Types Of Inclusions Research Articles

Refinement and Modification of Al2O3 Inclusions in High-Carbon Hard Wire Steel via Rare Earth Lanthanum.

In this paper, an experimental protocol of adding rare earth lanthanum (La) was used to refine and modify inclusions (Al2O3) in aluminum-deoxidized steel. An optical microscope (OM), a scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS) were used to study the impact of size distribution, number density, distribution uniformity, interfacial distance, area density, and so on of rare earth La on high-carbon hard wire steel inclusions. As indicated by the findings when the addition amount of La is 0.063%, the refining and homogenizing effect of Al2O3 inclusions in steel is the best. The average diameter of the inclusions is 1.75 μm, the uniformity is 0.84, the proportion of the interfacial spacing greater than 10 μm is 48.4%, and the area density of inclusions is set at 0.014. Based on classical thermodynamics and Factsage software, the effect of La activity on inclusion formation was computed. As indicated by the findings, the addition of rare earth La mainly combines with O and S in the liquid steel, and the La-containing inclusions wrap around the Al2O3 inclusions, hindering the Al2O3 inclusions. Through the evolution of inclusions during solidification, the modification of Al2O3 inclusions via rare earth La and the types of inclusions are discussed. The experimental results and theoretical calculations verify that the optimal treatment plan is to add 0.063% La.

The magmatic-hydrothermal transition in P-rich pegmatitic melts: Crystal-melt-fluid interactions recorded by phosphate minerals

Rare-element pegmatites are the crystallization product of melts strongly enriched in incompatible elements. Some of these elements, e.g., Li, B, P, F, and H2O, function as melt structure modifiers, allowing such melts to reach unusually low crystallization temperatures and regulating the saturation of aqueous-carbonic fluids from the melt. However, the timing of fluid saturation is highly debated, and the processes that mark the magmatic-hydrothermal transition in rare-element pegmatites are still elusive. The crystallization sequence of phosphate minerals can be used to assess the timing and nature of fluid-related processes in pegmatitic systems. In the Buranga pegmatite, western Rwanda, magmatic phosphates are replaced by (hydrous) alkali-rich phosphates and later by strongly hydrated phosphates as the dike cools. This reaction series indicates a disequilibrium in the crystal-melt-fluid system and records complex fluid-rock interactions during dike consolidation. This contribution compares these interactions with the fluid record preserved in fluid inclusions in the main phosphates of the crystallization sequence. Three major fluid inclusion types are observed, aqueous-carbonic (mostly-two-phase, L-V), carbonic-aqueous (two-phase, V-L, or three-phase, L-L-V), and crystal-rich inclusions (multiphase, L-V-Solids). Crystal-rich fluid inclusions in trolleite [Al4(PO4)3(OH)3], the last primary phosphate to precipitate from the melt, show a paragenesis of solid phases similar to the secondary phosphates observed in the dike. LA-ICPMS analyses of individual fluid inclusions show high concentrations of Na and K, with some content of Li, Rb, Cs, B, Fe, and Mn in the fluid. A similar composition is present in all inclusion types within the same mineral. Crystal-rich fluid inclusions demonstrate that during the magmatic-hydrothermal transition, primary phosphates react with the fluid in the presence of melt to generate secondary phosphates. No evidence of external fluid sources has been observed during the magmatic-hydrothermal transition. The fluid inclusion record shows that the fluid salinity is kept constant due to fluid-mineral interactions and corroborates the hypothesis that fluid-soluble elements are internally remobilized in the melt-crystal-fluid system during the magmatic-hydrothermal stage. These interpretations have implications for the general evolution of P-rich pegmatitic melts and the mineralization of Nb and Ta in these systems.

Age, Fluid Inclusion, and H–O–S–Pb Isotope Geochemistry of the Superlarge Huaaobaote Ag–Pb–Zn Deposit in the Southern Great Xing’an Range, NE China

