Infiltration of C/SiC composites with silica sol-gel solutions: Part II. Infiltration under isostatic pressure and oxidation resistance

1999 ◽  
Vol 14 (11) ◽  
pp. 4239-4245 ◽  
Author(s):  
Mario Aparicio ◽  
Alicia Durán
Keyword(s):  
Sol Gel ◽  
Applied Pressure ◽  
Process Variable ◽  
Solution Concentration ◽  
Silica Sol ◽  
Infiltration Process ◽  
Pressure Infiltration ◽  
C Fibers ◽  
Sic Composites ◽  
Infiltration Method

An infiltration process that uses silica sol-gel solutions was developed to protect C/SiC composites against oxidation. The infiltration is assisted using isostatic pressure. Different process parameters including substrate porosity and solution concentration and viscosity were varied to optimize the infiltration effectiveness. Applied pressure enhances penetration of solutions, reducing the importance of viscosity, an important process variable for dipping infiltration. The effectiveness of the isostatic pressure infiltration method, evaluated through the total weight gains and pore-size distribution of infiltrated samples, is compared with results of dipping infiltration. The oxidation behavior of the infiltrated samples, was evaluated by stepwise oxidation test as well as isothermal tests at 1200 and 1600 °C. The infiltrated SiO2 protects the C/SiC substrate, reducing the burnoff rate of C fibers at low temperature and delaying the oxidation of SiC.

Infiltration of C/SiC composites with silica sol-gel solutions: Part I. Infiltration by dipping

1999 ◽  
Vol 14 (11) ◽  
pp. 4230-4238 ◽  
Author(s):  
Mario Aparicio ◽  
Alicia Durán
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Ceramic Matrix Composites ◽  
Silica Sol ◽  
Residual Porosity ◽  
Ambient Conditions ◽  
Average Pore ◽  
Infiltration Process ◽  
C Fibers ◽  
Weight Gains

Oxidation resistance of ceramic matrix composites (CMC) of SiC reinforced with C fibers (C/SiC) can be improved by filling the residual porosity. The aim of this work was to design and analyze a dipping infiltration process under ambient conditions (1 atm pressure and room temperature) with silica sol-gel solutions prepared from tetraethyl orthosilicate. Different substrates and solutions have been studied. Thermal treatments, i.e., curing or sintering between infiltrations, increase the efficiency of the process since the densification of infiltrated silica opens up the remaining porosity. Increasing viscosity and/or concentration of the solution lead to greater weight gains. Weight gains are higher in the initial stages of the process because larger diameter porosity remains unfilled. As the process advances, the average pore size decreases, and only the lower viscosity solution can enter the residual porosity.

Microstructure and Hardness of Ni-Cr Porous Preform Reinforced Al-Based Composites by Low Infiltration Method

2011 ◽  
Vol 275 ◽  
pp. 251-254
Author(s):  
Hua Wei Rong ◽  
Cheol Hong Park ◽  
Won Jo Park ◽  
Han Ki Yoon
Keyword(s):  
Intermetallic Compounds ◽  
Rapid Development ◽  
High Hardness ◽  
Optical Microscope ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Infiltration Process ◽  
Pressure Infiltration ◽  
X Ray ◽  
Infiltration Method

With the rapid development of aerospace and automobile industries, metal matrix composites (MMCs) have attracted much attention because of its excellent performance. In this paper, Ni-Cr/AC8A composites reinforced with porous Ni-Cr preform were manufactured by low pressure infiltration process, infiltration temperatures are 700oC~850oC. The microstructure and phase composition of composites were evaluated using optical microscope, X-ray diffraction (XRD) and electro-probe microanalysis (EPMA), It's found that they're intermetallic compounds generated in the composites. Recently, intermetallic compounds have attracted much attention as high-temperature material. We study the hardness of Ni-Cr/AC8A composites, the results show the Ni-Cr/AC8A composite has high hardness due to the intermetallic compounds exist.

