The role of oxygen interstitials in the corrosion behavior of biomedical β-phase Ti-12Mo-5Hf alloy exposed to simulated inflammatory environment

A synchronous investigation of the degradation of metallic bipolar plates in real and simulated environments of polymer electrolyte membrane fuel cells

Cortest Columbus Technologies, Inc. (CC Technologies) is investigating the long-term performance of container materials used for high-level radioactive waste packages. This information is being developed for the Nuclear Regulatory Commission to aid in their assessment of the Department of Energy`s application to construct a geologic repository for disposal of high-level radioactive waste. This report summarizes the results of cyclic-potentiodynamic-polarization (CCP) studies performed on candidate container materials for the Tuff Repository. The CPP technique was used to provide an understanding of how specific variables such as environmental composition, temperature, alloy composition, and welding affect both the general- and localized-corrosion behavior of two copper-base and two Fe-Cr-Ni alloys in simulated repository environments. A statistically-designed test solution matrix was formulated, based on an extensive search of the literature, to evaluate the possible range of environmental species that may occur in the repository over the life of the canister. Forty-two CPP curves were performed with each alloy and the results indicated that several different types of corrosion were possible. The copper-base alloys exhibited unusual CCP behavior in that hysteresis was not always associated with pitting. The effects of temperature on the corrosions behavior were evaluated in two types of tests; isothermal tests at temperatures from 50{degrees}C to 90{degrees}C and heat-transfer tests where the solution was maintained at 50{degrees}C and the specimen was internally heated to 90{degrees}C. In the isothermal test, CPP curves were obtained with each alloy in simulated environments at 50{degrees}C, 75{degrees}C, and 90{degrees}C. The results of these CCP experiments indicated that no systematic trends were evident for the environments tested. Lastly, the effects of welding on the corrosion behavior of the alloys in simulated environments were examined.

Electrochemical corrosion characteristics of type 316 stainless steel in simulated anode environment for PEMFC

In a multi-barrier system of geological disposal for high-level radioactive waste (HLW), it is considered that the disposal container is the first layer of protective barrier to HLW. Low carbon steel is considered as the most promising candidate material for geological disposal container given its mechanical performances and cost-effectiveness. In a long-term geological disposal process, corrosion resistance and corrosion evolution law of low carbon steel in a deep geological environment determine the service life of the disposal containers. Based on a large number of electrochemical corrosion experimental results in a simulated groundwater environment in Beishan, a candidate site for geological disposal of HLW in China, this paper reviews corrosion behavior of low carbon steel from the principles of chemical thermodynamics and kinetics respectively. The effects of environmental factors such as deaeration, aeration, chemical compositions of groundwater on the evolution of corrosion products with immersion time were explored, and the secondary effect of corrosion product on the change of corrosion mode was proposed. In addition, by evaluating corrosion rate as a function of exposure time duration and simulated environment, the feasibility of manufacturing the geological disposal container with low carbon steel was introduced.

In recent years there has been an increased interest in drilling deeper geothermal wells to obtain more energy output per well with the corresponding higher temperature and pressure and increased corrosiveness of the geothermal environment. To explore the potential of the high alloy austenitic stainless steel UNS S31254 in future deep geothermal wells corrosion testing was done in simulated geothermal environment at 180°C and 350°C with a pressure of 10 bar. The simulated environment was composed of steam with H2S, HCl and CO2 gases, with a pH of 3 upon condensation. The testing was done in a flow through reactor for 1 and 3 week exposures. The stainless steel UNS S31254 performed well at 180°C with negligible corrosion rates both for the 1 and 3 week tests and no localized corrosion damage detected. After the testing at 350°C localized corrosion and substantial amount of NaCl crystals were observed on the surface of the samples. Microstructural and chemical composition analysis revealed large cracks in the cross-section of the sample most likely due to chloride induced stress corrosion cracking. The measured corrosion rate for the 1 and 3 week test was 0.024 mm/year and 0.24 mm/year respectively.

