Shock Resistance Properties Research Articles

Titania Effect on Sintering behavior of Alumina

The sintering behavior of Alumina was investigated by adding TiO2. The addition of TiO2 lowered the sintering temperature of the Alumina compared with those of pure Alumina. The result suggests that TiO2 acts as an activator for sintering of Alumina. Water absorption, apparent porosity and density were examined for both pure and TiO2 added to Alumina samples. The variations of sintering behavior were discussed in terms of shrinkage, porosity, water absorption and density. Thermal shock resistance was also examined. In term of this work, the way of improving the thermal shock resistance in oxide- based materials by adding reactive Titania powder to the Alumina samples. The laboratory results showed an improvement in thermal shock resistance property of the products which open the horizon of development of the final products.

Cyclic thermal shock resistance and tribological properties of AlCrSiN, AlTiSiN and AlCrSiN/AlTiSiN multilayer hard coatings

Cyclic thermal shock resistance and tribological properties of AlCrSiN, AlTiSiN and AlCrSiN/AlTiSiN multilayer hard coatings

Improving thermal shock and oxidation resistance of Cr3C2/WC-NiCr cermet coating by embedding large NiCrAlY superalloy particles

Improving thermal shock and oxidation resistance of Cr3C2/WC-NiCr cermet coating by embedding large NiCrAlY superalloy particles

The effect of pre-dehydrated magnesium-silicate-hydrate on the properties of the castables bonded with hydrable magnesium carboxylate

The effect of pre-dehydrated magnesium-silicate-hydrate on the properties of the castables bonded with hydrable magnesium carboxylate

Functionalization and morphology control of graphene oxide for intelligent barrier coatings against corrosion

Functionalization and morphology control of graphene oxide for intelligent barrier coatings against corrosion

Ti4+ doped high-entropy fluorite oxide ceramics ((ZrHfCeYEr)(1-x)/5Tix)O2-δ: Thermal, mechanical and cyclic thermal shock resistance properties studies

Ti4+ doped high-entropy fluorite oxide ceramics ((ZrHfCeYEr)(1-x)/5Tix)O2-δ: Thermal, mechanical and cyclic thermal shock resistance properties studies

Microstructure and properties of forsterite-zirconia composite ceramics for solar thermal storage

Microstructure and properties of forsterite-zirconia composite ceramics for solar thermal storage

Heat transfer mechanism and performance optimization scheme of refractory oxide solid heat storage materials

Heat transfer mechanism and performance optimization scheme of refractory oxide solid heat storage materials

Deposition voltages on the phase evolutions, microstructures, and oxidation behaviors of thermal-resistance Glass-MoSi2-SiC coating

ABSTRACT Due to the high oxidation activities at high temperatures, traditional SiC coating was difficult to act as an antioxidant material for ages. In this case, the multilayered Glass-MoSi2-SiC coating was fabricated on the C/C substrate, combined with hydrothermal electrophoresis deposition and simple embedding process. It was found that the composite obtained at 10 V performed outstanding combinations of oxidation resistance and thermal shock resistance properties. The weight loss of this Glass-MoSi2-SiC-C/C composite was only 0.99% after 212 h oxidation at 1773 K. After thermal shock for 130 times, the mass was just 0.05% lower than that of the initial. These excellent heat-resistant performances were much better than those in similar reports, which was attributed to the suitable coating composition and dense interlayer structure. As oxidized at 1773 K, the in-situ SiO2 phases had a self-healing ability to fill micropores and microcracks to protect the structure. The structure failure was related to SiO2 volatilization. This study emphasized the importance of simple techniques in the thermal-resistance coating fields at multiple length scales.

Use of alumina dispersant in alumina‐spinel castable: Comparison between in situ and preformed spinels

AbstractThe role of alumina dispersant as a flow modifier, completely replacing fume silica, on the properties of preformed and in situ spinel‐containing low cement high alumina castables was investigated with variations in spinel content and granulometry. Both 10 and 20 wt.% spinel‐containing compositions were prepared using preformed spinel or magnesia in alumina castable compositions with vibratable and self‐flowing consistency. The castables underwent conventional processing methods and accessed for various refractory‐related parameters post‐heat treatments. No glassy phase was observed in the castables upon firing. The presence of self‐flowing consistency led to improved characteristics. Preformed spinel‐containing compositions showed improved density, strength, hot strength, and thermal shock resistance properties, whereas slag corrosion and penetration resistances were found to be higher for in situ spinel‐containing castable.

