Increasing SiO2 Content Research Articles

Wettability Between Si–Mn‐Killed Steel and MgO‐Based Refractory Containing SiO2 Impurities

Herein, contact angles between the Si–Mn‐killed steel with and without cerium and the MgO–SiO2 refractory are measured in a reducing atmosphere. With the increase of the SiO2 in the refractory from 3 to 10 wt%, the initial contact angle for the steel without cerium decreases from 140.2° to 131.4°, and the equilibrium contact angle decreases from 136.8° to 127.8°. For the cerium‐containing steel, the initial contact angle and equilibrium contact angle decrease from 140.9° and 120.6° to 131.6° and 107.4°, respectively. With the increase of SiO2 content in the MgO‐based refractory, the increase of the Mg2SiO4 in the refractory causes the reduction of the initial contact angle between the Si–Mn‐killed steel and the refractory. The interfacial reaction between the steel and the refractory decreases the contact angle. The addition of cerium in the steel promotes the interfacial reaction, obviously decreasing the contact angle.

Mineral formation conditions in acid magmatic systems related to the formation of massive sulfide deposits of the Urals and Altai-Sayany area

Studies of melt inclusions in quartz indicate the similarity of acid magmatic systems of massive sulfde deposits in the Urals and Altai-Sayany region. The melts of normal alkalinity corresponding to rhyodacite and rhyolite compositions and related to the tholeiitic series are dominant in all the deposits considered. The magmas are characterized by the same type evolution with a decreasing content of main oxides (TiO2, Al2O3, FeO, MgO, CaO, Na2O, K2O) and an increasing SiO2 content. Our results show the accumulation of Cu in relatively low-H2O acidic melts of ancient (Cambrian) deposits of the Altai-Sayany region and low metal contents in the intermediate (Silurian–Devonian) and H2O-saturated magmas of the Urals. The youngest (Devonian) magmas of Siberia evolve simultaneously along these two directions. The analysis of melt inclusions in quartz suggests that the minimum contents of trace and rare earth elements are characteristic of the Silurian-Devonian acid melts of the Urals, with their maximum contents in the youngest (Devonian) magmas and the intermediate contents of ancient (Cambrian) magmatic systems of the Altai-Sayany region. The features of rare and rare earth element patterns in melt inclusions in quartz indicate the similarity of acid magmatic systems of massive sulfde deposits in the Urals and Altai-Sayany region with present-day suprasubduction melts in the ocean-continent transition zones. Computational modeling using data on melt inclusions in quartz confrms our previous conclusions (Simonov, Maslennikov, 2020) that the occurrence of contrasting (basic and felsic) volcanic complexes with massive sulfde deposits in the Urals and Altai-Sayany region is a result of evolution of basaltoid magmas. Keywords: conditions of mineral crystallization, basaltic-rhyolitic complexes, massive sulfde deposits, melt inclusions, quartz, acidic melts.

Graphene oxide-reinforced poly (ether-ether-ketone)/silica composites with improved mechanical performance and surface bioactivity

The control of interfacial interaction between polymers and fillers is essential for the fabrication of high-performance polymer composites. In this work, poly(ether-ether-ketone)/silica (PEEK/SiO2) and PEEK/SiO2/graphene oxide (GO) composite were prepared by ball milling-ultrasonic dispersion combined with melt extrusion injection molding. GO nanosheets were introduced as the interfacial enhancer to improve interfacial binding between SiO2 and PEEK. Mechanical tests showed that the incorporation of SiO2 and GO greatly optimized the modulus, strength, and fracture toughness of the composites. The tensile strength and Young's modulus of the PEEK/SiO2 composites increases with the increase of SiO2 content. The maximum tensile strength and Young's modulus of the PEEK/SiO2 composites are approximate 95.9 ± 0.6 MPa and 4.007 ± 0.005 GPa at 30 wt% of SiO2, an increase of 6.4% and 21.2% than that of pure PEEK. The maximum tensile strength and Young's modulus of the PEEK/SiO2/GO composite are further improved to approximate 101.5 ± 0.7 MPa and 4.62 ± 0.08 GPa at a GO content of 1.5% wt, which is 12.6% and 39.4% higher than that of pure PEEK. In addition, SEM images show that numerous HA formed on the surface of the PEEK/SiO2/GO composite after immersion in SBF for 7 days, and the HA layer becomes gradually thicker after 14 days, implying the good osteogenic activity of PEEK/SiO2/GO composites. Therefore, these results suggest that the use of GO as a novel filler surface modifier for the preparation of high-performance composites may become a novel interfacial design strategy for the development of high-performance composites.