Brake discs in drilling rig drawworks are exposed to harsh environmental conditions, including saline fluids, corrosive vapors, and mechanical wear under heavy loads. These factors can significantly reduce corrosion resistance and degrade tribological performance, both of which are critical for ensuring safe and reliable braking during drilling operations. This study examines the corrosion and wear behavior of AISI 4140 steel brake discs in combination with phenolic resin-based brake pads. The disc material was subjected to three simulated environments at room temperature: NaCl immersion, NaCl vapor, and HCl vapor. The highest corrosion rate occurred in NaCl immersion (0.1366% mass loss), followed by NaCl vapor (0.0365%) and HCl vapor (0.0230%). Surface degradation was confirmed through roughness measurements and visual inspection, with the most severe deterioration observed under NaCl immersion. Friction performance, assessed using pin-on-disc tests, showed that NaCl vapor exposure reduced the coefficient of friction, while HCl vapor led to a slight increase, likely due to pitting and surface hardening effects. These findings suggest that chloride-induced corrosion weakens the friction interface, whereas acidic vapors alter surface chemistry, influencing friction behavior.

Samples of commerical lots of rolled temper beryllium copper C17200 were selected with average surface roughnesses, Ra, of 1 and 5 microinch. Some of the material with 5 microinch Ra was roughened to produce strip with a 12 microincn Ra. These lots of material were cleaned and exposed to laboratory environments at Battel 1 e-Columbus Laboratories. A flowing mixed gas was used to simulate a typical office or warehouse environment and a severe industrial environment tor exposures of 0.5, 1, 2 and 5 d. Other coupons were plated with 20, 50, 100 and 200 microinch of cobalt-hardened gold and exposed to these same environments for j d Profilometry and scanning electron microscopy indicate that the original surface finish of the C17200 was uniform. The corrosion rate of clean, unplated beryllium copper was independent of the Ra over the range of 1 to 12 microinch. The visual appearance of gold plated beryllium copper showed similar corrosion behavior for surface roughnesses of 1 and 5 microinch. Corrosion appeared slightly greater on plated surfaces with an Ra of 12 microinch. Increasing the qold thickness on C17200 reduced the amount of corrosion for gold thicknesses between 20 and 200 microinch. Pore corrosion and creep corrosion from corroded pores were observed for a 5 d exposure in both simulated environments.

The combined effect of sulfate-reducing bacteria (SRB) and a microstructure on the stress corrosion behavior of heat-affected zones (HAZs) in pipeline steel for shale gas field applications was investigated. The results show that when the peak heating temperature reached 1020 °C, a coarse microstructure formed during multiple thermal cycles (MTCs), and Widmanstätten structures appeared in the HAZ. In the simulated environment, SRB intensified localized pitting corrosion of both the base metal and the HAZ. The welding HAZ was softened by the MTCs, and significant microcrack growth was observed in the presence of SRB. Among all subzones, the coarse-grained HAZ (CGHAZ) was the most susceptible to stress corrosion cracking (SCC) under shale gas service conditions. Cracks initiated at the metal surface and propagated vertically into the material. SRB activity further increased the SCC sensitivity of the CGHAZ.

The atmospheric corrosion of metals is a severe problem in marine environments. However, the effects of SO2 and NaCl on the atmospheric corrosion of Q235 steel have not been widely studied. In the present work, electrochemical impedance spectroscopy was conducted to exploit the initial corrosion properties of Q235 in simulated atmospheric environments containing different contents of SO2 and NaCl. The solution resistance (Rs) and polarization resistance (Rp) of electrodes covered with pre-deposited NaCl were continuously monitored. The results showed that both SO2 and NaCl promoted the corrosion rate of Q235 steel. The pre-deposited NaCl maintained the moisture of the metal surface to ensure continued corrosion. The thickness of the electrolyte layer on the metal surface decreased with increasing SO2 content. A thin electrolyte layer could increase the Cl− concentration and reduce the pH value of the layer. The thin electrolyte layer could also promote the mass transfer of oxygen, thereby accelerating the cathodic reduction reaction. However, the NaCl content played a more important role than that of SO2 in the simulated environments.

