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High-temperature corrosion of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho)environmental barrier coating materials by Volcanic ash

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1628-1638页

作者： Ayahisa Okawa Son Thanh Nguyen Tadachika Nakayama Thi-Mai-Dung Do Hisayuki Suematsu Shu Yin Takuya Hasegawa Tsuneo Suzuki Takashi Goto Koichi Niihara Institute of Multidisciplinary Research for Advanced Materials Tohoku UniversitySendai 980-8577Japan Department of Creative Engineering National Institute of TechnologyKushiro 084-0916Japan Extreme Energy-Density Research Institute Nagaoka University of TechnologyNagaoka 940-2188Japan Advanced Institute for Materials Research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan

Rare-earth silicates are promising environmental barrier coatings(EBCs)that can protect SiC_(f)/Si C_(m)substrates in next-genera tion gas turbine blades.Notably,RE_(2)Si_(2)O_(7)(RE=Yb and Ho)shows potential as an EBC due to its coefficient of thermal expansion(CTE)compatible with substrates and high resistance to water vapor corrosion.The target operating temperature for next-generation tur bine blades is 1400°C.Corrosion is inevitable during adhesion to molten Volcanic ash,and thus,understanding the corrosion behavior o the material is crucial to its reliability.This study investigates the high-temperature corrosion behavior of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho).Samples were prepared using a solid-state reaction and hot-press method.They were then exposed to Volcanic ash at 1400°C for 224,and 48 h.After 48 h of exposure,Volcanic ash did not react with Yb_(2)Si_(2)O_(7)but penetrated its interior,causing damage.Meanwhile Ho_(2)Si_(2)O_(7)was partially dissolved in the molten Volcanic ash,forming a reaction zone that prevented Volcanic ash melts from penetrating the interior.With increasing heat treatment time,the reaction zone expanded,and the thickness of the acicular apatite grains increased The Ca:Si ratios in the residual Volcanic ash were mostly unchanged for Yb_(2)Si_(2)O_(7)but decreased considerably over time for Ho_(2)Si_(2)O_(7).Th Ca in Volcanic ash was consumed and formed apatite,indicating that RE^(3+)ions with large ionic radii(Ho>Yb)easily precipitated apatit from the Volcanic ash.

关键词： environmental barrier coating Volcanic ash rare-earth disilicate corrosion

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Using zircon saturation thermometry of source magma in strongly altered Volcanic ashes

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Acta Geochimica 2022年第3期41卷 406-418页

作者： Tarmo Kiipli Department of Geology Tallinn University of Technology5 Ehitajate Road19086 TallinnEstonia

The present study deals with the possibilities of applying the zircon saturation thermometry, which is based on the equilibrium between the zircon crystals and the melt, to strongly altered Volcanic ashes—bentonites. It proposes an alternative to a widely used method of calculating magma temperature from Zr content and major component composition(Boehnke in Chem Geol351:324–333, 2013), that is not suitable for bentonites, as most of the major components have been largely altered in these rocks. For calculating source magma temperatures in strongly altered Volcanic ashes, the exponential function from the Zr(ppm)/Al_(2)O_(3)(%) ratio with compositional corrections from the TiO_(2)/Al_(2)O_(3) ratio was found applicable. The idea to use the ratios of these elements is based on the low mobility of these elements in the earth’s surface conditions. Temperatures of magma, forming in the partial melting process, are assessed from the bulk rock composition. Pre-eruption temperatures were estimated from the composition of fine fractions of bentonites. The accuracy of the new method was established from comparison with the method by Boehnke et al.(Chem Geol 351:324–333,2013). The difference between the two methods was mostly less than ± 30° to ± 50°. The comparison with the magma temperature, estimated from the sanidine composition,revealed 13° lower values on average. Although the proposed method for estimating the source magma temperatures is less precise than the method of accounting for detailed rock compositions, it can be used in strongly altered rocks, where other methods are not usable. The new method still enables differentiation between felsic source magmas originating at low or high temperatures. Early Palaeozoic bentonites in the Baltic Basin can be divided,according to the source magma temperatures, into two types:(1) Low temperature(650–790 ℃), containing potassium-rich sanidine and abundant biotite(S type),(2)high temperature(770–850 ℃) with sodium-rich sanidine and scarce biotite(I type).

关键词： Zircon Thermometry Volcanic ash Kbentonite Source magma Sanidine

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Effects of yttria content on the CMAS infiltration resistance of yttria stabilized thermal barrier coatings system

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Journal of Materials Science & Technology 2020年第8期36卷 74-83页

作者： Juan JGomez Chavez Ravisankar Naraparaju Peter Mechnich Klemens Kelm Uwe Schulz C.V.Ramana University of Texas at El Paso Department of Mechanical EngineeringEl PasoTX79968USA German Aerospace Center(DLR) Institute of Materials ResearchCologne51170Germany

The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were produced by electron beam physical vapor deposition(EB-PVD)techniques.The results reveal a trend of higher apatite formation probability with the higher free YO(1.5)available in the yttriazirconia system.Additionally,the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO(1.5)content in the coating.The thinnest reaction layer and lowest infiltration was found for the highest produced 67 YO(1.5)coating.Complementary XRD experiments with Volcanic ash/YO(1.5)powder mixtures with higher yttria contents than in the coatings(80 YO(1.5)and pure YO(1.5))also showed higher apatite formation with respect to increasing yttria content.The threshold composition to promote apatite-based reaction products was found to be around 50 YO(1.5)in zirconia which was proved in the coatings and XRD powder experiments.An YO(1.5)-ZrO2-Fe O-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation.This phase could be detrimental for CMAS/Volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y^(3+)available for glass crystallization.The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates.The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250°C.

