Dissolution Depth Research Articles

Study on the effect of aging heat treatment temperature on the microstructure and properties of soluble Al-Zn-Mg-Ga-In-Sn aluminum alloys in solid solution state

This study aimed to develop a soluble aluminum alloy material for isolation tools, characterized by high hardness, high tensile strength, and low dissolution rate. To achieve this, the Al-Zn-Mg-Ga-In-Sn soluble aluminum alloy was cast at high temperatures using a medium frequency metal induction melting furnace. The effects of different aging heat treatment processes on the mechanical properties and dissolution performance of the Al-Zn-Mg-Ga-In-Sn soluble aluminum alloy, which had undergone a solution heat treatment at 470℃ for 12 hours followed by air cooling to 25℃, were investigated. The results indicated that after aging heat treatment at 175℃ for 2 hours followed by air cooling to 25℃, the alloy exhibited uniform grain size, averaging 35±2μm. The precipitated phase Mg2Sn had an average size of 7.6±1.0 μm, with fewer in number, primarily located at the grain boundaries. Furthermore, the alloy demonstrated excellent mechanical properties, including a tensile strength of 334±1 MPa, yield strength of 226±1 MPa, and elongation of 16.6±0.5 %. Additionally, its hardness reached 91±3 HB. The dissolution rate in 90℃ distilled water was 1.6±1.0 g·h−1·cm−2, with the alloy surface showing relatively uniform dissolution characteristics during the process, and a dissolution depth of 741±5 μm.

Study on the calcium dissolution of self-compacting recycled concrete

Considering the effects of the replacement rate of recycled coarse aggregate (RCA), content of fly ash (FA), and solution temperature, the accelerated calcium dissolution test of self-compacting recycled concrete (SCRC) was simulated by using ammonium chloride solution. The results show that the physical properties (the mass loss ratio and the dissolution depth) and the strength degradation of SCRC increase with the increase of the replacement rate of RCA and solution temperature. With the increasing content of FA, the physical properties decrease approximately linearly, while the strength degradation first decreases and then increases. For the SCRC with 50% RCA and a dissolution age of 56 days, the dissolution depth of SCRC with the FA contents of 10%, 20%, and 30% decreased by 3.85%, 10.00%, and 15.56% respectively compared with that of SCRC without FA, and the degradation rate of compressive strength also decreased by 11.60%, 25.91%, and 15.01%, respectively. The peak stress of the stress-strain curve of SCRC under axial compression is negatively correlated with the dissolution age, replacement rate of RCA, and solution temperature, while the peak strain is positively correlated with these variables. When the dissolution age is more than 28 days, the calcium silicate hydrate (C-S-H) gels produced by low-volume (10%, 20%) FA after complete hydration lead to an increase in peak stress and a decrease in peak strain of SCRC, while high-volume (30%) FA has the opposite effect due to incomplete hydration. Finally, the performance degradation model of SCRC under calcium dissolution was established.

The role of marine fish-produced carbonates in the oceanic carbon cycle is determined by size, specific gravity, and dissolution rate

Rising CO2 emissions have heightened the necessity for increased understanding of Earth's carbon cycle to predict future climates. The involvement of marine planktonic species in the global carbon cycle has been extensively studied, but contributions by marine fish remain poorly characterized. Marine teleost fishes produce carbonate minerals (‘ichthyocarbonates’) within the lumen of their intestines which are excreted at significant rates on a global scale. However, we have limited understanding of the fate of excreted ichthyocarbonate. We analyzed ichthyocarbonate produced by three different marine teleosts for mol%MgCO3 content, size, specific gravity, and dissolution rate to gain a better understanding of ichthyocarbonate fate. Based on the species examined here, we report that 75 % of ichthyocarbonates are ≤0.91 mm in diameter. Analyses indicate high Mg2+ content across species (22.3 to 32.3 % mol%MgCO3), consistent with previous findings. Furthermore, ichthyocarbonate specific gravity ranged from 1.23 to 1.33 g/cm3, and ichthyocarbonate dissolution rates varied among species as a function of aragonite saturation state. Ichthyocarbonate sinking rates and dissolution depth were estimated for the Atlantic, Pacific, and Indian ocean basins for the three species examined. In the North Atlantic, for example, ~33 % of examined ichthyocarbonates are expected to reach depths exceeding 200 m prior to complete dissolution. The remaining ~66 % of ichthyocarbonate is estimated to dissolve and contribute to shallow water alkalinity budgets. Considering fish biomass and ichthyocarbonate production rates, our results support that marine fishes are critical to the global carbon cycle, contributing to oceanic alkalinity budgets and thereby influencing the ability of the oceans to neutralize atmospheric CO2.

