Diamond and Refractory Coatings of Gun Barrels for Electrothermal- Chemical Launchers
Abstract
Material surfaces of gun barrels in electrothermal-chemical launchers are subject to high heat fluxes, which may exceed l00GW/m2 over 0.01-5 ms pulse duration. Such high heat fluxes result in several deforming processes of barrel material, which reduce the efficiency and lifetime of the launcher. The successful operation requires minimum erosion over a large number of repetitive exposures. Diamond and refractory coated barrel material surfaces have been exposed to high heat fluxes from 2 to 60 GW/m2 over 100 microseconds duration using the electrothermal launcher, SIRENS. The high heat fluxes produced by SIRENS plasma are primarily from blackbody spectrum photons. The plasma boundary layer 'vapor shield' formed by surface vaporization helps to reduce heat transport to the surface. Coatings have been prepared by different methods (sputtering, molten salt, electroplating, chemical vapor deposition and low pressure plasma spray). Surface erosion is caused primarily by convection and radiation emitted from the plasma. The better performance of coated surfaces is attributed to the better thermal conductivity of the heat sink (substrate). Preliminary tests of diamond coating on silicon substrates were not successful because the wafers were destroyed, especially at higher values of incident heat fluxes. SEM micrographs showed that diamond coating has been removed from the silicon surface due to the thermal shock under high pressure.... Surface erosion, Diamond coatings, Refractory coatings, Diagnostics, ETC launchers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1992
- Accession Number
- ADA260749
Entities
People
- J. D. Hurley
- J. G. Gilligan
- M. A. Bourham
- O. E. Hankins
- P. D. Bogdanoff
- W. H. Eddy
Organizations
- North Carolina State University