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The performance of asphalt mixture affects the service of pavement. Nano-alumina was employed as asphalt mixture modification to improve pavement performances. Properties of asphalt mixtures including high-temperature properties, low-temperature properties, water stability properties, and fatigue properties were investigated through rutting tests, dynamic creep tests, low-temperature bending tests, indirect tensile tests, Marshall stability tests, freeze-thaw splitting tests, and indirect tensile fatigue tests. Considering the various performance of nano-alumina-modified asphalt mixture, the optimization decision was made based on 21 sets of performance data, and the optimal dosage of nano-alumina was further clarified. The results demonstrate that nano-alumina improved all properties of asphalt mixtures, except for low-temperature properties. The decision revealed that the performance of the modified asphalt mixture was the most balanced when the content of nano-alumina is 9%. When the optimal dosage of nano-alumina was 9%, the dynamic stability of the asphalt mixture at 60°C was increased by 34.2%, the cumulative permanent strain was reduced by 36.5–49.5%, the water stability performance was improved by 8.3–19.5%, and the fatigue performance was improved by 3.8–7.2%. However, the low-temperature flexural tensile strain was reduced by 2.1% but still meets the specification requirements. Nano-alumina can be used to modify asphalt pavement materials in high-temperature and rainy areas.

Considerable efforts are being invested to explore alternative ceramic materials to yttria stabilized zirconia (YSZ) for thermal barrier coating (TBC) applications. In this work, 18 mol% YO1.5 stabilized HfO2 (18YSH) is proposed as potential TBC material. Stoichiometric 18YSH was prepared by atmospheric plasma spraying. The 18YSH coating exhibits low thermal conductivity over the whole temperature range investigated and a minimum thermal conductivity of 0.832 W/m·K at 800 °C. Average hardness and Young's modulus values have been determined to be 7.01 ± 1.33 GPa and 111 ± 26.8 GPa respectively. These values are superior to those exhibited by YSZ coating. In addition, the sintering temperature of 18YSH coating is at least 100 °C higher than that of a 8 YSZ coating and thus 18YSH will be more resistant to sintering. Finally, 1) the coating reliability of 18YSH TBC has been studied by thermal cycling to 1100 °C and 2) calcium–magnesium–alumino-silicate-(CMAS)-induced degradation was investigated at 1250/1300 °C. The related failure mechanism was investigated and a model describing the CMAS degradation process is presented.

To expand the selection of preassigned shock surfaces, a new inverse design method called the local-turning osculating cones method has been proposed for waverider design. The new method discretize...

Molten siliceous deposits originating from environmental debris such as volcanic ash, pose a severe threat to the longevity of Yttria-stabilized Zirconia thermal barrier coatings (YSZ TBCs). Surface wetting of TBCs by molten volcanic ash, followed by infiltration into the TBCs, leads to both thermo-chemical and thermo-mechanical TBC deterioration. In particular, the consequences of such wetting and infiltration on the thermo-mechanical properties remain unexplored to date. Here, in-situ molten volcanic ash wetting of TBCs subjected to thermal shock at 1300 °C has been performed for the first time. We experimentally characterized the generation of micro-cracks, whose origin lies in the high elastic modulus of the infiltrated region (~262 GPa). Thermo-mechanical deterioration of the TBCs was due to the low fracture toughness and high thermal stresses (~1.67 GPa) evaluated at the infiltrated region, which were responsible for the propagation of micro-cracks in the TBCs. We provide quantification and preliminary interpretation of the thermo-mechanical degradation of TBCs under these common thermal shock conditions.

Poor fracture toughness of La2Ce2O7 (LC) seriously prevents its practical applications as thermal barrier coatings. In this study, 8 wt% yttria stabilized zirconia (YSZ) was introduced to toughen the plasma-sprayed LC coatings. The mechanical performance, thermophysical properties and thermal shock resistance of the coatings were improved significantly, although a solid solution reaction between LC and YSZ occurred during spraying. For instance, the toughness, adhesion and thermal conductivity at 1273 K for 20 mol% YSZ doped LC coating achieved ~1.25 MPa·m1/2, ~60 MPa and ~0.49 W/(m·K), respectively. Moreover, the thermal contraction was suppressed effectively. The enhanced toughness could be attributed to the increased fracture energy resulted from the reaction of LC with YSZ. The chipping spallation, caused by the high thermal stress as well as low fracture toughness, appeared within the ceramic top coat near the bond coat during cycling. These findings lay a theoretical foundation for the toughening of brittle coatings.