The localized corrosion of mild steel in carbonated cement pore solution under supercritical carbon-dioxide in a simulated geothermal environment

This research article discusses in detail how the‌ ‌rate‌ ‌of‌ ‌corrosion‌ ‌increases‌ for the Alloy 254 in the ‌molten‌ ‌salt‌ ‌mixture‌ ‌of‌ ‌10‌ ‌wt%‌ ‌NaCl‌ ‌+ 40‌ ‌wt%‌ ‌K‌2‌SO‌4‌ + 40‌ ‌wt%‌ ‌Na‌2‌SO‌4‌ ‌+‌ ‌10‌ ‌wt%‌ ‌KCl‌ ‌and‌ ‌corrosive‌ ‌gas‌ combination of ‌ ‌2.5‌%‌ ‌SO‌2‌ ‌+‌ ‌3‌%‌ ‌O‌2‌ ‌+‌ ‌25‌%‌ ‌CO‌2‌ ‌+‌ ‌69.5‌%‌ ‌N‌2 in simulated municipal‌ ‌solid‌ ‌waste‌ ‌‌incinerator environment at 700 °C and 800 °C.‌ ‌In addition, the article shows rate of ‌thermal corrosion abridged due to the addition‌ ‌of‌ ‌80‌ ‌Ni-‌ ‌20‌ ‌Cr‌ ‌-‌High-velocity oxygen fuel ‌coating‌ ‌on‌ ‌the‌ ‌SMO‌ ‌254‌ ‌specimen. Thermogravimetric analysis is adapted to analyze the corrosion rate. A‌ ‌higher‌ ‌hardness‌ ‌was‌ ‌obtained‌ ‌for‌ ‌the‌ ‌High-velocity oxygen fuel coated‌ ‌specimen‌ ‌than‌ ‌that‌ ‌of‌ ‌base‌ ‌metal.‌ ‌Surface‌ ‌roughness‌ ‌was‌ ‌measured‌ ‌on‌ ‌the‌ ‌thermal‌ ‌barrier‌ ‌coated‌ ‌surface.‌ As a result of the impact of molten salt and corrosive gas, hot corrosion by-products such as ‌sulphides, chlorides‌ ‌and‌ ‌Na‌ are produced, which are observed to increase the severity of corrosion rate. ‌‌ The study provides a detailed analysis of the metallurgical changes along the cross-section on the hot corroded samples by optical and Scanning electron microstructural image analysis. X-ray diffraction analysis was used to know about the corrosion products formed during corrosion. Formation‌ of the major protective oxide phases such as NiCr2O4, Cr2O3, NiO and CrMnO4 provide better corrosion resistance to the substrate in the coated samples. The diffusion of the corrosive elements along the cross-section of the weld interface, weld zone, and base metal zone was analyzed in detail using Electron dispersive spectroscopy‌ ‌data in the point scan, line scan, and x-ray mapping techniques. Thermal spray coatings were found to be effective to prevent the hot corrosion, however, a higher weight gain (17.75 mg cm−2) was observed on the pulse current gas tungsten arc weldment sample in the simulated environment compared to a weight gain (2.66 mg cm−2) base metal specimen at 700 °C. Spallation of coated surface occurred at 800 °C, and it could be concluded that the coating has found to be effective in preventing the hot corrosion and safe to operate at a temperature of 700 °C for Alloy 254 in this aggressive simulated environment.

The corrosion behaviour of typical positions in an SUS 30432 bend under simulated corrosive environments was investigated in this paper. A scanning electron microscope equipped with an energy dispersive spectrometer was used to characterise the surface and cross-section morphologies of specimens. Results show that the corrosion kinetics of all specimens were similar showing near parabolic law behaviour. The largest weight gain was located at the samples which were cut from the bottom of a bend. The corrosion scale consisted of an outer layer containing iron oxides and an inner layer containing Cr rich spinels and sulphides. The distances between grains in the samples from the bend were larger than that from the straight tube, which became smaller as the experimental time increased. It may be closely related to aggregation of dislocations near the grain boundaries after tube bending.

Influence of temperature on corrosion behavior, wettability, and surface conductivity of 304 stainless steel in simulated cathode environment of proton exchange membrane fuel cells

Effects of plastic strain of diamond-like carbon coated stainless steel on the corrosion behavior in simulated body fluid environment

Corrosion behavior and passive film characteristics of AlNbTiZrSix high-entropy alloys in simulated seawater environment