Distribution Of Elements Research Articles

Preparation of High‐Selectivity Li+ Adsorbents Based on Bauxite via Liquid‐Phase Alkaline Thermal Activation

ABSTRACTBauxite, as the main aluminium‐bearing mineral in China, is a crucial resource for the industrial production of aluminium and aluminium‐related products. In this study, bauxite‐based aluminium composite Li+ adsorbents were prepared using a liquid‐phase alkaline thermal activation—acid in situ method. The effects of various factors on Li+ adsorption from brine were investigated through single‐factor experiments. Multiple techniques, such as scanning electron microscopy (SEM), energy dispersive x‐ray spectroscopy (EDS), x‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectroscopy (FT‐IR), and x‐ray photoelectron spectroscopy (XPS), were employed to characterise and analyse the microstructure, pore size distribution, chemical element distribution, and mineral structure of the adsorbents. In addition, the changes in bauxite structure and properties before and after functionalization were investigated. Results indicate that the adsorption capacity of LATA‐AIS‐LDH‐BX adsorbent prepared by the acid in situ method reached 1.15 mg/g at pH = 7; the adsorption capacity of LATA‐Al‐LDH‐BX adsorbent prepared by the aluminium salt conversion method reached 2.16 mg/g. The adsorption behaviour of both adsorbents followed the pseudo‐second‐order kinetic model and the Langmuir model. In the presence of interfering ions (Na+, K+, SO24+, Mg2+), the composite adsorbents showcased strong selective adsorption capacity for Li+. After five cycles of adsorption–desorption, the adsorption rates decreased by 12.19% and 11.48%, respectively, demonstrating good recycling stability. Furthermore, the Li+ adsorption capacities in salt lake brine reached 0.82 mg/g and 1.48 mg/g, indicating promising potential for industrial application.

Unserpentinized harzburgites of the Voikaro-Synyinsky massif of the Polar Urals as the initial source of chromium for the formation of deposits

The composition and age of unserpentinized harzburgites, which are found in the Voikaro-Synyinsky massif in the form of budins and relict bodies in the fields of olivine-antigorite rocks development, have been studied. The structure, compositions of rocks and minerals, as well as the distribution of rare-earth elements and Sm-Nd absolute dating (≈2330 million years) allow us to consider these unserpentinized harzburgites as fragments of the mantle and the earliest formations among the ultramafic Voikaro-Synyinsky massif. The silicates of these harzburgites are characterized by increased chromium content, which in subsequent different processes turns into chromium spinelide. Based on the data obtained, the resources of chromium mobilized during the transformation of primary ultramafics were evaluated.

Geochemical Profiles of Deep Sediment Layers from the Kolubara District (Western Serbia): Contamination Status and Associated Risks of Heavy Metals

Global awareness of the harmful effects of heavy metal contamination in soil has increased significantly. Understanding the vertical distribution of oxides and elements is vital for tracing the history of potential contamination. Thus, this study focuses on deep sediment cores primarily composed of quartz and clay minerals from a small village in the western Tamnava Basin of Serbia. The aim was to assess the vertical distribution of 11 oxides and 21 elements and the ecological risks of eight heavy metals by analyzing 250 sediment samples from 18 boreholes at depths ranging from 5 to 58.5 m. Deep sediment core samples were analyzed using energy-dispersive X-ray fluorescence spectrometry (ED-XRF). Potential contamination levels were evaluated within the study area. Additionally, samples were analyzed for total carbonate and organic carbon contents and particles retained on a 0.063 mm sieve. Higher than permitted concentrations of vanadium (V), thallium (Tl), and barium (Ba) were found. Notably, this zone is located above a proposed lithium and boron mine in Gornje Nedeljice, making it crucial for monitoring efforts. Even if mining operations do not commence, examining the deep sediment layers in this rural area remains important. This study offers novel and valuable data on the concentrations of potentially toxic elements in undisturbed deep sediment, serving as a benchmark for future comparisons.

