Modeling Tape Cast Ceramics With Multiple Layers of Fugitive Phase Materials

2012 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Ming-Jen Pan ◽  
Virginia G. DeGiorgi ◽  
Edward P. Gorzkowski ◽  
Alan C. Leung
Keyword(s):  
Ceramic Body ◽  
Experimental Investigations ◽  
Green Body ◽  
Ceramic Component ◽  
Viscoelastic Deformation ◽  
Ceramic Phase ◽  
Precise Control ◽  
Phase Approach ◽  
New Processing ◽  
Tape Cast

The fabrication of complex ceramic components requires new processing methods that are able to produce components with intricate geometries and accurate dimensions. The accuracy of the finished ceramic component depends upon precise control of the green ceramic body dimensions and uniformity prior to sintering. The authors are investigating the application of the fugitive phase approach, where a sacrificial material is used to form cavities or channels in the finished ceramic component. This paper, a continuation of a previous work, examines the lamination step of the fugitive phase approach for ceramic fabrication. The lamination step is where the fugitive phase pieces are combined with the tape cast green ceramic pieces. The multilayer green body is pressed to laminate the ceramic tape and fugitive phase layers together. Topological complexity is greatly increased when the tape cast ceramic pieces are interspersed with fugitive phase pieces to build up a consolidated multilayer green body. This paper examines the movement of the fugitive phase pieces, viscoelastic deformation of the ceramic phase, the filling of voids, pressure gradients, and the rebounding that occurs when the green ceramic body is removed from the press. This information will be used to complement parallel experimental investigations of the fugitive phase approach to ceramic fabrication.

Modeling the Lamination of a Multilayered Tape Cast Ceramic Component With Fugitive Phases Before Sintering

2015 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Virginia G. DeGiorgi ◽  
Edward Gorzkowski
Keyword(s):  
Complex Geometry ◽  
Layer Structure ◽  
Ceramic Body ◽  
Dimensional Accuracy ◽  
Ceramic Component ◽  
Viscoelastic Deformation ◽  
Phase Layer ◽  
Phase Approach ◽  
Micro Channels ◽  
Tape Cast

A small finished ceramic component with micro-channels or other complex geometry requires a high degree of dimensional accuracy. The accuracy of the finished ceramic component depends upon the accuracy of the unfired ceramic body before sintering. One approach to creating micro-channels in ceramics is the fugitive phase approach. In this approach a sacrificial material is placed within the unfired ceramic to form channels or voids. The fugitive phase is removed or sacrificed during the subsequent sintering. For this paper, the authors examine the lamination step of the fugitive phase approach computationally. In the lamination step layers of unfired tape cast ceramic and layers of fugitive phase material are pressed together before sintering. The geometry examined in this paper is a quarter-symmetry model of a ten ceramic layer and nine fugitive phase layer structure. Three dimensional modeling is used to capture out of plane motion, displacement of the fugitive phase pieces, viscoelastic deformation, and rebounding when the layered structure is removed from the die press. The unfired ceramic is modeled as tape cast mullite and the fugitive phase is paper. The fugitive phase is modeled as linear elastic while the unfired ceramic is modeled as viscoelastic at a range of temperatures. The authors examine the filling of voids, pressure gradients, and conditions during unloading.

Three Dimensional Modeling of the Lamination of Unfired Ceramics With Fugitive Phases

2014 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Ming-Jen Pan ◽  
Virginia G. DeGiorgi
Keyword(s):  
Ceramic Body ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Pressure Gradients ◽  
Viscoelastic Deformation ◽  
Ceramic Phase ◽  
Phase Approach ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Ceramic Components