Study on calcium dissolution behavior of manufactured sand concrete

The accelerated calcium dissolution tests of concrete with different replacement rates of manufactured sand (ρms ) and different contents of stone powder (ρsp ) were carried out using the ammonium chloride solution. The results show that the dissolution resistance of manufactured sand concrete (MSC) is higher than that of ordinary concrete, although the ρms and ρsp influence its physical and mechanical properties. When the ρms is low, the mass loss ratio and dissolution depth of MSC after dissolution both increase with the increasing ρsp . They also increase with the increasing of ρms , but the ρsp no longer influences them when the ρms is high. The ρsp corresponding to the maximum ultrasonic velocity of MSC is different for the various ρms . The addition of manufactured sand inhibits the reduction of the compressive strength after dissolution, while stone powder has no significant impact on this. Finally, the fitting model of dissolution depth and prediction model of compressive strength of MSC after dissolution are established.

Innovative powder-based wettability evaluation of HfB2-ZrB2-SiC-B4C-CNT composite: Effect of surface roughness and ambient conditions

Active metal brazing, the most common method for joining UHTCs, necessitates the wettability of diborides in contact with filler layer, which is evaluated in present work using a powder-based approach. Ni powder is placed on pre-spark-plasma-sintered HfB2-ZrB2-SiC-B4C-CNT (HZSBC) composites with varying surface roughness (0.1 and 0.7 μm) and heated to 1450°C in Ar and Ar+H2 atmosphere. Formation of gas-liquid-Ni interface for rough surface (Ra:0.7 µm) restricted the spreading of molten Ni on HZSBC surface and increased contact angle (by ∼30°) compared to smooth surface (Ra:0.1 µm). Addition of 5% H2 into Ar atmosphere suppressed the oxide formation and improved molten Ni spreading at a contact angle of ∼10°. Cross-sectional analysis of droplets supports dissolutive wetting where enhanced surface roughness has reduced the dissolution depth (by ∼50% for Ar and ∼12% for Ar+H2 atmospheres). Furthermore, brazing of HZSBC composites with Ni interlayer is performed at 1450°C, in Ar and Ar+H2 atmosphere. Lower wettability of Ni with HZSBC in Ar resulted in detachment of composites during polishing, thus, indicating poor interfacial bonding. Successful brazing of these composites in Ar+H2 atmosphere resulted in microstructural inhomogeneity with decreased hardness and Young's modulus by ∼68% and ∼58%, respectively, from HZSBC region to Ni-Si rich filler layer. Lower interfacial residual stresses (∼0.4 GPa) have provided the structural integrity between ceramic and metal layer, thus making them suitable for applications involving complex shapes.

