Showing 13 results for yari
Farhad Seif, Mahdi Aghayari,
Volume 9, Issue 2 (12-2013)
Abstract
In modern energetic propellant formulations, conventional plasticizers are being gradually replaced by energetic plasticizers having nitro, nitroamino, azido and other energetic groups. Energetic Plasticizers used to improve processing, mechanical properties and index of energy. Designer of propellant for decrease migration and improve safety factors in propellant’s formulation should to notice incorporation and compatibility energetic plasticizer with polymer matrix. In this paper, energetic plasticizers that can be utilized in solid propellants are discussed
Saied Mahdi Amini, Mohhamad Hossein Keshavarz, Mohhamad Ghorbanifaraz, Mehran Hayati, Ali Mousaviazar, Mahdi Aghayari,
Volume 9, Issue 2 (10-2014)
Abstract
Concentrated suspension of binders in composite propellant causes a complex phenomena so that controlling of rheology properties is difficult due to high percentage of fillers. Composite solid propellant contains paste suspension of mixtures of different components, e.g. oxidizer, fuel and binder. Increasing the percentage of solid phase without increment of viscosity is an important subject in the production of solid propellant. This problem can be solved using two different particle sizes distribution. Five samples of composite solid propellants on the basis of hydroxyl terminated polybutadiene (HTPB) with 85% of solid phase containing dual sizes of ammonium perchlorate (AP) have been prepared. These samples have different coarse/fine ratios between 80/20 to 60/40. It was found that optimum temperature for casting of propellant is greater than 40C. The best ratio for obtaining the least viscosity is 70/30 coarse/fine ratio.
Mr Mahdi Aghayari, Mr Farhad Seif, ,
Volume 9, Issue 4 (12-2013)
Abstract
Ultrasonic technique, is one of the best nondestructive techniques for solid propellants motors evaluation. In this article ultrasonic technique use, has been reported for measuring solid propellant burning rate at different pressure with just one experiment and at the moment, for especial motors. The use of swept frequency method in a proper confine frequency and interrupted frequency method has been investigated for seperate specification liner-propellant and liner- case respectively. Ultrasonic device characteristic and way of working with that has been reported in order to investigate the micro cracks and micro cavities which cause to lowering mechanical properties and increasing burning surface and pressure and at last cause to motor explosion. In addition, the studies showed that in cold disposal of aged solid propellant motors, the case temperature is cooled till lower glass transition temperature (Tg) limits of binder and then by ultrasonic waves with 2 MHZ, is disposed. Also, in order to unity distribution of nano particle in mixture of slurry the ultrasonic mixer is used.
Saeed Yari, Peyman Soleimani, Ebrahim Balaghi, Ayatollah Kalantari, Farhad Seif,
Volume 10, Issue 1 (7-2014)
Abstract
Investigation shows that the some complex and expanded parameters are effective on the burning rate. In this paper we evaluate the effect of particles dispersion, size of AP particle, the size of Al particles, Fe2O3, viscosity, shape factor, the size of mixer and the mechanical parameters such as tensile and stress on the burning rate. These studies show that the decrease of AP particles, size distribution, using nano-size Al particles, decreasing the mixer size and adding burning rate catalysts such as Fe2O3 can increase the burning rate of composite propellant. Also loaded stress and strain can increase this parameter
Mr Mahdi Aghayari, Mr Farhad Seif, Mr Hadi Ahmadzade, ,
Volume 10, Issue 1 (7-2014)
Abstract
Solid propellant burning rate is highly dependent on the pressure, so that the combustion duration propellant rocket engines, combustion vibration leads to considerable changes in pressure. This could lead to an explosion in rocket engines. The best case is propellant combustion independent of pressure. Ballistic modifiers added to propellant formulation for reduce pressure sensitivity and reduce or increase of burning rate also. Lead and copper salts are materials that create plateau and mesa in double based propellant. In this article, mechanism of create plateau and mesa by burning rate catalysts investigated.
