Experimental and Computational Determination of the Heating Temperature of a Powder Mixture during Explosive Compaction

Resumo

The results of an experimental determination of the heating temperature of a powder mixture of chromium carbide and titanium binder during explosive loading on a metallic substrate are presented. The compression pressure of a powder mixture in shock waves during explosive compaction is 2.5 GPa. A thermal cycle of a back side of a metallic substrate playing the role of a heat-receiving cell with a coating deposited on it is fixed and the time-independent problem of heat conduction is solved until calculated and experimental thermal cycles coincided. The initial conditions are selected from the assumption that the compacted material is uniformly heated to a certain average temperature upon finishing the shock-wave processes. Thermal properties of the compacted material necessary for calculations are determined by the lased flash method using an LFA 427 installation (Netzsch, Germany). Calculations showed that the heating temperature of a powder mixture was 208 and 225°C when using the adiabatic approximation and allowing for heat emission into the environment, respectively. A comparison of these temperatures with those calculated by an increase in enthalpy during the shock-wave treatment (the density of the monolithic material under standard conditions and final density of the powder material determined after the explosive treatment—199 and 220°C, respectively) shows that they differ insignificantly. Thus, the use of an assumption of the equality of the material density in the shock wave and monolith density does not lead to a substantial error and can be used for practical calculations.