Calcium dissolution behaviors of recycled coarse aggregate concrete with the initial stress damage

The accelerated calcium dissolution tests of concrete with different replacement rates of recycled coarse aggregate (RCA) and different initial damage degrees D0 were carried out by using ammonium chloride solution. The results show that the dissolution resistance of recycled aggregate concrete (RAC) is negatively correlated with the replacement rate of RCA and the D0. The mass loss, dissolution depth, the attenuation of ultrasonic wave velocity, and the degradation of mechanical properties (compressive strength and splitting tensile strength) of RAC after calcium dissolution increase with the increasing replacement rate of RCA. When the D0 is less than 0.2, the dissolution resistance of RAC is not obviously affected by the initial stress damage; however, when the D0 is greater than 0.2, the mass loss, dissolution depth, the attenuation of ultrasonic wave velocity, and the deterioration of mechanical properties of RAC increase linearly with the increasing of D0. Compared with the compressive strength, the splitting tensile strength is more sensitive to the calcium dissolution and the initial stress damage of concrete. An obvious pH gradient is formed in the concrete after dissolution, and the pH value in a certain depth of the concrete decreases with the increasing of the replacement rate of RCA and the D0. Finally, the prediction model for compressive strength and splitting tensile strength of RAC after calcium dissolution is established.

Effect of temperature on the slag/refractory interfacial reaction with directed reduced iron (DRI) addition in an electric arc furnace (EAF) process: Diffusional growth of magnesiowüstite layer by Boltzmann-Matano analysis

This study investigated the effect of temperature (1550–1650 °C) on the electric arc furnace (EAF) slag and magnesia refractory interfacial reaction with 20% direct reduced iron (DRI) addition as an alternative iron source in an Ar atmosphere. Variations in MgO content from initial to final stage were proportional to the temperature, indicating that MgO degradation by molten EAF slag was affected by the concentration gradient between initial and saturation conditions depending on temperature. In addition, the temperature affected MgO content more dominantly than DRI did. In other words, temperature control in an EAF process using DRI is relatively more important than the control of DRI itself for preventing MgO refractory degradation. The magnesiowüstite (MW) intermediate layer thickness and MgO refractory dissolution depth increased as the temperature increased because MgO solubility in molten EAF slag is proportional to temperature. Finally, the inter-diffusivity (D˜Fe−Mg, m2/s), which was estimated by Boltzmann-Matano analysis, ranged D˜Fe−Mg=10−12.0−10−12.5 and logD˜Fe−Mg generally decreased with decreasing temperature. The activation energy was found to be approximately 240 kJ/mol. Therefore, it can be concluded that suitable control of temperature in an EAF process using DRI is important to minimize refractory degradation.

New protocol for the R134acryogen spray cooling assisted 1064-nmlaser lipolysis.

Laser lipolysis is a promising body contouring technology. However, the skin tissue could be thermally damaged owing to the laser energy absorption by water, which limits the lipolysis efficiency. To protect skin tissue and improve the lipolysis effect, cryogen spray cooling is introduced and synergized with the pulsed laser irradiation aiming to propose a new therapy protocol. By simulating heat conduction in the skin after spray cooling assisted laser lipolysis, the temperature distribution in the skin tissue was obtained to analyze the tissue damage by the Arrhenius integral. After parameter optimization according to the damage threshold of skin and adipose tissue, a new protocol with high laser intensity and short time was proposed including 150-ms R134a spray cooling with spray distance of 30mm, and 100ms 1064nm laser irradiation with energy density of 20J/cm2, with a relaxation for 9.75s. This cycle of 10s can be repeated 90 to 150 times for a total of 15 to 25min. Compared with previous treatment procedure, new protocol can increase the fat dissolution depth from 2 to 4.5mm beneath the dermis with same order laser fluence.