The dimensional accuracy of finished ceramic components depends upon the precise control of the unfired ceramic body prior to sintering. One approach for creating precise geometries is the fugitive phase approach. In the fugitive phase approach, the fugitive phase is a sacrificial material that can be removed to form channels in the finished ceramic component. In this paper, the authors computationally examine the fugitive phase approach; in particular, the lamination step of the fugitive phase approach is modeled. In the lamination step the unfired ceramic phases are combined with the fugitive phases through the application of pressure. For this research, the unfired ceramic phase consists of tape cast mullite and the fugitive phase is paper. These phases are laminated together in a die press to form a multilayer material. The compression of the die press causes pressure gradients, viscoelastic deformation, and rebounding of the unfired ceramic phases. In addition, the die press can cause movement of the fugitive phase pieces leaving unfilled voids. Three dimensional modeling is necessary to accurately capture the movement of the fugitive phase pieces. In this work the authors examine the viscoelastic deformation of the unfired ceramic phase, movement of the fugitive phase, the creation and filling of voids, pressure gradients, and the rebounding that occurs when the unfired ceramic body is removed from the die press. The information obtained from computational simulations will be used to help direct experimental investigations of the fugitive phase approach for fabrication of complex ceramic components.

Three Dimensional Modeling of Unfired Ceramics During Lamination

2014 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Ming-Jen Pan ◽  
Virginia G. DeGiorgi
Keyword(s):  
Ceramic Body ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Pressure Gradients ◽  
Viscoelastic Deformation ◽  
Ceramic Phase ◽  
Phase Approach ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Micro Channels

A finished ceramic component with complex geometries such as micro-channels requires a high degree of dimensional accuracy. This accuracy depends upon precise control of the unfired ceramic body before sintering. One method for creating precise micro-channel geometries is the fugitive phase approach. In this approach, a sacrificial material, the fugitive phase, is used to form channels or voids in the unfired ceramic body. The fugitive phase is removed or sacrificed during the subsequent sintering. For this paper, the authors examine the lamination step of the fugitive phase approach computationally. The lamination step is where the unfired ceramic and fugitive phase pieces are layered and pressed together to remove voids before sintering. The compression of the unfired ceramic during pressing causes pressure gradients, viscoelastic deformation, displacement of the fugitive phase pieces, and rebounding. Three dimensional modeling is used to capture out of plane movement or bending of the long fugitive phase pieces that are used to form long micro-channels. For this research, the unfired ceramic phase consists of tape cast mullite and the fugitive phase is paper. This work primarily examines viscoelastic material models of the unfired ceramic phase for a range of temperatures. The filling of voids, movement of the fugitive phases, pressure gradients, and the rebounding that occurs when the unfired ceramic body is removed from the die press are also noted. The information obtained from computational simulations is used to help direct concurrent experimental investigations.

Computational Modeling of Fugitive Phase Rotations Within Tape Cast Ceramics

2011 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Ming-Jen Pan
Keyword(s):  
Strain Energy ◽  
Fabrication Process ◽  
Experimental Investigations ◽  
Sintering Process ◽  
Phase Approach ◽  
Ceramic Components ◽  
Lamination Process ◽  
Carry Over ◽  
Geometric Layout ◽  
Tape Cast

For complex ceramic parts, new fabrication methods, such as the fugitive phase approach, are required. A common problem in the creation of ceramic parts is obtaining accurate dimensions of the final part. The sintering process makes it very difficult to create precise complex geometries. Tolerances achieved with green ceramics do not carry over to acceptable tolerances on the finished part due to non-uniform shrinkage and warping. The authors are investigating the application of the fugitive phase processing method, which might be able to fabricate topologically complex monolithic ceramic parts with precise tolerances. This paper is a continuation of previous work and examines the lamination step of the fugitive phase approach ceramic fabrication process; the step in which the fugitive phase material is integrated with the green ceramic material. In this step, the pressing along with the geometric layout of the fugitive phase material create an uneven pressure distribution in the green ceramic. Of particular concern is the rotation of the fugitive phase materials during the lamination step. A computational model of the lamination process is used to examine how the plasticity of the fugitive phase material along with computational boundary conditions affect the geometry of the green ceramic produced at the end of the lamination step prior to sintering. The resulting stress, strain energy, and deformed shapes are examined and compared. This information will be used to adjust the experimental investigations of the fugitive phase approach ceramic fabrication process that is working to create topologically complex ceramic components.

