Mechanism Of Scale Formation Research Articles

Atomic scale formation mechanism of the Amorphous-Nanocrystalline biphase structure in TiSiN Coating: Phase field crystal simulation and experimental characterization

TiSiN nanocomposite coatings have exceptional strength, toughness, and corrosion resistance due to their unique biphase amorphous/nanocrystalline structure with tiny TiN grains embedded in an amorphous Si3N4 phase. However, the unclear formation process makes microstructural control challenging. In this study the phase field crystal method has been employed to analyze the microstructure evolution in TiSiN coatings, uncovering a four-step formation mechanism for the amorphous-nanocrystalline structure. The initial stage results in appearance of concentration heterogeneities and the development of the triangular-like short-range order (Stage I). This stage is followed by the nucleation of nanocrystals in Ti-rich zones and the transformation of triangular short-range to the long-range order with a square symmetry (Stage II). Then, during coarsening stage, Ti-rich polycrystalline nanocrystals are formed (Stage Ⅲ) followed by the vacancy migration from the polycrystalline nanocrystals to amorphous phase and formation of monocrystalline Ti nanocrystals embedded in amorphous phase (Stage Ⅳ). The simulation results are compared qualitatively with aberration-corrected High-Resolution Scanning Transmission Electron Microscopy and High-Resolution Transmission Electron Microscopy images from our study.

High-Temperature Oxidation and Microstructural Changes of Al0.75CoCrFeNi High-Entropy Alloy at 900 and 1100 °C

The development of high-entropy alloys (HEAs) for high-temperature applications has been driven by the limitation of nickel-based superalloys in achieving optimal efficiency at higher temperatures for higher efficiency in power generation engines. The alloys must have high oxidation resistance and microstructural stability at high temperatures. Relatively equimolar multi elements involved in HEAs produce microstructure containing a single solid solution or multiphase that improves the mechanical properties and oxidation resistance resulting from sluggish diffusion and core effects. In this study, the oxidation behavior and microstructural changes of Al0.75CoCrFeNi HEA at 900, 1000, and 1100 °C in air atmosphere were investigated. Based on the XRD and SEM-EDS analysis, the mechanism of oxide scale formation and microstructural changes of the substrate are proposed. The results show that the oxidation behavior of the alloy follows a logarithmic rate law. Different oxide compounds of CoO, NiO, Cr2O3, and CrO3, θ-Al2O3, α-Al2O3, and Ni(Cr,Al)2O4 with semicontinuous oxides of Al2O3 with Cr2O3 subscale and an oxide mixture consisting of spinel of Ni(Cr,Al)2O4 and Co(Cr,Al)2O4 were found. During oxidation, Widmanstätten of FCC-A1 and BCC-B2/A2 phases in the substrate have changed. Spheroidization of B2 and a reduction in volume fraction decrease the hardness of the substrates.

The Behavior of Polymeric Pipes in Drinking Water Distribution System-Comparison with Other Pipe Materials.

The inner walls of the drinking water distribution system (DWDS) are expected to be clean to ensure a safe quality of drinking water. Complex physical, chemical, and biological processes take place when water comes into contact with the pipe surface. This paper describes the impact of leaching different compounds from the water supply pipes into drinking water and subsequent risks. Among these compounds, there are heavy metals. It is necessary to prevent these metals from getting into the DWDS. Those compounds are susceptible to impacting the quality of the water delivered to the population either by leaching dangerous chemicals into water or by enhancing the development of microorganism growth on the pipe surface. The corrosion process of different pipe materials, scale formation mechanisms, and the impact of bacteria formed in corrosion layers are discussed. Water treatment processes and the pipe materials also affect the water composition. Pipe materials act differently in the flowing and stagnation conditions. Moreover, they age differently (e.g., metal-based pipes are subjected to corrosion while polymer-based pipes have a decreased mechanical resistance) and are susceptible to enhanced bacterial film formation. Water distribution pipes are a dynamic environment, therefore, the models that are used must consider the changes that occur over time. Mathematical modeling of the leaching process is complex and includes the description of corrosion development over time, correlated with a model for the biofilm formation and the disinfectants-corrosion products and disinfectants-biofilm interactions. The models used for these processes range from simple longitudinal dispersion models to Monte Carlo simulations and 3D modeling. This review helps to clarify what are the possible sources of compounds responsible for drinking water quality degradation. Additionally, it gives guidance on the measures that are needed to maintain stable and safe drinking water quality.