Interfacial reactions between magnesia refractory and electric arc furnace (EAF) slag with use of direct reduced iron (DRI) as raw material

Interfacial reactions between the electric arc furnace (EAF) slag, i.e., CaO–SiO 2 –FeO–MgO–Al 2 O 3 –MnO system, and the magnesia refractory as a function of direct reduced iron (DRI) addition (0, 10, 20, 30 wt%) were investigated at 1550 °C under an Ar atmosphere. MgO solubility increases with increasing DRI content by decreasing basicity (i.e., CaO/SiO 2 ratio), which is due to an increase in SiO 2 supplied from DRI. The measured MgO content was always lower than the theoretical MgO saturation level irrespective of DRI content because the magnesiowüstite (MW) intermediate layer, which formed at the slag/refractory interface, retarded the direct dissolution of the refractory by acting as a self-protective layer. The thickness of the MW intermediate layer and dissolution depth were proportional to DRI content. However, the penetrativity decreased with increasing DRI content by decreasing the fluidity of the slag. Several kinetic parameters were estimated, including the dissolution rate constant of the MW intermediate layer, the dissolution rate of the MgO refractory, and the rate constant of MW growth. Dissolution of MgO refractory is controlled by the dissolution of the MW intermediate layer. Increasing the growth rate is very important for protecting refractory after the formation of a MW intermediate layer. In addition, we provided a schematic diagram of the slag/refractory interfacial reaction phenomena that compares situations of low and high DRI content. The results of the present study show that it is necessary to control DRI content to minimize refractory degradation during the EAF process. If a large amount of DRI must be used in the EAF process, then MgO content in the slag should be at the saturation limit at first, which accelerates growth of the MW intermediate layer.

Dissolution Depth and Surface Morphological Alterations in Ultrathin Glass Ceramic Etched with Different Hydrofluoric Acid-etching Protocols.

To evaluate the effect of different HF-etching protocols on the dissolution depth and micromorphology of the etched and adjacent surfaces of ultrathin glass-ceramic specimens. One hundred twenty specimens (6 x 6 x 0.3 mm) of leucite-reinforced glass-ceramic (LEU, IPS Empress, Ivoclar Vivadent) and lithium-disilicate-reinforced glass-ceramic (LD, IPS e.max, Ivoclar Vivadent) were prepared. Specimens were divided into 5 groups (n = 12) according to etching protocol: G1: control, untreated; G2: 5% hydrofluoric acid (HF) etching for 20 s (HF5%20s); G3: HF5%60s; G4: HF10%20s; and G5: HF10%60s. To analyze the dissolution depth, specimens were sectioned into two similarly sized halves using a chisel to create an internal surface (IS). Specimens were analyzed with scanning electron microscopy (SEM) on the following surfaces: HF application surface (AS), lateral surface (LS), internal surface (IS), and the surface opposite to the AS (OS). Dissolution patterns were identified. Data were submitted to one-way ANOVA and Bonferroni's test (α = 0.05). Dissolution depth data were submitted to Kruskal-Wallis and Mann-Whitney U-tests (α = 0.05). The prevalence of different dissolution patterns was analyzed using SEM. HF gel applied on the AS also affected the adjacent surfaces of all specimens. Different dissolution patterns were observed, which were dependent of HF-etching protocol and proportion of the glass phase in the ceramic. These patterns were categorized into four types for LEU (I-IV) and three for LD (I-III) according to the micropore size. The greater the micropore size, the more pronounced the etching pattern (p < 0.001). Higher HF times and concentrations showed prevalence of more severe etching patterns. HF10%60s produced greater dissolution depth in both materials when compared with other HF-etching groups (p < 0.05). Hydrofluoric acid etching not only affects the surface upon which it is applied, but internal, lateral and even opposite edges of glass ceramic. Different dissolution patterns and depths can be formed which are dependent of hydrofluoric acid concentration, application time, and proportion of the glass phase in the ceramic.