Manufacture of Al/SiC Composites by Pressure Infiltration Process

2005 ◽  
Vol 475-479 ◽  
pp. 913-916
Author(s):  
Fa Zhang Yin ◽  
Cheng Chang Jia ◽  
Xuezhen Mei ◽  
Bin Ye ◽  
Yanlei Ping ◽  
...  
Keyword(s):  
Relative Density ◽  
Process Parameters ◽  
Room Temperature ◽  
Sintering Process ◽  
Homogeneous Microstructure ◽  
Infiltration Process ◽  
Pressure Infiltration ◽  
Upper Limit ◽  
Thermal Debinding ◽  
Sic Composites

The SiCp performing sample was made first then Al/SiCp (65%) was manufactured. Appropriate component and proportion of binder and process parameters were selected to control the porosity. Debinding has succeeded by extractive and thermal debinding processes. SiCp preforming samples with good appearance, enough strength, and right porosity were obtained by pre-sintering process at 1100°C. Composites with high density and homogeneous microstructure were manufactured by pressure infiltration under 1050°C and 15MPa. The distribution of aluminium and silicon elements was homogeneous. The primary components of materials are aluminium, β-SiC and α-SiC. The thermal expand coefficient of composites is 8.0×10-6/°C at room temperature, which increases with temperature and reaches to 11.0×10-6/°C at 300°C. The density is 2.92g/cm3, and relative density is more than 97 %. The strength is about 500MPa, approaching to the upper limit of the theoretical value.

Manufacture of Al/SiC Composites by Pressure Infiltration Process

2005 ◽  
pp. 913-916
Author(s):  
Fa Zhang Yin ◽  
Cheng Chang Jia ◽  
Xuezhen Mei ◽  
Bin Ye ◽  
Yanlei Ping ◽  
...  
Keyword(s):  
Infiltration Process ◽  
Pressure Infiltration ◽  
Sic Composites

Fabrication of Carbon Nano-Fiber / Aluminum Composites by Low-Pressure Infiltration Method

2010 ◽  
Vol 654-656 ◽  
pp. 2692-2695 ◽  
Author(s):  
Gen Sasaki ◽  
Yoshimasa Hara ◽  
Zhe Feng Xu ◽  
Kenji Sugio ◽  
Hiroshi Fukushima ◽  
...  
Keyword(s):  
Pure Aluminum ◽  
Applied Pressure ◽  
Low Pressure ◽  
Aluminum Composites ◽  
Pressure Infiltration ◽  
Porous Preform ◽  
Plasma Sintering ◽  
Nano Fiber ◽  
Spark Plasma ◽  
Infiltration Method

In this study, the fabrication of carbon containing aluminum composites was attempted by using low-pressure infiltration method. At first, porous preform containing vapor grown nano-fiber (VGCF) and pure aluminum powder was fabricated by spark plasma sintering (SPS) method. Porosity in preform was controlled by changing the applied pressure during plasma sintering. Consequently, the porous preform with 40-50vol％ in porosity was obtained, which has enough compression strength for low-pressure infiltration (<1MPa). Then, the molten pure aluminum infiltrated to porous preform with 0.4MPa in applied pressure at 1023K, and consequently we can obtain the composite with 62-86% in density. The electrical and thermal conductivity of composites was affected by the porosity, strongly.

scholarly journals A simple approach to prepare fluorescent molecularly imprinted nanoparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (13) ◽  
pp. 7732-7737
Author(s):  
Fenying Wang ◽  
Dan Wang ◽  
Tingting Wang ◽  
Yu Jin ◽  
Baoping Ling ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Sol Gel ◽  
Silica Sol ◽  
Simple Approach ◽  
Imprinted Polymer ◽  
Molecularly Imprinted ◽  
Low Toxicity ◽  
Good Biocompatibility ◽  
Molecularly Imprinted Nanoparticles

Fluorescent molecularly imprinted polymer (FMIP) gains great attention in many fields due to their low cost, good biocompatibility and low toxicity. Here, a high-performance FMIP was prepared based on the autocatalytic silica sol–gel reaction.

Sol-gel synthesis of textured lanthanum titanate thin films

2003 ◽  
Vol 18 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Mary M. Sandstrom ◽  
Paul Fuierer
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Precursor Solution ◽  
Solution Concentration ◽  
Optical Measurements ◽  
Layered Perovskite ◽  
Orientation Factor ◽  
Anisotropic Structures ◽  
Sol Gel Films ◽  
Sol Gel Synthesis

Control over crystallographic orientation in thin films is important, particularly with highly anisotropic structures. Because of its ferroelectric nature, the layered perovskite La2Ti2O7 has interesting piezoelectric and electrooptic properties that may be exploited when films are highly textured. Sol-gel films with an orientation factor of greater than 95% were fabricated without relying on epitaxial (lattice-matching) growth from the substrate. Film orientation and crystallization were confirmed by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and optical measurements. The particle sizes in all precursor solutions were measured by dynamic light scattering experiments. Experimental results indicate that film orientation is a function of precursor solution concentration, size of the molecular clusters in the solution, and film thickness.

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