scholarly journals Debinding and Presintering of High Aspect Ratio Microbi-Lumen Tubes Produced by Extrusion of 17-4PH Feedstock

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Sandeep Kuriakose ◽  
Salvatore Cataldo ◽  
Paolo Parenti ◽  
Massimiliano Annoni
Keyword(s):  
Aspect Ratio ◽  
Structural Properties ◽  
Surface Finish ◽  
High Aspect Ratio ◽  
Three Dimensional ◽  
Processing Technologies ◽  
Green State ◽  
Aspect Ratios ◽  
Recent Developments ◽  
Thermal Debinding

Abstract Recent developments have showcased that micro-extrusion of feedstock can be used for manufacturing metallic microbi-lumen tubes with very high length-to-diameter aspect ratios, which are not viable by conventional metal extrusion or commonly used feedstock processing technologies like injection molding or hot pressing. The extrusion of high aspect ratio microcomponents faces the challenge of maintaining the geometrical accuracy, surface finish, and structural properties since the micro-extrusion in green state is followed by debinding and sintering operations, which result in shrinkage and variations in surface finish and structure. The stages of the process chain such as solvent/thermal debinding (TD), to remove the polymeric binder, and presintering (PS), to achieve a mild structural rigidity before the sintering, are of critical importance to achieve the surface and structural properties of high aspect ratio microparts and have not been yet studied in case of micro-extrusion of feedstock. In this study, the effect of debinding and PS on surface and structural properties of bi-lumen tubes processed at different extrusion conditions is discussed. Surface roughness of the tubes is analyzed using three-dimensional microscopy, and structural properties are studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The debinding and PS experiments on extruded microbi-lumen tubes retained very good surfaces integrity without any cracks or defects. The study shows that the interactions of extrusion temperature and extrusion velocity influence the surface finish of the extruded tubes the most. The sintered bi-lumen samples showed a good areal surface finish, Sa of 2.21 μm, which is near to the green state value confirming the suitability of the applied debinding and PS parameters.

scholarly journals Effect of Feedstock Properties on Extrusion of High Aspect Ratio Microbi-Lumen Tubes

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Sandeep Kuriakose ◽  
Paolo Parenti ◽  
Massimiliano Annoni
Keyword(s):  
Aspect Ratio ◽  
Structural Properties ◽  
Surface Finish ◽  
High Aspect Ratio ◽  
Research Work ◽  
Three Dimensional ◽  
Extrusion Process ◽  
Powder Size ◽  
Scanning Calorimetry ◽  
Processing Technologies

Abstract The micro-extrusion of feedstock is a promising and emerging technology for manufacturing very high length to thickness aspect ratio metallic microcomponents which are not feasible for conventional metal processing methodologies or commonly used feedstock processing technologies. Extrusion of high aspect ratio microcomponents using metallic feedstock confronts the challenges of achieving a continuous extrusion without any breakage, the geometrical accuracy, surface finish and structural properties for the component which are required for the micro-application, during micro-extrusion process. The type of metallic powder, powder size, type of binder, and binder properties are very decisive in making the extrusion process feasible for the micro-application. The influence of feedstock properties on micro-extrusion of high aspect ratio microcomponents are still unknown in case of micro-extrusion of feedstock. In this research work, the effect of type of feedstock on micro-extrusion is studied by extruding microbi-lumen tubes using biocompatible steel feedstocks AISI316 L and 17-4PH at two different aging states (no aging and 1.5 years aging). The geometrical features of the extruded bi-lumen tubes, surface roughness and structural properties are analyzed using three-dimensional (3D) focus variation microscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The analysis showed that feedstock type affects the feasibility of extrusion and geometrical size to a great extent. An average Sa roughness deviation from 1.73 to 4.57 μm was observed for feedstocks 17-4PH and AISI316 L. The study also confirms that binder properties and aging of the feedstocks also have to be taken into account for maintaining the surface finish and structural properties in case of metallic feedstock extrusion of high aspect ratio bi-lumen tubes.