Preparation of N-Methylpolyborosilazane -Derived Bulk Si-B-N-C Ceramics by Warm-Pressing and Pressureless Pyrolysis

2012 ◽  
Vol 557-559 ◽  
pp. 1148-1151
Author(s):  
Zhen Quan Liu ◽  
Jing Zhang ◽  
Xian Xing Qiu ◽  
Yu Qing Peng ◽  
Ke Qing Han ◽  
...  
Keyword(s):  
High Temperature ◽  
Ceramic Body ◽  
Thermo Gravimetric Analysis ◽  
Amorphous Structure ◽  
Cross Linking ◽  
Gravimetric Analysis ◽  
Green Body ◽  
Thermo Gravimetric ◽  
Temperature Resistance ◽  
Bulk Ceramic

Additive-free bulk Si-B-N-C ceramics were prepared by pyrolysis of preceramic precursor (PBS-Me), which mainly involves cross linking, warm-pressing and pyrolysis. The density of crack-free bulk ceramic attains 1.94 g/cm3 when Calcined at 1300 °C. The shaped workpieces exhibit amorphous structure even be pyrolysised at 1400°C in N2, and there are some pores existing in the green body derived from warm-pressing and the resulting Si-B-N-C ceramic body, and these pores allow the gaseous byproducts be expeled from bodies. The pyrolyzed samples were studied by high temperature thermo gravimetric analysis, it shows that the Si-B-N-C body had an excellent high temperature resistance.

New Low-Toxic PEG(200)DMA/AM Gel System for 3YSZ Gel-Casting

2014 ◽  
Vol 602-603 ◽  
pp. 159-163
Author(s):  
Hai Yan Wu ◽  
Heng Lu ◽  
Zhi Jie Liao ◽  
Feng Xia ◽  
Jian Zhong Xiao
Keyword(s):  
Flexural Strength ◽  
Ceramic Body ◽  
Monomer Concentration ◽  
Solid Loading ◽  
Green Body ◽  
Gel Casting ◽  
Body Strength ◽  
Low Toxic ◽  
Poly Ethylene ◽  
Gel System

Gel-casting is promising in fabricating uniform and complex-shaped ceramic body, but it is confined in industrial application for the neurotoxic acrylamid (AM) gel system. Ether-contained oligomer poly(ethylene glycol)(200) dimethacrylate (PEG(200)DMA) with methacrylate end-group on either side of the long chain can act as cross-linking agent in free radical polymerization to form branchy gel network structure, which improves the green body strength. In this study, low-toxic PEG(200)DMA was chosen as the main binder and crosslinker and small dosage AM was applied to adjust the viscosity of the ceramic slurry to gel-cast 3YSZ (PEG(200)DMA: AM = 4:1, mass ratio). Influence of monomer concentration, dispersant concentration and solid loading on the rheological behavior of the slurry and the flexural strength of the green body were investigated using aqueous PEG(200)DMA/AM gel system to gel-cast 3YSZ. The results show that the flexural strength of green bodies notably increases with the increasing of monomer concentration and reaches high up to 14.4 MPa when gel-cast 3YSZ ceramics using PEG(200)DMA/AM gel system with appropriate amount of PAA-NH4, monomer and solid loading. This gel system obviously reduces the toxicity of the conventional AM system and, at the same time, ensures high flexural strength of green bodies.

scholarly journals The influence of supercritical foaming conditions on properties of polymer scaffolds for tissue engineering

2017 ◽  
Vol 38 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Katarzyna Kosowska ◽  
Marek Henczka
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Process Parameters ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Porous Structures ◽  
Static Compression ◽  
Precise Control ◽  
Foaming Process ◽  
Supercritical Foaming

