Topic
Potassium perchlorate
About: Potassium perchlorate is a research topic. Over the lifetime, 474 publications have been published within this topic receiving 4225 citations.
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TL;DR: An example of gas generators based on periodate salts as oxidizers in nanoenergetic formulations is presented, producing the highest reported gas pressure pulses.
Abstract: Composite energetic materials are simple mixtures of the fuel and oxidizer (e.g., thermite). Although composite energetic materials usually have much higher energy density than monomolecular energetic materials such as 2,4,6-trinitrotoluene (TNT), nitrocellulose, cyclotrimethylenetrinitramine (RDX) etc., they suffer from slow rates of energy release, limited by the mass transfer rate between reactants. In large part, the idea of nanoenergetics is to promote intimate mixing between the fuel and oxidizer by decreasing the length scale. This relatively new class of energetic materials has been a topic of extensive research and has been investigated for applications involving gas generators, initiators, propellants, and explosives as well as propulsive power in micro-/nanoelectromechanical systems (MEMS/NEMS). In the most widely studied nanoenergetic formulations, nanoaluminum (aluminum nanoparticles) is employed as the fuel because of its high reaction enthalpy and ready availability, and metal oxide nanoparticles serve as oxidizers (e.g. Fe2O3, CuO, MoO3). [2,3] More recently, some other oxidizers, including KMnO4, [4a] I2O5, [4b] NaClO4, [4c,d] have been introduced into nanoenergetic formulations for their high oxygen content and strong oxidizing nature. These strong oxidizers also display very promising gas-generating behavior, however, most of them have a reduced shelf life compared to metal oxide nanoparticles, for reasons of light sensitivity or hygroscopicity. Recently, efforts have been made to encapsulate perchlorate salt nanoparticles with less reactive metal oxide layers as a moisture barrier. However, perchlorate salts, particularly potassium perchlorate (KClO4), have raised environmental and public health concerns during manufacture, transport, and applications, and have been targeted for elimination from many traditional pyrotechnic formulations. In a recent report, Moretti et al. introduced periodate salts as an alternative to perchlorate salts as pyrotechnic oxidizers because of their low toxicity and hygroscopicities. Their results show that periodate salt based formulations have good performance in illumination applications. The fabrication of periodate salt nanoparticles and their applications as gas generators, however, remains a challenge. Herein, we present an example of gas generators based on periodate salts as oxidizers in nanoenergetic formulations. A simple yet versatile aerosol spray drying approach was developed to produce periodate salt nanoparticles. The aerosol spray drying method is a promising method for the production of salt oxidizer nanoparticles with a high oxygen content and for the fabrication of salt nanoparticles that are not accessible by wet-chemistry methods. The prepared periodate salt nanoparticles were then tested as oxidizers in nanoenergetic formulations with nanoaluminum as the fuel. These periodate salt nanoparticles exhibit superior reactivity when evaluated as the oxidizers in nanoenergetic formulations, producing the highest reported gas pressure pulses. Fast heating scanning electron microscopy and temperature-jump mass spectrometry techniques were employed to probe the initiation/reaction mechanisms and provided direct evidence that gas phase oxygen release is responsible for the initiation of the periodate nanoenergetic formulations. The general pathway of preparing periodate salt nanoparticles by using an aerosol spray drying method is illustrated in Figure 1a (for details see the Supporting Information).
103 citations
103 citations
TL;DR: In this article, the effect of TMO catalysts on solid propellant burning and decomposition, oxidizer burning, and sandwich and condensed mixture combustion is discussed. But, the exact mechanism of the effect on the burning rate modification of composite solid propellants is not clear even today.
Abstract: Introduction T metal oxides (TMO) like Fe2O3, CuO, MnO2, CuCr2O4, etc., form a very popular group of catalysts for burning rate modification of composite solid propellants. Although it is well known that these oxides affect the decomposition characteristics of polymers and oxidizers like ammonium perchlorate (AP)' and potassium perchlorate, (KP) the exact mechanism of the effect on solid propellants is by no means clear even today. Much fragmentary literature is available on the effect of these oxides on propellant burning and decomposition, oxidizer burning and decomposition, and sandwich and condensed mixture combustion. It is the purpose of this review to bring the material together so that a comprehensive picture can be drawn of the mechanism of the action of these catalysts. It may be mentioned here that these oxides also catalyze hydrocarbon oxidation reactions by inducing free radical decomposition of hydroperoxides (formed by the contact of oxidizer and hydrocarbon).
91 citations
85 citations
TL;DR: In this article, the double-layer response to temperature increase is identified with the potential of maximum entropy of formation of the double layer, which is located in the doublelayer region (ca. 0.43 V vs Pd/H 2 ).
Abstract: Short pulses (10 ns) of high-power laser light produce a sudden increase in the surface temperature of a Pt(111) single-crystal electrode in acidified potassium perchlorate or sulfate solutions. The change of the electrode potential at open circuit was monitored during the relaxation of the temperature. At low pH, the potential transients in the hydrogen adsorption region exhibit a bipolar shape, which can be explained considering that the relaxation is influenced by the rate of hydrogen adsorption. With this assumption, we have estimated a value of the rate constant for hydrogen adsorption around 8 x 10 6 M - 1 s - 1 . By increasing the pH, the rate of hydrogen adsorption is reduced, making it possible to decouple the double-layer response from the hydrogen adsorption process. In this case, the potential where the double-layer response to the temperature increase is zero can be identified with the potential of maximum entropy of formation of the double layer. This potential is located in the double-layer region (ca. 0.43 V vs Pd/H 2 ) for a solution of pH 3. The relevance of this measurement in terms of the location of the potential of zero charge is discussed.
83 citations