Spectroscopic probing of ultraviolet-induced degradation in elastomeric polyurea

Aromatic polyurea has garnered assiduous research due to its excellent impact, shock, abrasion, moisture, and chemical resistance properties. Polyurea can be used in protective coating and impact mitigation applications but is inevitably exposed to harsh deployment conditions such as extended ultraviolet (UV) radiation. Fourier Transform Infrared (FTIR) spectroscopy, Terahertz-time domain spectroscopy (THz-TDS), and Excitation-Emission Matrix spectroscopy (EEMS) deciphered the effects of UV radiation on radiated polyurea samples under ambient and nitrogen-rich conditions. Samples were radiated continuously for up to 15weeks in increments of 3weeks. Comprehensive FTIR analyses revealed a monotonic increase in disordered hydrogen bonding as a function of exposure duration in an ambient environment. Otherwise, marginal changes were observed in UV-radiated samples under nitrogen. The hydrogen bond length exhibited significant variations in the former compared to their nitrogen atmosphere counterparts. The results infer the nitrogen shielding effect, protecting polyurea from the photodegradation and photo-oxidation observed in samples radiated under the ambient atmosphere. THz-TDS spectra affirmed the FTIR results by probing changes in the complex refractive index. Terahertz spectral peaks associated with torsional vibrations of intermolecular hydrogen bonds in polyurea were notably correlated with increased exposure duration in the ambient atmosphere. Changes in the complex index as a function of exposure duration under nitrogen are minimal. The excitation-emission spectra of polyurea samples reveal a strong fluorescent behavior in 9-week and 12-week ambient-exposed polyurea due to cluster-triggered emission mechanisms. The results synthesized based on three different spectroscopy techniques paint a holistic portrait of the adverse effects of extended ultraviolet radiation of macromolecules deployed in harsh environmental conditions.

Formation, conversion, and elimination of intermediate spinel phase in MgO/kaolin mixture firing for cordierite

AbstractCordierite ceramic is usually used for diesel particulate filter owing to its excellent low thermal expansion coefficient and high thermal shock resistance properties. However, the co‐exited intermediate spinel phase can deteriorate the thermal and mechanical performances of cordierite ceramic product, because the spinel phase has much higher thermal expansion coefficient comparing to that of cordierite. In this study, two methods are utilized to reduce the spinel impurity in the cordierite ceramic. On the one hand, rational reaction resources were introduced to decrease spinel production. The formation of intermediate spinel phase is systematically researched by X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman characterizations and the results clarified the preference of path “Enstatite + Mullite → Cordierite” for less spinel production in comparison to path “Enstatite + Al2O3 → Cordierite + Spinel.” Additionally, MgO was introduced as fluxing agent to promote liquid‐phase sintering, thus facilitating the conversion of spinel. On the other hand, the sintering schedule was improved by introducing a holding temperature gradient to promote the diffusion of Si4+ and further promote the conversion of spinel into cordierite. With these methods, the residual spinel phase is minimized, the resulting high‐purity cordierite has a 47% reduction in the thermal expansion coefficient from 3.07 × 10−6/K to 1.63 × 10−6/K compared to the original cordierite sample.

Improvement of thermal shock resistance and hot mechanical properties by FCC/BCC/B2 multiphase strengthened microstructure in laser cladded high-entropy alloy coatings

Improvement of thermal shock resistance and hot mechanical properties by FCC/BCC/B2 multiphase strengthened microstructure in laser cladded high-entropy alloy coatings

Preparation of MgAl2O4 solar thermal storage ceramics from different magnesium sources

AbstractIn order to study the performance and feasibility of magnesia‐alumina spinel (MgAl2O4) ceramics for thermal storage in solar thermal power generation, MgAl2O4 was prepared by theoretical composition using α‐Al2O3 as aluminium source, fused magnesia, magnesite, and light burned magnesia as different magnesium sources and kaolin as additive. The effects of magnesium source and the additive on sintering properties, thermal shock resistance and thermal properties of MgAl2O4 ceramics were researched. The results shown sample A1 (with fused magnesia) sintered at 1670°C possessed the optimum comprehensive properties, the bending strength increased by 7.71% after 30 thermal shock times (room temperature‐1000°C, air cooling), the specific heat capacity was 1.05 J/ (g·K). Therefore, the MgAl2O4 ceramics exhibited great potential in high‐temperature thermal storage material.