Self-Boundary Dissolution in Meditation: A Phenomenological Investigation

A fundamental aspect of the sense of self is its pre-reflective dimension specifying the self as a bounded and embodied knower and agent. Being a constant and tacit feature structuring consciousness, it eludes robust empirical exploration. Recently, deep meditative states involving global dissolution of the sense of self have been suggested as a promising path for advancing such an investigation. To that end, we conducted a comprehensive phenomenological inquiry into meditative self-boundary alteration. The induced states were systematically characterized by changes in six experiential features including the sense of location, agency, first-person perspective, attention, body sensations, and affective valence, as well as their interaction with meditative technique and overall degree of dissolution. Quantitative analyses of the relationships between these phenomenological categories highlighted a unitary dimension of boundary dissolution. Notably, passive meditative gestures of “letting go”, which reduce attentional engagement and sense of agency, emerged as driving the depth of dissolution. These findings are aligned with an enactive approach to the pre-reflective sense of self, linking its generation to sensorimotor activity and attention-demanding processes. Moreover, they set the stage for future phenomenologically informed analyses of neurophysiological data and highlight the utility of combining phenomenology and intense contemplative training for a scientific characterization of processes giving rise to the basic sense of being a bounded self.

Effect of fluorspar on the interfacial reaction between electric arc furnace slag and magnesia refractory: Competitive corrosion-protection mechanism of magnesiowüstite layer

The interfacial reaction between the CaO–SiO2–FeO–Al2O3–MnO–MgO-xCaF2 (CaO/SiO2 = 0.9–1.2, x = 0–10 wt%) type electric arc furnace (EAF) steelmaking slag and magnesia refractory was investigated. Using a microscopic analysis, the thickness of the (Mg,Fe)O, magnesiowüstite solid solution (intermediate) layer at the slag/refractory interface was measured. The thickness of the solid solution layer is affected by both slag penetration and refractory dissolution. Since the CaF2 in the slag affects the interfacial reaction between the slag and the refractory, it impacts the thickness of the solid solution layer. In addition, the depth of refractory dissolution was determined by changing the MgO content in the slag, and the depth of slag penetration was also quantitatively measured. Through these experiments, the refractory corrosion-protection mechanism by the CaF2-containing EAF slag was identified. Finally, the critical CaF2 content (= approx. 3 wt%), which had no significant effect on refractory corrosion, was proposed.

Reservoir Characteristics and Genetic Mechanisms of the Mesozoic Granite Buried Hills in the Deep‐water of the Qiongdongnan Basin, Northern South China Sea

AbstractDue to its structure, rock and mineral composition, fluid and other factors, the granite Buried Hill Reservoir is highly heterogeneous with a complex longitudinal structure and a reservoir space made up of a combination of dissolution pores and fractures. This paper is based on current understanding of tectonic evolution in the northern part of the South China Sea, in conjunction with the seismic phase characteristics. It is determined that the meshed fault system was formed by three stages of movement ‐ tectonic compression orogeny during the Indochinese epoch, strike‐slip compression‐tension during the Yanshanian Period, early fracture extension activation during the Himalayan – which controlled the distribution of the Buried Hill Reservoir. Drilling revealed two types of buried hills, faulted anticline and fault horst, their longitudinal structure and the reservoir space type being significantly different. The mineral composition, reservoir space and diagenetic characteristics of the reservoir rocks and minerals were analyzed by lithogeochemistry, microsection and logging etc., it thus being determined that the Mesozoic rocks of the Songnan Low Uplift in the Qiongdongnan Basin are mainly composed of syenogranite, granodiorite, monzogranite, which is the material basis for the development of the Buried Hill Reservoir. The content of felsic and other brittle minerals is more than 70%, making it easy for it to be transformed into fractures. At the same time, the weathering resistance of granodiorite and monzogranite is weaker than that of syenogranite, which is easily weathered and destroyed, forming a thick sand gravel weathering zone. With increasing depth of burial, weathering and dissolution gradually weaken, the deep acidic fluid improving the reservoir property of internal fractures and expanding the vertical distribution range of the reservoirs. The research results lay a foundation for the exploration of Buried Hill in the deep‐water area of the Qiongdongnan Basin.

