Microstructure Control of Porous In-Situ Synthesized Si2N2O-Si3N4 Ceramics

2007 ◽  
Vol 534-536 ◽  
pp. 1049-1052 ◽  
Author(s):  
Rajat Kanti Paul ◽  
Chi Woo Lee ◽  
Hai Doo Kim ◽  
Byong Taek Lee
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Extrusion Process ◽  
Filtration Efficiency ◽  
Carbon Addition ◽  
Microstructure Control ◽  
Sintering Additives ◽  
Network Type

Using 6wt%Y2O3-2wt%Al2O3 as sintering additives and Si as a raw powder, the continuously porous in-situ Si2N2O-Si3N4 bodies were fabricated by multi-pass extrusion process and their microstructures were investigated depending on the addition of carbon (0-9wt %) in the mixture powder. The introduction of Si2N2O fibers observed in the unidirectional continuous pores as well as in the pore-frame regions of the nitrided bodies can be an effective method in increasing the filtration efficiency. In the case of no carbon addition, the network type Si2N2O fibers with high aspect ratio appeared in the continuous pores with diameters of 150-200nm. However, in the case of 9wt% C addition, the fibers were found without any network type and had diameters of 200-250nm.

Laser in-situ synthesis of high aspect ratio TiB fiber bundle reinforced titanium matrix composite coating

2019 ◽  
Vol 115 ◽  
pp. 364-373 ◽  
Author(s):  
Yinghua Lin ◽  
Changchun Jiang ◽  
Zhenheng Lin ◽  
Qingtang Chen ◽  
Yongping Lei ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Composite Coating ◽  
Matrix Composite ◽  
High Aspect Ratio ◽  
Fiber Bundle ◽  
In Situ Synthesis ◽  
Titanium Matrix ◽  
Titanium Matrix Composite

Solidification Processing Routes to High Aspect Ratio Reinforcements in γ-TiAl

1990 ◽  
Vol 194 ◽  
Author(s):  
J. J. Valencia ◽  
J. P. A. Löfvander ◽  
J. Rösler ◽  
C. G. Levi ◽  
R. Mehrabian
Keyword(s):  
Solid Solution ◽  
Aspect Ratio ◽  
Creep Strength ◽  
High Aspect Ratio ◽  
Anisotropic Growth ◽  
Solidification Processing ◽  
Aspect Ratios ◽  
The Matrix ◽  
Solute Strengthening

AbstractAdditions of ∼5%B1 and ∼9%Ta to binary γ-TiAl result in the formation of a monoboride isomorphous with TiB but containing Ta in solid solution. This boride exhibits strongly anisotropic growth from the melt, producing rod-like primary phases which are of potential interest for creep strengthening of the γ matrix. Fibrous borides with aspect ratios larger than ∼20 and volume fractions of ∼0.12 have been produced in arc-melted Ti-48AI-9Ta-4.3B alloys. Creep testing at 1255 K indicates that these “in-situ” composites have much higher creep strength than γ-TiAl, but the contribution of the reinforcements is relatively small compared with the solute-strengthening of the matrix.

Synthesis and Photoelectrocatalytic Property of Two-Nonmetal-Codoped TiO2 Nanotube Arrays with High Aspect Ratio

2011 ◽  
Vol 412 ◽  
pp. 219-222 ◽  
Author(s):  
Hai Da Liao ◽  
Wei Ping Zhang ◽  
Xiao Ming Sun ◽  
Liang Shi ◽  
Ming Feng Qin
Keyword(s):  
Methyl Orange ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Mixed Crystal ◽  
Nanotube Arrays ◽  
Xenon Lamp ◽  
Metallic Elements ◽  
Nanotube Array ◽  
Natural Lighting

