The thermal decomposition of ammonium perchlorate (AP) with Al and Zn metallic particles was studied at different heating rates in dry air atmosphere and the combustion behavior of AP/Al/Zn propellant was evaluated. T...The thermal decomposition of ammonium perchlorate (AP) with Al and Zn metallic particles was studied at different heating rates in dry air atmosphere and the combustion behavior of AP/Al/Zn propellant was evaluated. The exothermic reaction kinetics was studied by differential thermal analysis (DTA) in non-isothermal conditions and compare with the thermal decomposition of pure AP and AP/aluminum particles analyzed in the same experimental conditions. The Arrhenius parameters were estimated according to the Ozawa and Kissinger methods. The calculated activation energies for the low and high temperature exothermic reactions were 91 and 229 kJ/mol for pure AP, 90 and 112 kJ/mol for 80 wt% AP/20 wt% Al particles. When zinc was incorporated, activation energy of 56 kJ/mol was determined for the only exothermic peak observed for 90 wt% AP/10 wt% Zn and 44 kJ/mol for 78.4 wt% AP/19.6 wt% Al/2 wt% Zn propellant composition.展开更多
The present work describes the viability of a mortar binder based on two industrial by-products: poly(vinyl chloride) (PVC) particles from scrap and anhydrite (CaSO4) from fluorgypsum. Mortar composites were made inco...The present work describes the viability of a mortar binder based on two industrial by-products: poly(vinyl chloride) (PVC) particles from scrap and anhydrite (CaSO4) from fluorgypsum. Mortar composites were made incorporating different amounts of PVC particles and cured at constant room temperature during various periods of time. From X-ray diffraction, it was possible to follow the hydration process and to estimate the effect of the PVC particles on anhydrite transformation to gypsum (CaSO4·2H2O). Compressive strength from uniaxial testing was measured from stress-strain curves carried out at room temperature. According to these results, the hydration rates of the composites depend on the concentration of PVC particles and there is an enhancement in their compressive strength as particle content increases, reaching values of 36 MPa after 28 days.展开更多
文摘The thermal decomposition of ammonium perchlorate (AP) with Al and Zn metallic particles was studied at different heating rates in dry air atmosphere and the combustion behavior of AP/Al/Zn propellant was evaluated. The exothermic reaction kinetics was studied by differential thermal analysis (DTA) in non-isothermal conditions and compare with the thermal decomposition of pure AP and AP/aluminum particles analyzed in the same experimental conditions. The Arrhenius parameters were estimated according to the Ozawa and Kissinger methods. The calculated activation energies for the low and high temperature exothermic reactions were 91 and 229 kJ/mol for pure AP, 90 and 112 kJ/mol for 80 wt% AP/20 wt% Al particles. When zinc was incorporated, activation energy of 56 kJ/mol was determined for the only exothermic peak observed for 90 wt% AP/10 wt% Zn and 44 kJ/mol for 78.4 wt% AP/19.6 wt% Al/2 wt% Zn propellant composition.
文摘The present work describes the viability of a mortar binder based on two industrial by-products: poly(vinyl chloride) (PVC) particles from scrap and anhydrite (CaSO4) from fluorgypsum. Mortar composites were made incorporating different amounts of PVC particles and cured at constant room temperature during various periods of time. From X-ray diffraction, it was possible to follow the hydration process and to estimate the effect of the PVC particles on anhydrite transformation to gypsum (CaSO4·2H2O). Compressive strength from uniaxial testing was measured from stress-strain curves carried out at room temperature. According to these results, the hydration rates of the composites depend on the concentration of PVC particles and there is an enhancement in their compressive strength as particle content increases, reaching values of 36 MPa after 28 days.
