Controlling the Electrical Properties of Reactively Sputtered High Entropy Alloy CrFeNiCoCu Films

Oxide-containing films were made by reactively sputtering a high-entropy alloy target of CrFeCoNiCu. We report on a wide range of changes to the electrical properties made by different heat treatments in oxidizing and reducing atmospheres, respectively. We combine temperature-dependent Hall effect measurements down to 10 K to study the transport mechanisms and correlate that with structural measurements by x-ray diffraction and scanning electron microscopy. The measured/effective resistivity could be varied between 1.3 × 10−4 Ω cm and 1.2 × 10−3 Ω cm by post-deposition processing. The temperature coefficient of resistivity could be varied between − 1.2 × 10−3 K−1 through 0 and to + 0.7 × 10−3 K−1. The key to the variation is controlling the morphology and topology of the film. The conduction of charge carriers is dominated by the relative contribution of weak localization and alloy scattering by varying the degree of disorder in the metallic high-entropy alloy and its topology.

Investigating the Effective Resistivity of Reinforced Concrete Waste Storage Tanks at the Hanford Site

Industrialized sites pose challenges for conducting electrical resistivity geophysical surveys, as the sites typically contain metallic infrastructure that can mask electrolytic-based soil and groundwater contamination. The Hanford site in eastern Washington State, USA, is an industrialized site with underground storage tanks, piping networks, steel fencing, and other potentially interfering infrastructure that could inhibit the effectiveness of electrical resistivity tomography (ERT) to map historical and monitor current waste releases. The underground storage tanks are the largest contributor by volume to subsurface infrastructure and can be classified as reinforced concrete structures with an internal steel liner. Directly measuring the effective value for the electrical resistivity of the tank, i.e., the combination of individual components that comprise the tank’s shell, is not reasonably possible because they are buried and dangerously radioactive. Therefore, we indirectly assess the general resistivity of the tanks and surrounding infrastructure by developing synthetic ERT models with a parametric forward modeling study using a wide range of resistivity values from 1×10−6 to 1×104 ohm-m, which are equivalent to steel and dry rock, respectively. The synthetic models used the long-electrode ERT method (LE-ERT), whereby steel cased metallic wells surrounding the tanks are used as electrodes. The patterns and values of the synthetic tomographic models were then compared to LE-ERT field data from the AX tank farm at the Hanford site. This indirect method of assessing the effective resistivity revealed that the reinforced concrete tanks are electrically resistive and the accompanying piping infrastructure has little influence on the overall resistivity distribution when using electrically based geophysical methods for characterizing or monitoring waste releases. Our findings are consistent with nondestructive testing literature that also shows reinforced concrete to be generally resistive.

Towards a Petrophysically Consistent Implementation of Archie’s Equation for Heterogeneous Carbonate Rocks

Archie’s empirical resistivity-saturation relation of 1942 is widely applied in the petroleum industry. Despite its shortcomings, Archie’s equation is the basis for inferring water saturation, even in carbonates with complex pore structure, albeit with empirical tuning of cementation and saturation exponents. Industry literature is replete with examples of why this approach leads to erroneous estimates of the water saturation, and methods have been proposed where the range of saturation present in the reservoir has been subdivided into segments, each having a different set of exponents. Here, based on a homogenization methodology, we propose an effective resistivity model of an inter- and intragranular vuggy carbonate, when the pore sizes in the subsystems are well separated. The model is applied both for water-wet and mixed-wet rocks with appropriate modifications. Methodologies for apportioning pore fractions and their sizes depend on the openhole logs and/or core data. Computed results show significant deviations from Archie correlations in microporous or vuggy intervals. Results are verified on several Middle East carbonate formations against core and evidence from nuclear logs.

Effective resistivity extraction of low-loss silicon substrates at millimeter-wave frequencies

The effective resistivity (ρeff) is a figure of merit commonly used to assess the radio-frequency performance of a substrate from the measurements of coplanar waveguide lines. For highly resistive substrates, such as the trap-rich (TR) substrate, the extracted ρeff decreases by several orders of magnitude at millimeter-wave frequencies. The explanation for this decay is twofold. First, the imaginary part of the characteristic impedance ${\rm \lpar \Im }\lpar Z_c\rpar \rpar$ is not well extracted, which leads to an incorrect separation of the total losses among the metal and substrate losses. Second, the original expression of ρeff does not include dielectric losses, which might become non-negligible at millimeter-wave frequencies. This paper solves both issues by presenting a new procedure to extract ρeff and the dielectric losses simultaneously, and by introducing a novel method to correct ${\rm \Im }\lpar {Z_c} \rpar$. Furthermore, it is shown that this extraction method enables the correct extraction of substrate parameters up to 220 GHz of TR and high-resistivity silicon substrates. Finally, the origin of the large extracted value of dielectric loss is discussed in the potential presence of surface roughness and surface wave radiation. Both phenomena are discounted thanks to measurements of an additional reflective structure and a standard impedance substrate.

