纳米金属粉对高氯酸铵热分解动力学的影响

The thermal decomposition characteristics of general ammonium perchlorate (g-AP) influenced by the addition of aluminum, nickel with different particle sizes (general and nano) are studied by TG and DSC. The results show that aluminum powders (both general and nano size) are nearly uninfluenced. Nano nickel powders have the greatest influence on the decomposition properties of g-AP among metal powders. Such accelerating effects of nanonickel powders are more apparent on the stage of high temperature decomposition than low temperature decomposition of g-AP and will be weakened with the decrease of the content of nanonickel. Nanonickel powders are also more effective than super fine nickel powders on accelerating the thermal decomposition of superfine AP (s-AP). The kinetic parameters of the thermal decomposition of s-AP and mixture of s-AP and nano nickel powders are obtained from the TG-DTG curves bythe integral method based on the Coats-Red fern equation. Nanonickel powders reduce the apparent activation energy of the thermal decomposition of s-AP from 157.9 kJ/mol to 134.9 kJ/mol. The most probable mechanism functions of the thermal decomposition reaction for s-AP and mixture of s-AP and nano nickel powders both belong to systems of Avrami-Erofeev equations. The mechanism of such accelerating effects has been discussed.     

Mg2NiH4对高氯酸铵热分解过程的影响

采用置换-扩散法制备了储氢材料Mg2NiH4, 用XRD, ICP和DSC-TG方法对其结构进行了表征. 用热分析法(DSC)研究了Mg2NiH4对高氯酸铵(AP)热分解过程的影响. 研究结果表明, Mg2NiH4对AP热分解过程有较大影响. Mg2NiH4可以显著促进AP的低温热分解过程, 降低高温热分解温度, 使DSC表观分解热明显增大. 随着加入量的增加, Mg2NiH4对AP热分解的催化促进作用增强, 当Mg2NiH4加入的质量分数为30％时, DSC表观分解热最大. 吸氢量越大, 储氢材料对AP的催化促进作用越强. Mg2NiH4催化促进AP分解过程的作用机理为: Mg2NiH4分解释放的H2及Mg和Ni与AP分解产物发生反应.     

Preparation of Ni/TiO2 Nanoparticles and Their Catalytic Performance on the Thermal Decomposition of Ammonium Perchlorate

Metal/oxide nanoparticles are attractive because of their special structure and better properties. The Ni/TiO₂ nanoparticles were prepared by a liquid phase chemical reduction method in this paper. The obtained‐products were characterized by inductively coupled plasma (ICP), X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The results show that Ni particles in Ni/TiO₂ nanoparticles exhibit better dispersion and the size of most Ni particles is 10 nm or so. The catalytic activity of Ni/TiO₂ nanoparticles on the thermal decomposition of ammonium perchlorate (AP) was investigated by simultaneous thermogravimetry and differential thermal analysis (TG‐DTA). Results show that composite process of Ni and TiO₂ can improve the catalytic activity of Ni nanoparticles on the thermal decomposition of AP, which is mainly attributed to the improvement of Ni dispersion in Ni/TiO₂ nanoparticles. The catalytic activity of Ni/TiO₂ nanoparticles increases with increasing the weight ratio of Ni to AP.     

Preparation of Al/Ni Reactive Multilayer Foils and its Application in Thermal Battery

The conventional heating materials of thermal battery have the disadvantages of low combustion rate and less heat release, so it is necessary to develop new heating materials. Al/Ni Reactive Multilayer Foils (RMFs) is an ideal heat source due to its high heat release, fast burning speed and no gas generated during combustion. Al/Ni RMFs were prepared by magnetron sputtering, and the heat transfer process of thermal battery using Al/Ni RMFs as heating material was simulated by the COMSOL MULTIPHYSICS simulation. The Al/Ni RMFs combustion reaction mechanism with different Al/Ni ratios was proposed according to DSC and XRD results. The effects of Al/Ni atomic ratio of RMFs on the melting time of electrolyte were investigated, and the temperature distribution during the activation was obtained, indicating the rapid activation process of the thermal battery.     

钛酸锌的制备及其对高氯酸铵热分解的催化性能

ZnTiO₃ nanocrystals were prepared by sol-gel method, using Zn(NO₃)₂ and Ti(C₄H₉O)₄ in the topic. The as-prepared ZnTiO₃ nanocrystals were characterized by XRD, FTIR and TEM, and the catalytic performance of ZnTiO₃ nanocrystals of different contents for the ammonium perchlorate(AP)decomposition was investigated by thermal analysis. The results indicate that ZnTiO₃ with pure cube structure can be synthesized at 600 ℃ by this procedure,which was spheroid with particle size of about 60~100 nm. The results expressed that the low temperature decomposition peaks of AP is advanced by 17 ℃ and the high temperature decomposition peaks of AP is advanced by 24 ℃ when adding 5% nanoparticle ZnTiO₃ powder. The catalytic effects of ZnTiO₃ powders on the high temperature decomposition of AP are less than that of nanometer metal powders, but all the micron metal powders decrease the low decomposition temperature of AP.     