Abstract The results of experimental investigations into foaming process of poly(ε-caprolactone) using supercritical CO2 are presented. The objective of the study was to explore the aspects of fabrication of biodegradable and biocompatible scaffolds that can be applied as a temporary three-dimensional extracellular matrix analog for cells to grow into a new tissue. The influence of foaming process parameters, which have been proven previously to affect significantly scaffold bioactivity, such as pressure (8-18 MPa), temperature (323-373 K) and time of saturation (1-6 h) on microstructure and mechanical properties of produced polymer porous structures is presented. The morphology and mechanical properties of considered materials were analyzed using a scanning electron microscope (SEM), x-ray microtomography (μ-CT) and a static compression test. A precise control over porosity and morphology of obtained polymer porous structures by adjusting the foaming process parameters has been proved. The obtained poly(ε-caprolactone) solid foams prepared using scCO2 have demonstrated sufficient mechanical strength to be applied as scaffolds in tissue engineering.

scholarly journals Characterization of Particle Orientation in Tape Cast Alumina Green Body Using a Polarizing Microscopy.

2003 ◽  
Vol 40 (3) ◽  
pp. 163-168 ◽  
Author(s):  
Hiroya Abe ◽  
Kenji Okamoto ◽  
Tadashi Hotta ◽  
Makio Naito ◽  
Keizo Uematsu
Keyword(s):  
Particle Orientation ◽  
Green Body ◽  
Polarizing Microscopy ◽  
Tape Cast

Fabrication of Tapered Bio Mimetic Cilia Using Bulk Lithography and Ceramic Mold

2014 ◽  
Author(s):  
Chandrashekar V. Adake ◽  
Parag Bhargava ◽  
Prasanna S. Gandhi ◽  
Bhargava Kashyap
Keyword(s):  
Soft Lithography ◽  
Ceramic Body ◽  
Aqueous Suspension ◽  
Slip Casting ◽  
Single Layer ◽  
Ceramic Mold ◽  
Green Body ◽  
Polydimethyl Siloxane ◽  
Casting Technique ◽  
Negative Impression

This paper presents fabrication of tapered, high aspect ratio bio mimetic cilia from Nickel-polydimethyl siloxane (Ni-PDMS) composite by using bulk lithography technique and ceramic molding. Many research groups suggested fabrication of bio mimetic cilia using various techniques which are based on soft lithography and VLSI techniques. Recently a novel single layer micro fabrication technique known as ‘bulk lithography’ which uses an unconstrained photopolymer has been reported by co-authors. This technique is used to fabricate a polymer cilia pattern (an array of photopolymerised inverted cone profile) and using this pattern a ceramic green body is fabricated by slip casting technique. An aqueous suspension containing sub micron size alumina is used to cast ceramic green body. After casting this cilia pattern makes negative impression of tapered holes on green ceramic body. During sintering of green ceramic body the polymer burns off resulting in ceramic mould with tapered holes imprinted on it. This mold retains shape of a tapered hole though it shrinks in size after sintering. This mold is used further to cast Ni-PDMS composite in the form of cilia structures.

scholarly journals Research on Nonlinear Control Method of Underactuated Gantry Crane Based on Machine Vision Positioning

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 987 ◽  
Author(s):  
Shi ◽  
Li ◽  
Bai ◽  
Huang
Keyword(s):  
Machine Vision ◽  
Control Method ◽  
Equilibrium Points ◽  
Gantry Crane ◽  
Experimental Investigations ◽  
Underactuated System ◽  
Precise Positioning ◽  
Precise Control ◽  
Vision Positioning ◽  
Load Swing

The movement of the gantry crane is controlled by an symmetry underactuated system, and has poor robustness in precise positioning. A new active control method based on the machine vision positioning is proposed in this paper, and the trajectories are planned after the detection of starting and ending points. A new type of energy storage function is given in this paper, and a coupling control law is derived to minimize the load swing in the process of precise positioning. The equilibrium point of the closed-loop system is checked though Lyapunov and LaSalle’s theorems, and the calculation results are verified through experimental investigations. The results show that the equilibrium points are asymptotically stable, and the proposed control method is of better robustness. The findings provide a new kind of control method with higher efficiency, and can help with the precise control of gantry cranes.

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