Margaret Ziomek-Moroz

An overview of corrosion - wear interaction for planarizing metallic thin films

Corrosion-wear interactions play a very crucial role in developing many technological processes. One of them is chemical-mechanical planarization (CMP) of metallic thin films for manufacturing semiconductor devices such as computer chips. In this paper, we present research approaches undertaken in developing CMP for different metallic thin films, such as tungsten and copper in aqueous media. Mechanisms of material removal during CMP are presented. The role of corrosion, wear, and their synergistic effect are explained. The importance of constructing corrosion-wear maps for these complicated tribo-corrosion-metallic thin film systems is addressed. The application of corrosion-wear maps in developing reliable CMP slurries and processes is discussed.

Investigation of Passive Films on α2 and γ Titanium Aluminides by X-Ray Photoelectron Spectroscopy

Abstract Passive films on α2 and γ titanium aluminide formed potentiostatically in sodium hydroxide (NaOH) and sulfuric acid (H2SO4) solutions were studied by x-ray photoelectron spectroscopy (XPS). In NaOH, potentiostatic experiments showed that titanium aluminides had very similar passive current densities to that of Ti. XPS sputter depth profile showed nearly no Al present in the outer layer of the passive films. In H2SO4, passive current densities increased for specimens with increasing Al content. XPS sputter depth profile showed that Al was enriched in outer layers of the passive films. These results indicated that the passive film dissolution rate increased with increasing amounts of Al in the passive film for titanium aluminides.

Technical Note: Characterization of Corrosion Films Formed on Austenitic Stainless Steel in Supercritical CO2 Containing H2O and O2

Future technologies require structural alloys resistant to corrosion in supercritical CO2 (sCO2) fluids containing impurities such as H2O and O2. Traditional pipeline steels are potentially unsuita...

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

The corrosion behavior of high-entropy alloys (HEAs) CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl) at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276) and stainless steel 316L (UNS 31600) to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV) can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS) elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM) analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

Fe Thin Film Coated Optics for Corrosion Monitoring

Fe thin film coated optics were developed to monitor the internal corrosion in natural gas transmission pipelines. The Fe thin film corrosion behavior was studied in CO2-saturated 3.5%wt. NaCl solution using in-situ direct electrochemical methods.

Surface and Electrochemical Behavior of HSLA Steel in Supercritical CO2-H2O Environment

General corrosion was observed on high strength low alloy carbon steel after electrochemical impedance spectroscopy experiments (EIS) performed in H{sub 2}O saturated with CO{sub 2} at 50 C and 15.2 MPa. However, general and localized were observed on the same material surfaces after the EIS experiments performed in supercritical CO{sub 2} containing approximately 6100 ppmv H{sub 2}O at 50 C and 15.2 MPa. The general corrosion areas were uniformly covered by the FeCO{sub 3}-like phase identified by X-ray diffraction (XRD). In the area of localized corrosion, XRD also revealed FeCO{sub 3}-rich islands embedded in {alpha}-iron. The energy dispersive X-ray (EDX) analysis revealed high concentrations of iron, carbon, and oxygen in the area affected by general corrosion and in the islands formed in the area of localized corrosion. The real and imaginary impedances were lower in H{sub 2}O saturated with CO{sub 2} than those in the supercritical CO{sub 2} containing the aqueous phase indicating faster corrosion kinetics in the former.

Effects of Inclusions in HSLA Carbon Steel on Pitting Corrosion in CaCl2

Susceptibility of high strength low alloy steel to localized corrosion was studied in 6.7 M CaCl{sub 2} for oil and natural gas drilling applications. Results of the immersion and electrochemical experiments showed that the steel is susceptible to pitting corrosion. Optical microscopy investigations of the polished samples revealed that 10% of the surface area was occupied by defects in the form of pits. The energy dispersive X-ray (EDX) and wavelength dispersive X-ray (WDX) chemical analyses revealed higher concentrations of Mn and S compared to the metal matrix in defected areas. These areas served as the sites for development of corrosion pits during both immersion and electrochemical experiments. The fatigue results of the corroded samples indicate that if the pit was the most significant defect, the fatigue crack initiated and propagated at this site.

Susceptibility of carbon steel to stress corrosion cracking in sodium hydroxide

Stress corrosion cracking susceptibility of carbon steel and decarburized steel was studied in 8.5 M sodium hydroxide at 100 °C. Potentiodynamic experiments were performed to determine the potential values to be applied in slow strain rate (ssr) experiments. Optical and scanning electron microcopy were used to investigate the surfaces of corroded samples. Severe intergranular stress corrosion cracking was observed on the carbon steel samples in comparison to the decarburized steel samples.Copyright

Electrochemical Noise Sensors for Detection of Localized and General Corrosion of Natural Gas Transmission Pipelines. Final Report for the Period July 2001-October 2002

The U.S. Department of Energy, National Energy Technology Laboratory funded a Natural Gas Infrastructure Reliability program directed at increasing and enhancing research and development activities in topics such as remote leak detection, pipe inspection, and repair technologies and materials. The Albany Research Center (ARC), U.S. Department of Energy was funded to study the use of electrochemical noise sensors for detection of localized and general corrosion of natural gas transmission pipelines. As part of this, ARC entered into a collaborative effort with the corrosion sensor industry to demonstrate the capabilities of commercially available remote corrosion sensors for use with the Nations Gas Transmission Pipeline Infrastructure needs. The goal of the research was to develop an emerging corrosion sensor technology into a monitor for the type and degree of corrosion occurring at key locations in gas transmission pipelines.