Stress Intensity Factors for High Aspect Ratio Semi-Elliptical External Surface Cracks in Cylindrical Vessels

2014 ◽  
Vol 986-987 ◽  
pp. 882-886
Author(s):  
Hong Yu Qi ◽  
Peng Chao Guo
Keyword(s):  
Stress Intensity ◽  
Aspect Ratio ◽  
Stress Intensity Factors ◽  
High Aspect Ratio ◽  
External Surface ◽  
Superposition Principle ◽  
Three Dimensional ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Aspect Ratios

External surface cracks can occur in cylindrical vessels due to damage and propagate in the manufacturing process and during service life. Most of research focuses on stress intensity factors for surface cracks with low aspect ratios, i.e., a/c ≤1.0. Situation may well arise where the aspect ratio of cracks is larger than one. An external longitudinal surface crack is assumed to be subjected to different types of hoop stress distributions acting perpendicular to the crack faces. The stress intensity factors (SIFs) along the crack front were determined through the three-dimensional finite element method. Then these results are used to compute approximate values of SIFs in the case of complex loadings by employing both the superposition principle and the power series expansions of the actual hoop stresses. It is found that the maximum stress intensity factor for external surface cracks with high aspect ratio occurs at different point to that with low aspect ratio.

scholarly journals Strength Analysis of Alternative Airframe Layouts of Regional Aircraft on the Basis of Automated Parametrical Models

Aerospace ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 80
Author(s):  
Dmitry V. Vedernikov ◽  
Alexander N. Shanygin ◽  
Yury S. Mirgorodsky ◽  
Mikhail D. Levchenkov
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Performance ◽  
Strength Analysis ◽  
Labor Input ◽  
Aerodynamic Loading ◽  
Aspect Ratios ◽  
Wide Range ◽  
Parametrical Design

This publication presents the results of complex parametrical strength investigations of typical wings for regional aircrafts obtained by means of the new version of the four-level algorithm (FLA) with the modified module responsible for the analysis of aerodynamic loading. This version of FLA, as well as a base one, is focused on significant decreasing time and labor input of a complex strength analysis of airframes by using simultaneously different principles of decomposition. The base version includes four-level decomposition of airframe and decomposition of strength tasks. The new one realizes additional decomposition of alternative variants of load cases during the process of determination of critical load cases. Such an algorithm is very suitable for strength analysis and designing airframes of regional aircrafts having a wide range of aerodynamic concepts. Results of validation of the new version of FLA for a high-aspect-ratio wing obtained in this work confirmed high performance of the algorithm in decreasing time and labor input of strength analysis of airframes at the preliminary stages of designing. During parametrical design investigation, some interesting results for strut-braced wings having high aspect ratios were obtained.

Accelerating ion diffusion with unique three-dimensionally interconnected nanopores for self-membrane high-performance pseudocapacitors

Nanoscale ◽  
2017 ◽  
Vol 9 (46) ◽  
pp. 18311-18317 ◽  
Author(s):  
Yuan Gao ◽  
Yuanjing Lin ◽  
Zehua Peng ◽  
Qingfeng Zhou ◽  
Zhiyong Fan
Keyword(s):  
Aspect Ratio ◽  
Surface Area ◽  
Structural Stability ◽  
High Aspect Ratio ◽  
High Performance ◽  
Three Dimensional ◽  
Rate Capability ◽  
Large Surface Area ◽  
Nanoporous Structure ◽  
Ion Diffusion

Three-dimensional interconnected nanoporous structure (3-D INPOS) possesses high aspect ratio, large surface area, as well as good structural stability. Profiting from its unique interconnected architecture, the 3-D INPOS pseudocapacitor achieves a largely enhanced capacitance and rate capability.

scholarly journals Self-ordered nanospike porous alumina fabricated under a new regime by an anodizing process in alkaline media

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mana Iwai ◽  
Tatsuya Kikuchi ◽  
Ryosuke O. Suzuki
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Porous Alumina ◽  
Three Dimensional ◽  
Alkaline Media ◽  
Alkaline Electrolyte ◽  
Subsequent Formation ◽  
Interpore Distance ◽  
Wide Range ◽  
Ordered Porous

