br Materials and methods br

Materials and methods
Results and discussion The nanoparticles of RDX and HMX were precipitated immediately on the injection of their respective solution into antisolvent (water). Stirring was continued up to a few minutes after the injection to complete the mixing to precipitate smaller particles with narrow size distribution [30]. Precipitation of the HECs did not produce any turbidity due to the tiny size as well as the very low concentration of the particles. However, the particles could be detected using DLS. Precipitation was performed from a number of different solvents in order to study the effects of solvents on the size and shape of nanoparticles. While varying the solvents, the previously optimized experimental conditions for obtaining small particles of RDX from acetone were used [26]. The experimental conditions were: temperature (70 °C), solvent to antisolvent ratio (1:250) and concentration (5 mM) [26]. The particle sizes and morphologies of the prepared nano-RDX and nano-HMX were studied using FESEM imaging. The representative FESEM images of nano-RDX and nano-HMX are given in Figs. 1 and 2, respectively. Average particle sizes were calculated from the FESEM images using Image J software. The average particle sizes that ampa receptor were calculated from FESEM images of solvents are listed in Table 1.
Conclusions
Acknowledgements Thanks are due to IIT Mandi for providing laboratory facilities. Financial assistance from ARMREB (DRDO) under grant No. ARMREB/CDSW/2012/149 and research fellowship to Mr. Raj Kumar from UGC are gratefully acknowledged. Mr. Sudhir Scarlch, NIT Hamirpur and Dr. Kenny Pandey, (Sophisticated Instrument Centre) IIT Indore are also thanked for FESEM imaging.
Introduction Metal matrix composites synthesized by incorporating the hard ceramic particles like silicon carbide (SiC) into the aluminum alloys achieve good mechanical properties. These composites are light weight and show good hardness property which qualifies them as structural materials especially for wear resistant and weight critical application. This motivates the researchers to investigate the aging behavior of this category of metal matrix composites [1]. The age hardening characteristics of an alloy can be generally tailored by introducing the reinforcement. Many changes may be due to manufacturing process, reaction between reinforcement and matrix, size, morphology and volume fraction reinforcement [2]. Many studies have been carried out to develop the improved aluminum-based composites with the aim of achieving better mechanical properties. In general, many techniques have been developed to fabricate the SiC particle reinforced aluminum alloy composite, including casting, powder metallurgy, pressure infiltration and spray deposition methods. Among all the fabrication methods, the stir casting technique is attractive due to its uniform distribution of reinforcement, flexibility and mass production [3]. These composites play a vital role in the engineering applications like aerospace, military, and civil manufacturing industry. Skibo et al. [4] studied the age hardening behavior of a 30 wt% SiCp/Al composite and found that the aging response was very rapid, in that order only 1 h aging at 120 °C, peak tensile strength of 45% and peak hardness of 69% were attained, compared to Al alloy. Das et al. [5] discussed no difference in the aging response of as-cast without reinforcement of Al(6061) and 10 and 20 wt% of SiC reinforced 6061 Al composites in their studies of strength and elongation of these materials as a function of aging time at 175 °C. With extensive data available on the heat treatment of 8011 Al alloys with conventional alloying elements, no much has been documented on the age hardening characteristics of this alloy, particularly with silicon carbide reinforcement. Hence, the need for research on this area is justified. The aim of the present research is to study the aging hardening characteristics of 15% SiCp/8011 Al particulate composites.