Effect of SiO2 and TiO2 on the Crystal Morphology of CaF2Al2O3CaO‐Based Electroslag Remelting Slag

The effect of SiO2 and TiO2 on the crystal morphology of 60%CaF220%Al2O320%CaO‐type electroslag remelting (ESR) slags are investigated by thermodynamic simulations, differential scanning calorimetry, X‐ray diffraction, scanning electron microscope, and energy dispersive X‐ray spectroscopy. The results suggest that the addition of TiO2 and SiO2 changes the type, amount, and sequence of crystal precipitation. CaF2 is confirmed to be the main crystalline phase in the slag, the morphology of which depends on the slag composition and cooling rate: As SiO2 content increases, the crystal morphology of CaF2 in the slag changes from dendrites with smooth surface and relatively large secondary dendrite arm spacing to dendrites with sharp tips and relatively small secondary and tertiary dendritic arm spacings. A classical crystallographic model, Jackson α factor, is proved to correctly predict the crystal morphology as observed in the experiments. It is inferred that the addition of 5 wt% TiO2 and 4 wt% SiO2 and a proper cooling rate are favorable to improve the lubrication property of 60%CaF220%Al2O320%CaO‐type ESR slags.

Development of an Iron-Based Fischer—Tropsch Catalyst with High Attrition Resistance and Stability for Industrial Application

In order to develop an iron-based catalyst with high attrition resistance and stability for Fischer–Tropsch synthesis (FTS), a series of experiments were carried out to investigate the effects of SiO2 and its hydroxyl content and a boron promoter on the attrition resistance and catalytic behavior of spray-dried precipitated Fe/Cu/K/SiO2 catalysts. The catalysts were characterized by means of N2 physisorption, nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman spectrum, X-ray photoelectron spectroscopy (XPS), H2-thermogravimetric analysis (H2-TGA), temperature-programmed reduction and hydrogenation (TPR and TPH), and scanning and transmission electron microscopy (SEM and TEM). The FTS performance of the catalysts was tested in a slurry-phase continuously stirred tank reactor (CSTR), while the attrition resistance study included a physical test with the standard method and a chemical attrition test under simulated reaction conditions. The results indicated that the increase in SiO2 content enhances catalysts’ attrition resistance and FTS stability, but decreases activity due to the suppression of further reduction of the catalysts. Moreover, the attrition resistance of the catalysts with the same silica content was greatly improved with an increase in hydroxyl number within silica sources, as well as the FTS activity and stability to some degree. Furthermore, the boron element was found to show remarkable promotion of FTS stability, and the promotion mechanism was discussed with regard to probable interactions between Fe and B, K and B, and SiO2 and B, etc. An optimized catalyst based on the results of this study was finalized, scaled up, and successfully applied in a megaton industrial slurry bubble FTS unit, exhibiting excellent FTS performance.

The Structure, Morphology, and Complex Permittivity of Epoxy Nanodielectrics with In Situ Synthesized Surface-Functionalized SiO2.

Epoxy nanocomposites have demonstrated promising properties for high-voltage insulation applications. An in situ approach to the synthesis of epoxy-SiO2 nanocomposites was employed, where surface-functionalized SiO2 (up to 5 wt.%) is synthesized directly in the epoxy. The dispersion of SiO2 was found to be affected by both the pH and the coupling agent used in the synthesis. Hierarchical clusters of SiO2 (10–60 nm) formed with free-space lengths of 53–105 nm (increasing with pH or SiO2 content), exhibiting both mass and surface-fractal structures. Reducing the amount of coupling agent resulted in an increase in the cluster size (~110 nm) and the free-space length (205 nm). At room temperature, nanocomposites prepared at pH 7 exhibited up to a 4% increase in the real relative permittivity with increasing SiO2 content, whereas those prepared at pH 11 showed up to a 5% decrease with increasing SiO2 content. Above the glass transition, all the materials exhibited low-frequency dispersion effect resulting in electrode polarization, which was amplified in the nanocomposites. Improvements in the dielectric properties were found to be not only dependent on the state of dispersion, but also the structure and morphology of the inorganic nanoparticles.

