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In-Operando Study of Shape Retention and microstructure development in a Hydrolyzing Sol-Gel Ink during 3D-Printing

ACS APPLIED MATERIALS & INTERFACES 2020年第45期12卷 51044-51056页

作者： Arango, Maria A. Torres Zhang, Yugang Li, Ruipeng Doerk, Gregory Fluerasu, Andrei Wiegart, Lutz Brookhaven Natl Lab Natl Synchrotron Light Source Ii Upton NY 11973 USA Brookhaven Natl Lab Ctr Funct Nanomat Upton NY 11973 USA

3D printing of amorphous and crystalline ceramics is of paramount importance for the fabrication of a wide range of devices with applications across different technology fields. Printed ceramics are remarkably enabled by the sol-gel synthesis method in conjunction with continuous filament direct ink writing. During printing, multiple processes contribute to the evolution of inks including shape retention, chemical conversion, solidification, and microstructure formation. Traditionally, depending on the ink composition and printing environment, several mechanisms have been associated with the shape retention and solidification of 3D printed structures: gelation, rapid solvent evaporation, energy-driven phase transformation, and chemical-driven phase transformation. Understanding the fundamental differences between these mechanisms becomes key since they strongly influence the spatiotemporal evolution of the materials, as the out-of-equilibrium processes inherent to the extrusion, relaxation, and solidification of printed materials have significant effects on the materials properties. In this work, we investigate the shape retention mechanism and the hydrolysis-induced material conversion and microstructure formation during the 3D printing of a water reactive sol-gel ink that transforms into titanium dioxide-based ceramic. This study aims at identifying characteristic mechanisms associated with the material transformation, establishing connections between the microstructure development and the timescales associated with solidification under operando 3D-printing conditions. The investigation of this material's out-of-equilibrium pathways under processing conditions is enabled by time-resolved coherent X-ray scattering, providing simultaneous access to temporospatially resolved microstructural and dynamics information. Furthermore, we explore X-ray speckle tracking as a tool to resolve deformations of the microstructure in a printed filament associated with the depositi

关键词： X-ray photon correlation spectroscopy additive manufacturing 3D printing shape retention microstructure development

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Aspects of Sintering Additives for Processing and microstructure development of HIP-SSiC

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INTERNATIONAL JOURNAL OF MATERIALS RESEARCH 2021年第2期92卷 135-140页

作者： Oberacker, Rainer Thuemmler, Fritz Fetahagic, Tarik Univ Karlsruhe Inst Keram Maschinenbau Karlsruhe Germany Jozef Stefan Inst Ljubljana Slovenia

Additives out of the systems Al-C, Al-B-C and B-C have been investigated with respect to densification and microstructure development of SiC produced by pressureless sintering and subsequent post-hot isostatically pressing (HIP) treatment. Within the investigated compositional range, the Al-B-C and B-C systems provide sufficient densification to reach pore closure during pressureless sintering and nearly theoretical density during the HIP step of the process. Densification in the Al-B-C system takes place at significantly reduced temperatures, namely similar to 1900 degrees C vs. similar to 2050 degrees C in the Al- free product. Dilatometer experiments and microstructure development indicate the presence of a liquid phase in this system during sintering. Liquid phase sintering in the SiC/(Al-B-C) system vs. solid state sintering in the SiC/(B-C) system will be discussed on the basis of literature data and previous experimental studies of the authors.

关键词： Sintering additives HIP-SSiC Processing microstructure development

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Effect of phosphorus on microstructure development in cordierite transparent glaze

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CERAMICS INTERNATIONAL 2018年第8期44卷 9991-9994页

作者： Chen, Peng Lv, Ming Ji, Yi China Qual Supervis & Test Ctr Gas Appliances Foshan Peoples R China South China Univ Technol Sch Mat Sci & Engn Guangzhou 510641 Guangdong Peoples R China

The study aimed at assessing the effect of phosphorus on the microstructure development of cordierite transparent glaze. Crystallization path of glaze was investigated by X-ray diffractometry (XRD), whereas microstructure development was determined by scanning electron microscopy (SEM). Results suggested the addition of phosphorus to reduce the melting temperature of spodumene and anorthite by 150 degrees C and 180 degrees C respectively, and to widen the existence temperature of cordierite by 40 degrees C where cordierite was detected as the only phase. In addition, phosphorus addition decreased the high temperature viscosity, thus making cordierite more easily to assemble and crystallize on the glaze surface.