Enhancing the thermal shock resistance of Al2O3-SiC-C castables via the generation of in-situ SiC whiskers

ABSTRACT The demand for Al2O3-SiC-C castables (ASCs) with excellent strength and thermal shock resistance has expanded considerably. Here, the effects of Fe-Si3N4 on the thermal shock resistance and physical properties of ASCs were studied. The addition of Fe-Si3N4 to ASCs lead to the formation of SiC whiskers, enhancing the cold modulus of rupture and the cold crushing strength of the castables. The formed SiC can fill the pores left by the oxidation of carbon after heating at 1450°C for 3 h, thereby improving the bulk density of the castables. Additionally, the residual strength ratio of the castables after three thermal shock cycles was improved and this was attributed to the generation of microcracks due to the release of N2 and the generation of the whiskers. The optimal Fe-Si3N4 content was 4 wt%. Therefore, the results of this study revealed that the thermal shock resistance and physical properties of ASCs were enhanced by the addition of Fe-Si3N4.

Characterization of underwater shock transient effects on naval E-glass biaxial fiberglass laminates: An experimental and numerical method

• Underwater explosions can cause large deformations on naval composite structures. • Historically transient effects on fiberglass are predicted by quasi-static methods. • A dedicated shock test campaign is realized to characterize laminates dynamically. • A dynamic finite element model is validated to predict shock response in tests. • Experimental+numerical analyses validate modeling strategies for ships shock design. Non-contact underwater explosions (UNDEX) can cause extremely large deformations on naval composite structures related to heavily nonlinear phenomena. For this reason, for military purposes, used materials must have excellent shock resistance properties. Historically, the underwater shock transient effects on fiberglass laminates are predicted using quasi-static approaches. In this paper, the composite materials are characterized by experimental modal analysis as well as by a comprehensive series of shock tests, whose results are compared with numerical models. Namely, the MIL S 901 D Medium Weight Shock Machine (MWSM) was used to perform dedicated shock tests, in which composite specimens are supported on a special constraining structure designed to create large deflections and providing reproducible results. A dynamic implicit finite element model has been set, validated by modal analysis at first, and then applied to simulate the MWSM test behavior and to predict the structural response of different E-Glass polyester resin laminates. In the end, the complete comparison of numerical results and experimental data is reviewed to validate the modeling strategies for shock design of navy ships.

Transcriptome analysis of heat resistance regulated by quorum sensing system in Glaesserella parasuis.

The ability of bacteria to resist heat shock allows them to adapt to different environments. In addition, heat shock resistance is known for their virulence. Our previous study showed that the AI-2/luxS quorum sensing system affects the growth characteristics, biofilm formation, and virulence of Glaesserella parasuis. The resistance of quorum sensing system deficient G. parasuis to heat shock was obviously weaker than that of wild type strain. However, the regulatory mechanism of this phenotype remains unclear. To illustrate the regulatory mechanism by which the quorum sensing system provides resistance to heat shock, the transcriptomes of wild type (GPS2), ΔluxS, and luxS complemented (C-luxS) strains were analyzed. Four hundred forty-four differentially expressed genes were identified in quorum sensing system deficient G. parasuis, which participated in multiple regulatory pathways. Furthermore, we found that G. parasuis regulates the expression of rseA, rpoE, rseB, degS, clpP, and htrA genes to resist heat shock via the quorum sensing system. We further confirmed that rseA and rpoE genes exerted an opposite regulatory effect on heat shock resistance. In conclusion, the findings of this study provide a novel insight into how the quorum sensing system affects the transcriptome of G. parasuis and regulates its heat shock resistance property.