Airborne silicate pollutants in flight corridors pose a serious threat to aviation safety whose severity is directly linked to the wettability of molten silicates on thermal barrier coatings (TBCs) at high temperatures (1200–2000 °C). Despite its importance, the wettability of silicate melt on TBCs has not been well investigated. In particular, the surface morphology characteristics of TBCs can be expected to have a first-order effect on the wettability of silicate melt on such TBCs. Here, a series of atmospheric plasma spray (APS) yttria-stabilized zirconia (YSZ) TBCs with varying surface roughness were generated through the application of mechanical polishing. The metastable non-wetting behavior of three representative types of airborne silicate ash (volcanic ash, fly ash and a synthetic calcium–magnesium–aluminum–silicates (CMAS) powder) on these TBCs with varying surface roughness was investigated. It was observed that the smoother the surface of TBCs was, the larger the contact angle was with the molten silicate melts, and consequently, the smaller the area of damage was on the TBCs. Thus, the reduction in TBCs surface roughness (here via mechanical polishing) led to an improvement in the wetting and spreading resistance of TBCs to silicate melts at high temperature. In support of these observations and conclusions, the surface morphology of the TBC (both before and after polishing) had been characterized, and the mechanism of the surface roughness-dependence of wettability had been discussed. These results should contribute to reducing the deposition rate of silicate melt on TBCs, thus extending the lifetime of turbine blades and reducing maintenance costs.

Two standard 7YSZ coatings were deposited by EB-PVD techniques and tested against CMAS infiltration at short time intervals (up to 8 min.) at 1250 °C in air. They exhibited different microstructures, i.e. porosities and microstructural features. Two species of CMAS with different compositions were used and their viscosities were determined using the concentric cylinder method and their contact angles were measured using high temperature heating microscopy. The theoretical viscosities, which were calculated using a statistical model based on the chemical composition of the melts, differed from the measured values of the viscosities by one order of magnitude. A large variation in the contact angles within a very short range of temperature (1243–1266 °C) was observed as well. The porosity and surface area measurements were performed on both EB-PVD microstructures using the nitrogen physisorption method. Additionally, the produced coatings exhibited porosities of 14.5 and 29.5 percent and the infiltration experiments have shown that the more porous coating provides higher infiltration resistance. The effect of porosity on CMAS infiltration kinetics was investigated and the results elucidate that the porosity network plays a more preeminent role than the amount of porosity. The experimental infiltration results have been compared with calculated infiltration data using a novel mathematical approach proposed in previous studies in which the permeability of the coatings is assessed with two contrasting methods termed “concentric pipe” and “open pipe” models. The infiltration was calculated by incorporating the experimentally determined properties such as contact angle, viscosity and porosity. A fitting parameter has been derived from the equations for the geometry factor for both microstructures. The calculated and experimental results are in good agreement with the concentric pipe model supporting the validity of this CMAS infiltration model.

A series of TaO2.5-doped ZrO2 (1-x)ZrO2-xTaO2.5 (x = 0.08, 0.15, 0.2 and 0.28) ceramics were synthesized by solid state reaction at 1600 °C for 20 h. XRD results reveal that no tetragonal ZrO2 phase forms in the TaO2.5–ZrO2 system. Instead, a mixture of monoclinic ZrO2 (m-ZrO2) and orthorhombic TaZr2.75O8 can be detected for (1-x)ZrO2-xTaO2.5 ceramic within compositions x ≤ 0.2. As the doping content increases, the content of m-ZrO2 decreases and the final product in the composition of 0.72ZrO2-0.28TaO2.5 is primarily composed of TaZr2.75O8. Microstructure together with the thermophysical and mechanical properties of TaZr2.75O8 ceramic were investigated for possible applications as thermal barrier coatings (TBCs). The thermal conductivity with a minimum value of 1.65 W/m·K at 800 °C for TaZr2.75O8 ceramic is ∼30% lower than that of dense YSZ and the dense ceramic also has a moderate average thermal expansion coefficient (TEC), about 9.14 × 10−6 K−1 from room temperature (RT) to 1300 °C. Besides, TaZr2.75O8 exhibits a high microhardness (11.85 ± 0.42 GPa) and fracture toughness (3.15 MPa·m1/2). These preliminary results indicate that TaZr2.75O8 can be used as an alternative material for the ceramic layer in TBCs system with respect to its superior thermal and mechanical properties.