Investigations on the use of chemical modifiers for the direct determination of trace impurities in Al2O3 ceramic powders by slurry electrothermal evaporation coupled with inductively-coupled plasma mass spectrometry (ETV-ICP-MS)

The direct determination of trace impurities in Al2O3 ceramic basic powders by ICP-MS using electrothermal evaporation (ETV) with slurry sampling has been investigated. To increase interference-free analyte volatilization, the use of the palladium-group modifiers (PGM) IrCl3, Pd(NO3)2, and PdCl2 for the determination of Ca, Fe, Ga, Mg, Mn, Na, Ni, and V in Al2O3 powders was studied. Their role, which in ETV-ICP-MS and ETV-ICP-OES is to stabilize the investigated analyte during the ashing phase, to increase vaporization of the matrix, and to reduce transport losses was investigated. Optimum analysis results were obtained with PdCl2 modifier when 500 ng Pd was used for a sample weight of 100 microg Al2O3 injected into the ETV. Calibration was performed by standard addition with aqueous solutions of the analytes. The RSDs calculated from triplicate analysis ranged form 5 to 10%. Detection limits between 0.07 microg g(-1) (Ga) and 1.1 microg g(-1) (Na) were achieved. The accuracy was proven for the elements Ca, Fe, Ga, Mg, Mn, Na, Ni, and V by analyzing an NIST standard reference Al2O3 material (SRM 699) with a middle grain size of 16.4 microm. The analytical method was used for the analysis of Al2O3 powder (AKP 30, Sumitomo, Japan) with impurities in the low microg g(-1) range and a middle grain size of 1.1 microm. The results obtained for the elements Ca, Fe, Ga, Mg, Mn, Na, Ni, and V were comparable with those obtained by ICP-MS subsequent to conventional decomposition with hydrochloric acid at high pressure.     

Thermal studies on metal complexes of 5-nitrosopyrimidine derivatives IV

The thermal decomposition processes of the complexes of 6-amino-5-nitrosouracil with Fe(II), Co(II), Ni(II) and Cu(II) have been studied using TG and DSC techniques. Dehydration energies have been calculated from the DSC curves.     

Dinuclear (Ferrocenylmethyl)imidazolium Ionic Compounds with Polycyano Anions. Characterization,Migration, and Effects during Combustion

Alkyl‐substituted ferrocene‐based burning rate catalysts exhibit high migration and volatility during curing process and prolonged storage of the composite solid propellants. To deal with the drawbacks twenty‐one dinuclear (ferrocenylmethyl)imidazolium compounds paired with polycyano anions, were synthesized and characterized by ¹H NMR, ¹³C NMR, UV/Vis, elementary analysis, and both 2 and 11 were further characterized by single‐crystal X‐ray diffraction. The migration test revealed that the compounds have excellent anti‐migration ability. The cyclic‐voltammetry results suggested that they are quasi‐reversible or irreversible redox systems. The TG/DSC analyses showed that the compounds are highly thermal stable. Their effects on the thermal decomposition of ammonium perchlorate (AP) and 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX) were additionally examined. The results showed that the new compounds have strong effects on the thermal decomposition of both AP and RDX during combustion. Both 13 and 21 are more excellent than catocene for increasing the released heats of AP and can be used as alternatives of catocene in the composite solid propellants.     

Effect of catocene on the thermal decomposition of ammonium perchlorate and octogen

Simultaneous TG/DSC-FT-IR was employed to study the effect of catocene with a high concentration (5, 15, and 25 %) on the thermal decomposition of ammonium perchlorate (AP) and octogen (HMX) with different particle sizes. The experimental results show that catocene has effect on the thermal decomposition of AP and HMX, but the role that catocene playing changes with the concentration of catocene and the particle size of AP and HMX. High concentration of catocene (more than 15 %) benefits the decomposition of fine AP and HMX at low temperature, but has little effect on the decomposition of median and coarse AP. The thermal decomposition of HMX is affected by catocene mainly through increasing the heat release of the first decomposition step, while through both increasing the heat release and decreasing the decomposition temperature of the first decomposition step for the thermal decomposition of AP.     