The superlarge Huaaobaote Ag–Pb–Zn deposit is located on the western slope of the southern Great Xing’an Range (SGXR). The deposit includes four ore blocks, namely, ore blocks I, II, III, and V. Except for the no. I orebody of ore block I, which is hosted in the contact zone between the Carboniferous serpentinized harzburgite and the Permian siltstone, the other orebodies all occur as veins controlled by faults. The mineralization process at the deposit can be divided into four stages: cassiterite–arsenopyrite–pyrite–quartz stage (stage I), cassiterite–chalcopyrite–pyrite–freibergite–arsenopyrite–pyrrhotite–quartz stage (stage II), sphalerite–galena–jamesonite–stibnite–freibergite–silver mineral–quartz–calcite–chlorite stage (stage III), and argentite–pyrargyrite–pyrite–quartz–calcite (stage IV). Cassiterite U–Pb dating of the Huaaobaote deposit yielded ages of 136.3–134.3 Ma, indicating that the deposit formed in the Early Cretaceous period. Two types of fluid inclusions (FIs), including liquid-rich and gas-rich FIs, have been distinguished in the quartz vein and sphalerite. The homogenization temperature during the four stages gradually decreases, with temperatures of 302–340 °C for stage I, 267–304 °C for stage II, 186–273 °C for stage III, and 166–199 °C for stage IV, respectively. The salinity (wt% NaCl eqv.) at stages I, II, III, and IV is 3.7–6.6, 0.2–4.5, 0.2–5.0, and 0.4–1.6, respectively, indicating that the ore-forming fluid is characterized by low salinity. The δ18Owater and δD values of the ore-forming fluid range from −11.9‰ to 7.9‰ and −168‰ to −76‰, respectively, indicating that the ore-forming fluid was dominantly derived from a mixture of magmatic and meteoric water. The calculated δ34SH2S values range from −3.6‰ to 1.2‰, indicating that the sulfur mainly came from granitic magma. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of sulfides are in the ranges of 18.195–18.317, 15.509–15.667, and 37.965–38.475, respectively, implying that the ore-forming material was mainly derived from felsic magma that may be formed by the partial melting of orogenic materials. Fluid mixing, cooling, and immiscibility were the three primary mechanisms for mineral precipitation in the Huaaobaote deposit.

Progressive algorithm for the scattering of electromagnetic waves by a multilayered eccentric sphere.

This paper presents a general progressive algorithm for the computational study of electromagnetic wave scattering by a multilayered eccentric nanoparticle. The presented methodology is based on a combination of the vector addition theorem for spherical wave functions and an efficient progressive algorithm that matches the boundary conditions of every two adjacent shell layers from the outmost to the innermost layer. As a result, only a solution of small-sized matrices is required rather than solving a large set of system equations as reported in other works. With the developed approach, explicit expressions of the Mie scattering coefficients of the eccentric particle can be obtained. Moreover, the Mie coefficients of a specific inner layer could be calculated selectively, instead of having to compute those of all layers of the entire particle as required by other algorithms. The presented methodology can be used to study practically any type of spherical particle inclusions and the most widely studied cases such as scattering by solid particles, concentric particles, and inclusions with centers displaced along a straight line are just special cases of the algorithm presented. Computed results are also presented, illustrating that the eccentric structure allows extra freedom in the design of multilayered nanoparticles for optical applications.

Effect of La Content on Inclusion Morphology in Automobile Sulfur‐Containing Gear Steel SCr420H

The inclusion morphology of sulfur‐containing gear steel with different La addition (0, 0.08, 0.5, and 1%) is investigated in laboratory experiments. The La and S concentrations in steel melt significantly decrease with the holding time after La addition increases, leading to different types of inclusions with specific shapes. Inclusion transformation routes with the holding time increased under different La addition are summarized as follows: 1) 0%La addition: cluster‐like Al2O3 + cluster‐like MnS → irregular block‐like MgAl2O4 + cluster‐like MnS; 2) 0.08%La addition: cluster‐like LaAlO3 + spherical‐like La‐Al‐O‐S‐(MnS) → spherical‐like La‐Al‐O‐S‐(MnS) + spherical‐like La‐Al‐O‐S‐(MgO)‐(MnS) + cluster‐like MnS; 3) 0.5%La addition: flower‐like La‐O + spherical‐like La‐O‐S → spherical‐like La‐O‐S; and 4) 1%La addition: flower‐like La‐O + spherical‐like La‐O‐S → spherical‐like La‐O‐S + cubic‐like La‐O‐S‐N‐As. The results of hot compression suggest that La‐containing inclusions are less prone to the shape change than MnS; moreover, microcracks are formed at the surface of La‐containing inclusions. The nanoindentation test demonstrates that the hardness of La‐O‐S is higher than MnS. The high La addition has a remarkable effect on refractory degradation. For 0.5% and 1% La, dissolved La reacts with the MgAl2O4 phase in the MgO‐MgAl2O4 dual‐phase refractory and changes into LaAlO3.