Forsterite-type Mg2SiO4 was investigated systematically for thermal barrier coating (TBC) applications. Results showed that Mg2SiO4 synthesized by solid-state reaction possessed the good phase stability up to 1573 K. The thermal conductivity of Mg2SiO4 at 1273 K was lower ˜20% than that of yttria stabilized zirconia (8YSZ). Mg2SiO4 also presented moderate thermal expansion coefficients, which increased from 8.6 × 10−6 K−1 to 11.3 × 10−6 K−1 (473˜1623 K). Mechanical properties including hardness, fracture toughness, and Young’s modulus of Mg2SiO4 were comparable to those of 8YSZ. The sintering results indicated a promising low-sintering activity of Mg2SiO4. Mg2SiO4 samples were subjected to water quenching test at 1573 K and showed a superior thermal shock resistance compared to 8YSZ. Mg2SiO4 coating with stoichiometric composition was produced by atmospheric plasma spraying. The thermal cycling test result showed that Mg2SiO4 coating had a lifetime more than 830 cycles at 1273 K, which is desirable for TBC applications.

The turbine technology incorporated in jet engines is inherently vulnerable to attack by environmental silicate debris. Amongst the various kinds of such debris, volcanic ash is a particular threat as its glass softens to a liquid at temperatures of 500–800 °C, far below jet engine operating temperatures of ∼1500 °C. As a result, ingested re-molten droplets impact and form splats on the protective thermal barrier coatings (TBCs). Investigation of the damage to jet engines ensuing from this process has, to date been restricted to forensic observations after critical encounters. Here, we employ a thermal spray technology to recreate the ‘in-situ’ generation of molten volcanic ash droplets and observe their morphological evolution and interaction with TBCs. The mechanism of splat formation is found to depend both on substrate topography and on in-flight droplet characteristics, whereby splat circularity increases with surface roughness and with the product of the Weber and Reynolds numbers. The experiments reveal that the molten ash droplet adhesion rate is dictated by droplet temperature and viscosity, ash concentration and substrate roughness. A new dimensionless number, S, is developed to quantify the molten ash droplet adhesion rate to both substrate topography and in-flight droplet characteristics. These findings provide a greatly improved basis for the quantification of the hazard potential of volcanic ash to jet engines and should be incorporated into protocols for operational aviation response during volcanic crises.

Volcanic ash (grain size The physico-chemical and phase state of ash influences substantially the thermal behavior of volcanic ash and our ability to predict that behavior and therefore depends on reliable characterization of this state. Here, we have investigated the chemical composition and mineralogy (phase state) of fresh volcanic ash from Tungurahua volcano, Ecuador, as a function of grain size (below 180 μm) in order to evaluate differences between ground-sampled ash and airborne ash, interacting with jet engines. For the sieved grain size fractions (down to Using an optical dilatometer image analysis, we have characterized the thermal behavior of the volcanic ash upon heating, which we parameterize in terms of four characteristic temperatures. Using these data the determination of the flow temperature is refined to improve measurement accuracy for fine-grained (

The properties of Sm2(Zr0.7Ce0.3)2O7 (SZ7C3) as a novel thermal barrier coating (TBC) candidate have been evaluated. There is no evidence for a phase transformation for SZ7C3 from room temperature to 1600 °C. SZ7C3 exhibits a higher sintering resistance than the conventional yttria-stabilized zirconia (YSZ). The Vickers hardness for the SZ7C3 bulk is ca. 9.6 GPa, and the fracture toughness lies in a range of 1.5-2.5 MPa m1/2. Single SZ7C3 coatings and SZ7C3/8YSZ double-ceramic-layer (DCL) coatings were prepared by plasma spraying. The thermal conductivities of SZ7C3 coatings range from 0.4 to 0.6 W m−1 K−1 (significantly lower than those of 8YSZ). SZ7C3 coatings also exhibit moderate thermal expansion coefficients (TECs), near 10.8 × 10−6 K−1 at 1200 °C. The values of thermal expansion coefficients and fracture toughness are higher than those of La2(Zr0.7Ce0.3)2O7 (LZ7C3), which has been proposed as a promising high-temperature (> 1250 °C) TBC candidate material. The thermal cycling lifetime of SZ7C3/8YSZ DCL coating is much longer than that of LZ7C3/8YSZ TBC as demonstrated by the furnace thermal cycling tests, further confirming that SZ7C3 coatings have great potential as high-temperature TBCs for use in the next generation of advanced engines.

