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Vapor Infiltration (vapor + infiltration)

Distribution by Scientific Domains

Polymers and Materials Science	87%

Kinds of Vapor Infiltration

chemical vapor infiltration

Selected Abstracts

Chemical Vapor Infiltration of Rhenium

CHEMICAL VAPOR DEPOSITION, Issue 2 2003
H.C. King
Abstract Rhenium is of interest as a matrix material and fiber coating for high-temperature structural composites. Despite prior success in the CVD of rhenium, there have been no studies on the chemical vapor infiltration (CVI) of this metal. The current work investigates the CVI of rhenium via the pyrolytic decomposition of ReCl5, prepared both by chlorination of rhenium metal and the sublimation of ReCl5. The feasibility of the CVI of rhenium was demonstrated for both methods. Statistical analyses showed that the amount of rhenium deposited increased for higher chlorine flow rates and lower preform temperatures, 750,°C vs. 900,°C, for the chlorination and sublimation processes, respectively. [source]

Colloidal Crystals as Templates for Macroporous Carbon Electrodes of Controlled Thickness

ELECTROANALYSIS, Issue 2-3 2007
Stéphane Reculusa
Abstract Macroporous carbon films were synthesized using colloidal crystals as a template and were characterized using scanning electron microscopy (SEM) and Raman spectroscopy. The colloidal crystals were elaborated by the Langmuir-Blodgett technique and were infiltrated with carbon by a controlled chemical vapor infiltration (CVI) process. After removal of the template, thin free-standing carbon membranes whose thicknesses match perfectly those of the templates were obtained. Their ability to act as electrodes was checked by carrying out cyclic-voltammetry experiments. [source]

Thermal Shock Damage of a 3D-SiC/SiC Composite,

ADVANCED ENGINEERING MATERIALS, Issue 11 2005
S. Wu
Thermal shock of a three-dimensional (3D) SiC/SiC composite prepared by chemical vapor infiltration (CVI) process was conducted using water quenched method. Thermal shock damage of the composite was assessed by SEM characterization and measurement mechanical properties using three-point flexure after quenching. After quenched from 1200°C to 25°C water for 100 cycles, the composite retained 80% of the original flexural strength in the longitudinal direction while cracked through the width direction. Thermal shock damage of the composite was analyzed by thermal stress analysis based on the braiding structure of the composite as well as the distribution and shape of flaws referred to residual pores in the matrix. The braided structure and the dimension difference resulted in the anisotropy of mechanical properties and the matrix pores configuration of the composite, which led to the thermal shock damage anisotropy of the composite. [source]

Microstructure and Mechanical Properties of Lu2O3 -Doped Porous Silicon Nitride Ceramics Using Phenolic Resin as Pore-Forming Agent

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2010
Xiaowei Yin
The joint process consisting of pressureless sintering and chemical vapor infiltration (CVI) was developed to prepare porous Si3N4 ceramics with controlled microstructure. Lu2O3 and phenolic resin acted as sintering aid and pore-forming agent, respectively. The 5 wt% Lu2O3 -doped ceramics using 12,57 vol% phenolic resin attained a porosity ranging from 46% to 53%. With increasing the resin content, the average pore size increased from 1 to 2 ,m. The porous ceramic infiltrated with CVI Si3N4 had an improved microstructure. The decreased pore size and porosity led to an increase in flexural strength, and the densified surface led to an improved surface hardness. [source]

Modeling the Effects of Reactor Inlet Configuration on Isothermal CVI Process of C/SiC Composites

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2007
Xi Wei
Two comparative models were proposed to simulate the effects of the reactor configuration on the isothermal chemical vapor infiltration (ICVI) process of C/SiC composites. The difference in the two models is that there is an expansion zone near the reactor inlet in one model while no expansion zone exists in another model. Calculation results show that the existence of the expansion zone has rather negligible effects on the ICVI process. It is accordingly suggested that the simplification of the reactor configuration by neglecting the expansion zone of the reactor is reasonable and acceptable for the ICVI process of C/SiC composites. [source]

A Global Approach to Fiber nD Architectures and Self-Sealing Matrices: From Research to Production

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2005
F. A. Christin
Thermostructural composites (TSC) improvement is one of the key factors to ensure future competitiveness of aeronautical and space engines. The TSC technology developed in Snecma Propulsion Solide is based on continuous fiber-reinforced composites and carbon or ceramics matrices deposited by chemical vapor infiltration. This article presents a status of the latest improvements for cost savings of composite reinforcements (so-called texture) and specific matrices developed to increase both durability and temperature capability of previous ceramic composites, operating in oxidative environments. [source]

Fabrication and Characteristics of Carbon Nanofiber-Reinforced Carbon/Carbon Composites by Fast Catalytic Infiltration Processes,

CHEMICAL VAPOR DEPOSITION, Issue 1-3 2009
Jin-Cao Zhang
Abstract The simultaneous in-situ growth of carbon nanofibers (CNFs) and densification of a CNFs/CF hybrid multiscale felt are accomplished in a single step by thermal gradient chemical vapor infiltration using Fe as the catalyst and vaporized kerosene under atmospheric pressure. A three-dimensional CNF network which could bridge dissimilar components of composites is formed on carbon fibers (CFs). The length of CNFs can reach several micrometers and the diameters are about 80,nm. Smooth and rough surface densified CNFs can be produced after further higher temperature infiltration. CNFs, anchoring to CFs by the adherence of the catalyst nanoparticles, enhance the bonding between CFs and pyrocarbon as well as promoting the formation of a rough laminar pyrocarbon matrix. The deposition mechanisms and physical model are also discussed. This fast catalytic infiltration process can be applied to other ceramic materials and has significant enlargement potential. [source]