Static and dynamic evaluation of formation damage due to barium sulfate scale during water injection in carbonate reservoirs

One of the major challenges during water injection into oil reservoirs is mineral scales formation. Barium sulfate is one of the hardest inorganic scales in oil fields and insoluble in chemical solvents. Therefore, in this study, the formation conditions of barium sulfate scale were investigated. The experiments were performed in two parts including static and dynamic compatibility tests and the impact of brines volume ratio, temperature, pH, and salinity of injection water were explored. In addition, the scale formation tendency was simulated and the results were compared with the measured data. The results of static experiments indicated that the maximum amount of barium sulfate scale equals 63 mg/l forms at 90% formation water. Comparing the results of static and dynamic compatibility tests revealed that the increase of pH value increases barium sulfate scale in dynamic tests while having no effect in static experiments. This finding confirms that a different scale formation mechanism prevails in the presence of reservoir rock. The experimental results also approve that the amount of barium sulfate scale decreases by reducing the salinity of injection water, so that by diluting injection water 5 times, the maximum amount of scale decreased 21% and 44% at ambient and reservoir temperatures, respectively. The findings of this study help for better determination of water properties to increase the efficiency of water injection operations, enhance oil production and simultaneously diminish formation damage. Concurrent assessment of static and dynamic tests leads to determining the dominant mechanisms of scale formation in the presence of reservoir rock which helps to select the appropriate remediation methods.

Oxide scale formation and damage mechanism of the alloy 625 weldments in air and simulated boiler environment under cyclic condition

Alloy 625 joining was employed by pulsing current gas tungsten arc (PCGTA) welding method using ERNiCrMo-4 filler wire. The cyclic high-temperature performance of the weldments was investigated at 700 °C in molten salt (MS) K2SO4-60 %NaCl and air environment. The weldments' corrosion kinetics were accessed by the weight change method. A thin scale with no significant failure was found on the surface of the oxidized weldment. The oxide scale cracking and spallation occurred on the weldment in MS condition due to the deposited salts. The damage mechanism of the scales developed on the weldments is discussed in MS condition.

High-Quality Genomes of Pangolins: Insights into the Molecular Basis of Scale Formation and Adaption to Myrmecophagous Diet.

Pangolins are one of nature's most fascinating species being scales covered and myrmecophagous diet, yet relatively little is known about the molecular basis. Here, we combine the multi-omics, evolution, and fundamental proteins feature analysis of both Chinese and Malayan pangolins, highlighting the molecular mechanism of both myrmecophagous diet and scale formation, representing a fascinating evolutionary strategy to occupy the unique ecological niches. In contrast to conserved organization of epidermal differentiation complex, pangolin has undergone large scale variation and gene loss events causing expression pattern and function conversion that contribute to cornified epithelium structures on stomach to adapt myrmecophagous diet. Our assemblies also enable us to discover large copies number of high glycine-tyrosine keratin-associated proteins (HGT-KRTAPs). In addition, highly homogenized tandem array, amino content, and the specific expression pattern further validate the strong connection between the molecular mechanism of scale hardness and HGT-KRTAPs.

High temperature oxidation resistance of TNM alloy coated with/without 8YSZ/NiCoCrAlY thermal barrier coatings

The oxidation resistance of the TNM alloy (Ti-44Al-4Nb-1.5Mo (B, Y) (at. %)) coated with/without 8YSZ/NiCoCrAlY thermal barrier coating (TBC) was conducted through cyclic oxidation at 950 ℃. The formation mechanism of oxide scale, interface interdiffusion mechanism, and evolution law of thermal growth oxide (TGO) were systematically investigated. Results show that the weight gains of the TNM alloy coated with/without TBC are 2.45 mg/cm2 and 6.98 mg/cm2, respectively. The Ti-Al-N layer and the (Nb, Mo)-rich layer near the surface play a role in blocking the internal diffusion of air and the external diffusion of metal ions. After a comprehensive analysis of EPMA and SEM results, it is concluded that the diffusion rate of elements in NiCoCrAlY is Ni > Co > Cr. At the same time, the relationship between the interface diffusion layer thickness and oxidation time is built based on Fick’s first law. In addition, as the oxidation time increases, TGO evolves from a dense Al2O3 layer to CS (chromia, spinel oxide) layer, and CSN (chromia, spinel, and nickel oxide) cluster oxides. The mixed oxides induce crack nucleation and growth, thereby reducing TBC lifetime.