Effect of ferrochromium (FeCr) and ferroniobium (FeNb) alloys on inclusion and precipitate characteristics in austenitic stainless steels

Lab-scale alloying experiments were carried out by first adding commercial low-carbon ferrochrome (LCFeCr) alloys and then adding ferroniobium (FeNb) alloys in 316-grade austenitic stainless steel in this study. The inclusion and precipitation characteristics in LCFeCr and FeNb were evaluated as well as in a 316 austenitic stainless steel after the alloy additions by using two- and three-dimensional characterization methods in combination with thermodynamic calculations. The results showed that MnCr2O4 spinels and pure Al2O3 were the main types of inclusions in LCFeCr alloys, while pure TiOx, Al2O3 inclusions and complex TiOx-Al2O3 aggregates were mainly found in FeNb alloys. After the addition of LCFeCr alloy to the steel, the SiO2 contents in liquid inclusions decreased to some extent, while more inclusions containing higher MnO contents were observed. Some MnCr2O4 spinel inclusions can be reduced by Si in steel and form liquid inclusions. Some MnCr2O4 spinel and Al2O3 inclusions from LCFeCr alloy can remain in the steel melt, which decreased the steel cleanliness. After the addition of FeNb alloy, pure TiOx inclusions present in this alloy can hardly be found in the steel melt. The inclusion types in steel were not changed so much but high Nb-containing phases were found around the inclusions and coarse Laves phases were formed in the matrix. Overall, this work aims to understand the impurity particle behavior during the alloying process when using ferroalloys to produce high-performance stainless steels.

Diversity-Related Positions in Orthopaedic Surgery Residency Programs.

The Association of American Medical Colleges and the American Academy of Orthopaedic Surgeons have incorporated diversity and inclusion as one of their primary goals. Orthopaedic surgery remains the least diverse medical specialty when measured for practicing physicians and trainees. The purpose of this study was to determine the number and distinct types of diversity, equity, and inclusion (DEI) positions within orthopaedic surgery residency programs in the United States. The Fellowship and Residency Electronic Interactive Database was used to obtain a list of all Accreditation Council for Graduate Medical Education-accredited orthopaedic surgery residency programs. The following was collected from 193 residency program websites between June 6, 2022, and June 26, 2022: program location, university or community based, allopathic or osteopathic recognition, number of faculty in the orthopaedic department, number of residents per year, diversity-related statements, and diversity-focused faculty positions. Of the 193 programs evaluated, 74 (38.9%) included DEI statements on their website while only 42 (21.8%) had at least one DEI-specific faculty role (e.g., diversity committee, diversity liaison, vice chair for DEI). For 16 (8.3%) programs, the faculty role was nonspecific to the orthopaedic residency program. Nonspecific roles were primarily created by the affiliated school of medicine, but in 4 (2.1%) outlier cases, faculty members assumed DEI roles through a medical center, a graduate medical education program, or a department of surgery. Less than half of orthopaedic surgery residency programs currently advocate for DEI on their associated websites while fewer than 25% have a DEI faculty position. Previous studies have called for a greater number of DEI positions and committees among orthopaedic residencies because of the lower admittance rate of qualified Under Represented in Medicine (URiM) applicants. A role dedicated to DEI may increase the number of women and URiM applicants pursuing a career in orthopaedic surgery.

FUZZY LINEAR PROGRAMMING MODEL FOR INVERSE MULTIPLE CRITERIA SORTING PROBLEM: AN APPLICATION IN A PUBLIC TRANSPORTATION COMPANY

Multi-criteria decision making (MCDM) techniques are among the methods used by the decision maker in the decision phase in practice, as in the literature. MCDM problems are grouped as classifications and sorting problems according to the type of inclusion or ranking in existing classes. Inverse multi-criteria sorting problem, a new topic in recent years, is defined as choosing among existing actions in order to improve the status of alternatives. In this study, in order to find out which action plan should be chosen for providing the minimum cost for the improvement of public transportation vehicles in case the boundaries of the classes to be assigned are uncertain, the inverse multi-criteria ranking problem is used. Because the boundaries of the classes to be assigned are fuzzy, fuzzy linear programming method will be used to solve the problem.

