Effect of BN coating on the strength of a mullite type fiber

被引：29

作者：

Chawla K.K. ^{[1
]}

Xu Z.R. ^{[1
]}

Ha J.-S. ^{[1
]}

Schmücker M. ^{[2
]}

Schneider H. ^{[2
]}

机构：

[1] Dept. of Materials and Met. Eng., New Mexico Tech., Socorro, 87801, NM

[2] Institute for Materials Research, German Aerospace Research Establishment (DLR), Cologne

来源：

Applied Composite Materials | 1997年 / 4卷 / 5期

关键词：

Boron Nitride; fiber; mullite; Nextel; 480; Weibull;

D O I：

10.1007/BF02481393

中图分类号：

学科分类号：

摘要：

Nextel 480 is a polycrystalline essentially mullite fiber (70 wt.-% Al2O3+28 wt.-% SiO2+2 wt.-% B2O3). Different thicknesses of BN were applied as coatings on this fiber. Optical, scanning electron, and transmission electron microscopy were used to characterize the microstructure of the coatings and fibers. The effects of coating and high temperature exposure on the fiber strength were investigated using two-parameter Weibull distribution. TEM examination showed that the BN coating has a turbostratic structure, with the basal planes lying predominantly parallel to the fiber surface. Such an orientation of coating is desirable for easy crack deflection and subsequent fiber pullout in a composite. The BN coated Nextel 480 fiber showed that Weibull mean strength increased first and then decreased with increasing coating thickness. This was due to the surface flaw healing effect of the coating (up to 0.3 μm) while in the case of thick BN coating (1 μm), the soft nature of the coating material had a more dominant effect and resulted in a decrease of the fiber strength. High temperature exposure of Nextel 480 resulted in grain growth, which led to a strength loss. © 1997, Kluwer Academic Publishers.

引用

页码：263 / 272

页数：9

共 18 条

[1]

Chawla K.K., Ceramic Matrix Composites, (1993)

[2]

Bender B., Shadwell D., Bulik C., Incorvati L., Lewis D., Effect of Fiber Coatings and Composite Processing of Zirconia-Based Matrix SiC Fiber Composites, Am. Ceram. Soc. Bull., 65, pp. 363-369, (1986)

[3]

Evans A.G., Marshall D.B., The Mechanical Behavior of Ceramic Matrix Composites, Acta Metall., 37, pp. 2567-2583, (1987)

[4]

Budiansky B., Hutchinson J.W., Evans A.G., Matrix Fracture in Fiber-Reinforced Ceramics, J. Mech. Phys. Solids, 34, pp. 167-189, (1986)

[5]

Prewo K.M., Tension and Flexural Strength of Silicon Carbide Fibre-Reinforced Glass Ceramics, J. Mater. Sci., 21, pp. 3590-3600, (1986)

[6]

Chawla K.K., Ferber M.K., Xu Z.R., Venkatesh R., Interface Engineering in Alumina/Glass Composites, Mater. Sci. Eng., 162, pp. 35-44, (1993)

[7]

Ha J.S., Chawla K.K., Effect of SiC/BN Double Coating on Fibre Pullout in Mullite Fibre/Mullite Matrix Composites, J. Mater. Sci. Lett., 12, pp. 84-87, (1993)

[8]

Thouless M.D., Sbaizero O., Sigl L.S., Evans A.G., Effect of Interface Mechanical Properties in SiC-Fiber Reinforced Lithium Aluminum Silicate Glass-Ceramic, J. Am. Ceram. Soc., 74, pp. 525-532, (1989)

[9]

Nunes J., Tensile Properties Evaluation of Polycrystalline Alumina Filaments and Their Composites, Comp. Tech. Rev., 5, pp. 53-60, (1983)

[10]

Patankar S.N., Venkatesh R., Chawla K.K., Effect of Tin Dioxide Coating on Tensile Strength of Alumina Fibers, Scripta. Met., 25, pp. 361-366, (1991)

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