Mechanisms of Exclusive Scale Formation in the High Temperature Oxidation of Alloys

The high temperature oxidation of alloys is most often considered within the continuum framework developed by C. Wagner. We argue that in order to make progress in understanding exclusive scale formation, one needs to examine the atomic-scale kinetic processes that today are amenable to a variety of experimental, computational and theoretical approaches. In our discussion, we suggest that there is an analogy between the kinetic processes required for exclusive scale formation and thin film layer-by-layer growth. In both cases, the magnitude of the Ehrlich-Schwoebel barrier sets an effective length scale for growth, that if too large, results in three-dimensional rather than lateral island or oxide growth. In this event, exclusive scale formation can only occur if there is a sufficiently large density of oxide nucleation events at the surface of the alloy. We suggest that a suitably identified, dilute alloy component, could serve as a “surfactant” that segregates to the surface and is capable of enhancing the nucleation density.

Review on corrosion and corrosion scale formation upon unlined cast iron pipes in drinking water distribution systems

The qualified finished water from water treatment plants (WTPs) may become discolored and deteriorated during transportation in drinking water distribution systems (DWDSs), which affected tap water quality seriously. This water stability problem often occurs due to pipe corrosion and the destabilization of corrosion scales. This paper provides a comprehensive review of pipe corrosion in DWDSs, including corrosion process, corrosion scale formation, influencing factors and monitoring technologies utilized in DWDSs. In terms of corrosion process, corrosion occurrence, development mechanisms, currently applied assays, and indices used to determine the corrosion possibility are summarized, as well as the chemical and bacterial influences. In terms of scale formation, explanations for the nature of corrosion and scale formation mechanisms are discussed and its typical multilayered structure is illustrated. Furthermore, the influences of water quality and microbial activity on scale transformation are comprehensively discussed. Corrosion-related bacteria at the genus level and their associated corrosion mechanism are also summarized. This review helps deepen the current understanding of pipe corrosion and scale formation in DWDSs, providing guidance for water supply utilities to ensure effective measures to maintain water quality stability and guarantee drinking water safety.

Scaling and corrosion formation mechanism in geothermal piping system based on Pourbaix-Lindal diagram-Ryznar index and fluid velocity profile

Geothermal fluid flow contains scale and corrosion species whose levels differ from each location of geothermal sources. The velocity of scale formation and corrosion mechanism due to specific parameters in case of total key species, flow rate, pressure and temperature of the geothermal fluid based on the Pourbaix-Lindal diagram -Ryznar index. The reduction in pipe diameter due to the scaling formation on the internal surface of the pipe correlates with the flow rate of geothermal fluid into the turbine, which drives the generator to produce electrical energy. This paper describes the mechanism of scale formation and the potential for corrosion on the internal surface of the piping through the momentum transfer approach of geothermal fluids to the turbine. Through this mechanism, curative and preventive measures can be taken to prevent premature degradation of the function and economic life of the geothermal piping system. The mathematical simulation results of fluid displacement momentum, the velocity of geothermal fluid flow, show that the velocity profile at the fluid-internal surface contact of the pipe is zero, which means that the species is at rest on the internal surface of the pipe. Thus, for scale species it will form a scale, while for corrosive species there will be a corrosion process on the internal surface of the pipe.

On the formation of antiphase boundaries in Fe4Al13 intermetallics during a high temperature treatment

In this paper, we report atomic scale observations and formation mechanisms of a high-density of antiphase boundaries (APBs) within an ultra-fine-grained Fe4Al13 intermetallic layer at an Al/steel interface after a heat treatment at 596 °C. The results reveal that the APBs are formed by nucleation and the glide of partial dislocations with Burgers vector of b/3[010] (b = 12.47 Å). The intensive activation of APBs locally transforms the Fe4Al13 structure from the quasicrystal approximant structure to a quasicrystal. Very few stacking faults and nanotwins are observed indicating that the formation of planar defects is mainly driven by this transformation. This new insight on the formation of high density of APBs could possibly lead to an improvement in toughness by increasing the strength/ductility balance of this intermetallic.