Cavity growth behavior and fracture mechanism of 9.5Cr-1.5MoCoVNbNB heat-resistant steel during long-term tensile rupture at 620 °C

Heat-resistant materials appropriate for use in long-term ultra-supercritical coal-fired power generation are increasingly important. To this end, we tested a series of 9.5Cr-1.5MoCoVNbNB heat-resistant steel samples at 620 °C under applied stresses of 155–225 MPa until rupture. The microstructural characteristics, cavity growth behavior, and fracture mechanism of the tensile rupture samples were investigated. Stress promotes the motion of dislocations density, subgrain formation, and cavity nucleation. The cavities continuously grow and coalesce, but the growth rates and coalescence rates may be lower under low stress values than those under high applied stress. A detailed assessment revealed two types of inclusions, BN and Al2O3, in the tested steel. The cavities around the BN inclusions tend to deform with stress, while those around the Al2O3 inclusions tend to promote nucleation of cracks. 9.5Cr-1.5MoCoVNbNB heat-resistant steel fracture is mainly induced by cavity coalescence around inclusions.

EFFECT OF SOLVENT AND EXTRACTION TIME VARIATION ON THE COFFEE OIL EXTRACTION RESULTS

The traditional coffee with the greatest taste is called arabica. One of the ingredients made from coffee beans and used for air freshener is coffee oil. The Soxhlet extraction method, a separation technique that is often used to separate one or more compounds from a solid or liquid by adding a solvent, is one of the processes for making coffee oil. This research has been done before, but a comparison of different types of solvents and inclusion of differences in extraction time has not been done. The purpose of this research is to understand how the difference in extraction time and the comparison of solvent types affect the yield, density, and acid number produced. Extraction of hexane and ethanol by distillation for 120 minutes is a research technique. Extraction times were 90, 120, 150 and 180 minutes. In this study, the largest extraction with ethanol solvent was produced within 120 minutes of 25.75%, while the highest percent yield of coffee oil with hexane solvent was obtained within 120 minutes of 17.3%. The maximum specific gravity for 180 minutes with ethanol solvent is 0.94 gr/ml, while for 180 minutes with hexane solvent is 0.91 g/mL. Coffee oil with hexane solvent produced an acid value between 3.2 and 7 mg KOH/g, while coffee oil with ethanol solvent produced an acid value between 4.6 and 11.2 mg KOH/g.

Analyses of L-Type Corner Joints Connected with Auxetic Dowels for Case Furniture.

Tests were carried out to develop and manufacture various types of auxetic dowels using 3D printing technology. These dowels were then used to connect L-type corner joint specimens for case furniture, and their strength and stiffness were analyzed through experimental, theoretical, and numerical means. In the scope of the study, eight different types of auxetic dowels including two inclusion types, two inclusion sizes, and two dowel hole diameters, as well as a reference non-auxetic dowel, were designed. Accordingly, a total of 180 specimens that included 10 replications for each group were tested; 90 were tested under tension and the remaining 90 were tested under compression. The results demonstrated that the assembly force required for the corner joints connected with auxetic dowels was significantly lower compared to non-auxetic dowels. Furthermore, the numerical and theoretical analyses yielded similar outcomes in this study. Both analyses revealed that the dowels used to connect the corner joints experienced substantial stresses during mounting and bending, ultimately leading to their failure. Upon concluding the test results, it was observed that the corner joints connected with dowels featuring rectangular inclusions exhibited superior performance when compared to those with triangular inclusions. In light of these findings, it can be concluded that further enhancements are necessary for auxetic dowels with rectangular inclusions before they can be utilized as alternative fasteners for traditional dowels.

Educational needs and opportunities for adaptation of students with disabilities and persons with health limitations in the tertiary education system

The article is devoted to the definition consideration of the educational needs of persons with health limitations (hereinafter – HL) and disabled persons in the tertiary education system; the aspects in which these needs are expressed. The article highlights the adaptation possibilities of disabled people in the tertiary education system, as well as the specifics of the organization and goals of an educational institution for teaching people with HL. The authors identify the barriers of social relations faced by students with HL, disabled students and their teachers at universities; analyze the degree of involvement of a student with HL in the educational process. The paper pays attention to the main approaches to the organization of educational activities of persons with HL and disabled people, namely: competence-based, project-based and activity-based approaches. The main types of inclusion, identified on the basis of medical indicators, as conditions for organizing the training of students with HL and disabled students are considered. It is determined that the education organization at the university of students with HL allows to adapt educational programs to the special needs of students, depending on the state of health of students with HL and of disabled students.

