Project Title:

Electrically Conducting Diamond Films for Wear and Erosion

Materials Modification Inc., (MMI)
2929-P1 Eskridge Road
Fairfax, Va 22031

93-1-04     22   1371

Electrically Conducting Diamond Films for Wear and Erosion
Resistance

Abstract:

Wear resistant electrically conducting diamond coatings are
desired in extending the lifetime of components in electric
rocket thrusters for space applications. These may include hollow
cathodes, various electrode surfaces, and extraction grids, to
name only a few. Although several methods exist for the
deposition of diamond coatings, many of these processes are
limited in their ability to produce doped diamond films with
reproducible quality. In this Phase I effort, we will demonstrate
the feasibility of producing diamond that is doped using two
different deposition techniques. We will first use a modified hot
filament CVD method to deposit doped diamond films from
acetone/methanol mixtures containing the p-type dopant as a
boron-containing compound, and measure their electrical
resistivities. Since large area deposition at high rates will be 
desired, we will also attempt to use a DC-arcjet to deposit
boron-doped diamond films using boron containing precursors.
Analytical instrumentation such as scanning electron microscopy
and Raman spectroscopy will be used to characterize the films.
Preliminary electrical resistivity measurements will be performed
on films produced using a four-point probe. We expect to scale up
the technique in Phase II to deposit doped diamond coatings over
prototype electrode and insulator components for extensive
evaluation so that the technique can be adapted for production
during Phase III.

The potential applications of this project are: a method of
deposition of high performance electrically conducting diamond
films with good wear resistance on a large variety of components.
The process or processes can be applied to form semiconductor
devices and optical switches, insulating gates and active/passive
components.

Diamond Films, Electrically Conducting, Chemical Vapor
Deposition, Protective Coatings, Doping, wear resistance.