Study on the thermal decomposition kinetics of DNTF

3,4-Dinitrofurazanylfuroxan (DNTF) is a representative of the third-generation energetic materials with complex thermal decomposition behavior. Understanding thermal decomposition process of DNTF is of great significance for the safety of its production, storage and use. In this paper, the dynamic differential scanning calorimetry (DSC) test is carried out to study its thermal decomposition characteristics. The quench and reheat experiments and isothermal tests were performed to determine the types of decomposition reactions. A four-step consecutive reaction model, A→B→C→D→E, where each step is an N-order reaction was established for the decomposition process. The established kinetic models were verified by 250°C isothermal test.

PENGELOLAAN BATUAN REAKTIF (REACTIVE GROUND) DALAM KEGIATAN PELEDAKAN PADA TAMBANG TERBUKA UNTUK PENINGKATAN KESELAMATAN PERTAMBANGAN

ABSTRAK PT.Multi Nitrotama Kimia merupakan salahsatu perusahaan jasa pertambangan yang bergerak pada bidang penyedia jasa peledakan dan penjualan bahan peledak terbesar di Indonesia yang bekerjasama dengan banyak perusahaan tambang besar dan terkenal di Indonesia. PT.Adaro Indonesia merupakan salahsatu kostumer dari PT.Multi Nitrotama Kimia yang memiliki indikasi adanya terdapat kondisi batuan reaktif di area operasional penambangannya. Kondisi batuan reaktif ini merupakan suatu kondisi dimana adanya perubahan temperature batuan akibat adanya konten mineral tertentu dalam batuan yang bereaksi dengan Ammonium Nitrate. Jika, kondisi ini tidak diperhatikan, maka berpotensi menimbulkan kondisi tidak aman berupa, peledakan dini. Penelitian dan percobaan dilakukan untuk pemetaan terhadap gambaran kondisi batuan reaktif di beberapa Pit untuk kemudian dimasukkan kepada proses analisa laboratorium untuk mengetahui kondisi reaktif batuan. Uji laboratorium yang dilakukan adalah isothermal test dan mineral content test dengan tujuan mengetahui kondisi reakifitas batuan. Sehingga control dan kelola dalam tindakan preventif bisa dilakukan untuk mencegah terjadinya peledakan dini. Dengan tingkat ketelitian dan akurasi dalam uji laboratorium yang dilakukan terkait kondisi batuan reaktif, lokasi Pit yang memiliki kondisi batuan reaktif bisa teridentifikasi. Pada lokasi Pit yang positif memiliki kondisi batuan reaktif, PT Multi Nitrotama Kimia memberikan tindakan preventif dalam campuran bahan peledak inhibitor dan berhasil membuat kondisi batuan reaktif di PT Adaro Indonesia terkelola dan terkontrol dengan baik. Kata Kunci : Batuan Reaktif, Ammonium Nitrate, Peledakan ABSTRACT PT. Multi Nitrotama Kimia is one of the big mining services company in Indonesia with explosive supply and blasting services as the main business. PT. Adaro Indonesia is one of their customer’s with reactive ground potential problem in field situation. Reactive ground is situation were the ground has an exothermic reaction if mixed with Ammonium Nitrate. This situation getting worst to be premature blasting condition if there is no control of that situation. Researches had been develop to do mapping reactive ground situation at the Pits and get sample to do reactive ground laboratory test. These laboratory tests are held to get preventive action for reactive ground control. With high accuracy from laboratory test and sampling process, all of reactive ground spot in operational area been mapped. Every single location with reactive ground situation has a special treatment, which using an inhibitor bulk explosives and successes to control safety issues related reactive ground situation. Keyword : Reactive Ground, Ammonium Nitrate, Blasting

Study on Effects of Non-Isothermal Condition and Strain Holding on Environmentally Assisted Fatigue in PWR Primary Water Environment (Step III)

To further understand the environmentally assisted fatigue (EAF) behavior of Type 316 austenitic stainless steels (SS) in a pressurized water reactor (PWR) primary water environment, the influence of non-isothermal transient conditions was investigated using hollow, small-scale fatigue specimens. In our previous study (Step I: PVP2016-63798), isothermal and non-isothermal EAF tests were performed. The non-isothermal transient conditions for the fatigue tests investigated transients that consisted of both in-phase and out-of-phase temperature and strain variations. The result of this test series showed longer fatigue lives than those predicted using the modified rate approach and the EAF multiplier (Fen) presented in the draft of NUREG/CR-6909, Revision 1. In our follow-on study (Step II: PVP2017-66233), one extra non-isothermal test was performed and application of the Weighted Stress Intensity Factor (K) Rate (WKR) method was discussed. In the latest Step III testing, an extra non-isothermal test with periodic beachmarking has been performed. This paper discusses, based on the completion of all EAF tests performed in Steps I – III of this project, the effects of non-isothermal conditions and recommendations which are made for treatment of non-isothermal conditions in EAF assessments.

A Strategy to Improve O2 Gas Response of La-SnO2 Nanofibers Based Sensor through Temperature Modulation

Generally sensing mechanisms of gas sensors based on metal-oxide semiconductors greatly depend on temperature, suggesting temperature modulation can be applied as a vital method to effectively enhance the sensor response. In this paper, we reported a strategy of quick-cooling operating temperature mode in the course of gas sensing process to elevate the O2 gas response while maintaining low heating energy consumption. La-SnO2 nanofibers synthesized by electrospinning were chosen as gas sensing materials. The O2 gas responses by employing quick-cooling operation mode are significantly improved compared with those obtained by traditional isothermal test. The improved O2 response is contributed to a higher coverage of negatively charged oxygen ions as a result of quick cooling. Our research offers a facile route to detect gas at low temperature with high response. More importantly, the strategy demonstrated here could also be extended to other gas sensor as long as its gas response is related to the sensor temperature.