The fully bio-based bilayered flame retardant treatment for paper via natural bio-materials

In this paper, we report a novel method for enhancing the flame retardancy of wood-based paper by utilizing natural biomaterials. The research constructed a bilayered structure coating on paper fiber surfaces, incorporating mixed starch (MS), adenosine triphosphate (ATP), and phytic acid (PA) as natural bio-based flame retardants. The structural configuration of the coating comprises MS/ATP and MS/PA, which were sequentially assembled as bottom and top parts, respectively, through pneumatic spraying. The surface morphological features and elemental distribution analysis of treated paper indicated that bio-materials were successfully assembled, which resulted in a uniform flame retardant coating on the paper fiber surface. Compared to the untreated paper, the limiting oxygen index of 20 bilayers (BL) treated paper increased substantially from 19.07% to 24.00%, and the thermogravimetric analysis showed out the residual char yield enhanced from 23.80% to 38.10% under nitrogen atmosphere. The cone calorimeter test results of 20 BL treated paper have approximately a 50.00% reduction than the untreated paper in both peak and total heat release rates. During thermal exposure, the top and bottom parts of the bilayered structure coating are successively flame retarded prior to paper fiber degrading. The method presented in this paper provides an environmentally sustainable approach for producing flame retardant wood-based paper.

Biogeochemistry of peat deposits of the Holocene section of the Vydrinsky bog (southern Baikal region)

Drilling cores from peat deposits of the Vydrinsky bog with a thickness of 4.4 m and an age of 13,100 cal. years, composed of lowland, transitional and high-moor types of peat, were studied in detail. The processes of post-sedimentary transformations of swamp sediments during early diagenesis are considered, the distribution of elements, the formation of authigenic minerals and the chemical composition of swamp waters are studied. The destruction of organic matter begins already in the upper intervals of peat at the early stages of diagenesis. Pyrograms do not have clearly defined high-temperature peaks, “rudiments” of the macromolecular structure of kerogen, which indicates a low degree of transformation of peat organic matter. A high number of organotrophic, ammonifying, nitrifying, phosphate-mobilizing microorganisms, a small number of Fe- and Mn-oxidizing microorganisms, and sulfate-reducing bacteria were revealed. The presence of organotrophic microorganisms throughout the section indicates that the biogeochemical processes of the carbon cycle cover the entire thickness of the peat deposit. A small amount of S (II) indicates a low intensity of sulfate reduction processes. Lowland peat is characterized by high contents of Si, Al, Fe, Ca, Sr, Ba, Zr, La and anomalous contents of Cu, Zn, which is a consequence of the formation of the bog under conditions of rich mineral nutrition. In the ash part of the transitional peat, a decrease in the contents of Si, Fe, Sr, Br, K Si, Ca, Ba, Cu, Zn and La is noted, which reflects the gradual weakening of the connection of the peat deposit with the underlying rocks. In the near-surface horizon of high-moor peat, there is an increase in the contents of K, Mn, Zn, Hg, Pb and As, which is associated with an increase in atmospheric dust and anthropogenic impact on the bog ecosystem in the 20th and 21st centuries. Bog waters of low-lying peat are characterized by high contents of the main ions, Al, Fe, Mn, Sr, while transitional peat is characterized by a decrease in DOC, SO42–, HCO3–, Al, Fe, Ni, Ca, Mg. The oligotrophic strata is characterized by the development of Fe oxides and hydroxides, the presence of vivianite is noted for transitional peats, and the eutrophic part of the peat deposit includes rhodochrosite and sulfides of Fe, Cu, and Zn.

High-speed laser-directed energy deposition of crack-free wear-resistant and anti-corrosive Al/Cu bimetal components

ABSTRACT Al/Cu bimetal components (BMCs) possess higher thermal conductivity, better wear resistance and corrosion resistance than Al and Al alloys. It is a big challenging task to fabricate a high-performance Al/Cu BMC by a conventional infrared (IR) laser-directed energy deposition (L-DED) process due to the crack formation and high IR laser reflectivity. A novel high-speed L-DED process was proposed to successfully fabricate a crack-free Al/Cu BMC by controlling the residual stress distribution and brittle intermetallic compounds (IMCs) formation. The damaging effect of the reflective IR laser rays on the laser equipment can also be suppressed. Compared with the Al base metal, the microhardness, wear and electrochemical corrosion performances of the Al/Cu BMC were significantly improved. The residual stress distribution was predicted and measured. The IMC formation mechanism was revealed based on element distributions, the formation energy and the effective heat of formation of each IMC. The study would provide the basis for manufacturing crack-free and high-performance multi-material components in many applications in different industries.