Petrogenesis of biotite granite with transitional I-A-type affinities: Implications for continental crust generation

The I-S-A-type classification scheme for granites has been widely used to identify potential sources and the tectonic setting of granitic magmatism. Recent geochemical studies have shown that most granites are derived from a mixture of mantle and crustal sources, and that granitic magmatism contribute to generation and differentiation of the continental crust. However, the origin of granites with transitional affinities remains unclear, along with their role in the growth and differentiation of the continental crust. In this contribution, the ca. 91 Ma Bozhushan biotite granites in the southwestern Cathaysia Block, China, are characterized by high abundance of high-field-strength elements (HFSEs), with Zr + Nb + Ce + Y > 350 ppm and 10000*Ga/Al > 2.6, which are features typical of A-type granites. However, biotites in the Bozhushan granites are compositionally distinct from those of typical A- and S-type granites. Decreasing P2O5 contents with increasing SiO2 contents are consistent with an I-type rather than a S-type granite. Petrographic observations and geochemical data suggest that the Bozhushan granites have transitional I-A-type affinities. The Bozhushan granites contain remarkably evolved isotopic compositions, with εNd(t) = −9.2 to −8.0 and εHf(T) = −9.8 to −7.3, which are slightly lower than values for Late Cretaceous Baiyunshan alkaline igneous rocks. The Bozhushan granites have the low Y/Nb and Yb/Ta ratios, which are similar to the Baiyunshan alkaline igneous rocks, and continental alkaline basalts from the East African Rift and eastern China, ocean island basalts, and A1-type granitoids. Geochemical data indicate that the Bozhushan granites were likely generated by high-temperature melting of a hybrid source containing underplated alkaline igneous rocks and Precambrian basement rocks. Although the Bozhushan granites have crustal isotopic compositions, our data indicate that these granites also represent the formation of new crust. Thus, granites with transitional I-A-type affinities, such as the Bozhushan granite, have a role in the generation of continental crust.

Effects of SiO2 on the preparation and metallurgical properties of acid oxidized pellets

The effects of SiO2 content on the preparation process and metallurgical properties of acid oxidized pellets, including compressive strength, reduction, and softening—melting behaviors, were systematically investigated. Mineralogical structures, elemental distribution, and pore size distribution were varied to analyze the mechanism of the effects. The results show that with an increase in SiO2 content from 3.51wt% to 7.18wt%, compressive strength decreases from 3150 N/pellet to 2100 N/pellet and reducibility decreases from 76.5% to 71.4%. The micro-structure showed that pellets with high SiO2 content contained more magnetite in the mineralogical structures. Additionally, some liquid phases appeared, which hindered the continuous crystallization of hematite. Also, the softening—melting properties of the pellets clearly deteriorated as the SiO2 content increased. With increasing SiO2 content, the temperature range of the softening—melting zone decreased, and the maximum differential pressure and the comprehensive permeability index increased significantly. When acid oxidized pellets are used as the raw materials for blast furnace smelting, it should be combined with high basicity sinters to improve the softening—melting behaviors of the comprehensive charge.

Forearc magmatic evolution during subduction initiation: Insights from an Early Cretaceous Tibetan ophiolite and comparison with the Izu-Bonin-Mariana forearc