关键词： CMAS Volcanic ash Infiltration Electron beam physical vapor deposition Thermal barrier coating

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RAYLEIGH WAVE VELOCITY FOR FROST SUSCEPTIBLE Volcanic ash DEPOSITS IN ASAMA VOLCANO

RAYLEIGH WAVE VELOCITY FOR FROST SUSCEPTIBLE VOLCANIC ASH DE...

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岩石力学与环境岩土工程国际会议

作者： Ryoji Sakurada Hideo Miyaguchi Ichiro Kuroshima Akita National College of Technology Akita 011 Japan Civil Engineers Co. Ltd.Tokyo 110 Japan Mitsui Construction Co. Ltd.Tokyo 110 Japan

＜正＞In the regions covered with pyroclastic fall deposits,most of the frost-heave damages of road relates to hydrogeological conditions of a location.In this study,emphasis is given to the effect of soil stratification on the frost damages of road.As a geological exploration Rayleigh wave method was employed for the ashy deposits in the foot of Asama volcano.The frost damages attributed to geological conditions can be summarized as following two forms:（1）Frost damages dominated by the thickly covered,high-heaving soils,（2）Frost damages dominated by drainage conditions of roadbed formed by low-heaving soils.The low-heaving soils easily become mid-heaving soils if once groundwater flows into the soils.

关键词： Rayleigh wave method frost heave Volcanic ash

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Effect of interfacial properties on mechanical stability of ash deposit

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第2期8卷 187-197页

作者： A.Ontiveros-Ortega J.A.Moleon I.Plaza C.Guillén Department of Physics Campus Universitario de las Lagunillas s/nEdificio A-3University of JaénJaén23071Spain Instituto Andaluz de Geofísica University of GranadaGranada18071Spain Department of Geography Campus Universitario de Guajara s/nUniversity of La LagunaIslas Canarias38071Spain

The paper presents a study on the cohesion of Volcanic ash particles using surface free energy determination and zeta potential analyses.This is a subject of great interest in physical volcanology,as many researches on volcanic particle aggregation are frequently reported.In this case,special attention is paid to the role of structural or hydration forces between hydrophilic surfaces,which are a consequence of the electron-donor/electron-acceptor character of the interface.From this point of view,the results are potentially interesting as they could give valuable insights into this process.The results are presented in terms of the total energy of interaction between dispersed particles,computed from the extended DLVO theory.Contributions to the total free energy of interaction were determined from the zeta potential and surface free energy of ash,measured under different experimental conditions.Two samples of basaltic Volcanic ash(black and white)with silica contents of 44% and 63% respectively are studied.The surface free energy and zeta potential were analysed for ashes immersed in different electrolytes(NaCl,CaCl,FeCl).The presence of electrolytes changes the surface properties of the solid materials.The analysis of total interaction energy between the ash particles in aqueous medium shows that soil cohesion strongly depends on ash surface properties,chemical nature,the adsorbed cation on the surface,and p H value.

关键词： Zeta potential Surface free energy Volcanic ash Deposits stability El Hierro Island

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The petrological characteristics and signif icance of organic-rich shale in the Chang 7 member of the Yanchang Formation,south margin of the Ordos basin,central China

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Petroleum Science 2019年第6期16卷 1255-1269页

作者： Sen Li Ru-Kai Zhu Jing-Wei Cui Zhong Luo Jing-Gang Cui Han Liu Wei-Qiang Li Research Institute of Petroleum Exploration and Development Beijing 100083China Tight Oil and Gas Research Center of National Energy Beijing 100083China Key Lab of Oil and Gas Reservoir of PetroChina Beijing 100083China

The organic-rich shale of the Chang 7 member is the most important source rock in the Ordos basin.The sedimentary environment and the controlling factors of organic matter enrichment,however,are still in contention.In this investigation,the Yishicun outcrop,located on the south margin of the Ordos basin,has been considered for the study.X-ray diffraction,polarizing microscopy,field emission scanning electron microscopy and cathodoluminescence(CL)were used to investigate the petrological features of the organic-rich shale.The content of Volcanic ash and the diameter of pyrite framboid pseudocrystals were measured to illustrate the relationship between oxygen level,ash content and the enrichment of organic matter.It has been found that the diameter of pyrite framboid pseudocrystals has a strong correlation with the total organic carbon,demonstrating that the redox status degree of the water column has a positive impact on the enrichment of organic matter.Additionally,with an increase in the ash content,the content of organic matter increased at first and then decreased,and reached a maximum when the ash content was about 6%,illustrating that the ash input has a double effect on the enrichment of organic matter.

关键词： Organic-rich shale Volcanic ash Framboidal pyrite pseudocrystal Chang 7 member Ordos basin

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USE OF INDUSTRIAL WASTE OF PERLITE IN BUILDING MATERIALS INDUSTRY

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Journal of Wuhan University of Technology(Materials Science) 1990年第1期5卷 1-11页

作者：孙复强马保国

We have observed the components, structure and properties of perlite ore. Through a series of ex- periments, it has been proved that the perlite has higher pozzolanic activity and maybe used as addi- tion of cement in manufacturing pozzolanic cement. The paper also proposes the way to increase the early strength of this kind of cement and utilize it to make many kinds of silicate concrete products.

关键词： Perlite Tailing Mixing materials Volcanic ash Cement

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