Creep Propagation Research for the Interface Cavities of the 316L Stainless Steel Diffusion Welded Joint

The dynamic measurement model for the interface cavities of the diffusion welded joint, which based on the effective resistivity, is established by using the damage factor and the Derby Model of the Bridgman Law. Then the quantitative relationship, which between the direct current potential and the effective area of the joint at high temperature and high pressure, can be obtained. In addition, on the basis of the dynamic four-probe DC potential method and the fieldbus technology, the computer measuring system is established, so that the creep propagation behaviour for the interface cavities of the 316L stainless steel can be monitored in real-time.

Diagnosing the landslide areas of Angren open pit marginal mass according to the data of seismo- and electrical prospecting

Introduction. Sloping structures (quarry sides, dumps, banks, cuts, dams, etc) stability forecasting accuracy improvement requires detailed elaboration of physical-mechanical properties of the rock mass under consideration. Traditional methods of well engineering-geological exploration and hydrogeological monitoring are therefore supplemented by geophysical study. Research aim is to diagnose unstable deconsolidated and wetted zones in marginal masses for the purpose of further forecast of quarry sides stability. Methodology. Databases of geophysical studies obtained by the expeditions of the services of the Republic of Uzbekistan at Angren open pit. Results. For the test area represented by 11 seismic stations at the southern side of the quarry, the criterion assessing the state of the site as potentially landslide hazardous according to the results of circular seismic sounding has been experimentally obtained. With the use of this criterion, in the plan of the landslide zone the borders have been established. For the test area represented by 16 geophysical profiles at the northers side, by electrical profiling graphs and geological sections for the corresponding profiles, 58 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 1. 2020 ISSN 0536-1028 the following regularities have been found: at profile areas adjacent to the runs (rivers), local negative anomalies of effective resistivity up to 20–50 Ohm ∙ m are observed connected with soils wetting; between the anomalous areas the alternation of effective resistivity qualitatively coincides with the alternation of the thickness of a layer of loose deposits. By the arrangement of the negative anomalies borders at the graphs pf effective resistivity dependence on the spread of the profile along all profiles (PR1–PR16), the borders of the wetted zones were established in the plan of the test area. Summary. For geomechanical processes monitoring in the landslide zones it is advisable to apply the method of circular seismic sounding determining the value and the anisotropy coefficient according to the extreme values of compressional arrival time. For the conditions of the Angren open pit, the criterion of potential hazard of landslide development is the value of the anisotropy coefficient higher than 1.6. When elaborating the detailes of the physical properties of landslide zones in quarry sides which are weakened by sand-clay Quaternary sediments, by the method of electrical profiling it is advisable to use: the linear dependence on the thickness of Quaternary sediments on the value of the effective resistivity; hyperbolic dependence of soils relative wetness within the water saturation zones on the value of the effective resistivity ascribed to the reference value defined in the site of soil samples collection, and the borders of wetting zones are to be established by the negative anomalies at electrical profiling graphs. In order to construct the solid geologicalgeophysical models of the landslide zones of the sides, in addition to the geological sections data, the following results of geophysical sounding should be used: the boundaries of landslide zones in the plan, detailed contact geometry of loose Quaternary sediments with bedrock; soil properties modified by wetting

Hygroexpansion, Surface Roughness and Porosity Affect the Electrical Resistance of EVOH-Aluminum- Coated Paper

When aluminum is applied to paper by physical vapor deposition, substrate roughness contributes to the defect density and hygroexpansion can cause defects that impair the aluminum coating. Both effects can manifest as an increase in electrical resistance. We quantified the effect of substrate paper hygroexpansion (0–95% relative humidity) and paper surface roughness on the effective resistivity (ρEFF) of aluminum coatings. To create different degrees of roughness, five different papers were used. Each of them had one pigment coated side and one side without pigment coating. These different rough paper surfaces were pre-coated with ethylene vinyl alcohol co-polymer (EVOH). Hygroexpansion was promoted by pre-coating and increased more when the coating was applied on rough and porous surfaces. Simultaneously, the pre-coating reduced surface roughness; especially porosity. The reduction of porosity decreased effective resistivity (ρEFF). Based on these results, an aluminum thickness of ≥35 nm is recommended to ensure maximum mechanical stability during hygroexpansion in combination with minimum material usage. Moreover, the resistivity did not regain its initial value when the paper substrate shrank during re-drying.