Energy-resolved fast-neutron radiography using an event-mode neutron imaging detector

Energy-resolved fast-neutron radiography is a powerful non-destructive technique that can be used to remotely measure the quantity and distribution of elements and isotopes in a sample. This is done by comparing the energy-dependent neutron transmission of a sample with the known cross-sections of individual isotopes. The reconstruction of the composition is possible due to the unique features (e.g. resonances) in the cross-sections of individual isotopes. At short-pulsed ( 1 ns) neutron sources, such information is accessible via time-of-flight neutron imaging in principle, but requires a detector with nanosecond temporal resolution. Conventional neutron detectors can meet this requirement only by heavily compromising spatial resolution or efficiency. Here, we present a unique approach on fast neutron resonance radiography using a scintillator-based event-mode imaging detector at a short-pulsed neutron source, including first results on spatially mapped resonance profiles using MeV neutrons. The event mode approach applied in the presented detector allows recording of individual neutron interactions with nanosecond precision in time and sub-mm resolution in space. As a result, the entire available neutron energy spectrum can be measured for each pulse. At the same time, the use of a thick scintillator screen and lenses to focus the produced light results in a highly flexible field of view and a high interaction probability in the sensitive volume of the detector.

Moss biomonitoring of lithogenic impact on the distribution of various chemical elements in the air in the region of Mariovo, North Macedonia.

A study was conducted to investigate the air deposition and explore the distribution of potentially toxic elements in the Mariovo region, North Macedonia, using moss samples as biomonitors of air pollution. The distribution of 44 chemical elements was detected in 20 moss samples collected in the area. The moss samples were analyzed after microwave digestion using inductively coupled plasma - atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). It was found that atmospheric deposition for some potentially toxic elements in the moss samples in the study area was influenced only by lithogenic origin. R-mode factor analysis was used to identify and characterize elemental associations. Three factors were separated from the group of macroelements determined by ICP-AES: Factor 1 (Cr, Fe, Ni, V, Al, Zn, Pb, and Li), F2 (Li, Sr, and Ba), and F3 (P, and K); and two associations were separated from the group of trace elements determined by ICP-MS: Factor 1 (Ga, Sc, Ti, Co, Zr, Rb, As, Cs, Ge, Y, Sn, Mo, and rare earth elements - REEs) and Factor 2 (Br, B, Cd, I, and Sb).

Geochemical distribution of elements in the environmental media from the surroundings of open pit areas

The results of geochemical investigations - carried out within the framework of the European project LIFE IP RESTART - in the degraded areas of the Kopriva (deposit of natural stone-limestone) and Lipovški vrh (deposit of limestone for industrial purposes) open pits are presented. There test sites of the installation of secondary raw materials (a mixture of recycled materials and mineral raw materials) with the aim of revitalizing degraded surfaces are planned. The main goal of this study is to define the baseline geochemical distribution of elements in environmental materials (rocks, soil, stream sediment and surface water) for the purpose of monitoring the potential environmental impacts of installed secondary raw materials. In rocks Ca content predominates due to the geological setting (predominantly limestone) of the studied areas. According to the legislative guidelines for soil, exceedances have been found for Pb in one sample (origin can be natural or anthropogenic) and Ni in two samples (presumably natural origin) from the area of Kopriva. In the area of Lipovški vrh in the stream Suhi Potok, higher contents of Mg, Na, Sr, Ca, Mn and S occur in the downstream sediment compared to upstream sediment. It is assumed higher contents occur due to anthropogenic contribution of carbonate material along the stream (washing of materials from nearby open pit and road). In the surface water of Suhi Potok, higher concentrations of S, Sr, B, U and Zn were determined. However, the concentrations did not exceed the legislative guidelines.