FEATURES OF WATER TREATMENT FOR BOILER ROOMS

Thousands of medium and low steam boilers and hot water boilers operate in the country's industry, municipal energy and agriculture. Their reliable operation is largely determined by the maintenance of a rational water-chemical regime. The main problems of source water are the presence of dissolved oxygen, iron ions, salts of calcium, and magnesium.
 The aim of the work is to analyze the existing technologies and equipment for water treatment for different types of boilers. Determination of physicochemical parameters and requirements for source and prepared water. Presentation of new multi-purpose energy-efficient and resource-saving water treatment equipment.
 The article considers the negative impact of dissolved iron, hardness salts, dissolved gases present in the feed water on the operation of boiler equipment.
 The main requirements for feed water in terms of hardness, the content of dissolved oxygen, and oils for steam and hot water boilers are given. The mechanism of scale formation is given. The main existing methods of feed water treatment are considered, namely softening on Na-cation exchange resin, liming, softening, and reduction of total salt content on reverse osmosis units, softening, and reduction of total salt content by the sequential passage of water through H, OH-ion exchange filters. A multi-purpose aeration-oxidation setup of rotor type (AORT) is presented, which implements the method of discrete-pulse energy input, on which it is possible to carry out operations to remove iron, manganese, hardness salts, increase pH and degassing from water.

Mechanisms of Silica Scale Formation on Organic Macromolecule-Coated Surfaces

Mechanisms of Silica Scale Formation on Organic Macromolecule-Coated Surfaces

Precipitation/dissolution and precipitants movement mechanisms effects on injectivity variations during diluted produced water re-injection into a layered reservoir - experimental investigation

ABSTRACT Permeability reduction is one of the significant problems in the water injection process. Several mechanisms may be involved in permeability reduction including scale formation, suspended particle invasion and fines migration. On the other hand, rock dissolution may also lead to permeability improvement of carbonate rocks. In this research, effect of rock lithology along with incompatibility of injection and formation brines, scale formation and plugging of pores by particles in the injection water for a layered reservoir were examined. Diluted formation brine (produced from desalination unit) was considered as injection water. Simulation of scale formation due to thermodynamic conditions and mixing of formation and injection brines were performed to investigate amount and types of scales. Simulation and jar tests showed that Scale precipitation decreased with increasing the mixing ratio of injection water to 75%. For core flooding tests, both carbonate and sandstone core samples from a layered candidate reservoir were selected for monitoring of formation damage and permeability variation due to incompatibility of fluids. SEM and EDX analysis were used for static and dynamic tests. Carbonate core sample showed sever damage and competition between scale precipitation and rock dissolution. Higher flow rates contribute to permeability enhancement of carbonate rocks by prevention of scale sedimentation (less scale formation) and acceleration of carbonate rock dissolution. As a pressure difference increasing of 60% was shown in the first stage of water injection process into the carbonate rock. Eventually, after increasing and decreasing the injection rate, the pressure difference decreased to 30 presences. Scale formation mechanism is dominant in sandstone rock samples and can be removed by backflow. As pressure difference decreased 27% in sandstone rock sample, which resulted in permeability decrease from 365 to 265 mD.

High-temperature oxidation performance of wire-arc additively manufactured Inconel 718 superalloys

This work investigated the high-temperature oxidation kinetics and evolution of oxide phases of as-fabricated (AF) and heat-treated (HT) Inconel 718 alloys in air fabricated by the wire-arc additive manufacturing process. The results showed that the oxidation kinetics of all samples followed the parabolic time dependence. The microstructural study revealed the formation of very similar oxide scales in both AF and HT conditions. The oxide surface was found to be a mixture of complex spinel-MnCr2O4 and rutile-TiO2 phases. The cross-sectional view yielded an outer layer of protective Cr2O3 scale, an inner layer of Nb-rich Ti0.67Nb1.33O4 oxide and discretely formed internal Al2O3 oxides. The mechanism of scale formation is suggested on the basis of thermodynamic and kinetic abilities of cationic species.

Transcriptome sequencing and analysis for the pigmentation of scale and skin in common carp (Cyprinus carpio).

Teleost scale not only provides a protective layer resisting penetration and pathogens but also participate in coloration. It is interesting to study the mechanism of teleost scale formation. Furthermore, whether there existed consensus genes between scale coloration and skin coloration has not been examined yet. We analyzed the transcriptome profiles of red scale, white scale, red skin, and white skin of common carp (Cyprinus carpio). Pair-wise comparison identified 3391 differentially expressed genes (DEGs) between scale and skin, respectively. The 1765 up-regulated genes (UEGs) in scale, as the down-regulated genes in skin, preferred mineralization and other scale development-related processes. The 1626 skin UEGs were enriched in the morphogenesis of skin and appendages. We also identified 195 UEGs in white scale and 223 UEGs in red scale. The white scale UEGs primarily participated in regulation of growth and cell migration. The UEGs in red scale preferred pigment cell differentiation and retinoid metabolic process. A total of 22 DEGs had consensus expression patterns in skin and scale of the same coloration. The expression levels of these DEGs clearly grouped skin and scale of the same coloration together with principle component analysis and correlation analysis. Eleven consensus DEGs were homologous to the orthologs of Poropuntius huangchuchieni, 82% of which were under strong purifying selection. Eight processes including lipid storage and lipid catabolism were shared in both scale pigmentation and skin pigmentation. We identified consensus DEGs and biological processes in scale and skin pigmentation. Our transcriptome analysis will contribute to further elucidation of mechanisms of teleost scale formation and coloration.