Saeed Yari, Ahmad Hakimi, Ali Sarallahi, Hatef Irvani, Ali Bolukian,
Volume 10, Issue 3 (12-2014)
Abstract
Recent studies in solid composite propellants indicate that acceleration field cause to increase in burning rate. Relation between acceleration field and burning rate of propellant have an important effect on missile systems ballistic, especially on perforated grain missiles. If these effects has neglected in design phase, the pressure-time profile shifted out of acceptable rage and result in increasing pressure and motor fail. Therefor in order to design rockets, need to know the acceleration effect on solid rocket performance. In this work influence of acceleration field in burning rate of non-aluminized and aluminized propellant has been investigated. Also models with a good accuracy to predict the performance of propellant in accelerated field, has been introduced.
Saeed Yari, Hasan Eslami, Farhad Seif, Ali Bolukian,
Volume 12, Issue 2 (1-2017)
Abstract
By comparing the empirical and predicted performance diagrams of the composite solid propellants, it appears that there is a discrepancy between these two graphs .This deviation has been attributed to spatial burning rate variation which is related to burning rate fluctuation or hump effect. The most important reasons for this spatial burning rate variation are casting process. In order to approve the effects of propellant flow during casting, on burning rate, the ballistic model include measuring burning rate of casted sample based on flow analysis may be used. In this paper, there are two assumptions which affect the burning rate deviation, the first one is based on the influence of oxidizer orientation on linear burning rate and the second one is based on the effect of casting method and slurry flow line on burning rate deviation and local burning behavior of propellant in grain. Hump effect is related to the spatial variation in burning rate which is result of rheology process of propellant slurry.
Mr Hatef Irvani, Hasan Eslami, Saeed Yari, Ali Abdi Amiri, Ali Bolukian,
Volume 12, Issue 2 (1-2017)
Abstract
The reaction between fine aluminum particles and water over the past fifty years, due to high energy generation and green products is in consideration. But all aluminum particles have an inactive oxidative layer and in case of Nano-Al this layer has high ratio of particles. So, efficiency of hydrogen produced by the reaction between water and aluminum is less than the theoretical value. There are two ways to reduce the amount of aluminum oxide and thus increase the hydrogen efficiency, which one is the replacement of nano-aluminum components with micro-aluminum and the other is the introduction of hydrogen-rich components. Aluminum hydride or alane are used in many high-energy materials due to their high hydrogen storage. Many studies show that using hydrogen peroxide in Alice and alane propellants promote its performance.
Zahra Khodadadipour, Seyed Ghorban Hosseini, Mojtaba Mahyari, Javad Mohebbi,
Volume 13, Issue 3 (9-2018)
Abstract
Nanoparticles (NPs) tend to agglomerate consequently their catalytic activities decrease during propellant operation. Therefore, loading the nanoparticles onto the support is a general method to prevent the agglomeration and maintain the catalytic activities of the nanoparticles. Three dimensional (3D) graphene has high surface area and porous structur. Furthermore,, 3D-graphene is an efficient support to grow and anchor NPs with high loading and better dispersity. In this study, firstly CuCr2O4 spinel NPs and CuCr2O4@3D-GFs nanocomposite were synthesized. Thenthe the structure and size of the particles were determined by XRD,FESEM and TG. The as-prepared CuCr2O4 NPs and CuCr2O4@3D-GFs nanocomposite were used as a promising catalyst for the thermal decomposition of ammonium perchlorate (AP) and their catalytic performance was investigated by differential scanning calorimetry and thermal gravimetric analysis (DSC/TGA). Thermal decomposition of AP in the presence 4 wt % CuCr2O4 NPs and 2 and 4 wt % CuCr2O4@3D-GFs nanocomposite prepared by solvent-antisolvent method showed that two exothermic peaks of AP merges into one peak and high-temperature decomposition appeared at 348, 332 and 321°C, respectively.