Optimization of the resistance of thermal barrier coatings (TBCs) to environmental particles is an area of considerable current research. Here, we present a novel methods, incorporating plasma spray physical vapor deposition (PS-PVD), in order to fabricate a novel yttria-stabilized zirconia (YSZ) TBC which is highly phobic (i.e. non-wettable) with respect to CaO-MgO-Al2O3-SiO2 (CMAS) particles. At 1250 °C, CMAS particles form liquid droplets which are readily repelled by the TBC surface, diminishing adherence to and penetration into the TBC. This effectiveness of the TBC in resisting wetting by molten CMAS deposits is interpreted to result from its lotus-leaf-like dual-scale microstructure.

Solar-driven hydrogen evolution reaction (HER) via water splitting is an attractive technology to address the growing demand for clean fuels. g-C3N4 is a promising candidate among photocatalysts, but it is plagued by its puny HER activity and miserly quantum efficiency. Tremendous efforts have been made to enhance g-C3N4 performance on HER; however, it is still far below the expectations in industrial production. Herein, we report a monodisperse CoP QDs-modified ultrafine g-C3N4 fiber (CoP/CNF) via in situ electrostatic adsorption deposition followed by low-temperature phosphatization treatment. The CoP/CNF showed an HER activity of 2.42 mmol h−1 under visible light, 34.9 times higher than that of Pt/CNF, in which hydrogen bubbles evolution was observed with an apparent quantum efficiency of 59.9% at 420 nm. This benchmark HER activity was mainly because the CoP QDs could significantly suppress photoinduced charge recombination and improve the heterointerface HER rate. This work provides a useful strategy for designing highly active catalysts for solar-to-hydrogen fuel conversion.

Magnetoplumbite-type LaMgAl11O19 with high thermal stability and excellent sintering resistance has been proposed as a promising thermal barrier coating (TBC) material for next generation gas turbines. However, LaMgAl11O19 shows poor stability at 1500 °C in humid environments caused by H+/Mg2+ ionic exchange. In this work, a LaZnAl11O19 coating which is supposed to possess enhanced anti-deliquescent property was produced by plasma spraying and its properties as a potential TBC were comprehensively investigated. The results show that the thermal conductivity of the as-sprayed LaZnAl11O19 coating ranges from 1.24 W m−1 K−1 to 1.46 W m−1 K−1 and the average thermal expansion coefficient is less than 6.0 × 10−6 K−1 due to the presence of an amorphous phase in the as-sprayed coating. During exposure to 1300 °C, a total porosity of ∼10.5% can be maintained even after 1000 h aging, indicating a high sintering resistance. Besides, nano-sized grains recrystallized from the molten lamellae give the LaZnAl11O19 coating enhanced mechanical properties. In 1100 °C furnace cyclic testing, the LaZnAl11O19/YSZ double-ceramic-layer TBC exhibits a thermal cycling lifetime of ∼669 cycles, which is about 1.7 and 1.16 times as long as the conventional YSZ coating and the LaMgAl11O19/YSZ TBC, respectively. The results indicate that LaZnAl11O19 might be a promising candidate for advanced TBC applications.

Dynamic spreading of 1 mm diameter volcanic ash bead on thermal barrier coatings (TBCs) surfaces and the infiltration and subsurface lateral flow of these melts within TBCs were quantitatively investigated at 1200−1600 °C for 1−10000 min. The spreading areas, infiltration depths and lateral flow distances are controlled by melt viscosity, coating surface roughness and microstructures. The lateral flow along the inter-column of the coating was dramatically accelerated at higher temperature with a diffusion distance of more than 5.3 mm within 1 min at 1600 °C. These findings are critical for understanding the corrosion mechanism of TBC in contaminated environments.