Nanocrystalline ZrC coated graphite and its effect on mechanical properties and thermal shock resistance of low-carbon Al2O3–C refractories

Nanocrystalline ZrC coated graphite was synthesized in mixed molten salt system, and the effect of different zirconium sources and reaction temperature on its synthesis was studied. The effects of nanocrystalline ZrC coated graphite on the microstructure, thermal shock resistance and cold mechanical properties of low-carbon Al 2 O 3 –C refractories in different atmospheres were studied. The results indicated that nanocrystalline ZrC coated graphite synthesized by Zr powder had a more uniform coating structure than ZrO 2 as a zirconium source, and increasing the reaction temperature was beneficial for the synthesis of ZrC. The sample with nanocrystalline ZrC coated graphite fired in nitrogen atmosphere had better mechanical properties, the cold modulus of rupture was 15.67% and 50.67% higher than that of the samples fired under argon atmosphere and carbon-embedded atmosphere, respectively. Meanwhile, Sialon played a significant role in improving the mechanical properties of the samples after thermal shock. In addition, the treatment in argon or carbon-embedded atmosphere was beneficial in improving the thermal shock resistance of the samples.

The microstructure evolution, damage behavior and failure analysis of fine-grained W-Y2O3 composites under high transient thermal shock

Extreme thermal environment, especially transient high thermal load, is one of the great challenges for plasma facing tungsten materials. In this work, the fine-grained W-Y 2 O 3 composites fabricated by nano in-situ composite method were exposed to transient heat loading using electron beams. The microstructure evolution, damage behavior and failure analysis were investigated by experimentally combing with finite element modelling (FEM). Besides, the correlation among thermal shock resistance, microstructure and mechanical properties of the W-Y 2 O 3 composites were initially analyzed. Results show the W-Y 2 O 3 composites obtains superfine microstructure and coherent interface. The surface morphology evolves from smooth to roughness, cracks and melting as the power density increases. Simultaneously, four crack patterns of surface micro-cracks, crack networks, longitudinal cracks and internal transverse cracks were observed. The W-0.3 wt%Y 2 O 3 composites exhibit superior resistance to crack formation attributed to excellent interfacial performance and diffuse Y 2 O 3 hindrance. No obvious damage was found on the surfaces when the power density reached 600 MW/m 2 . With the increasing Y 2 O 3 contents, the thermal resistance of W-Y 2 O 3 composites significantly decreases. Finite element modelling (FEM) analysis shows that the surface damage is the most serious compared to the interior after thermal shock. The damage, especially cracks, are preferentially formed on the surface, and then migrate and expand to the interior. The damage and its evolution are attributed to the palstic thermal strain on the surface caused by thermal stress. Moreover, the higher the mechanical properties of W-Y 2 O 3 composites, especially the high temperature yield stress and elongation, the better high thermal load resistance. These results should be of relevance for the optimum design of W plasma facing materials in future nuclear fusion reactors. • The W-Y 2 O 3 composites prepared by nano in-situ composite method obtains superfine grains and excellent thermal resistance. • The damage and failure process under thermal shock are investigated by experimentally combing with finite element modelling. • Four crack patterns of surface micro-cracks, crack networks, longitudinal and internal transverse cracks are observed. • The correlation among thermal shock resistance, microstructure and mechanical properties of W-Y 2 O 3 composites has proposed.

Preparation of Si3N4-BCxN-TiN composite ceramic aerogels via foam-gelcasting

Recently, high-performance ceramic aerogels (CAs) have become a research hotspot because of their multi-functional properties. Compared to their oxide counterparts, non-oxide CAs show better thermal shock resistance and other high-temperature properties, making them suitable for applications in harsh environments. In this work, Si 3 N 4 -BC x N-TiN ceramic aerogels (SBCNT CAs) with molar ratios of B/C/Si/Ti = 2:1:5:5 were synthesized at 1623 K for 3 h via foam-gelcasting, from Si, Ti, melamine and boron acid raw materials. The prepared SBCNT CAs containing 91.0% porosity exhibited the highest compressive strength up to 1.0 MPa, and thermal conductivity of 0.144 W/(m·K) at 298 K. They also exhibited excellent service performance at 1473 K in Ar, demonstrating their great potential for high-temperature applications.