Ablation behavior of boron nitride based ceramic composites reinforced by continuous silicon oxynitride fiber

High strength particulate ceramic composites are in general reinforced by strong dispersoids, such as strong ceramic particles (SiC, TiB2, ZrO2, et al) and strong metallic particles (Mo, W, et al). In this work high strength ceramic composites with in-situ synthesized hexagonal boron nitride (h-BN) have been prepared and characterized. As an example, we manufactured mullite-BN composites by reactive hot pressing (RHP) using aluminum borates (9Al2O3·2B2O3 and 2Al2O3·B2O3) and silicon nitride as starting materials. The obtained material RHPed at 1800°C showed a strength of 540 MPa, which was 1.64 times higher than that of the monolithic mullite ceramics. TEM observation revealed that the composite had an isotropic microstructure with a fine mullite matrix grain size of less than 1 μm and a nano-sized h-BN platelets of about 200 nm in length and 60∼80 nm in thickness. The high strength was suggested to be from the reduced matrix grain size and the small toughening effect by the h-BN platelets. In addition, this kind of ceramic composite demonstrates low Young’s modulus that is beneficial to the thermal/mechanical shock resistance, and excellent machinability.

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Investigation of the Physical and Mechanical Properties of Hot-Pressed Boron Nitride/Oxide Ceramic Composites

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1999.tb02123.x ◽

1999 ◽

Vol 82 (9) ◽

pp. 2563-2565 ◽

Cited By ~ 43

Author(s):

Rodney W. Trice ◽

John W. Halloran

Keyword(s):

Mechanical Properties ◽

Boron Nitride ◽

Physical And Mechanical Properties ◽

Ceramic Composites ◽

Oxide Ceramic ◽

Nitride Oxide

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Facility for Continuous CVD Coating of Ceramic Fibers

MRS Proceedings ◽

10.1557/proc-250-269 ◽

1991 ◽

Vol 250 ◽

Author(s):

Arthur W. Moore

Keyword(s):

Boron Nitride ◽

High Temperatures ◽

Weight Ratio ◽

High Strength ◽

Ceramic Coatings ◽

Ceramic Composites ◽

Ceramic Fiber ◽

Ceramic Fibers ◽

Fiber Properties ◽

Nitride Coatings

The development of new and improved ceramic fibers has spurred the development and application of ceramic composites with improved strength, strength/weight ratio, toughness, and durability at increasingly high temperatures. For many systems, the ceramic fibers can be used without modification because their properties are adequate for the chosen application. However, in order to take maximum advantage of the fiber properties, it is often necessary to coat the ceramic fibers with materials of different composition and properties. Examples include (1) boron nitride coatings on a ceramic fiber, such as Nicalon silicon carbide, to prevent reaction with the ceramic matrix during fabrication and to enhance fiber pullout and increase toughness when the ceramic composite is subjected to stress[l]; (2) boron nitride coatings on ceramic yarns, such as Nicalon for use as thermal insulation panels in an aerodynamic environment, to reduce abrasion of the Nicalon and to inhibit the oxidation of free carbon contained within the Nicalon[2]; and (3) ceramic coatings on carbon yarns and carbon-carbon composites to permit use of these high-strength, high-temperature materials in oxidizing environments at very high temperatures[3,4].

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Hot-Pressed Hexagonal Boron Nitride - Aluminum Nitride Ceramic Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.108-110.85 ◽

1995 ◽

Vol 108-110 ◽

pp. 85-96 ◽

Cited By ~ 3

Author(s):

K. Tanemoto ◽

T. Kanai

Keyword(s):

Boron Nitride ◽

Aluminum Nitride ◽

Hexagonal Boron Nitride ◽

Ceramic Composites

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Boron nitride‐reinforced polysilazane‐derived ceramic composites via direct‐ink writing

Journal of the American Ceramic Society ◽

10.1111/jace.17084 ◽

2020 ◽

Vol 103 (8) ◽

pp. 4043-4050 ◽

Cited By ~ 1

Author(s):

James W. Kemp ◽

Nadim S. Hmeidat ◽

Brett G. Compton

Keyword(s):

Boron Nitride ◽

Ceramic Composites ◽

Direct Ink Writing

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Microanalyses Of Structural Defects In Polymer-Derived Ceramic Fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134910 ◽

1990 ◽

Vol 48 (2) ◽

pp. 262-263

Author(s):

H. A. Freeman ◽

J. A. Rabe

Keyword(s):

Surface Defects ◽

Fiber Strength ◽

Thermal Exposure ◽

Ceramic Composites ◽

Silicon Oxynitride ◽

Structural Defects ◽

Ceramic Fibers ◽

High Fiber ◽

Polymer Derived Ceramic ◽

Primary Fracture

Microanalyses were performed with a Cameca MBX scanning electron microprobe and a JEM 2000FX analytical electron microscope to determine the composition of foreign defect structures found on primary fracture surfaces of ceramic fibers derived from melt-spun Si-N-C-O polymeric precursors. The defects were the critical flaws responsible for deterioration of tensile strength in these fibers after thermal exposure in the range of 1400°C and above. High fiber strength is necessary to provide reinforcement and toughening in structural ceramic composites during high temperature use.Among the defects found were roughly spherical internal nodular flaws which contained Pb (Fig. 1) as well as others (Fig. 2) containing both Pb and Sn. Granular aggregates were also seen in which Fe and Cr were detected. Other nodular surface defects contained Ca, minor Al, and levels of 0 higher than that in the surrounding fiber (Fig. 3) . Extremely fine whisker growths at discrete sites along the length of some fibers were identified as silicon oxynitride by electron diffraction.

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