The Asia‐Pacific Conference on CombusƟon (ASPACC) is an important biennial event in the calendar of the CombusƟon InsƟtute. Now in its 11 th conference, the ASPACC was iniƟated in 1996 with the aim of promoƟng and advancing combusƟon science and technology in the Asia‐ Pacific region. A key objecƟve of ASPACC is to promote global and regional scienƟfic partnerships that will accelerate the advent of clean, efficient and versaƟle combusƟon technologies. The first ASPACC conference was held in Osaka, Japan in 1997, followed by Tainan, Taiwan (1999), Seoul, Korea (2001), Nanjing, China (2003), Adelaide, Australia (2005), Nagoya, Japan (2007), Taipei, Taiwan (2009), Hyderabad, India (2010), Gyeongju, Korea (2013), and Beijing, China (2015). The 11th ASPACC will be hosted by the Australia and New Zealand SecƟon of the CombusƟon InsƟtute (ANZCI) and is scheduled for December 10‐14, 2017. It will be held at the University of Sydney in conjuncƟon with the 2017 Australian CombusƟon Symposium and the Eighth Australian Conference on Laser DiagnosƟcs in Fluid Mechanics and CombusƟon. The technical program is already enriched with seven leading Keynote Speakers promising exciƟng presentaƟons in broad areas of combusƟon (see next page). Please access conference website: hƩp://www.anz‐combusƟoninsƟtute.org/ASPACC2017/index.php The University of Sydney, is Australia’s oldest and one of its leading research‐intensive universiƟes. Sydney is a beauƟful desƟnaƟon that promises to provide visitors with beauƟful landscape, famous beaches and amazing entertainment. Serene mountains and wine country are only within a 3‐hour drive. Sydney is easily accessible to delegates around the world, with more than 40 internaƟonal airlines offering over 670 flight arrivals each week. 11 TH ASIA PACIFIC CONFERENCE ON COMBUSTION (ASPACC-11), 10-14 DECEMBER, 2017 THE UNIVERSITY OF SYDNEY, AUSTRALIA Submission of full paper (4 pages): 7 th July 2017 NoƟficaƟon of paper acceptance: 28 th August 2017 Submission of revised paper: 11 th September 2017 Conference dates: 10 th ‐14 th December 2017 Important Dates:
Transcript
The Asia‐Pacific Conference on Combus on (ASPACC) is an important biennial event in the
calendar of the Combus on Ins tute. Now in its 11th conference, the ASPACC was ini ated in
1996 with the aim of promo ng and advancing combus on science and technology in the Asia‐
Pacific region. A key objec ve of ASPACC is to promote global and regional scien fic partnerships
that will accelerate the advent of clean, efficient and versa le combus on technologies. The first
ASPACC conference was held in Osaka, Japan in 1997, followed by Tainan, Taiwan (1999), Seoul,
Korea (2001), Nanjing, China (2003), Adelaide, Australia (2005), Nagoya, Japan (2007), Taipei,
Taiwan (2009), Hyderabad, India (2010), Gyeongju, Korea (2013), and Beijing, China (2015).
The 11th ASPACC will be hosted by the Australia and New Zealand Sec on of the Combus on Ins tute (ANZCI) and is scheduled for December 10‐14, 2017. It will be held at the University of Sydney in conjunc on with the 2017 Australian Combus on Symposium and the Eighth Australian Conference on Laser Diagnos cs in Fluid Mechanics and Combus on. The technical program is already enriched with seven leading Keynote Speakers promising exci ng presenta ons in broad areas of combus on (see next page). Please access conference website:
h p://www.anz‐combus onins tute.org/ASPACC2017/index.php
The University of Sydney, is Australia’s oldest and one of its leading research‐intensive universi es. Sydney is a beau ful des na on that promises to provide visitors with beau ful landscape, famous beaches and amazing entertainment. Serene mountains and wine country are only within a 3‐hour drive. Sydney is easily accessible to delegates around the world, with more than 40 interna onal airlines offering over 670 flight arrivals each week.