Low/high temperature relationships in dinitramide salts by DEA/DSC and study of oxidation of aluminum powders by DSC/TG

The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tan value at the low temperature transition peak. As the cation basicity increased in the series ADN相似文献   

Thermal decomposition of RDX/AP by TG–DSC–MS–FTIR

The method of TG–DSC–MS–FTIR simultaneous analysis has been used to study the thermal decomposition mechanism of the RDX/AP (1/2) mixture. TG–DSC showed that there were two mass loss processes for thermal decomposition of RDX/AP. The first one was mainly ascribed to the thermal decomposition of RDX. Addition of AP to RDX causes decomposition to take place abruptly, after melting, resulting in a very sharp and strong peak at lower temperature. The apparent activation energies, calculated by model-free Friedman method, of this process were negative. The second mass loss process of RDX/AP was confirmed to be the thermal decomposition of AP, catalyzed by RDX. This process can be divided into three stages, which were an nth-order autocatalytic and two one-dimensional diffusion stages, respectively. There was a competition among the formation reactions of N₂O, HNCO, and HCl for the first stage and between NO₂ and N₂O for the later two stages. The production of N₂O dominated in the second stage, while NO₂ did in the third stage.     

Effect of iron-containing catalysts on thermal decomposition of cured GAP-AP propellants

The effects of various burning rate catalysts on thermal decomposition of cured glycidyl azide polymer (GAP)-ammonium perchlorate (AP) propellants have been studied by means of thermal analysis and a modified vacuum stability test (MVST). Four types of iron-containing catalysts examined in this paper are catocene, ferrocenecarboxaldehyde (FCA), ferrocene, and ferric oxide. Results of differential thermal analysis (DTA) and thermogravimetric analysis (TG) revealed that the catalysts play an important role in the decomposition of both AP and GAP. The peak decomposition temperature (T _m) of DTA curves and onset decomposition temperature (T _o) of TG patterns considerably shifted to a lower temperature as the concentration of catalysts increased in the propellants. The endothermic temperature of AP, however, is unaffected by the presence of burning rate catalysts in all cases. The activation energy of decomposition of the propellants in range of 80 to 120°C is determined, based on the MVST results.     

Effects of Aluminum on Thermal Decomposition of Hexogen/Ammonium Perchlorate

Thermogravimetry-differential scanning calorimetry-mass spectrometry-Fourier transform infrared spectrometry（TG-DSC-MS-FTIR） simultaneous analysis was used to study the effects of 10.7 μm and 40 nm Al on the thermal decomposition of the Hexogen/ammonium perchlorate（RDX/AP,1/2,mass ratio） mixture.TG-DSC results show that there are two mass loss processes for the thermal decomposition of RDX/AP/Al.The first one is mainly ascribed to the thermal decomposition of RDX.The reaction rate of RDX/AP/10.7 μm Al is so fast that the apparent activation energy,calculated by model-free Friedman method,is negative,which is the same as that of RDX/AP.30％（mass fraction） 40 nm Al added in RDX/AP change the activation energy from negative to positive value.The second mass loss process of the RDX/AP/A1 mixture is ascribed to the thermal decomposition of AP.This process can be divided into three stages for RDX/AP with and without Al.The kinetics model is not changed in the presence of micro-sized Al,while it is changed from CnB/D1/D1 to CnB/D1/D4 after the addition of 40 nm Al to RDX/AP.The reaction rate constant of the first stage and the end temperature of the second stage decrease,while the end temperatures of the third stage increase in the presence of 40 nm Al.The MS-FTIR results show there is a competition between the formation reactions of HNCO,N2O and NO2 during the second mass loss process.     

纳米镍包覆超细铝复合粉末的氧化性能

通过置换还原法, 快速、简洁、定量地制备出了纳米镍包覆的超细铝粉复合粉末. 利用扫描电子显微镜(SEM)、热重分析(TGA)、差示扫描量热(DSC)和X射线衍射(XRD)等分析手段对原料Al粉和复合粉末的形貌及其氧化性能进行研究. 结果表明, 原料Al粉在1050 ℃时增重率为122%, 当包覆的纳米镍粉质量分数为0.75%时, 可以使铝粉在1050 ℃时的增重率达到135%, 并且随着镍粉含量的增加, 铝粉的增重率进一步提高. 当镍的质量分数达到8.93%时, 复合粉末在约1000 ℃时出现点火燃烧现象. 纳米镍粉的氧传递对促进超细铝粉的氧化起到了至关重要的作用.     

Evaluation of food-processing conditions of various particle sizes of <Emphasis Type="Italic">Tremella fuciformis</Emphasis> powder via DSC and TG analyses

Tremella fuciformis (Berk.), also known as silver ear, has a high economic value due to being a valuable edible and medicinal mushroom. The focus of this study was on the various particle sizes of 80–300 mesh (particle diameters from 2 mm to 250 μm) for freeze-drying silver ear powder in order to determine the water-holding capacity, viscosity, and crude polysaccharide content of various particle sizes. Our aim was to determine the possible conditions for silver ear powder for food processing under the conditions of oxidation/non-oxidation and heat treatment. Overall, we obtained various particle sizes of silver ear powder, the water-holding capacity decreased from 21.84 to 14.82 g g^?1, the viscosity increased from 8.53 to 71.20 cP, and the content of crude polysaccharides, which remained almost constant, was approximately 300 mg g^?1. In addition, the smaller the particle size of silver ear powder, the greater the thermal stability of the particles by differential scanning calorimetry (DSC) and thermogravimetric (TG) tests. The results for various particle sizes of silver ear powder in food processing are never more than ca. 240 °C by DSC tests. Moreover, comparing the results of thermal decomposition using TG analyzer under nitrogen and air conditions, in nitrogen, the various particle sizes have better preservation for storage conditions and the smaller particle size powders retained good thermal decomposition characteristics.     