A Low Temperature Calciothermic Reduction Approach for the Synthesis of LaB6 Powders

In this work, we report the synthesis of a polycrystalline LaB6 powders with a uniform morphology by a low-temperature metallothermic reduction route using calcium as a reductant. The processing methodology and heat treatment parameters are optimized based on thermodynamic estimates in order to favour the reaction kinetics and for complete formation of LaB6 powders with highest purity. The synthesised powder was subjected to comprehensive characterization studies. X-Ray Diffraction (XRD) revealed the complete formation of LaB6 compound without any traces of reactants. Scanning Electron Microscopy (FE-SEM) along with chemical mapping shows the morphology and elemental distribution of LaB6 powder. X-Ray Photoelectron Spectroscopy (XPS) results show the futuristic peaks with photon energies that are assigned to the core levels of the La and B without significant impurities whereas the Fourier transform infrared (FTIR) spectrum indicates an apparent presence of La-B bonds at 1045.4 cm−1, 585.5 cm−1, and at 463.1 cm−1.

Geochemical Characteristics of Modern River-Sand and Its Bearing on the Mineral Exploration in the Manufahi Area, Timor-Leste

Geochemical mapping of river sands in the Manufahi area of Timor-Leste revealed potential areas for future mineral exploration. River sand samples from the study area were collected and geochemically analyzed to identify anomalous concentration distributions of several valuable elements and locate potential target areas and geological formations that may host mineral deposits. The 26 major and minor elements were identified using wavelength-dispersive X-ray fluorescence. The river sands exhibited varying elemental concentrations, with Cr, Cu, Zn, and Ba showing deviations from the normal distribution patterns. Identification of geochemical anomalies is an important task in mineral exploration geochemistry. The mean+2 standard deviations (mean+2STD), median+2 median absolute deviations (median+2MAD), and Tukey’s inner fence (TIF) methods were used to determine the geochemical thresholds. This study shows that TIF and principal component analysis (PCA) methods are highly effective in calculating appropriate threshold values and identifying relevant elemental associations. These approaches have proven useful for delineating target areas for mineral deposits, resulting in reliable outcomes. Four predicted target areas with high potential for deposits and mineralization anomalies of Cr, Cu, Ni, and Ba were delineated in the study area.

Element contents in edible seaweeds and assessment of human health from their consumption

ABSTRACT Seaweed, traditionally part of the daily diet of Asian countries, has become a common dish in Western countries. In Brazil, although contributing to lesser amounts, seaweed consumption has been incorporated into the population eating habits. It is well established that seaweed contains (1) several biologically active components and (2) the ability to accumulate minerals and trace elements, both of which are essential and potentially toxic. Therefore, the objective of this study was to determine the concentrations of essential, trace and toxic elements present in edible seaweeds sold in São Paulo city market, considering the species, origin, and potential impact on the health of the consumers. Data demonstrated that the elemental distribution is characteristic of the species and due to low quantity consumption seaweed may be considered a reliable source for iodine alone.

Molecular-scale free volume and dynamic properties of a model ionomeric elastomer: Effect of curative systems

Cross-links significantly influence the chain packing efficiency and free volume in elastomeric materials, affecting their segmental dynamics. In this context, ionomeric elastomers serve as model systems that can undergo vulcanization through covalent and ionic cross-linking, enabling tuning their macroscopic properties. In this study, we investigate the effects of sulfur (covalent) and zinc oxide (ionic) cross-linking (with and without stearic acid) on the cross-link density, molecular-scale free volume, segmental relaxation and mechanical properties of carboxylated nitrile butadiene rubber (XNBR) networks by using a combination of analytical techniques including swelling studies, positron annihilation lifetime spectroscopy (PALS), dynamic mechanical analysis (DMA) and tensile testing. PALS measurements revealed a distinctive bimodal distribution of free-volume elements in the ionomeric networks, observed for the first time. This feature provided evidence of ionic aggregation-induced immobilization of polymer chains, which resulted in smaller free volume elements (1.5–2 Å) than in the bulk ionomeric matrix (3.0–3.5 Å). DMA studies revealed two segmental relaxations (α and α′) in the cross-linked elastomers, which could be tailored based on the cross-link density of the networks. The frequency-dependent DMA master curves, derived through time-temperature superposition, showed broad tan δ (loss factor) vs. frequency profiles for the networks with tan δ values exceeding 0.50, indicating their potential suitability for passive vibration damping applications. The ionically cross-linked networks exhibited superior mechanical properties compared to the networks prepared by covalent and mixed modes of curing.