Vinyl-terminated butadiene acrylonitrile improves the toughness, processing window, and thermal stability of bismaleimide resin

Structural materials with excellent toughness, a wide processing window, outstanding mechanical performance, and high thermal stability are highly desired in engineering. This work reports a novel bismaleimide (BMI) resin system fabricated using bis[4-(4-maleimidephen-oxy)phenyl)]propane (BMPP), 1-(2-methyl-5-(2,5-dioxo-2H-pyrrol-1(5 H)-yl) phenyl)-1H-pyrrole-2,5-dione (BTM), and diallyl bisphenol A (DABPA) by a melt method. The behaviors of the BTM/BMPP/DABPA resin were modified by adding vinyl-terminated butadiene acrylonitrile (VTBN) in various amounts. The cured BTM/BMPP/DABPA/VTBN resin system exhibited all of the abovementioned desirable properties. Excellent performance was achieved by the post-cured BMI resin containing 6 phr of VTBN (VTBN-6). The glass transition temperature ( Tg) and the 5% weight loss temperature of VTBN-6 were 278°C and 408°C, respectively. Relative to VTBN-0 (BMI resin without VTBN), the impact strength of cured VTBN-6 (12.32 KJ/m2) improved by 45.6%, and the fracture toughness values, KIC and GIC, increased by 48.7% and 26%, respectively. Moreover, the prepolymer of VTBN-6 exhibited low viscosity over a wide temperature range (70–200°C) under dynamic conditions and for an extended time (70 min; 75% improvement over VTBN-0) in an isothermal test. These results confirm the wide processing window of VTBN-6. The high toughness of the VTBN-containing BMI resin was compatible with other excellent performances of the modified resin.

Penuaan Elektrode CuCr1Zr Spot Welding dengan Pendekatan Numerical

This study is to develop the constitutive equations to describe the mechanical deformation of the surfaces active of electrode. Most of tests are isotherms to characterize the material behavior at each temperature. The results isothermal test are used to identify the parameters of the law by using softwere SiDoLo, it shows the difference affected temperature. We can determine the value of the variable aging is a value between 0-1, the results identification of material aging through numerical calculations show the final result 0.9, then we can say that the specimens have been tested aging

DSC Cure Kinetics of an Unsaturated Polyester Resin Using Empirical Kinetic Model

In this paper, the kinetics of curing of unsaturated polyester resin initiated with benzoyl peroxide was studied. In case of unsaturated polyester (UP) resin, isothermal test alone could not predict correctly the curing time of UP resin. Therefore, isothermal kinetic analysis through isoconventional adjustment was used to correctly predict the curing time and temperature of UP resin. Isothermal kinetic analysis through isoconversional adjustment indicated that 97% of UP resin cures in 33 min at 120 °C. Curing of UP resin through microwaves was also studied and found that 67% of UP resin cures in 1 min at 120 °C. The crosslinking reaction of UP resin is so fast at 120 °C that it becomes impossible to predict correctly the curing time of UP resin using isothermal test and the burial of C=C bonds in microgels makes it impossible to be fully cured by microwaves at 120 °C. The rheological behaviour of unsaturated polyester resin was also studied to observe the change in viscosity with respect to time and temperature.

Catalytic Performance of Oxidized Ni3Sn2 for Hydrogen Production from Methanol Decomposition

The catalytic properties of oxidized Ni3Sn2 powders were investigated for producing hydrogen from decomposing methanol in the temperatures ranging from 240 to 480 ºC. The oxidized Ni3Sn2 had much higher catalytic activity than that of Ni3Sn2 in the temperature range of 320~400 ºC. The results of an isothermal test performed at 320 ºC revealed that the oxidized Ni3Sn2 was spontaneously activated within 4 h of the reaction and slowly deactivated in the followed reaction time. The oxidized Ni3Sn2 suppressed side reactions such as methanation and water-gas shift reaction and showed a high efficiency for H2 production from methanol decomposition. Surface analysis revealed that the activity of oxidized Ni3Sn2 was attributed to the formation of Ni/SnO2 catalyst, which was supposed to serve as active sites for methanol decomposition.

Rheological Characterization of Semi-Solid A356 Aluminium Alloy

Rheological behavior of semi-solid slurries forms the backbone of semi-solid processing of metallic alloys. In particular, the effects of several process and metallurgical parameters such as shear rate, shear time, temperature, rest time and size, distribution and morphology of the primary phase on the viscosity of the slurry needs in-depth characterization. In the present work, rheological behaviour of the semisolid aluminium alloy (A356) slurry is investigated by using a high temperature Searle type Rheometer using concentric cylinders. Three different types of experiment are carried out: isothermal test, continuous cooling test and steady state test. Continuous decrease in viscosity is observed with increasing shear rate at a fixed temperature (isothermal test). It is also found that the viscosity increases with decreasing temperature for a particular shear rate due to increasing solid fraction (continuous cooling test). Thixotropic nature of the slurry is confirmed from the hysteresis loops obtained during experimentation. Time dependence of slurry viscosity has been evaluated from the steady state tests. After a longer shearing time under isothermal conditions the starting dendritic structure of the said alloy is transformed into globular grains due to abrasion, agglomeration, welding and ripening.