochemical method that uses cathodic polarization to control the kinetics of the electrode processes occurring on the metal/electrolyte interface. The chapter categorizes CP systems into two types based on the type of the polarization used to protect the structure: sacrificial anode and impressed current systems. The criteria for CP are documented by National Association of Corrosion Engineers (NACE). The successful application of CP depends upon the selection, design, installation, and maintenance of the system. Before designing cathodic protection, adequate field data must be collected, analyzed, and evaluated. It discusses that the effectiveness of the CP can be determined by monitoring the pipeline potential using the close interval potential survey (CIPS) method or by using direct current voltage gradient (DCVG) or IR coupons techniques.