Utilization of Novel (KNbO3)1−x(Ba2FeNbO6)x (x = 0.1, 0.2, 0.3) Solid Solutions for Efficient Photo‐Assisted Fenton Degradation of Methylene Blue Dye

Novel (KNbO3)1−x(Ba2FeNbO6)x (x = 0.1, 0.2, 0.3) solid solutions corresponding to K0.82Ba0.18Fe0.09Nb0.91O3, K0.64Ba0.36Fe0.18Nb0.82O3, and K0.46Ba0.54Fe0.27Nb0.73O3 compounds have been synthesized via molten salt method. X‐ray diffraction confirms the formation of solid solutions, while transmission electron microscopy combined with energy‐dispersive spectroscopy results demonstrates a homogeneous distribution of elements. The obtained solid solutions crystallized in a cubic crystal structure, whereas the parent KNbO3 possesses an orthorhombic structure. The wide bandgap semiconductor KNbO3 transformed into a visible‐light‐active material, with its bandgap energy reduced from 3.56 eV to ≈2.4 eV. The substitution of K in KNbO3 with Ba is responsible for structural modification from orthorhombic to cubic symmetry, whereas both structural modification and the substitution of Nb with Fe correlated with optical properties. The photocatalytic activities of all obtained solid solutions are improved compared with the parent KNbO3 and Ba2FeNbO6 compounds for photocatalytic degradation of methylene blue (MB) dye. Among the series of solid solutions, K0.82Ba0.18Fe0.09Nb0.91O3 photocatalysts show the highest MB removal efficiency owing to its relatively higher surface area, suppressed charge carrier recombination, and more negative conduction band edge. Moreover, K0.82Ba0.18Fe0.09Nb0.91O3 photocatalyst (0.1 g) combined with hydrogen peroxide (H2O2) to form a novel photo‐Fenton system, achieving almost complete degradation of 100 mL of 10 mg L−1 MB dye in 30 min.

Trace Elements Spatial Distribution in the Groundwater near the Subarnarekha River Basin - Jamshedpur, India

The present study assessed the spatial distribution of trace elements in the groundwater near the Subarnarekha River Basin - Jamshedpur, India. Half of this city's water need (48.11%) relies on groundwater resources. GIS-based maps were constructed using ArcGIS 10.3 software to describe the spatial distribution of Arsenic (As), Barium (Ba), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), and Strontium (Sr). The concentration of trace elements was investigated in the groundwater sample of 30 wells by the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Many samples contained levels of Sr (100 µg/L), Cu (50 µg/L), Co (10 µg/L), and Mn (300 µg/L) that vastly exceeded the limits of the Bureau of Indian Standards (BIS) limit, which may directly affect the human health. The northern region of the study area exhibits higher concentrations of heavy metals. The groundwater table was monitored using a sensor-based water level recorder during pre and post-monsoon seasons. A significant fluctuation of 4.9 meters below ground level (mbgl) was observed, indicating potential water scarcity in the summer. The findings of this study offer valuable insights into various sources of contamination affecting groundwater in river basins within industrial regions.

Fabricating High-Efficiency Sb2(S,Se)3 Solar Cells by Novel Additive-Assisted Longitudinal Component Engineering.

Antimony selenosulfide (Sb2(S,Se)3) solar cells have achieved an efficiency of over 10.0%. However, the uncontrollable hydrothermal process makes preparing high-quality Sb2(S,Se)3 thin films a bottleneck for efficient Sb2(S,Se)3 solar cell. To address this problem, triethanolamine (TEA) additive is innovatively utilized to regulate the reaction kinetic process of Sb2(S,Se)3 thin films in this work. The results show that TEA chelator can realize the time-domain control of the reaction process, optimizing the Se/(S+Se) elemental distribution of Sb2(S,Se)3 thin film and shrinking the bandgap offset of Sb2(S,Se)3 thin film. Meanwhile, the (021) and (061) crystal orientation of Sb2(S,Se)3 thin film are enhanced and the harmful VSe1 defects in Sb2(S,Se)3 solar cells are passivated. Interestingly, a uniform back surface gradient for Sb2(S,Se)3 thin film is formed to reduce the minority carrier recombination at the back contact, increase the photocurrent and decrease the diode current of Sb2(S,Se)3 solar cells. Finally, the Jsc and FF of Sb2(S,Se)3 solar cells are significantly improved by 8.6% and 5.5% respectively, and the open-circuit voltage deficit of the device is reduced by 44mV, which leads to an efficiency of 9.94% which is the highest values of Sb2(S,Se)3 solar cells by sodium selenosulfate system.