Abstract Subduction initiation is a key process in the operation of plate tectonics. Our understanding of melting processes and magmatic evolution during subduction initiation has largely been developed from studies of the Izu-Bonin-Mariana forearc. Many suprasubduction zone ophiolites are analogous to the Izu-Bonin-Mariana forearc sequence. However, whether there are differences between Izu-Bonin-Mariana subduction initiation sequences and suprasubduction zone ophiolites remains unclear. Here, we report field geological, geochemical, and geochronological data from mafic and felsic rocks in the Xigaze ophiolite (southern Tibet) mantle and crustal section; the same types of published data from both this ophiolite and the Izu-Bonin-Mariana forearc are compiled for comparison. The ophiolite section is intruded by various late-stage dikes, including gabbroic pegmatite, diabase, basalt, and plagiogranite. The compositions of clinopyroxene and amphibole suggest that gabbroic pegmatite formed from hydrous high-SiO2 depleted melts, while whole-rock compositions of basaltic and diabase dikes show negative Nb and Ta anomalies, suggesting flux melting of depleted mantle. Along with the mafic rocks, plagiogranite has a roughly constant content of La and Yb with increasing SiO2 contents, implying hydrous melting of mafic amphibolite. Early-stage pillow basalts exhibit geochemical affinities with Izu-Bonin-Mariana forearc basalts, but they are slightly enriched. Synthesized with the regional geological setting and compared with Izu-Bonin-Mariana forearc magmatism, we propose that the transition from mid-ocean ridge basalt–like lavas to subduction-related mafic and felsic dikes records an Early Cretaceous subduction initiation event on the southern flank of the Lhasa terrane. However, the mantle sources and the magmatic evolution in the Xigaze ophiolite are more variable than those for the Izu-Bonin-Mariana forearc.

Synthesis and Properties of Polyimide Silica Nanocomposite Film with High Transparent and Radiation Resistance.

In order to prepare flexible glass cover sheet materials suitable for space solar cells, fluorinated diamine 2,2’-bistrifluoromethyl benzidine (TFDB) and fluorinated dianhydride 4,4’ (hexafluoroisopropyl) diphthalic dianhydride (6FDA) as the monomer, polyimide (PI)/SiO2 composite film was synthesized by in situ polymerization, and the influence of coupling agent and SiO2 nanoparticle content on the film structure and properties was studied. The results show that PI synthesized from fluorine-containing monomers has better light transmittance, and the highest transmittance can reach 91.4%. The average visible light transmittance of the composite film decreases with the increase of SiO2 content, and the transmittance of the film decreases less in the high-wavelength region and greatly decreases in the low-wavelength region. The tensile strength and elastic modulus of PI/SiO2 composite film increase with the increase of SiO2 content, first increase and then decrease, reaching the maximum when the content is 10%; while the elongation at break of the composite film gradually increases with the increase of SiO2 content reduce. The thermal stability of PI/SiO2 composite film increases with the increase of SiO2 content. The doping of nano-SiO2 significantly suppresses the influence of irradiation on the mechanical properties of the film.

Improving Mechanical and Morphological Characteristics Pva/Sio2 Nanocomposites for Food Packing Applications

This study deals with using nano-SiO2 to enhance the characteristics of PVA for food packing applications. Thin-film of Polyvinyl alcohol (PVA)/nano-silica (nano-SiO2) was prepared by adding different weights of silica (0, 5, 7, 9) wt. %. Differential scanning calorimetry, atomic force microscopy (AFM), FTIR, and mechanical properties such as tensile strength, modulus, elongation at break, and micro-hardness used to examine the characteristics of PVA/nano-SiO2 films. The results revealed a dramatic improvement in the PVA/nano-SiO2 mechanical properties, increasing nano-SiO2 content to 7 wt %, the value of tensile strength increasing from 62 MPa to 143 MPa. While increasing SiO2 content to 9 wt.%, the tensile strength decreased to 65 MPa. The study also showed that the value of elongation at break and modulus of elasticity of film increment with increases in the nano-SiO2 content. There was also an increase in the crystallinity from 0.97 (for pure PVA) to 1.154 at 7wt. % nano-SiO2. Crystallinity, however, decreased to 0.012 with the increase of SiO2 to 9 wt. %. FTIR results revealed that there was physical interaction between nano-SiO2 and PVA. AFM result showed less roughness at 7wt. % from nano-SiO2. Generally, the results showed that the concentration of 7% of the nano –SiO2 in thin films resulted in a significant improvement in the mechanical properties of the films. These findings suggest that nano-SiO2 can be useful as food packaging material to maintain food quality.