Quasi-Equilibrium and Unsteady Mass Transfer of Low-Grade Bloedite in the Process of Static Water Dissolution

Hydrometallurgical extraction and treatment of bloedite waste is one necessity for the sustainable development of sodium sulfate subtype salt lake mining areas, but the industrial dissolution of bloedite is not stable. One of the reasons for this is the unsteady mass transfer of dissolved electrolytes in water according to the diffusion model and static water dissolution experiment in this work. The diffusion behaviors of aqueous Na2SO4 and MgSO4 released from bloedite in water are similar, and their mass transfer coefficients decrease in a nonlinear manner as the diffusion process continues. Within 720 h of dissolution time, there is a quasi-steady-state quasi-linear stage of rapid increase in the solute concentration of leaching water, and a water depth of 20–40 mm is recommended as the optimal dissolution depth. Under such operating conditions, the amount of evaporated water required for salt production decreases in a quasi-linear manner with respect to dissolution time. However, after 720 h of dissolution and extraction time, the growth rate of brine concentration slows. The information provided by the model can be used in practice as a quantitative reference for bloedite recycling.

Multiscale study of CO[formula omitted] impact on fluid transport and carbonate dissolution in Utica and Eagle Ford shale

In this work, we study the impact of CO2 on carbonate-rich Utica and Eagle Ford shale with respect to mineralogical alteration, fluid transport, and enhanced oil recovery. The study encompasses diagnostic tools that include Computed Tomography (CT), pulse decay techniques for core or centimeter scale investigations, Scanning Electron Microscopy (SEM), and μ-CT for micro-scale evaluations. The core-scale findings did not show any significant contributions to matrix flow or oil recovery in the presence of the water saturated (wet) sc-CO2 or carbonated water. Computed Tomography was able to capture aperture reduction during pure carbonated water injection. This effect is likely a result of matrix softening near the fracture surface and reduction in aperture due to effective stress. These results made it apparent that finer diagnostics such as SEM and μ-CT are essential in capturing any interaction between the CO2-water fluids and the carbonate-rich shale. The micron scale investigations showed that indeed carbonated water dissolves calcite but not dolomite over the time scale of observations; however, the depth of dissolution was limited to 100’s of microns. Additionally, Energy Dispersive Spectroscopy (EDS) and μ-CT images reveal that the water moisture residing in the wet sc-CO2 phase does not cause any measurable carbonate dissolution in rocks in contact with that phase. Finally, our analysis proves that the gold-coating used in sample preparation for SEM imaging does not affect the outcome of dissolution observed in our experiments.

Continuous and ordered surface microtexturing on Cu and Ni-based alloys by novel electrochemical dissolution

The present study discusses the formation of surface micro-texture on flat samples of Cu-based and Ni-based alloys by two-step electrochemical dissolution. Prior to the electrochemical dissolution, laser marking only on the araldite coating has been carried out for effective dissolution of the selectively exposed metal surfaces along the laser cut regions. After second stage dissolution, the circular truncated conical grids with average base diameter of 210.7 μm for the Cu-based alloy and truncated square pyramid like grids with base width of 203.2 μm for the Ni-based alloy have formed. Similarly, maximum dissolution depths of 61.8 and 39.3 μm for the Cu-based and Ni-based alloys, respectively, could be observed. Moreover, excellent hydrophobicity of the textured Cu-based as well as Ni-based alloys correlating to grid dimensions along with air entrapment beneath the water droplet has been analysed with the help of Wenzel and Cassie-Baxter models. Nano-hardness of the as-received alloys as well as the textured alloy surfaces shows minor variation. Similarly, the micrographs of the flat surfaces of the as-received alloys and cross-sectional microstructure of the textured alloys have also portrayed little difference suggesting negligible heat or stress affected zone after dissolution process. Moreover, the textured surfaces have showed significant increment in surface area: ∼62.7% for the Cu-based alloy and ∼71.4% for the Ni-based alloy as compared to the flat specimens.