Electrolyte containing F–was employed to conduct two-step anodic oxidation. Through adjustment of the composition of electrolyte, TiO2nanotube array with high aspect ratio was grown in situ on Ti matrix, and meanwhile the binary doping with non-metallic elements, namely, F and S, was achieved. Using FSEM, XRD and EDS, the characterization on the topography, structure and doped elements of TiO2nanotubes were performed. Taking methyl orange as the target degradation substance and using xenon lamp to simulate natural lighting, the comparison between the doped non-high-aspect-ratio nanotube and the doped high-aspect-ratio nanotube was made to investigate the related photoelectrocatalytic property. The results showed that the photoelectrocatalytic property of doped nanotube with high aspect ratio was significantly superior to that with non-high aspect ratio. The mixed crystal ratio of anatase and rutile obtained after calcination for 2h at 500°C enabled higher photoelectrocatalytic activity of TiO2nanotube array.

scholarly journals Microfabrication of High-Aspect Ratio KNN Lead-Free Piezoceramic Pillar Arrays by Aqueous Gelcasting

Ceramics ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 287-296
Author(s):  
Cailing Wu ◽  
Benke Li ◽  
Xiaofeng Wang ◽  
Feng Ji ◽  
Dou Zhang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Lead Free ◽  
Solid Loading ◽  
High Mechanical Strength ◽  
Pillar Array ◽  
Novel Approach ◽  
Pillar Arrays ◽  
Gelcasting Process

The present paper reported a novel approach for the fabrication of a high-aspect ratio (K, Na)NbO3 (KNN) piezoelectric micropillar array via epoxy gelcasting, which involves the in situ consolidation of aqueous KNN suspensions with added hydantoin epoxy resin on a polydimethylsiloxane (PDMS) soft micromold. KNN suspensions with solid loadings of up to 45.0 vol.% have rheological behavior, which was suitable for the gelcasting process. The uniform green KNN bodies derived from the optimized suspension of 42.0 vol.% solid loading and 15.0 wt.% resin had exceptionally high mechanical strength (9.14 MPa), which was responsible for the integrity of the piezoceramic micropattern structure. The square-shaped KNN piezoelectric pillar array with lateral dimensions of up to 5 μm and an aspect ratio of up to five was successfully fabricated.

scholarly journals Thin-Rib and High Aspect Ratio Non-Stochastic Scaffolds by Vacuum Assisted Investment Casting

2019 ◽  
Vol 3 (2) ◽  
pp. 34
Author(s):  
Vitor H. Carneiro ◽  
Hélder Puga ◽  
Nuno Peixinho ◽  
José Meireles
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Aspect Ratio ◽  
Investment Casting ◽  
High Aspect Ratio ◽  
Cellular Materials ◽  
Investment Model ◽  
Transportation Industry ◽  
Small Deviations

Cellular structures are a classic route to obtain high values of specific mechanical properties. This characteristic is advantageous in many fields, from diverse areas such as packaging, transportation industry, and/or medical implants. Recent studies have employed additive manufacturing and casting techniques to obtain non-stochastic cellular materials, thus, generating an in situ control on the overall mechanical properties. Both techniques display issues, such as lack of control at a microstructural level in the additive manufacturing of metallic alloys and the difficulty in casting thin-rib cellular materials (e.g., metallic scaffolds). To mitigate these problems, this study shows a combination of additive manufacturing and investment casting, in which vacuum is used to assist the filling of thin-rib and high aspect-ratio scaffolds. The process uses 3D printing to produce the investment model. Even though, vacuum is fundamental to allow a complete filling of the models, the temperatures of both mold and casting are important to the success of this route. Minimum temperatures of 250 °C for the mold and 700 °C for the casting must be used to guarantee a successful casting. Cast samples shown small deviations relatively to the initial CAD model, mainly small expansions in rib length and contraction in rib thickness may be observed. However, these changes may be advantageous to obtain higher values of aspect ratio in the final samples.

Simulation of arsenic in situ doping with polysilicon cvd and its application to high aspect ratio trenches

2003 ◽  
Vol 22 (3) ◽  
pp. 285-292 ◽  
Author(s):  
C. Heitzinger ◽  
W. Pyka ◽  
N. Tamaoki ◽  
T. Takase ◽  
T. Ohmine ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio
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