Removal of Saturated Monoglyceride in Biodiesel Using Adsorption and Its Effect on Low-Temperature Properties of Biodiesel Blends

Saturated monoglyceride (SMG) is a main cause of precipitate formed above cloud point of biodiesel (B100), which leads to filter plugging in diesel engine. In this work, we studied the effect of SMG content (0.1–0.7 wt%) of palm biodiesel (PO-B100) on the cloud point (CP) of diesel fuels blended with PO-B100 at different concentrations (B0, B7, B10 and B20). Euro 4 and Euro 5 diesels with a high and low aromatic content were used, respectively. The effect of SMG concentration on CP of biodiesel blends was more pronounced in case of a low aromatic Euro 5 diesel. An extent of CP change was also affected by the initial SMG concentration of PO-B100 and biodiesel blending ratios since they determined the SMG content of the final biodiesel blends. An adsorptive removal of SMG in PO-B100 was investigated by using natural zeolite as much cheaper adsorbents than commercial magnesium silicate (MS) and silica gel. The crystalline structure of natural zeolite and MS was studied by X-ray diffraction. Both MS and silica gel exhibited higher performance than natural zeolite in the SMG removal at 45 °C. To improve the SMG adsorption capacity, the natural zeolite was treated with 1 M nitric acid solution at 60 °C. The resulting modified zeolite had an increased SiO2 content, as measured by X-ray fluorescence spectroscopy, due to dealumination effect. Moreover, it showed an improved adsorption performance: the capacity of SMG adsorption was 31.5 mgSMG g-1, corresponding to a decrease of SMG content of PO-B100 from 0.7 wt% to 0.35 wt%, when using 10 wt% adsorbent loading at 45 oC for 50 min. As a result, an increase in the cloud point of biodiesel blends was significantly retarded.

Preparation and evalution water resistance, mechanical and morpholgical characteristics of PVA/SiO2 nanocomposites for food industry applications

Thin films prepared from Poly vinyl alcohol (PVA) and silica nanoparticles(SiO2 ) by using solvent casting method have been studied as potential packaging materials. PVA/ SiO2 nanocomposites were characterized by Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM), Differential scanning calorimetry, atomic force microscopy (AFM), Water contact angle, Water absorption capacity ,Water solubility ,and mechanical properties. The results showed that the mechanical properties such as ( tensile strength, elongation at break ,modulus) increased with increasing nanoparticle content to7wt. % compared with pure PVA, while the mechanical properties decreasing with increasing SiO2 content to 9 wt. % , but it remains higher than the matrix material, also an increase in the crystallinity with addition 7wt. % from SiO2 which interpreted and supported the improvement of results of mechanical properties for nanocomposites PVA/SiO2, but Crystallinity decreased to 0.012 with increase SiO2 to 9 wt. %. The result of water contact angle showed the surface of nanocomposite films less hydrophilic. Result of FTIR showed that it does not create chemical bond between PVA and nanoparticles but only physical interaction. AFM measurements indicated a reduced the surface roughness with increase nanoparticles and was less roughness at percent 7wt. % SiO2 .However, the roughness is increased at 9 wt. % due to agglomerate the nanoparticles. The SEM results showed the good desperation between PVA and nanoparticles.

Inhibition of Cr6+ by the formation of in-situ Cr3+ containing solid-solution in Al2O3–CaO–Cr2O3–SiO2 system

The pseudo-ternary Al2O3–CaO–Cr2O3 system is of great interest due to various pyrometallurgical applications. However, Cr3+ might be oxidized into toxic and carcinogenic Cr6+ during service, causing harm to humans and the environment. So, doping an adequate amount of SiO2 could suppress the generation of Cr6+. In this experiment, the Al2O3–CaO–Cr2O3 ternary system was doped with different amounts of SiO2 (0–47 wt%) and heat-treated at 1400 °C in the air atmosphere. The reaction mechanism and the phase evolution process were studied by implementing XRD, SEM-EDS, leaching tests, XPS, and associated software. In the Al2O3–CaO–Cr2O3 system under the air atmosphere, chromium primarily exists as a Cr3+ compound CaAl2Cr23+O7 and a Cr6+ compound Ca4Al6Cr6+O16 as a secondary phase. The Cr6+ leaching process was diffusion-controlled and more effective at elevated temperatures. However, Ca4Al6Cr6+O16 disappeared with the addition of SiO2. With the increase of SiO2 content, Cr2O3 tends to be in the Cr3+ form with gehlenite phase (Ca2(Al, Cr)2SiO7) and anorthite phase (Ca(Al, Cr)2Si2O8), thereby inhibiting the Cr6+. Nevertheless, the investigated compositions in the quaternary systems do not exhibit Cr6+ in the air atmosphere at 1400 °C.