Some Novel Estimates of Integral Inequalities for a Generalized Class of Harmonical Convex Mappings by Means of Center-Radius Order Relation

In interval analysis, integral inequalities are determined based on different types of order relations, including pseudo, fuzzy, inclusion, and various other partial order relations. By developing a link between center-radius (CR) order relations, it seeks to develop a theory of inequalities with novel estimates. A (CR)-order relation relationship differs from traditional interval-order relationships in that it is calculated as follows: q = q c , q r = q ¯ + q ¯ / 2 , q ¯ − q ¯ / 2 . There are several advantages to using this ordered relationship, including the fact that the inequality terms deduced from it yield much more precise results than any other partial-order relation defined in the literature. This study introduces the concept of harmonical h 1 , h 2 -convex functions associated with the center-radius order relations, which is very novel in literature. Applied to uncertainty, the center-radius order relation is an effective tool for studying inequalities. Our first step was to establish the Hermite−Hadamard H . H inequality and then to establish Jensen inequality using these notions. We discuss a few exceptional cases that could have practical applications. Moreover, examples are provided to verify the applicability of the theory developed in the present study.

Effects of inclusion type and inclusion radius on deformation characteristic and failure mechanism inside monocrystalline NiFeCr alloy

The effect of different inclusion types, inclusion radius, and strain rates (STRs) on the mechanical property, deformation behaviors, energy absorption, and failure mechanisms of NiFeCr alloy is investigated through a molecular dynamic simulation of a tensile process. The tensile strength, strain energy, and dislocation densities of the sample without and with inclusion all increase as increasing STRs. However, the tensile strength, strain energy, and dislocation densities of the sample without inclusion are all larger than those of the sample with inclusion. Moreover, Young’s modulus (E) of the none-inclusion sample is a little smaller than that of the Fe-inclusion sample while larger than that of the Ni-inclusion and Cr-inclusion samples. The results also show that the effect of inclusion radius is complex, which depends on the type of material that makes up the inclusion. E values decrease as increasing inclusion radius for all inclusion types. The phase transformations from FCC to HCP structure and the dislocation length for the none-inclusion sample are much larger than that of the inclusion samples. Besides, the nuclear deformed appears at the contact area between the inclusion and the NiFeCr workpiece and then widely develops as increasing strain. The Stair-rod and Shockley partial dislocations consider a dominant proportion for all samples.

Multiple pulses of fluids involved in the formation of carbonatite-related REE deposits as revealed by fluorite

Formation of carbonatite-related REE deposits generally associated with hydrothermal fluids exsolved from carbonatite melts. Deciphering the nature and evolution of the fluids is critical for establishing ore-formation models, and was mostly benefited from multi-analytical investigation of specific minerals presenting in multi-generation veins. However, there is a risk that the minerals in specific-generation veins not always precipitated solely from the single-stage fluids particularly for a dynamic mineralizing system. In order to evaluate this potential risk, this study conducted a combined textural, in situ trace elemental and fluid inclusion investigation of fluorite from multiple generations of veins in the Muluozhai carbonatite-related REE deposit, SW China. The veins dominate the mineralization system of the deposit, and include four generations/stages: fenitization (Stage I), pre-REE (Stage II), early REE (Stage III) and late REE (Stage IV) stages in which the ore minerals are all dominated by bastnäsite. Fluorite grains are widely present in these generations of veins, but high-resolution CL imaging reveal that most of them display complex internal textures composed commonly of core, mantle and rim domains from center outward. These domains exhibit different CL-intensities that are well correlated with chemical compositions and even types of fluid inclusions they hosted. This study confirmed that the “core-mantle-rim” textures of fluorite are essentially responses to interaction of early grains (i.e., represented by cores) with multi-stage fluids through dissolution-reprecipitation processes. Trace elemental and fluid-inclusion microthermometric results show that the cores (also for mantles or rims) in fluorite from Stages I to III veins have comparable REE concentrations and patterns and homogenization temperatures of fluid inclusions, strongly suggesting that the core-mantle-rim fluorite grains in these veins are originally formed at Stage I, and were variably captured or metasomatized by fluids of Stage II or III during development of these generations of veins. Similar core-mantle-rim fluorite grains are also present in Stage IV veins, and thus are constrained to be also “xenocrysts” formed in a similar manner. They are surrounded or even locally disturbed by a number of euhedral and/or slightly oscillatory fluorite grains which are supposed to be formed from a different manner. On the basis of their close association with bastnäsite and relatively high homogenization temperatures of fluid inclusions they host, we proposed that these euhedral fluorite grains are products of Stage IV fluids.Clear understanding of the internal textures and paragenesis of fluorite allows us to propose a genetic model for the Muluozhai deposit that the REE mineralization in Stages III and IV involves likely different pulses of carbonatite-related REE-rich fluids, and REE deposition was possibly mainly triggered by incursions of external fluids (e.g., meteoric water). This study also highlights that the phenomenon regarding presences of early-stage “xenocrysts” in late-generation veins of carbonatite-related vein systems may be more common than previously thought, and thus investigation in a textural context is critical for deciphering ore genesis.