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.     

Preparation of nano-cerium dioxide and its effect on the thermal decomposition of ammonium perchlorate

Detonation synthesis method was introduced to prepare nano-cerium dioxide. Nano-cerium oxide was obtained by this novel method and its effect on the thermal decomposition of ammonium perchlorate (AP) was studied. X-ray diffraction and transmission electron microscope were used to characterize as-prepared materials. Results showed that as-prepared cerium dioxide was cubic phase and its morphology was nearly spherical. The mean size of as-prepared cerium dioxide particles was 55 nm. Differential scanning calorimetry (DSC) was used to test the effect of as-prepared nano-cerium dioxide on the thermal decomposition of AP. Kissinger method was introduced to calculate activation energy of different specimens according to DSC data. Results indicated that nano-cerium dioxide synthesized by detonation method had catalytic effect on thermal decomposition of AP and could decrease activation energy of AP/CeO₂ mixture.     

Preparation and characterization of the AP/Al/Fe2O3 ternary nano-thermites

A novel ammonium perchlorate (AP)/aluminum (Al)/iron oxide (Fe₂O₃) nano-thermites was prepared by orderly using sol–gel, wet impregnation, and solvent-anti-solvent processes. Samples prepared in this work were characterized by scanning electron microscope (SEM), nitrogen adsorption–desorption tests, X-ray diffraction (XRD), and differential scanning calorimetric (DSC) measurements. The results showed that AP and nano-aluminum were dispersed in the pores of the iron oxide gel, resulting in a large specific surface area (84.7 m² g^?1). The XRD results showed that AP dispersed homogeneously in the energetic composites at nano-scale. DSC analyses indicate that the Al/Fe₂O₃ nano-thermites played a catalytic role in the thermal decomposition of AP, thus the interaction of thermite reaction was greatly enhanced by accelerated decomposition of AP. The experimental results showed that the as-prepared AP/Al/Fe₂O₃ nano-thermites were of high energy, making it a competitive candidate material in the field of micro-propellants.     

Effects of nano nickel powders addition on flash pyrolysis of poly(ethylene glycol)

Pure PEG and the mixture of PEG and nano nickel powders (PEG/n-Ni) were pyrolyzed at 500 °C for 5 min in N₂ atmosphere. GC/MS and FTIR were employed to detect the volatile products. Some important regularity in the mass spectra of the PEG pyrolysis products was discovered, and 11 series of PEG pyrolysis products were identified. The experimental results show that the nano Ni powders evidently change the relative contents of each products series. The statistical results of the ratio of C-O cleavage to C-C cleavage, as well as the ratio of hydrogenation to dehydrogenation, indicate that nano Ni powders have remarkable effects on the bonds cleavage and free radicals annihilation. The process of hydrogenolysis and hydrogenation were propounded to explain the effects of nano Ni addition on PEG flash pyrolysis.     

Mono‐ and Dinuclear Ferrocenyl Ionic Compounds with Polycyano Anions. Characterization,Migration, and Catalytic Effects on Thermal Decomposition of Energetic Compounds

Neutral ferrocene‐based burning rate (BR) catalysts show strong migration trends and volatility during long‐time storage and curing of the composite solid propellants. To reduce these disadvantages thirty‐two ferrocenyl quaternary ammonium compounds, paired with polycyano anions, were synthesized and characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectroscopy, as well as elemental analysis. Additionally, crystal structures of eight compounds were confirmed by single‐crystal X‐ray diffraction. TG and DSC analyses indicated that the compounds containing 1,1,2,3,3‐pentacyanopropenide anions show high thermal stability. Cyclic voltammetry studies suggested that they are quasi‐reversible or irreversible redox systems. Anti‐migration tests verified that the tested compounds show very low migration tendency and some of them exhibit no migration after 30 days aging at 70 °C. Their catalytic efficiency in the thermal decomposition of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC analyses. The results revealed that most of the compounds exhibit distinct effects on the thermal degradation of AP and RDX. Two compounds have good catalytic ability in the thermal decomposition of HMX, representing rare examples of the reported ferrocenyl ionic compounds, which display catalytic property during combustion of HMX.