The formation of shoshonitic magma and its relationship to porphyry-type mineralisation: the Maronia pluton in NE Greece

The Oligocene shoshonitic Maronia pluton in NE Greece is part of an age-progressive belt of calc-alkaline intrusions and associated with a porphyry Cu-Mo±Re±Au mineralisation. We present new data on mineral and whole rock compositions as well as Sr, Nd and Pb isotopes of the monzodioritic to granitic rocks from Maronia, including the mineralised microgranite, which crosscuts the main intrusion. The age progression of the plutons in NE Greece follows the southward-directed trench retreat implying that the magmas formed during subduction of continental lithosphere after the closure of the Pindos ocean. The shoshonitic magmas of Maronia were generated by hydrous melting of a phlogopite-bearing mantle that was enriched by 3-5% of slab-derived sediment melts. A lower degree of melting controls the higher K, LILE and incompatible element contents of the shoshonitic magmas in comparison to the neighbouring calc-alkaline magmas. The mafic shoshonitic rocks in NE Greece contain much higher P2O5 contents than the associated calc-alkaline magmas, which probably reflects subducted phosphate-rich sediments in their source. Constant Sr- and Nd-isotopes with increasing SiO2 contents imply minimal crustal assimilation and that felsic magmas including the mineralised porphyritic granite were generated by fractional crystallisation of mafic magmas. Amphibole and apatite analyses provide evidence for the intrusion of S-poor, Cl-rich magmas at 5 to 6 km depths, followed by rapid uplift and exsolution of magmatic fluids. Late granitic dikes at Maronia indicate that volatiles, sulphur and metals became enriched during the late stages of the magma evolution.

Decoupling of indentation modulus and hardness in silicate glasses: Evidence of a shear- to densification-dominated transition

Prediction of the composition dependence of Calcium aluminosilicate (CAS) glasses mechanical properties is essential to aid in the development of new glasses with tuned properties for specific applications. In this investigation, we use microindentation to measure the hardness (H) and modulus (M) and the inelastic volume that dissipates the inelastic energy is elucidated using annealing and AFM to decompose it into contributions from densification and shear flow. We chose a family of CAS glasses with a constant CaO/Al2O3 ratio but varying SiO2 content, as well as a commercial >99% SiO2 glass. We observe a decoupling between M & H, M systematically decreases upon increasing SiO2 content, however, H exhibits a non-monotonic behavior with a minimum around 79% SiO2. The inelastically deformed volumes show a high contribution from shear flow for SiO2-poor glasses and a high contribution of densification for SiO2-rich glasses, demonstrating a shear to densification dominated transition between these two extremes.

Microstructure and photocatalytic activity of TiO2-SiO2 composite materials

TiO2-SiO2 composite materials with different composition (from 0 to 50 mol % SiO2) were prepared by sol-gel method. Microstructure, optical property and photocatalytic activity of TiO2-SiO2 composite materials were characterized by Raman scattering, ultraviolet-visible (UV-vis) spectrometer and photocatalytic degradation of methylene blue. The Raman spectra results showed that TiO2-SiO2 composite materials contained only a single crystalline phase of anatase TiO2. It also indicated the inclusion of SiO2 suppressed the growth of anatase TiO2. The UV-vis absorption spectra showed that the absorption edge of TiO2-SiO2 composite materials has a blue shift as the SiO2 increased. The optical band gap of TiO2-SiO2 increased from 3.06 eV to 3.32 eV for TiO2 and 0.5TiO2-0.5SiO2. The adsorption performance and photocatalytic activity of TiO2-SiO2 was enhanced with the increase of SiO2 content. 0.5TiO2-0.5SiO2 has the best absorption performance and photocatalytic activity in our experiment. And it has potential application value in the field of photocatalytic materials.

