Field deployable impedance-based corrosion sensor

Electrochemical impedance spectroscopy (EIS) has been used in various applications, such as metal corrosion monitoring. However, many conventional corrosion monitoring setups are bulky and inconvenient for in-situ testing. The purpose of this work is to reduce the size of the whole corrosion monitoring system. We utilized EIS to design a field deployable impedance-based corrosion sensor (FDICS), capable of performing in-situ EIS analysis. Experiments verified the sensor’s accuracy, and the results showed that the sensor performed similarly to a bench-top EIS machine when we tested on circuit models. Furthermore, we used the proposed FDICS to monitor a metal corrosion experiment and performed EIS. The result showed that the proposed FDICS is able to obtain the sample’s impedance spectroscopy, which could help researchers test its corrosion severity on a metallic sample in-situ. Compared to other bulky conventional setups, our device eliminates the design complexity while still showing insights into the corrosion reaction.

Adsorption of Carbon Dioxide on Mono-Layer Thick Oxidized Samarium Films on Ni(100)

Studies of adsorption of CO2 on nanoscopic surfaces are relevant for technological applications in heterogeneous catalysis as well as for sorption of this important greenhouse gas. Presently, adsorption of carbon dioxide on pure and oxidized thin samarium layers near mono-layer thickness on Ni(100) has been investigated by photoelectron spectroscopy and temperature programmed desorption. It is observed that very little CO2 adsorb on the metallic sample for exposures in the vacuum regime at room temperature. For the oxidized sample, a large enhancement in CO2 adsorption is observed in the desorption measurements. Indications of carbonate formation on the surface were found by C 1s and O 1s XPS. After annealing of the oxidized samples to 900 K very little CO2 was found to adsorb. Differences in desorption spectra before and after annealing of the oxidized samples are correlated with changes in XPS intensities, and with changes in sample work function which determines the energy difference between molecular orbitals and substrate Fermi level, and thus the probability of charge transfer between adsorbed molecule and substrate.

In Vitro Physical-Chemical Behaviour Assessment of 3D-Printed CoCrMo Alloy for Orthopaedic Implants

In this study, a CoCrMo-based metallic alloy was manufactured using a 3D-printing method with metallic powder and a laser-based 3D printer. The obtained material was immersed in a simulated body fluid (SBF) similar to blood plasma and kept 2 months at 37 °C and in relative motion against the SBF in order to mimic the real motion of body fluids against an implant. At determined time intervals (24, 72, 168, 336, and 1344 h), both the metallic sample and SBF were characterized from a physical-chemical point of view in order to assess the alloy’s behaviour in the SBF. Firstly, the CoCrMo based metallic sample was characterized by scanning electron microscopy (SEM) for assessing surface corrosion and X-ray diffraction (XRD) for determining if and/or what kind of spontaneous protective layer was formed on the surface; secondly, the SBF was characterized by pH, electrical conductivity (EC), and inductively coupled plasma mass spectroscopy (ICP-MS) for assessing the metal ion release. We determined that a 3D-printed CoCrMo alloy does not represent a potential biological hazard in terms of the concentration of metal ion releases, since it forms, in a relatively short period of time, a protective CoCr layer on its exposed surface.

Boundary-Element Analysis of Magnetic Polarization Tensor for Metallic Cylinder

The magnetic polarization tensor has a promising capability of determining the geometry and material properties of metallic samples. In this paper, a novel computation method is proposed to estimate the magnetic polarization tensors for the metallic samples using the boundary element method. In this method, the metallic sample is placed in a uniformly distributed magnetic field. Based on assumptions that the excitation frequency and/or the conductivity of the sample is very high, the metallic sample is regarded as a perfect electrical conductor (PEC). Therefore, the scattered field at a certain distance can be simulated. By utilising the boundary element method, the magnetic polarization tensor can be derived from the simulated scattered field. The theoretical calculation is presented and simulations and experiments have been carried out to validate the proposed method. The results from the simulation are matched with the analytical solution for the case of sphere samples. Moreover, there is a good agreement between the simulation results and the experimental results for the copper cylindrical samples.

Measurement of Electrical Conductivity Degree of some Metallic Conductors by Using the LC Circuit

Metallic conductors have different degrees of their electrical conductivity. The aim of this research is to measure the electrical conductivity degree for some metallic conductors by measuring the induced voltage in a coil probe, which moves inside the metallic conductor sample tube. When a low frequency of alternating current flows through the LC circuit, it will pass through the solenoid and will generate a magnetic field, which will be reduced due to the presence of the metallic sample tube. The magnetic flux strength generated inside the solenoid determine the electrical conductivity (σ ) of this metallic tube by measuring the EM force induced on the solenoid in the presence the sample tube and without it. Measurements are conducted on two sample models (zinc and aluminum). Test results shows deviation of 10 % compared with the reference values ​​.

Thermal non-destructive testing and evaluation for subsurface slag detection: numerical modelling

Among various non-destructive testing and evaluation (NDT&E) methodologies, active infrared thermography (IRT) has emerged as a viable testing technique for the inspection of materials used in various industrial applications. In recent years, pulse compression favourable IRT techniques and the associated post-processing schemes have been proposed by various research groups to enhance the inspection capabilities of existing conventional techniques, as well as to make experimentation simple and more reliable. This paper exploits a novel complementary coded thermal wave imaging scheme for NDT&E applications, along with the associated data processing method, to enhance the test resolution and sensitivity. The proposed scheme has been numerically modelled on a metallic sample in order to test its capabilities for subsurface defect detection and characterisation.

The effect of nanoparticle presence on aerosol formation during nanoparticle-enhanced laser ablation inductively coupled plasma mass spectrometry

The presence of gold nanoparticles on the metallic sample surface positively changes the particle size distribution of the laser ablation aerosol.

Thermochemical Non-Equilibrium in Thermal Plasmas

In this paper, we analyze the departure from equilibrium in two specific types of thermal plasmas. The first type deals with the plasma produced during the atmospheric entry of a spatial vehicle in the upper layers of an atmosphere, specifically the one of Mars. The second type concerns the plasma produced during the laser-matter interaction above the breakdown threshold on a metallic sample. We successively describe the situation and give the way along which modeling tools are elaborated by avoiding any assumption on the thermochemical equilibrium. The key of the approach is to consider the excited states of the different species as independent species. Therefore, they obey to conservation equations involving collisional-radiative contributions related to the other excited states. These contributions are in part due to the influence of electrons and heavy particles having a different translation temperature. This ‘state-to-state’ approach then enables the verification of the excitation equilibrium by analyzing Boltzmann plots. This approach leads finally to a thorough analysis of the progressive coupling until the equilibrium asymptotically observed.