Genesis of the Xiaobeigou gold deposit in the Jiapigou gold district, Northeast China: Constraints from fluid inclusions, quartz H–O isotopes, and pyrite in situ sulfur isotope and trace element compositions

The Xiaobeigou gold deposit (>20 t @ 17.36 g/t) is located in the Jiapigou gold district (JGD), Northeast China, representing a large-sized quartz vein-type gold deposit hosted by Neoarchean basement gneiss and is related to Mesozoic intrusions in space and time. Four hydrothermal stages were identified from early to late, namely, (1) barren quartz stage, (2) quartz–pyrite stage, (3) gold–quartz–polymetallic sulfide stage, and (4) quartz–carbonate stage. Three main types of fluid inclusions (FIs) have been identified: water-rich (H2O–NaCl; W-type), mixed aqueous-carbonic (CO2–H2O–NaCl; C-type) and pure carbonic (CO2; PC-type) FIs. The early-stage quartz contains W- and C-type FIs that yield moderate homogenization temperatures (270–379 °C) and moderate-low salinities (4.82–17.87 wt% NaCl equivalent). The main-stage quartz grains contain all three types of FIs that yield medium–low temperature (179–263 °C) and moderate-low salinity (2.82–9.86 wt% NaCl equivalent). Only W-type FIs are recognized in late-stage quartz grains, which have low temperatures (133–183 °C) and low salinities (1.91–7.73 wt% NaCl equivalent). The initial ore-forming fluid of the Xiaobeigou gold deposit was a moderate homogenization temperature and moderate-low salinity CO2–H2O–NaCl ± CH4 ± N2 hydrothermal fluid system. Fluid immiscibility is the main mechanism leading to the precipitation of gold and other metal sulfides. The H–O isotopic values (δ18OH2O = −6.87 to 5.90‰; δD = −102 to −78‰) and composition of the quartz suggest that the initial ore-forming fluids consisted mainly of magmatic water mixed with meteoric water during the late stage of the mineralization process. The S isotope data (δ34S = 3.2 to 4.4‰, avg. 3.6‰) indicate that the ore-forming materials are magmatic sources. EPMA and LA–ICP–MS data show that a large amount of gold mineralization mainly occurs in the main ore-forming stage. The high Co/Ni ratio indicates that the pyrite may be a magmatic–hydrothermal source. Taking into account all available data and regional geological history, we suggest that a magmatic–hydrothermal source for the Xiaobeigou gold deposit in the JGD and the ore formation is related to the subduction of the Paleo-Pacific Plate beneath Eurasia.

Localized attack at inclusions in 42CrMo4 QT steel

Localized attack can negatively affect the mechanical properties and durability of high strength low alloy steels. The present work investigates the effect of inclusions on the susceptibility to pitting attack of 42CrMo4 QT steel (quenched and tempered condition). A detailed characterization of the microstructure of the steel was performed by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy in order to evaluate the morphology and chemical composition of the inclusions. The initiation of pitting corrosion at the inclusion sites was investigated with a localized approach combining topographic and surface potential maps obtained by means of the scanning Kelvin probe force microscopy technique and the morphology of inclusion sites after the immersion in an aggressive electrolyte. The effect of different inclusion types (clusters combining Al2O3 and MnS and containing Ca and Mg or single MnS based inclusions) is discussed in the present work taking into account their galvanic coupling with the surrounding steel matrix and the existence of gaps at the periphery of the inclusions promoting the formation of an occluded cell.