Surface micro-texturing of dual phase steel and copper by combining laser machining and electrochemical dissolution

The main objective of the present work is to fabricate continuous regime of surface micro-texturing on flat surfaces of a dual phase steel (DPS) and a commercial pure Cu by laser micro-texturing only on the araldite mask laid on the specimen followed by electrochemical dissolution. The sharp and blunt conical grids with average base width (maximum distance between two consecutive micro-channels) of 174 and 214.3 μm as well as 42.2 and 54.3 μm of average depth of dissolution were achieved using two steps electrochemical dissolution process in the DPS and Cu specimens, respectively. Solution used for electrochemical dissolution of the DPS was freely aerated 3.5 wt% NaCl, whereas, etchant for Cu consisted of nitric acid, acetic acid and sulfuric acid with deionized water. Different aspects of creating micro-texturing, like masked coating thickness, micro-channel dimension, depth of dissolution and grid patterns were discussed. No change in hardness of the surface as well as absence of cracks before and after micro-texturing suggested negligible variation in the microstructure due to processing. In addition, the two-step preparation of micro-textured surfaces showed considerable hydrophobicity in addition to the considerable increase in surface area.

Study of Corrosion Behaviors of 316L Stainless Steel Welds in Liquid Lithium with Hydrogen Impurity

The corrosion behaviors of 316L stainless steel welds in stagnant liquid lithium and lithium with 0.2%H at 325°C for 1000 h was investigated by using weight loss method, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and laser-induced breakdown spectroscopy. After liquid Li corrosion, a large number of (M)23C6 and NiCx particles (sizes of 1 ~ 2 μm) were found on the weld surface, while almost no such particles were found on the weld surface after corrosion in liquid Li with 0.2%H. The corrosion rates of welds were about 4.10 × 10−3 and 6.65 × 10−3 g · m−2 · h−1 in liquid Li and Li with 0.2%H, respectively, while the penetration depth of Li increased by 1.375 times after adding 0.2%H to Li. It was found that the penetration depth of Li was basically consistent with the dissolution depth of Cr, and the dissolution depth of Cr was larger than that of Ni and Fe in liquid Li and Li with 0.2%H.

Statistical pattern analysis of surficial karst in the Pleistocene Miami oolite of South Florida

A robust airborne light detection and ranging digital terrain model (LiDAR DTM) and select outcrops are used to examine the extent and characteristics of the surficial karst overprint of the late Pleistocene Miami oolite in South Florida. Subaerial exposure of the Miami oolite barrier bar and shoals to a meteoric diagenetic environment, lasting ca. 120 kyr from the end of the last interglacial highstand MIS 5e until today, has resulted in diagenetic alteration including surface and shallow subsurface dissolution producing extensive dolines and a few small stratiform caves.Analysis of the LiDAR DTM suggests that >50% of the dolines in the Miami oolite have been obscured/lost to urbanization, though a large number of depressions remain apparent and can be examined for trends and spatial patterns. The verified dolines are analyzed for their size and depth, their lateral distribution and relation to depositional topography, and the separation distance between them. Statistical pattern analysis shows that the average separation distance and average density of dolines on the strike-oriented barrier bar versus dip-oriented shoals is statistically inseparable. Doline distribution on the barrier bar is clustered because of the control exerted on dissolution by the depositional topography of the shoal system, whereas patterning of dolines in the more platform-ward lower-relief shoals is statistically indistinguishable from random. The areal extent and depth of dissolution of the dolines are well described by simple mathematical functions, and the depth of the dolines increases as a function of their size. The separation and density results from the Miami oolite are compared to results from other carbonate terrains. Near-surface, stratiform caves in the Miami oolite occur in sites where the largest and deepest dolines are present, and sit at, or near, the top of the present water table.

Electrorefining of CuZr Alloy Using Ba2ZrF8-LiF Electrolyte

In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that Ba2ZrF8 precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a Ba2ZrF8-LiF binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by O2 gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.