EXPERIMENTAL STUDY OF CARBON MATERIALS MASS LOSS IN DISSOCIATED FLOW OF PURE NITROGEN
A study of mass loss of carbon materials in subsonic flows of dissociated nitrogen was carried out using the IPG-4 plasmatron of IPMech RAS. Three carbon materials such as carbon-carbon material and two types of artificial graphite (V-2 and GMZ) have been tested. Experiments were made at surface temperature range 1600-2300 K and in the pressure range 25-400 hPa. Surface temperature of tested samples were regulated by means of changing of power injected to nitrogen plasma. Extra pure nitrogen was used in experiments at constant flow rate 2.4 g/s. Special measures were undertaken to avoid interaction of samples with residual oxygen and contact of heated samples with another high-temperature materials. Temperature dependencies of mass loss rate for tested materials have been obtained in the temperature range 1600÷2300 K at constant pressure 100 hPa and it turned out mass loss rate of the V-2 graphite increases with surface temperature but carbon-carbon material and the GMZ graphite shows decrease of mass loss rates at surface temperature increase. Also it was found that mass loss rate of the V-2 graphite decreases with pressure increase in the pressure range 25÷400 hPa and at constant surface temperature 2130 K. It should be specially emphasized that mass loss rates of tested carbon materials in dissociated nitrogen flows is only 1-2 orders of magnitude lower those in dissociated air flows with close governing parameters.