Microtexture and Rolling Deformation Behavior Analysis of the Formation Mechanism Fe3O4 at the Interface Formed on Hot-Rolled High-Strength Steel

In order to better understand the formation mechanism of tertiary oxide scale in high-strength steel during hot rolling, the microtexture of the oxide layer has been characterized and analyzed by the electron backscatter diffraction (EBSD) method. The results show that the Fe3O4 phase in the oxide layer has a two-phase heterogeneous morphology, Fe3O4 in the oxide layer comprises columnar grains, and Fe3O4 near the substrate comprises spherical grains. As the reduction rate increases, the Fe2O3 layer is gradually wedged into the surface of the Fe3O4 layer. Fe3O4 forms a <110> fiber texture at a reduction rate of 10%. The inner layer of the oxide scale comprises spherical grains, and Fe3O4 is preferentially nucleated and precipitated in the direction of Fe surface grains <110> texture. With the increase in the reduction rate, the {112}<−1−21> directional slip system shows the lowest Schmidt factor value, so the grains with a low Schmidt factor exhibit higher stored strain energy. The formation of the spherical Fe3O4 seam layer close to the steel matrix is the result of the combined effect of the stress state at the matrix and ion diffusion.

Characteristics of scales and their impacts on under‐deposit corrosion in an oil production well

AbstractThis study examined the composition and characteristics of scales formed at different depths in an oil production well, which had developed over years of well operation, workovers, and interventions, by the combined use of optical microscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and X‐ray diffraction. The iron‐rich scales consist of several mineral phases, including a dominant portion of akagneite and hibbingite, some barite, silicon dioxide, copper sulfide, and small amounts of iron oxide and calcium carbonate. The scales typically have a layered structure consisting of five to six distinct layers, which impacts steel corrosion processes. The type of corrosion beneath the scale surface was found to be diversified. Pitting morphology corresponding to different stages in the development of scales was observed. The relation between pitting density and the extent of corrosion was analyzed. The effects of environmental factors, including calcium, chlorine, oxygen content, steel microstructure, and multiphase flow, on scale formation and corrosion mechanisms, were discussed. The results provide important insights into the formation of scales and the under‐deposit corrosion processes in the oil production tubes.

Formation mechanism of iron scale in membrane capacitive deionization (MCDI) system

In this study, we investigated the scaling behaviors of Fe in the membrane capacitive deionization (MCDI) systems through batch experiments. By analyzing the migration and transformation of Fe in the MCDI system, it was found that Fe scale was deposited on the ion exchange membrane rather than on the electrode. The characterizations of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) showed that the FeOOH formed in the solution deposited on the anion exchange membrane, while the iron scale on the cation exchange membrane was mainly Fe2O3. In the presence of 1 mg/L iron ions, the amount of iron ions adsorbed by the MCDI system was about 25% less than that by the capacitive deionization (CDI). However, at 10 mg/L iron ions, the amount of iron ions absorbed by the MCDI system was almost twice that by the CDI system. This was because that the high concentration of iron ions produced a large number of yellow flocs which were adsorbed by the cation exchange membrane. Ion exchange membrane increased the adsorption capacity of the CDI system, but it did not alleviate the scaling caused by Fe.

Numerical Simulation of Skin Formation: Modeling of Scale Peeling

Skin is formed by cell division, and the cells eventually mature into corneums and drop off. This process is known as turnover. With normal turnover, skin disease rarely occurs. However, the disturbance of turnover leads to skin inflammation and associated effects such as scale formation. The mechanisms that underpin scale formation are not fully understood. This study analyses the impact of scale formation in atopic dermatitis using a numerical simulation. The numerical simulation model of the skin was constructed by theoretically setting the main parameters i.e. transepidermal water loss (henceforth TEWL) of atopic dermatitis, thereby allowing the elucidation of the mechanism of scale formation. As a result, thick corneum and scale of atopic dermatitis were successfully modeled. In addition, the variation of desmosome distribution in stratum corneum was shown to be associated with scale formation.