Gas turbines, used to propel aircraft or generate electricity, are vulnerable to attack by environmental silicate debris. When silicate ash is ingested into gas turbines, it melts and may adhere to the hot-section components of gas turbines (typically operating at > 1250 °C), infiltrating into their thermal barrier coatings (TBCs). These ash-related TBC issues pose a critical hazard for aircraft aviation. Here, we have developed here a novel NdYbZr2O7 coating substrate which addresses these challenges. We have quantitatively analyzed the in-situ wetting process of three representative silicate ash compositions—CMAS, volcanic ash and fly ash, and compare their infiltration behavior in the newly-developed NdYbZr2O7 coating substrate. The widely differing chemical compositions of the three ash samples yield differences in their high temperature viscosities which in turn impact their respective propensities for wetting and infiltration. CMAS exhibits the greatest dynamic wettability due to its lower viscosity over the entire range of temperature. Volcanic ash exhibits the largest infiltration depth, probably related to the relatively high solubility of rare-earth oxides (RE2O3) in volcanic ash melt. Nevertheless, compared with a traditional YSZ coating, the NdYbZr2O7 coating exhibits a better corrosion resistance in the presence of all three silicate ash samples due to the rapid precipitation of (Nd, Yb)-apatite and c-ZrO2 phases, which build a dense reaction layer, inhibiting further melt infiltration.

The spontaneous polarization of domains in ferroelectric materials has been used to spatially separate photogenerated electrons and holes, reducing recombination and thereby improving the efficiency of photochemical reactions. Here, the influence of the magnitude of the polarization on photochemical reactivity is investigated. The magnitude of the out-of-plane component of the polarization was characterized by scanning Kelvin probe force microscopy (KFM). By examining crystals with orientations that deviate by only a few degrees from (001), two types of domains were identified: those with polarization vectors nearly perpendicular to the surface and those with polarization vectors nearly parallel to the surface. The photochemical reactivity was measured using topographic atomic force microscopy to determine the amount of Ag+ (Pb2+) that was photochemically reduced (oxidized) to Ag (PbO2) on the surface. For the reduction reaction, the reactivities of domains with polarizations nearly perpendicular to the surface were only about 3 times greater than the reactivities of the domains with polarizations nearly parallel to the surface, indicating that, for this reaction, the magnitude of the out-of-plane polarization is less important than its sign. For the oxidation of lead, only the domains with polarizations nearly perpendicular to the surface were reactive, indicating that for this reaction, both the sign and magnitude of the polarization are important.

When particulate photocatalysts promote a reaction, the overall reaction rate is limited by the constraint that the photoreduction and photooxidation reactions must occur on the surface of the same particle and at the same solution potential. The optimized solution potential would be the one where the photoanodic and photocathodic reactions proceed at the same maximum rate. Here, the relative photochemical reactivity of BaTiO3 was investigated as a function of the surrounding aqueous solution pH. Topographic atomic force microscopy (AFM) was used to quantify the amount of metallic silver produced from the photochemical reduction of Ag+ (Ag+→Ag) under UV light illumination. The overall reaction rate was observed to increase with pH. A similar pH-dependence existed for both high concentration (0.1 M) and low concentration (10−4 M) Ag+ solutions. When the pH is changed, the adsorbed charge at the surface is changed and this has the same effect as applying an external electric field. The observations are consistent with the idea that increasing the pH increases the net negative charge adsorption on the surface, increasing the upward band bending and promoting the oxidation half reaction, which is the rate-limiting factor for the overall reaction. As a result, the rate of Ag+ reduction increases with pH. The results show that adjusting the aqueous solution pH has the potential to control the rates of the two half reactions and increase the overall photochemical reaction rate.

Thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition (EB-PVD) or plasma spray (PS) usually suffer from molten calcium-magnesium-alumino-silicate (CMAS) attack. In this study, columnar structured YSZ coatings were fabricated by plasma spray physical vapor deposition (PS-PVD). The coatings were CMAS-infiltrated at 1250 °C for short terms (1, 5, 30 min). The wetting and spreading dynamics of CMAS melt on the coating surface was in-situ investigated using a heating microscope. The results indicate that the spreading evolution of CMAS melt can be described in terms of two stages with varied time intervals and spreading velocities. Besides, the PS-PVD columnar coating (∼100 μm thick) was fully penetrated by CMAS melt within 1 min. After the CMAS attack for 30 min, the original feathered-YSZ grains (tetragonal phase) in both PS-PVD and EB-PVD coatings were replaced by globular shaped monoclinic ZrO2 grains in the interaction regions.