Soodabeh Morovatipoor, Fathollahi, Seyed Ghorban Hosseini, Mojtaba Mahyari,
Volume 15, Issue 1 (3-2019)
Abstract
The oxidant forms the most part of the propellants, and ammonium perchlorate is the most applicable oxidizer in composite solid propellants. Therefore, its thermal decomposition and immunity properties have been a great effect on the propellants properties. The using of polymeric additives is one of the different methods for improving the thermal and immunological properties of ammonium perchlorate. The types of additive materials are usually selected based on the applicable purpose. In this research, the effects of polymeric additives materials are investigating due to improve the sensitivity, the increase of thermal and chemical stability, and also the prevention of ammonium perchlorate particle agglomeration that have been used up to now.
Manoochehr Fathollahi, Mohsen Goodarzi, Mojtaba Mahyari, Seyed Gorban Hosseni, Mohammad Ali Zarei,
Volume 17, Issue 1 (10-2022)
Abstract
Being non-polar and considerably high electrical resistivity are significant drawbacks of the crystalline paraffin wax used for desensitizing energetic materials. Herein, as a practical approach to improve the wax properties, maleic-anhydride was reacted with paraffin wax in the presence of a free-radical initiator. Then, the reaction success was approved by employing Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) to spot carboxyl groups onto the aliphatic backbone. In addition, the thermal properties of the modified wax were investigated using differential-scanning-calorimetry and thermogravimetry analysis (DSC-TGA). Finally, to estimate the improvement in the wax polarity, an experiment was designed in which HMX coated via a two-step procedure was conducted for DSC and tribocharing tests. The second layer utilized 0.5 w% glyceline as a deep eutectic solvent (DES). In brief, our observation exhibited that the modified wax caused a 50% decrease in charge accumulation compared to the unmodified paraffin. In addition, our experimental outcomes .showed that the modified paraffin exhibited a better distribution over the substrate surface than the unmodified one
Dr Mojtaba Mahyari, Mr Iman Shater Khabazi, Dr Fatemehe Abrishami, Dr Seyed Ghorban Hoseini,
Volume 17, Issue 2 (9-2022)
Abstract
In this paper, the effect of nanocatalytic metal-organic framework based on copper metal and bis-tetrazolamine (CuBTA) ligand functionalized with cobalt (II) oxide nanoparticles on the thermal decomposition behavior of ammonium perchlorate (AP), using differential survey calorimetry (DSC) has been reviewed. First, the metal-organic framework (CuBTA) was synthesized from the raw materials of copper chloride and bistetrazole amine using the solvothermal method and with the help of .... Then, using cobalt (II) nitrate and co-precipitation method, the desired metal-organic framework was functionalized with cobalt (II) oxide nanoparticles. Fuzzy studies were performed with X-ray diffraction pattern (XRD) apparatus, as well as formation investigations using Fourier transform infrared spectroscopy (FT-IR). The results of thermal decomposition of ammonium perchlorate in the presence of metal-organic framework (CuBTA) and nanoparticle functionalized framework showed that 5% by weight of the catalyst, the thermal decomposition temperature of ammonium perchlorate was 34.1 °C and 91.1 °C. Reduced for the metal-organic framework and the metal-organic framework functionalized by nanoparticles, respectively. The combustion enthalpies of 1570 J.g-1 and 1375 J.g-1 were obtained in the same way.
Mohammad Ali Zarei, Dariush Fallah, Mohsen Akbaripour, Seyyed Morteza Razavi, Mojtaba Mahyari, Saeed Tavangar,
Volume 18, Issue 2 (9-2023)
Abstract
Today, vacuum stability test is one of the best methods to investigation the compatibility of different plasticizers and polymers. In this research, the compatibility of polydimethylsiloxane resin with trimethylolethane trinitrate energetic plasticizer was investigated. The applied approaches included vacuum stability test (VST) and glass transition temperature determination using DSC analysis. The acceptance limit of TMETN plasticizer by polydimethylsiloxane resin was determined using retardation and it was found that this polymer can accept the plasticizer at least 20% (w/w). Investigating the glass transition temperature with DSC analysis test showed that polydimethylsiloxane has good compatibility with TMETN plasticizer. The amount of gas released from the sample in standard conditions (VR) in the VST test was calculated as 4.77 cm3, which was within the allowed range and indicates the compatibility of TMETN plasticizer with polydimethylsiloxane.
