Iron/aluminum nanocomposites prepared by one-step reduction method and their effects on thermal decomposition of AP and AN

Aluminum(Al)powder is widely used in solid propellants.In particular,nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al.However,the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder,which greatly limits its application.Hence,this paper used iron,a component of solid propellant,to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder.SEM,TEM,EDS,XRD,XPS,and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes.The results show that Fe was uniformly coated on the surface of Al powder.There was no reaction between Fe and Al,and Fe/Al composite fuels had a larger specific surface area than pure Al,which could better improve the reactivity of pure Al.Besides,the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored.The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder.Especially,the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder.Hence,Fe/Al composite fuels are expected to be widely used in solid propellants.

Thermogravimetric,kinetic study and gas emissions analysis of the thermal decomposition of waste-derived fuels

A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their recovery.In this research,we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime,biomass,waste oils,and blends on their basis.We also analyze the concentrations of gaseous emissions.The results show that biomass,oils,and coal slime significantly affect each other in the course of their co-combustion when added to slurry fuels.The preparation of coal-water slurry based on slime and water reduced the ignition and burnout temperature by up to 16%.Adding biomass and waste oils additionally stimulated the slurry ignition and burnout,which occurred at lower temperatures.Relative to dry coal slime,threshold ignition temperatures and burnout temperatures decreased by 6%–9%and 17%–25%,respectively.Also,the use of biomass and waste oils as part of slurries inhibited NOхand SO_(2)emission by 2.75 times.According to the kinetic analysis,added biomass and waste turbine oil provide a 28%–51%reduction in the activation energy as compared to a coal-water slurry without additives.

Hydrolysis Lignin as a Sorbent and Basis for Solid Composite Biofuel

New powdered sorbent Lignosorb based on the hydrophobized hydrolysis lignin has been developed at the Belarusian State University. Hydrolysis lignin is a commercial waste product of biomass processing in the hydrolysis production of ethanol. In spite of the various proposals for hydrolysis lignin usage, the wide application has not found yet. Special area of hydrophobized hydrolysis lignin usage as a sorbent for oil spills removal and oil products waste recovery is discussed. Lignosorb, thanks to the rather high bulk density, can be applied manually or mechanically by conventional sprayers. It does not sink after oil adsorption and transforms liquid oil film on the water surface into the solid mass. The solid product is a complete mass and is easily collected from the surface of water. Lignosorb when blended with oil products waste in the volume forms the granular free-running product. The rheological properties of the Lignosorb suspensions in oil products at different sorbent to oil product ratio have been estimated. Saturated by different oil products Lignosorb one can granulate or pellet and utilize as a composite solid fuel including the co-firing regime of combustion. It has the higher heating value of 32.1 - 38.8 MJ/kg while the coal has 20.9 - 30.1 MJ/kg. It has been shown that composite fuel burning has less longstanding inflammation stage, more long stable burning stage and less longstanding phase of smoldering in the comparison to wood and Lignosorb burning.

Modeling of Mesoscale Creep Behaviors and Macroscale Creep Responses of Composite Fuels Under Irradiation Conditions

A finite-strain homogenization creep model for composite fuels under irradiation conditions is developed and verified,with the irradiation creep strains of the fuel particles and matrix correlated to the macroscale creep responses,excluding the contributions of volumetric strain induced by the irradiation swelling deformations of fuel particles.A finite element(FE)modeling method for uniaxial tensile creep tests is established with the irradiation effects of nuclear materials taken into account.The proposed models and simulation strategy are numerically implemented to a kind of composite nuclear fuel,and the predicted mesoscale creep behaviors and the macroscale creep responses are investigated.The research results indicate that:(1)the macroscale creep responses and the mesoscale stress and strain fields are all greatly affected by the irradiation swelling of fuel particles,owing to the strengthened mechanical interactions between the fuel particles and the matrix.(2)The effective creep rates for a certain case are approximately two constants before and after the critical fission density,which results from the accelerated fission gas swelling after fuel grain recrystallization,and the effects of macroscale tensile stress will be more enhanced at higher temperatures.(3)The macroscale creep contributions from the fuel particles and matrix depend mainly on the current volume fractions varying with fission density.(4)As a function of the macroscale stress,temperature,initial particle volume fraction and particle fission rate,a multi-variable mathematical model for effective creep rates is fitted out for the considered composite fuels,which matches well with the FE predictions.This study supplies important theoretical models and research methods for the multi-scale creep behaviors of various composite fuels and provides a basis for simulation of the thermal–mechanical behavior in related composite fuel elements and assemblies.