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Research paper thumbnail of Thermodynamic analysis of corrosion of carbides of titanium, niobium and tungsten

Research paper thumbnail of Analysis of Film Formation in High Chromium White Iron Hardfacing Alloys in Alkaline Solution using EIS and SIMS

Journal of Bio- and Tribo-Corrosion

Research paper thumbnail of Significance of Pourbaix Diagrams to Study the Corrosion Behaviour of Hardfacing Alloys Based on Chromium Carbides at 298 K (25 °C)

Journal of Bio- and Tribo-Corrosion

The Pourbaix diagrams also known as the E-pH diagrams were constructed for hardfacing alloys base... more The Pourbaix diagrams also known as the E-pH diagrams were constructed for hardfacing alloys based on three chromium carbides: Cr 7 C 3 , Cr 23 C 6 and Cr 3 C 2 at 298 K (25°C). Using the thermodynamic data available for the main species at 298 K (25°C), Pourbaix diagrams for the chromium carbides are constructed at a concentration of 10-6 M of aqueous species. It was found that the diagrams are able to explain the results of experimental work performed on chromium carbides in NaOH. It was found that the stability of carbides is described only by the immune region of the Pourbaix diagram for carbides. Although passive region has been included in the study, it was unclear from the literature if there was a passive film or how protective it was.

Research paper thumbnail of Corrosion Behaviour of High-Chromium White Iron Hardfacing Alloys in an Alkaline Solution

Journal of Bio- and Tribo-Corrosion, 2016

Hardfacing alloys of high-chromium white irons (HCWI) deposited using welding are well known for ... more Hardfacing alloys of high-chromium white irons (HCWI) deposited using welding are well known for their wear resistance. These materials are applied in conditions needing not only wear resistance but also corrosion. In this study, the HCWI alloys were exposed to alkaline solutions of pH 14. Anodic polarization technique was used to study the corrosion behaviour. The experimental results found that corrosion occurs on carbides in preference to the matrix. Pourbaix diagrams of carbides were found to be very useful in explaining the corrosion behaviour of the hardfacing alloys. The significance of carbide corrosion to the use of hardfacing alloys is discussed. Possible methods to mitigate corrosion are proposed.

Research paper thumbnail of Corrosion Behaviour of High Chromium White Iron Hardfacing Alloys in Acidic and Neutral Solutions

Journal of Bio- and Tribo-Corrosion, 2016

Hardfacing alloys of High Chromium White Irons (HCWI) were deposited on low carbon steel using Sh... more Hardfacing alloys of High Chromium White Irons (HCWI) were deposited on low carbon steel using Shielded Metal Arc Welding. Microstructure of HCWI consists of primary carbides, eutectic carbides and eutectic austenitic/martensitic matrix. This study investigated the corrosion behaviour of HCWI in both acid and neutral solutions. The corrosion behaviour of HCWI was evaluated using anodic polarisation technique. It was found that in acid solution at pH 1.5, corrosion occurs on eutectic austenite/martensitic matrix whereas at pH 2, the corrosion occurs on eutectic carbides. In the neutral environment at pH 7, corrosion of HCWI occurred in the eutectic austenite/martensite matrix in the presence of chloride ions, while in the buffered solution, corrosion occurred in the carbides. The results of this study show that the corrosion mechanism of HCWI for both acid and neutral environments was due to potential difference between carbides and eutectic austenite/martensitic matrix. The superimposed Pourbaix diagrams of chromium carbides with iron (Fe) and niobium carbide were useful in explaining the behaviour of HCWI in both acid and neutral solutions. Keywords Hardfacing Á High chromium white irons Á Acid Á Neutral Á Chloride ions Á Pourbaix diagram of carbides

Research paper thumbnail of Thermodynamic analysis of corrosion of carbides of titanium, niobium and tungsten

Research paper thumbnail of Analysis of Film Formation in High Chromium White Iron Hardfacing Alloys in Alkaline Solution using EIS and SIMS

Journal of Bio- and Tribo-Corrosion

Research paper thumbnail of Significance of Pourbaix Diagrams to Study the Corrosion Behaviour of Hardfacing Alloys Based on Chromium Carbides at 298 K (25 °C)

Journal of Bio- and Tribo-Corrosion

The Pourbaix diagrams also known as the E-pH diagrams were constructed for hardfacing alloys base... more The Pourbaix diagrams also known as the E-pH diagrams were constructed for hardfacing alloys based on three chromium carbides: Cr 7 C 3 , Cr 23 C 6 and Cr 3 C 2 at 298 K (25°C). Using the thermodynamic data available for the main species at 298 K (25°C), Pourbaix diagrams for the chromium carbides are constructed at a concentration of 10-6 M of aqueous species. It was found that the diagrams are able to explain the results of experimental work performed on chromium carbides in NaOH. It was found that the stability of carbides is described only by the immune region of the Pourbaix diagram for carbides. Although passive region has been included in the study, it was unclear from the literature if there was a passive film or how protective it was.

Research paper thumbnail of Corrosion Behaviour of High-Chromium White Iron Hardfacing Alloys in an Alkaline Solution

Journal of Bio- and Tribo-Corrosion, 2016

Hardfacing alloys of high-chromium white irons (HCWI) deposited using welding are well known for ... more Hardfacing alloys of high-chromium white irons (HCWI) deposited using welding are well known for their wear resistance. These materials are applied in conditions needing not only wear resistance but also corrosion. In this study, the HCWI alloys were exposed to alkaline solutions of pH 14. Anodic polarization technique was used to study the corrosion behaviour. The experimental results found that corrosion occurs on carbides in preference to the matrix. Pourbaix diagrams of carbides were found to be very useful in explaining the corrosion behaviour of the hardfacing alloys. The significance of carbide corrosion to the use of hardfacing alloys is discussed. Possible methods to mitigate corrosion are proposed.

Research paper thumbnail of Corrosion Behaviour of High Chromium White Iron Hardfacing Alloys in Acidic and Neutral Solutions

Journal of Bio- and Tribo-Corrosion, 2016

Hardfacing alloys of High Chromium White Irons (HCWI) were deposited on low carbon steel using Sh... more Hardfacing alloys of High Chromium White Irons (HCWI) were deposited on low carbon steel using Shielded Metal Arc Welding. Microstructure of HCWI consists of primary carbides, eutectic carbides and eutectic austenitic/martensitic matrix. This study investigated the corrosion behaviour of HCWI in both acid and neutral solutions. The corrosion behaviour of HCWI was evaluated using anodic polarisation technique. It was found that in acid solution at pH 1.5, corrosion occurs on eutectic austenite/martensitic matrix whereas at pH 2, the corrosion occurs on eutectic carbides. In the neutral environment at pH 7, corrosion of HCWI occurred in the eutectic austenite/martensite matrix in the presence of chloride ions, while in the buffered solution, corrosion occurred in the carbides. The results of this study show that the corrosion mechanism of HCWI for both acid and neutral environments was due to potential difference between carbides and eutectic austenite/martensitic matrix. The superimposed Pourbaix diagrams of chromium carbides with iron (Fe) and niobium carbide were useful in explaining the behaviour of HCWI in both acid and neutral solutions. Keywords Hardfacing Á High chromium white irons Á Acid Á Neutral Á Chloride ions Á Pourbaix diagram of carbides

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