Petrogenesis of ~2.1 Ga mafic and granitic magmatism and tectonic implication of Jiaobei Terrane in North China Craton

Paleoproterozoic magmatism in the Jiaobei Terrane has not been well studied, but it is important for understanding the tectonic evolution of Jiao-Liao-Ji belt in the east North China Craton. In this work, ~2.1 Ga mafic and granitic intrusions in the Jiaobei Terrane, including the Xiliu amphibolite, Dongbaishishan granite and Gujiacun granite, are studied in detail. The Xiliu amphibolite intruded the Archean basement and the Dongbaishishan granite intruded the Paleoproterozoic Jingshan Group. SHRIMP zircon UPb geochronology shows that both amphibolite and granite were emplaced simultaneously at ~2.1 Ga and were metamorphosed at ~1.87–1.84 Ga. The ~2.1 Ga Xiliu amphibolite samples show a tholeiitic basalt composition; they exhibit enriched light rare earth elements (REEs) and large ion lithophile elements (LILEs, e.g., U and K), but depleted high field strength elements (HFSEs, e.g., Nb, Ta, P, Zr, Hf and Ti). They experienced the fractional crystallization of clinopyroxene. Whole-rock Nd isotopes show that the ~2.1 Ga amphibolites were generated from partial melting of the Archean enriched mantle, and that the mantle source was affected by the addition of subduction-related fluids/melts. The ~2.1 Ga Dongbaishishan and Gujiacun granite samples in the Jiaobei Terrane show granodiorite to granite compositions with metaluminous and calc-alkaline characteristics. They show decreasing Fe2O3T, TiO2, Al2O3, CaO, Na2O and P2O5, but increasing K2O, with increasing SiO2 contents. This indicates that FeTi oxide, plagioclase and apatite were fractionated during magmatic evolution, which is confirmed by the negative Eu, Sr, P, and Ti anomalies. Compared with the 2.18 Ga A-type granites derived from partial melting of tonalites in the Jiaobei Terrane, major elemental geochemistry and zircon Hf isotopes showed that ~2.1 Ga granites were generated from partial melting of the low-K mafic lower crust possibly due to mantle-derived magmatic underplating.The ~2.1 Ga Jiaobei amphibolites show similar geochemical and isotopic characteristics to the contemporaneous mafic rocks in the north Liaoji and south Anhui areas of the Jiao-Liao-Ji belt. Together with the volcano-sedimentary series and A2- and I-type granitic gneiss in the belt, these ~2.1 Ga mafic rocks probably formed in a subduction-related back-arc extension environment. In addition, both episodes of the 2.18 Ga and 2.1 Ga granites in the Jiaobei Terrane show high-temperature magmatic characters, which can be attributed to mantle-derived magmatic heating. The younger episode (2.1 Ga) granites indicate that there was stronger mantle-derived magmatism in a back-arc extended zone.

Mechanical and dielectric properties of direct ink writing Si2N2O composites

Si2N2O composites were achieved via direct ink writing technique and pressureless sintering. The design and optimization of inks and the effect of mass ratio of Si3N4 and SiO2 on the phase composition, microstructure, mechanical properties and dielectric properties of composites were systematically investigated. The inks exhibit superior stability and printability. Increasing SiO2 content facilitated densification and enhancement of mechanical property. The generation of β-Si3N4 and Si2N2O and the nucleation of cristobalite were restrained by high content SiO2. The ceramic composites with the flexural strengths from 74.1MPa to 104.9MPa and low dielectric constant (≤4.68) were fabricated. This strategy provides a systematic reference for synthesis of high-performance porous Si2N2O composites based on the DIW.

Effect of SiO2 Addition on Chromium Transitions in Borate Glasses

Melt-quenching technique was used to prepare borosilicate glasses of composition xSiO2- (75-x) B2O3–24.7Li2O-0.3Cr2O3 (x = 0, 10, 20, 30, 40 and 50 mol%). With increasing the former content, both Cr6+ and Cr3+ optical transitions undergo strong intensity variations. The crystal field strength (10Dq) is increased, while Racah parameters (C,B) are decreased with increasing SiO2 content. The ratio estimated Dq/B values confirmed a weak crystal field environment for Cr3+ions, and further suggest a more covalent bond character. The ESR results revealed that Si-contained samples exhibit a strong microwave absorption signal, and justified the presence of both Cr3+ and Cr6+(charge transfer into 3d0 2p6+ = 3d1Cr5+) oxidation states. The fingerprints of borate and silicate relevant structural groups were clearly identified from FTIR spectroscopy.