Accession Number:

ADA200613

Title:

Investigation of Near-Surface Chemical, Physical and Mechanical Properties of Silicon Carbide Crystals and Fibers Modified by Ion Implantation

Descriptive Note:

Final rept.

Corporate Author:

WESTINGHOUSE RESEARCH AND DEVELOPMENT CENTER PITTSBURGH PA MATERIALS TECHNOLOGY DIV

Personal Author(s):

Report Date:

1988-08-17

Pagination or Media Count:

109.0

Abstract:

Modification of chemical, physical and mechanical properties of ceramicsemiconductor surfaces by ion implantation provides an opportunity to define and obtain desirable properties for a variety of applications. These include interfaces in composite materials, electrical properties of devices and contacts, and specialized surfaces for optical waveguides, wear and corrosion resistance, etc. In this study, single crystals 6H, and whiskers of high purity silicon carbide were implanted with a variety of n- and p-type dopants B, N, A1, P, an isovalent dopant Ti, inert species Ne and hydrogen. Isochronal anneals at temperatures up to 1173 K permitted systematic evaluation of thermal effects in the implanted region. Implants fluences were normalized to permit comparisons on the basis of equal concentrations of displaced Si atoms for each ion. microstructural, mechanical and chemical effects were studied by a series of RBSchanneling, TEM, SEM, microhardness, microtensile, AES, SIMS, and wetting sputtered and molten metal measurements. Recovery of crystalline structure during annealing is shown to be relatively independent of the implant species but depends upon the number of atomic displacements in the Si sublattice. Near-surface mechanical and chemical effects, however, are very dependent on the chemicalelectrical nature of the implanted ions. Applications to ceramicmetal interfaces in metal matrix composites are discussed.

Subject Categories:

  • Inorganic Chemistry
  • Ceramics, Refractories and Glass

Distribution Statement:

APPROVED FOR PUBLIC RELEASE