AbstractHigh-aspect ratio ordered nanomaterial arrays exhibit several unique physicochemical and optical properties. Porous anodic aluminum oxide (AAO) is one of the most typical ordered porous structures and can be easily fabricated by applying an electrochemical anodizing process to Al. However, the dimensional and structural controllability of conventional porous AAOs is limited to a narrow range because there are only a few electrolytes that work in this process. Here, we provide a novel anodizing method using an alkaline electrolyte, sodium tetraborate (Na2B4O7), for the fabrication of a high-aspect ratio, self-ordered nanospike porous AAO structure. This self-ordered porous AAO structure possesses a wide range of the interpore distance under a new anodizing regime, and highly ordered porous AAO structures can be fabricated using pre-nanotexturing of Al. The vertical pore walls of porous AAOs have unique nanospikes measuring several tens of nanometers in periodicity, and we demonstrate that AAO can be used as a template for the fabrication of nanomaterials with a large surface area. We also reveal that stable anodizing without the occurrence of oxide burning and the subsequent formation of uniform self-ordered AAO structures can be achieved on complicated three-dimensional substrates.

scholarly journals A novel fabrication technique for high-aspect-ratio nanopillar arrays for SERS application

RSC Advances ◽  
2020 ◽  
Vol 10 (73) ◽  
pp. 45037-45041
Author(s):  
Tianli Duan ◽  
Chenjie Gu ◽  
Diing Shenp Ang ◽  
Kang Xu ◽  
Zhihong Liu
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Fabrication Technique ◽  
Novel Technique ◽  
Aspect Ratios ◽  
Nanopillar Arrays

A novel technique is demonstrated for the fabrication of silicon nanopillar arrays with high aspect ratios.

scholarly journals Saturation Profile Based Conformality Analysis for Atomic Layer Deposition: Aluminum Oxide in Lateral High-Aspect-Ratio Channels

2020 ◽  
Author(s):  
Jihong Yim ◽  
Oili Ylivaara ◽  
Markku Ylilammi ◽  
Virpi Korpelainen ◽  
Eero Haimi ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Atomic Layer Deposition ◽  
High Aspect Ratio ◽  
Atomic Layer ◽  
Profile Measurement ◽  
Aspect Ratios ◽  
New Information ◽  
Layer Deposition ◽  
Rectangular Channels ◽  
Saturation Profile

<p>ABSTRACT: Atomic layer deposition (ALD) raises global interest through its unparalleled conformality. This work describes new microscopic lateral high-aspect-ratio (LHAR) test structures for conformality analysis of ALD. The LHAR structures are made of silicon and consist of rectangular channels supported by pillars. Extreme aspect ratios even beyond 10 000:1 enable investigations where the adsorption front does not penetrate to the end of the channel, thus exposing the saturation profile for detailed analysis. We use the archetypical trimethylaluminum (TMA)-water ALD process to grow alumina as a test vehicle to demonstrate the applicability, repeatability and reproducibility of the saturation profile measurement and to provide a benchmark for future saturation profile studies. Through varying the TMA reaction and purge times, we obtained new information on the surface chemistry characteristics and the chemisorption kinetics of this widely studied ALD process. We propose new saturation profile related classifications and terminology. </p>

Focused Ion Beam: Advanced Technique for Device Modification

1994 ◽  
Vol 337 ◽  
Author(s):  
Marsha Abramo ◽  
Loren Hahn
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Materials ◽  
Advanced Technique ◽  
Aspect Ratios ◽  
Chip Technology ◽  
Design Changes ◽  
Critical Feedback

ABSTRACTFocused ion beam (FIB) technology is used to modify circuits for early-product design debug; it also has the capability to create probe points to underlying metallurgy, allowing device characterization while maintaining full functionality. These techniques provide critical feedback to designers for rapid verification of proposed design changes.Current FIB technology has its limitations because of redeposition of sputtered material; this phenomena may induce vertical electrical shorts and limit the achievable aspect ratio of a milled via to 6:1. Therefore, innovative enhancements are required to provide modification capability on planar chip technology which may utilize up to five levels of metallurgy. The ability to achieve high-aspect-ratio milling is required to access underlying circuitry. Vias with aspect ratios of 10:1 are necessary in some cases.This paper reviews a gas-assisted etching (GAE) process that enhances FIB milling by volatilizing the sputtered material, examines the results obtained from utilizing the GAE process for high-aspect-ratio milling, and discusses selectivity of semiconductor materials (silicon, aluminum, tungsten and silicon dioxide).

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