Confirming Debonding of Non-Metallic Inclusions as an Important Factor in Damage Initiation in Bearing Steel

Damage in bearings is closely associated with the presence of microstructural alterations, known as white etching areas (WEAs) and white etching cracks (WECs). One of the main reasons for the creation of these microstructural alterations is the presence of defects in the material, such as non-metallic inclusions. Manganese sulfides and aluminum oxides are widely reported in the literature as the most common types of non-metallic inclusions found in bearing steels. This study classifies 280 non-metallic inclusions in an investigated bearing steel according to several criteria: bonded/debonded with the matrix, size, shape, orientation angle, depth below the raceway surface, and chemical composition. Contrary to the findings in the literature, this investigation reports that the chemical composition of the inclusion (MnS + Al2O3) is of secondary importance when considering factors for damage initiation. The orientation of the microstructural alterations is observed to coincide with the high-stress regions, indicating a relation between the formation of butterfly wings and the white etching crack. In our investigation, butterfly wings typically exhibit a 45-degree pattern originating from the non-metallic inclusions. Conversely, the white etching crack starts from the non-metallic inclusion at a shallower angle in correspondence to the raceway. This can be attributed to the stress state, which corresponds to a region where extensive white etching cracks are formed. In conclusion, the microstructural observations demonstrate that the state of non-metallic inclusion—i.e., whether they are bonded or not to the steel matrix—plays an essential role in initiating rolling contact fatigue damage.

Study on Oil and Gas Inclusions and Oil and Gas Accumulation Stages in Majiatan Area, Western Margin of Ordos Basin

The western edge of the Ordos Basin has abundant oil and gas resources. To explore the stages and direction of hydrocarbon fluids migration in petroliferous basins, the hydrocarbon-bearing strata in the Majiatan area on the west margin of the Ordos Basin was analyzed based on petrographic observations, homogenization temperature, salinity and composition of inclusions. The inclusions can be identified as five types. Type I, II and III inclusions exhibit abundant hydrocarbon content, whereas Type IV and V show poor hydrocarbon content. Based on homogenization temperature and salinity analysis, the five types of inclusions can be divided into two-stage formation, Type I, II and III included in the early stage and Type IV and V formed in the late stage. The direction of the hydrocarbon fluid migration of the early and late stages was from the southeast to the northwest, and the difference between the two stages of hydrocarbon fluid migration and inclusions formation depends on the fault activity from the Triassic to the Jurassic. This study is of great significance for future exploration of oil and gas in the Ordos Basin's western margin.

Fluid inclusions geochemical characteristics as indicators of the organic matter transformation degree in Jurassic sediments of the Em-Ega crest (Krasnoleninsky arch, Western Siberia)

Fluid inclusions in quartz crystals from the Abalak formation carbonate rocks of 5 wells on the Em-Egovskaya summit of the Krasnoleninsky arch (Western Siberia) were investigated. Two-phase fluid inclusions with water-salt solutions, inclusions containing organic liquid, and single-phase gas fluid inclusions were found. For fluid inclusions with two-phases, the values of the homogenization temperature were obtained. For single-phase inclusions, the temperature of the second phase forming was revealed. It was established that two types of primary inclusions are present in one well, with oil and with water-salt solution. The homogenization temperature of the primary fluid inclusion containing a water-salt solution is 267°C, the homogenization of the oil-containing inclusion exceeds 300°C. In primary-secondary inclusions, the homogenization temperature reached 136 °C. Studies of the composition of inclusions by infrared spectrometry have shown that in single-phase inclusions, the gas is represented by methane. In primary-secondary inclusions, the composition may vary, while in the gas phase, the predominant components may be hydrocarbons with two or more carbon atoms. Studies of organic matter from the deposits of the Tutleim source-rock formation overlying the Abalak formation have shown that the stage of catagenetic transformation of kerogen in the studied wells changes. It was found that in wells in which organic matter is most transformed, the homogenization temperature of fluid inclusions exceeds 130°C. Thus, it is proved that on the territory of the Em-Egovskaya summit of the Krasnoleninsky arch, Jurassic deposits were effected by heat flows created by high-temperature fluids. Not only rocks of the Abalak formation were exposed by thermal processes, but also organic matter from the Tutleim formation was changed, as a result its maturity increased and the generation of hydrocarbon compounds was stimulated. The results obtained explain the difference in the catagenetic transformation of the organic matter of the Tutleim formation in this area. The study of the molecular composition of inclusions will allow us to more accurately reconstruct the conditions of hydrothermal processes. The study of fluid inclusions makes it possible to develop new criteria for the search for oil and gas deposits.