In this work, biobased hydrogels with temperature and pH responsive properties were prepared by copolymerizing N-isopropylacrylamide (NIPAM), itaconic acid (IA), and methacrylated lignosulfonate (MLS), where the multifunctional MLS served as a novel macro-cross-linker. The network structures of the lignosulfonate-NIPAM-IA hydrogels (LNIH) were characterized and confirmed by elemental analysis, Fourier transform infrared, and 13C nuclear magnetic resonance. The equilibrium swelling capacity of the LNIH hydrogel decreased from 31.6 to 19.1 g/g with MLS content increasing from 3.7 to 14.3%, suggesting a strong dependence of water absorption of the gel on MLS content. LNIH hydrogels showed temperature-sensitive behaviors with volume phase transition temperature (VPTT) around the body temperature, which was also influenced by MLS content. Moreover, all LNIH hydrogels exhibited pH sensitivity in the range of pH 3.0 to 9.1. Rheological study indicated that mechanical strength of the gel also increased with MLS c...

A soy protein (SP)-poly(acrylic acid) (PAA) superabsorbent hydrogel was synthesized from soy protein isolate and potassium acrylate. Alkali-treated SP was turned into macromonomer through the functionalization of its primary amine groups using methacrylic anhydride. The SP-PAA hydrogel was formed by free radical copolymerization of the SP macromonomer and potassium acrylate monomer. It was demonstrated that the SP macromonomer acted as a macro-crosslinker and no additional crosslinker was needed. The whole synthesis was conducted in a one-pot process. The chemical structure and degree of functionalization of the SP macromonomer were characterized by 1 H NMR spectroscopy and UV–vis spectrophotometry, respectively. The SP to acrylic acid weight ratio at the preparation of the hydrogel was 1/3 and the SP content in the final product was 11–19%. As a result of the functionalization of SP, compressive gel strength was significantly improved, gel content was increased and extractable SP was reduced. Free swelling in distilled water was reduced for SP macromonomer gels due to increased crosslink density. The SP-PAA hydrogels displayed a stable swelling performance in buffer solutions with pH ranging from 6 to 11.5.

Sodium lignosulfonate (SLS) was aminated to obtain a lignin amine (LA) compound, which was subsequently crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE) to obtain hydrogels. The chemical structure of the resulting LA-derived hydrogel (LAH) was characterized by Fourier transform infrared (FTIR) spectroscopy, solid-state 13C NMR spectroscopy, and elemental analysis, and the interior morphology of the freeze-dried hydrogel was examined by scanning electron microscopy. NMR and FTIR spectroscopy results indicated that the amino groups of LA reacted with PEGDGE in the crosslinking reaction. The lignin content in the resulting hydrogel increased with an increase in the LA/PEGDGE weight ratio in the reaction, approaching a maximum (∼71 wt %) and leveling off. The hydrogel with such a composition happened to be the same as the one prepared by reacting the primary amines of LA and epoxy groups of PEGDGE in equal stoichiometry. These results strongly suggest that the formation of the hydrogel network structure was largely dictated by the reactions between the primary amines and epoxy groups. The gels with lignin contents at this level exhibited a superior swelling capacity, viscoelasticity, and shear properties.

New ceramic materials for thermal barrier coating (TBC) are a key to more powerful and efficient next-generation gas turbines. Here, we investigate the effect of the two novel dopants, Ta2O5 and Y2O3, on the phase stability, thermophysical and mechanical properties of the HfO2-based ceramic systems (i.e., Ta2O5-HfO2; Y2O3-HfO2). For the Ta2O5-HfO2 system, we observe the formation of a new compound, Hf6Ta2O17. In the Y2O3-HfO2 system, stabilized HfO2 with up to 18 mol% YO1.5 (YSH) is generated, whereby monoclinic HfO2 transforms to cubic HfO2. The cubic YSH ceramics demonstrate enhanced phase stability, compared with Hf6Ta2O17 at temperatures up to 1300 °C. The mechanical properties, thermal expansion and fracture toughness of 18–24 mol% YSH (YO1.5 = 18–24 mol%) indicate that cubic YSH exhibits enhanced suitability for higher-temperature.

The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200–2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines., Volcanic ash is hazardous to jet engines, with high temperatures in turbines causing ash particles to melt and stick to the engine, adversely affecting turbine function. Here, the authors explore the spectrum of natural ash compositions and their behaviour and impact at high temperatures.