Understanding the phase evolution and elemental distribution in MoWTaNbVTix manufactured via powder metallurgical approach

Understanding the phase evolution and elemental distribution in MoWTaNbVTix manufactured via powder metallurgical approach

COMPOSITION DESIGN OF 316LN AUSTENITIC STAINLESS STEEL FOR LIQUID-HYDROGEN STORAGE BASED ON HIGH-FLUX PREPARATION

Designing multi-element alloy compositions to achieve target performance was the first step in the development of modern materials, but the traditional trial-and-error experiment seriously restricted the development of new materials due to its low efficiency. In this investigation, the composition design of 316LN austenitic stainless steel for enhanced liquid-hydrogen storage using multi-crucible synchronous metallurgy in a high-flux experiment was proposed. Sixteen groups of as cast austenitic stainless steel samples with different compositions were smelted using high-flux material preparation. Then, through the observation of their microstructures, the chemical composition that best matched the target performance was finally selected. The results show that high-throughput experiments can greatly improve the efficiency of composition design optimization of new stainless steel products. At the same time, this investigation also analyzed the elemental composition of δ-ferrite and the method for effectively controlling the δ-ferrite content. In 316LN stainless steel, Cr and Mo were easily enriched in ferrite grains or grain boundaries, forming Cr and Mo enriched regions. This resulted in a gradient transition of Cr and Mo from the ferrite region to the austenite region, forming galvanic corrosion. In this study, the distribution of Cr, Mo and other elements in 316LN stainless steel was studied by means of a metallographic microscope, electron probe microanalysis, transmission electron microscope and scanning electron microscope. In addition, the relationship between the ferrite content and chemical composition was explored. Finally, it was determined that high-temperature, long-term sensitization treatment is an effective method for controlling the δ-ferrite content.

Evaluation of the dynamics of nutrients and potentially toxic elements along a major river in Ethiopia using multivariate statistical techniques: Implications of possible co-occurrences

This study utilized established field and laboratory methods and multivariate statistical tools to evaluate the nutrient and potentially toxic elements (PTEs) distribution, identify possible sources, and determine potential co-existence in the Awash River. The levels of soluble reactive phosphorus (SRP), total phosphorus (TP), NO3-N, Mn, Ni, Cr, and Cu generally increased downstream in the upper Awash, with the highest respective values of 0.70, 1.34, 1.19, 1.58, 1.03, 0.85, and 0.11 mg L−1 at the inlet to Lake Koka. Sites found downstream of the inflow of Lake Beseka and Metehara town showed the highest levels of Fe, B, Zn, and dissolved silica. Principal components and correlation analysis findings revealed strong associations (r ≥ 0.80, p < 0.05) between nutrient parameters (SRP, TP, and NO3-N) and PTEs (Cu, Ni, Mn, and Cr), implying common origins and potential co-occurrences. The potential co-occurrences of these parameters may strengthen their potential individual impacts due to complex interactions.

Investigating the thermal-chemical-mechanical coupling effects on the cracking behavior of machine gun barrel: Microstructural insights

The presence of severe cracks at the inner bore of the gun barrel accelerates the erosion failure, whereas the evolution and failure mechanism of crack tips under the thermal-chemical-mechanical coupling effects needs further investigation. Herein, the elemental distribution, phase structure, and strain surrounding the perpendicular and circumferential cracks in a failed gun barrel were investigated in detail by utilizing scanning electron microscopy (SEM), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). Results indicated that the perpendicular crack was covered by double continuous layers composed of inner FeO oxides and outer Fe0.96S sulfides. Notably, a high-density precipitation of FeO oxides together with severe lattice distortion and localized amorphization was observed at the crack tip, accelerating the growth of the cracks. For the circumferential crack, the presence of fine recrystallized grains alongside coarsened M23C6 carbides was observed at the crack tip. There was a high level of strain concentration along high-angle grain boundaries at the forefront of the circumferential crack tip, resulting in the cracking along grain boundaries. Furthermore, the models for propagation of perpendicular and circumferential cracks under the thermal-chemical-mechanical coupling effects were proposed respectively.