Journal ArticleDOI
Graded compositions and microstructures by infiltration processing
B. R. Marple,David J. Green +1 more
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TLDR
In this article, an electron microprobe analysis was performed to obtain concentration profiles across sections of the sintered composites and it was concluded that while the presence of mullite limits grain growth in alumina, the mullite content must be at least ∼5 % in order for grain growth to occur in a controlled fashion.Abstract:
Mullite/alumina particulate composites were fabricated by infiltrating porous alumina preforms with an SiO2-containing sol followed by a heating step to cause mullite formation and densification. Electron microprobe analysis was performed to obtain concentration profiles across sections of the sintered composites. These analyses revealed the existence of concentration gradients, the mullite content decreasing with increasing distance from the surface of the bodies. Analyses with a scanning electron microscope also indicated a microstructural effect; the alumina grain size in composite bodies tended to increase with distance from the surface of the sample. These two effects (microstructural and compositional) have been related and it has been concluded that while the presence of mullite limits grain growth in alumina, the mullite content must be at least ∼5 wt % in order for grain growth to occur in a controlled fashion. The results point out the potential of the infiltration approach as a means for tailoring the composition and microstructure of ceramic bodies.read more
Citations
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Journal ArticleDOI
Processing techniques for functionally graded materials
TL;DR: The importance of modeling of gradient formation, sintering and drying for the production of defect-free parts with predictable gradients in microstructure is discussed, and examples of a successful application of numerical simulations to the processing of functionally graded materials are given.
Book ChapterDOI
Processing and Fabrication
TL;DR: Since the mid-1980s the processing of FGM materials and structures has become of increasing academic interest, and the spectrum of processing options ranges from methods already established before FGMs became a well-defined subject, to more recently developed methods, such as solid freeform fabrication.
Journal ArticleDOI
Transmutation of Actinides
TL;DR: In this paper, an advanced process has been developed on a laboratory scale at the Institute for Transuranium Elements (ITU) for the fabrication of transmutation fuels and targets.
Journal ArticleDOI
Graded Casting of Materials with Continuous Gradients
Basil R. Marple,Jean Boulanger +1 more
TL;DR: In this article, a process is introduced for producing continuously graded materials by slip casting with a continuous flow of slip of changing composition, and the approach has been tested using alumina and zirconia slips to produce alumina composites with a graded composition.
Journal ArticleDOI
Fabrication of fine-grained alumina ceramics by a novel process integrating stereolithography and liquid precursor infiltration processing
Wei Liu,Haidong Wu,Zhou Maopeng,Rongxuan He,Qiangguo Jiang,Wu Ziwei,Yanling Cheng,Xuan Song,Yong Chen,Shanghua Wu +9 more
TL;DR: In this paper, a novel approach, integrating stereolithography and liquid precursor infiltration techniques, was reported to fabricate fine-grained alumina ceramics, which contained Al2O3 and t-ZrO2 as the major phase and minor phase, respectively.
References
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Journal ArticleDOI
Hindrance of Grain Growth in Al2O3 by ZrO2 Inclusions.
TL;DR: In this article, a colloidal mixture of Al2O3/ZrO2 composite powders was mixed and consolidated by a colloid method, sintered to >98% theoretical density at 1550°C, and subsequently heat-treated at temperatures up to 1700°C for grain-size measurements.
Journal ArticleDOI
Mullite/Alumina Particulate Composites by Infiltration Processing
Basil R. Marple,David J. Green +1 more
TL;DR: In this paper, a method was developed for incorporating mullite into alumina by infiltrating an alumina preform with a prehydrolyzed ethyl silicate solution, followed by heating to decompose the infiltrant, form mullite, and densify the mullite/alumina composite.
Journal ArticleDOI
Mullite/Alumina Particulate Composites by Infiltration Processing: III, Mechanical Properties
Basil R. Marple,David J. Green +1 more
TL;DR: The effect of incorporating mullite into alumina by an infiltration process on the mechanical properties was investigated in this paper, where data for Young's modulus, strength and fracture toughness for various composite compositions were compared with those for the unreinforced matrix (alumina).
Journal ArticleDOI
Crack Stability and T‐Curves Due to Macroscopic Residual Compressive Stress Profiles
Rajan Tandon,David J. Green +1 more
TL;DR: In this article, the possibility of using residual compressive stresses to induce crack stabilization is examined theoretically nonmonotonic forms for the residual compressed stress profiles are assumed The stress intensity factors for linear through-the-thickness cracks subjected to these profiles are derived and then used to construct the T-curves for the stress profiles considered.
Journal ArticleDOI
Mullite Alumina Particulate Composites by Infiltration Processing: II, Infiltration and Characterization
Basil R. Marple,David J. Green +1 more
TL;DR: In this paper, the authors show that initial infiltration occurred without complete filling of the porosity by the sol, which led to blockage of the pores in the surface of the preform.
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