Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

scholarly journals Powder Metallurgical Tungsten Fiber-Reinforced Tungsten

2015 ◽  
Vol 825-826 ◽  
pp. 125-133 ◽  
Author(s):  
Bruno Jasper ◽  
Jan W. Coenen ◽  
Johann Riesch ◽  
Till Höschen ◽  
Martin Bram ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Hot Isostatic Pressing ◽  
Chemical Vapor ◽  
Mechanical Tests ◽  
Chemical Vapor Infiltration ◽  
Interface Debonding ◽  
Fiber Reinforced ◽  
Tungsten Fiber ◽  
Push Out

The composite material tungsten fiber-reinforced tungsten (Wf/W) addresses the brittleness of tungsten by extrinsic toughening through introduction of energy dissipation mechanisms. These mechanisms allow the release of stress peaks and thus improve the materials resistance against crack growth. Wf/W samples produced via chemical vapor infiltration (CVI) indeed show higher toughness in mechanical tests than pure tungsten. By utilizing powder metallurgy (PM) one could benefit from available industrialized approaches for composite production and alloying routes. In this contribution the PM method of hot isostatic pressing (HIP) is used to produce Wf/W samples. A variety of measurements were conducted to verify the operation of the expected toughening mechanisms in HIP Wf/W composites. The interface debonding behavior was investigated in push-out tests. In addition, the mechanical properties of the matrix were investigated, in order to deepen the understanding of the complex interaction between the sample preparation and the resulting mechanical properties of the composite material. First HIP Wf/W single-fiber samples feature a compact matrix with densities of more than 99% of the theoretical density of tungsten. Scanning electron microscopy (SEM) analysis further demonstrates an intact interface with indentations of powder particles at the interface-matrix boundary. First push-out tests indicate that the interface was damaged by HIPing.

Fabrication and Characteristics of Carbon Fiber Reinforced C–SiC Dual Matrix Composites

2007 ◽  
Vol 334-335 ◽  
pp. 145-148 ◽  
Author(s):  
Dong Mei Zhu ◽  
Fa Luo ◽  
Hong Na Du ◽  
Wan Cheng Zhou
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Final Density ◽  
Carbon Fiber Reinforced ◽  
Sic Composites ◽  
Xylene Solution

A series of carbon fiber reinforced C-SiC dual matrix composites (C/C-SiC composites) were developed through precursor infiltration of polycarbosilane (PCS) and pyrolysis (PIP), using porous C/C composites with different density from chemical vapor infiltration (CVI) as the preform. The density, mechanical properties, and microstructure of the composites were investigated and the effects of the preform density and the PCS concentration of the infiltration solution on the final density and the mechanical properties of the composites were discussed in detail. The results show that the final density of the C/C-SiC composites prepared at the infiltration concentration of 50% is the highest, indicating that 50% is the proper PCS concentration of the PCS/ Xylene solution to prepare the C/C-SiC composites. The final densities of C/C-SiC composites were closely related to the preform density and the highest final density corresponds to the highest original preform density. For the composites prepared using infiltration solution of 50% PCS, the C/C-SiC composite whose preform density is 1.23 g/cm3 possesses the best mechanical properties while that whose preform density is 1.49 g/cm3 the worst mechanical properties.

scholarly journals The Effect of Fiber Coatings on Interfacial Shear Strength and the Mechanical Behavior of Ceramic Composites

1989 ◽  
Vol 170 ◽  
Author(s):  
Richard A. Lowden ◽  
Karren L. More
Keyword(s):  
Mechanical Behavior ◽  
Elevated Temperatures ◽  
Chemical Vapor ◽  
Ceramic Composites ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Ceramic Fibers ◽  
Fiber Matrix ◽  
Infiltration Techniques

AbstractThin coatings deposited on ceramic fibers prior to densification employing chemical vapor infiltration techniques have been used to limit fiber-matrix bonding. This has resulted in improvements in strength and toughness at room and elevated temperatures in Nicalon® fiber-reinforced/SiC matrix composites. The properties of the fiber-matrix interface in fiber-reinforced ceramic composites have been examined utilizing an indentation method in which a standard microhardness indentor is used to push on fibers embedded in the ceramic matrix. Compositions and microstructures at the interface have been characterized employing analytical electton microscopy. Correlations between interfacial phenomena and observed mechanical behavior have been made.

scholarly journals Effects of Water Absorption on the Fiber–Matrix Interfacial Shear Strength of Carbon Nanotube-Grafted Carbon Fiber Reinforced Polyamide Resin

2019 ◽  
Vol 3 (1) ◽  
pp. 4 ◽  
Author(s):  
Kazuto Tanaka ◽  
Saya Okuda ◽  
Yoshitaka Hinoue ◽  
Tsutao Katayama
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Carbon Fiber ◽  
Water Absorption ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Fiber Matrix ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced thermoplastics (CFRTPs) are expected to be used for the structural parts of automobiles and aircraft due to their mechanical properties, such as high specific stiffness, high specific strength, short molding times and high recyclability. The fiber/matrix interface of the composite plays an important role in transmitting stress from the matrix to the reinforcing fibers. It was reported that grafting of carbon nanotubes (CNTs) on the carbon fiber can improve the fiber/matrix interfacial property. We have reported that CNTs, which are directly grafted onto carbon fiber using Ni as the catalyst by the chemical vapor deposition (CVD) method, can improve the fiber/matrix interfacial shear strength (IFSS) of carbon fiber/polyamide 6 (PA6). For practical use of CFRTPs, it is important to clarify the effects of water absorption on the mechanical properties of the composite material. In this study, the effects of water absorption on the fiber–matrix interfacial shear strength (IFSS) of carbon fiber reinforced polyamide resin and CNT-grafted carbon fiber reinforced polyamide resin were clarified by the single fiber pull-out test for specimens preserved in air, then in water for 24 h and re-dried after water absorption. The IFSS of carbon fiber/PA6 was significantly decreased by water absorption. In contrast, CNT-grafted carbon fiber/PA6 showed smaller degradation of the IFSS by water absorption.

Fiber-Reinforced Tubular Composites by Chemical Vapor Infiltration°

1991 ◽  
Vol 250 ◽  
Author(s):  
D. P. Stinton ◽  
R. A. Lowden ◽  
T. M. Besmann
Keyword(s):  
Mechanical Properties ◽  
Thermal Gradient ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Forced Flow ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Infiltration Process ◽  
Filament Wound ◽  
Vapor Infiltration

AbstractA forced-flow thermal-gradient chemical vapor infiltration process has been developed to fabricate composites of thick-walled tubular geometry common to many components. Fibrous preforms of different fiber architectures (3-dimensionally braided and filament wound) have been investigated to accommodate components with different mechanical property requirements. This paper will discuss the fabrication of tubular, fiber-reinforced SiC matrix composites and their mechanical properties.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Sign in / Sign up

Export Citation Format

Share Document