关键词： Cordierite Transparent glaze Glass-ceramic microstructure development

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Thermal stability and microstructure development of cast and powder metallurgy produced Mg-Y-Zn alloy during heat treatment

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Journal of Magnesium and Alloys 2017年第2期5卷 173-180页

作者： Tomas Kekule Bohumil Smola Martin Vlach Hana Kudrnova Veronika Kodetova Ivana Stulikova Charles University in Prague Faculty of Mathematics and PhysicsKe Karlovu 3Praha 212116Czech Republic

Response to isochronal annealing up to 440 ℃ of squeeze cast Mg–Y–Zn alloy and of the same alloy prepared by powder metallurgy(PM)and extruded at 280 ℃ was studied by resistivity and microhardness measurement,differential scanning calorimetry(DSC)and microstructure *** resistivity was measured at 77 K and microhardness was measured at room temperature after each annealing *** measurement was performed at various heating *** and scanning electron microscopy and optical microscopy revealed ribbons of long-period ordered structure(LPSO)18R and planar defects within grain *** high density of planar defects was found in grain interiors of the cast alloy with the grain size approximately 50μ*** pronounced subgrains were observed in the PM prepared *** phase particles decorate grain boundaries in this *** precipitation processes were detected in the cast alloy during repeated isochronal annealing up to 440 ℃,whereas only one significant process was revealed in the PM *** processes were identified as embedding of stacking faults by solutes,development and rearrangement(18R→14H)of LPSO phase and development of grain boundary particles.A coarsening of grain boundary particles rich in Y and Zn only proceeds in the PM *** energies of the precipitation processes were *** exhibits good thermal stability against annealing up to 360 ℃ in the PM alloy.

关键词： Mg-Y-Zn alloys Powder metallurgy Microhardness microstructure development Electrical resistivity

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microstructure development and texture formation in lead-free piezoelectric ceramics prepared by templated grain growth process

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JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 2016年第4期124卷 268-282页

作者： Kimura, Toshio Keio Univ Minato Ku 2-15-45 Mita Tokyo 1088345 Japan

Templated and reactive-templated grain growth is a convenient preparation method for textured ceramics. In this method, green compacts composed of aligned template grains and randomly oriented matrix grains are sintered. The matrix grains must be eliminated to obtain highly textured materials and an understanding of the growth behavior for both template and matrix grains is essential to the design of the conditions for effective elimination of matrix grains. This review paper addresses the microstructure development in BaBi4Ti4O15 and Bi4Ti3O12 prepared by the templated grain growth method and in Bi-0.5(Na1-xKx)(0.5-)TiO3 and K0.5Na0.5NbO3 textured by the reactive-templated grain growth method. The grains of these materials are faceted, and critical driving force is required for the growth of faceted grains. It is illustrated that the relative magnitude of the driving force of the template grains and the critical driving force determines the mode of grain growth behavior and the microstructure of the final products. A discussion on the grain growth behavior is presented to give the criteria for designing the preparation conditions. (C) 2016 The Ceramic Society of Japan. All rights reserved.

关键词： Textured ceramics Lead-free piezoelectrics Templated grain growth microstructure development Mechanisms

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NUMERICAL AND PHYSICAL MODELLING OF microstructure development DURING THE HOT ROLLING OF 30MnB4 STEEL ROUND BARS 25

NUMERICAL AND PHYSICAL MODELLING OF MICROSTRUCTURE DEVELOPME...

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25th Anniversary International Conference on Metallurgy and Materials (METAL)

作者： Laber, Konrad Dyja, Henryk Kawalek, Anna Koczurkiewicz, Bartosz Czestochowa Tech Univ Inst Plast Working & Safety Engn Fac Prod Engn & Mat Technol Czestochowa Poland

ISBN: (纸本)9788087294673

The paper presents the results of numerical and physical modelling of the development of microstructure during the process of hot rolling of 20 mm diameter plain round bars. The tests described in the paper were carried out for the technological conditions of a sample bar rolling mill. The material used for the tests was lowcarbon cold heading steel, 30MnB4. The numerical modelling studies were carried out using the FORGE (R) and QTSteel programs. For the physical modelling of the process under examination, the metallurgical process simulator GLEEBLE 3800 was employed.

关键词： Numerical modelling physical modelling microstructure development cold upsetting steel

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Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount

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CONSTRUCTION AND BUILDING MATERIALS 2014年 65卷 140-150页

作者： Yu, R. Spiesz, P. Brouwers, H. J. H. Eindhoven Univ Technol Dept Built Environm NL-5600 MB Eindhoven Netherlands

This paper presents the effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount. The design of UHPC is based on the modified Andreasen and Andersen particle packing model. The results reveal that by utilizing this packing model, a dense and homogeneous skeleton of UHPC can be obtained with a relatively low binder amount (about 440 kg/m(3)). Moreover, due to the high amount of superplasticizer utilized to produce UHPC in this study, the dormant period of the cement hydration is extended. However, due to the nucleation effect of nano-silica, the retardation effect from superplasticizer can be significantly compensated. Additionally, with the addition of nano-silica, the viscosity of UHPC significantly increases, which causes that more air is entrapped in the fresh mixtures and the porosity of the hardened concrete correspondingly increases. In contrary, due to the nucleation effect of nano-silica, the hydration of cement can be promoted and more C-S-H gel can be generated. Hence, it can be concluded that there is an optimal nano-silica amount for the production of UHPC with the lowest porosity, at which the positive effect of the nucleation and the negative influence of the entrapped air can be well balanced. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Ultra-High Performance Concrete (UHPC) Low binder amount Nano-silica Hydration microstructure development

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Modeling and Control Techniques for microstructure development

Modeling and Control Techniques for Microstructure Developme...

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5th International Conference on Mechanical, Industrial, and Manufacturing Technologies (MIMT)

作者： Karthikeyan, R. Ram, R. K. Ganesh Kalaichelvi, V. BITS Pilani Dept Mech Engn Dubai Campus Dubai U Arab Emirates BITS Pilani Dept EIE Dubai U Arab Emirates

ISBN: (纸本)9783038350552

True stress-strain data is obtained for 6061Al/ 10% SiC composites by hot compression test. Mathematical models for % volume of recrystallization and diameter of the recrystallized grains are developed with process parameters such as strain, strain rate and temperature. These models are applied for optimization of the grain size and % volume of recrystallization. An attempt has been made to control microstructure evolution during hot deformation using fuzzy logic controller through simulation in MATLAB software. The fuzzy logic controller parameters are tuned using genetic algorithm.

关键词： Metal matrix composites hot compression Regression analysis microstructure development Fuzzy Logic Controller Genetic Algorithm

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Extracting Three-Dimensional Cellular Automaton for Cement microstructure development using Gene Expression Programming 6

Extracting Three-Dimensional Cellular Automaton for Cement M...

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6th World Congress on Nature and Biologically Inspired Computing (NaBIC)

作者： Liang, Zhifeng Yang, Bo Wang, Lin Zhang, Xiaoqian He, Nana Abraham, Ajith Univ Jinan Shandong Prov Key Lab Network Based Intelligent C Jinan 250022 Peoples R China Tech Univ Ostrava IT4Innovat Ostrava Czech Republic MIR Labs Auburn WA USA

ISBN: (纸本)9781479959372

A three-dimensional CA model for the simulation of Portland cement microstructure development has been developed in this paper. The Gene Expression Programming (GEP) algorithm is employed as the learning algorithm to evolve the transition rule reversely from the microstructure development characteristic data due to hydration reactions. The characteristic data is extracted from 8-bit gray images that based on the processing of real cement acquired by Micro Computed Tomography (micro-CT) technology. Starting with initial micro-CT image, cement microstructure evolution images of 28 days is constructed through CA rule discovered by GEP. The experimental results show that this model with the CA rule designed by GEP has higher agreement between the model predictions and experimental measurements for degree of hydration than other models. Furthermore, this model still has good generalization ability when changing the water-cement ratio and chemical composition.

关键词： three-dimensional cellular automaton cement microstructure development gene expression programming reverse modeling

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microstructure development and Phase Evolution of Alumina-mullite Nanocomposite

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SCIENCE OF SINTERING 2013年第3期45卷 293-303页

作者： Sedaghat, A. Taheri-Nassaj, E. Soraru, G. D. Ebadzadeh, T. Tarbiat Modares Univ Dept Mat Sci & Engn Tehran Iran Univ Trento Dept Mat Engn & Ind Technol I-38050 Trento Italy Mat & Energy Res Ctr Tehran Iran

In this work, alumina-mullite composites (5-15 vol.%) were prepared using sol-gel derived alumina composite nanopowders. The results revealed the formation of intragranular and intergranular mullites inside and between the alumina grains, respectively. Accordingly, the intragranular mullites (average grain size, 0.3 mu m) were smaller than the intergranular mullites (average grain size, 0.5 mu m). Moreover, the alumina grains (average grain size, 1.0 mu m) are larger than the mullites. Meanwhile, the mullites showed positive results in the prevention of the alumina grains growth and the retardation of densification. The relative density of alumina-15 vol.% mullite that was sintered at 1650 degrees C for 2 h, was obtained as 98.7 %. After sintering at 1750 degrees C for 2 h, the mullite was decomposed.

关键词： Phase evolution microstructure development Alumina Mullite Nanocomposite

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