11TH ASIA PACIFIC CONFERENCE ON COMBUSTION (ASPACC-11),
10-14 DECEMBER, 2017 THE UNIVERSITY OF SYDNEY, AUSTRALIA
Website: h p://www.anz‐combus onins tute.org/ASPACC2017/index.php
Full length papers (four (4) pages maximum including figures and tables) should follow the format
given on the conference web site. The Technical Commi ee will select papers for presenta on on
the basis of peer reviews of each full length paper. All selected papers should be presented by one
of the authors. Technical papers are solicited in all areas of combus on science and technology
including the following areas:
‐ Clean Coal Combus on ‐ Environmental & Pollu on Control ‐ Reac on Kine cs
‐ Combus on Diagnos cs ‐ Laminar & Turbulent Flames ‐ Fire Research
‐ Heterogeneous Combus on ‐ Spray & Droplet Combus on ‐ Alterna ve Fuels
‐ Sta onary Combus on Systems ‐ Detona on, Explosion & Supersonic Combus on
‐ IC Engine, Gas Turbines ‐ Microcombus on and New Combus on Devices
Assaad Masri, The University of Sydney (Chair) Eva Hawkes, The University of NSW
Ma hew Cleary, The University of Sydney Shawn Kook ,The University of NSW
Ma hew Dunn, The University of Sydney Shaun Chan ,The University of NSW
Paper Submission:
Local Organising Commi ee:
Contact:
Professor Michael Brear The University of Melbourne Combus on in Engines
Professor In Seuck Jeung Seoul Na onal University, Korea Supersonic Combus on
Dr Lyle Picke Sandia Na onal Laboratories, USA Diagnos cs in Engines
Professor Fei Qi Shanghai Jiao Tong University, China Chemical Kine c
Professor William Roberts KAUST, Saudi Arabia High‐Pressure combus on
Professor Satyanarayanan
Chakravarthy IIT‐Madras, India Instabili es in Flames
Professor Hiroaki Watanabe Kyushu University Japan Par cle‐Laden Flows.
Keynote Speakers:
Name Affilia on Topic
8:30
Room LT-1040 CS-1050 LT-1130 CS-1060 CS-1170 CS-2140 CS-2150 CS-2090 CS-2080Laminar FlamesProfessor Nam Il
Kim
Turbulent Flames
Professor Zhuyin Ren
IC-EnginesProfessor Patel Brijeshkumar
Assisted Combustion
Professor Kaoru Maruta
Stationary Combustion
Professor Gus Nathan
FiresDr Shaun Chan
Gas TurbinesProfessor Robert
Dibble
Spray, Droplets & Supercritical
Professor Damon Honnery
Solid FuelsDr Anirudha
Ambekar
9:30 P171: Flow and Flame Dynamics of Confined Buoyant Inverse Diffusion FlamesXuren Zhu,Xi Xia,Peng Zhang
P121: Simulation of Propane-Air Premixed Combustion Process in Randomly Packed BedsLinsong Jiang,Hongsheng Liu,Dan Wu,Maozao Xie,Minli Bai
P112: Experimental Study on the Effect of Lubricant Oil on Ignition Characteristics of Hydrocarbons Using a Rapid Compression MachineYuusuke Wachi,Kazuki Iwakura,Kotaro Tanaka,Mitsuru Konno,Ying Jiang,Yasuyuki Sakai
P143: The effects of positive electric field on the spherical flame propagation at elevated pressuresYiming Li,Jinhua Wang,Xuxing Wei,Xiaomin Wu,Zuohua Huang,Haibo Mu,Guanjun Zhang
P027: Experimental study of combined effect of acoustic agglomeration and sprayed droplet on coal-fired ashHuang Xiaoyu,Shen Guoqing,He Chunlong,Zhang Shiping,An Liansuo,Wang Liang,Chen Yanqiao,Li Yongsheng
P162: Effects of pressure and oxygen concentration on a stabilized premixed combustionJean-Michel Most,Michel Champion
P063: Modeling of Ammonia/air Non-premixed Turbulent Swirling Flames in a Gas Turbine like CombustorK.D.K.A. Somarathne,A. Hayakawa,N. Iki,O. Kurata,H. Kobayashi
P224: Study on evaporation and combustion of n-heptane droplet in a heated tubeMang Feng,Junwei Li,Ningfei Wang,Xinjian Chen,Rong Yao
P164: A Kinetic Study of Pyrolysis of Pine Wood using a Thermogravimetric Analyser and a Combined Model-free and y(α)Master Plot MethodZhezi Zhang,Mingming Zhu,Pengfei Liu,Hendrix Y Setyawan,Dongke Zhang
Tuesday, 12 December 2017Plenary Lecture: Modeling and Simulation of Pulverized Coal Combustion, Professor Hiroaki Watanabe
numerical study of the autoignited laminar lifted methane/hydrogen mixtures in heated coflow airKi Sung Jung,Seung Ook Kim,Bok Jik Lee,Suk Ho Chung,Chun Sang Yoo
P132: Large Eddy Simulation of Turbulent Flame with Inhomogeneous InletsT.Z. Hou,P. Wang,Q. Yu,C.J. Wang
P185: The Control of Mixture Homogeneity in a Double-Injection Gasoline Compression Ignition (GCI) EngineH. Goyal,S. Kook,E.R. Hawkes,Q.N. Chan
P119: Combustion and Reformulation Characteristics of Biogas in Plasma Assisted Combustion Using Microwave Induced Non-Equilibrium PlasmaT. Yamamoto,S. Uchiyama,H. Matsune,M. Kishida
P287: Lean methane combustion over palladium loaded on alumina and HBETA zeolite – the role of the support on water vapour inhibitionHadi Hosseiniamoli,Eric M. Kennedy,Michael Stockenhuber
P118: Experimental Study on the Improvement of Fire Retardant Performance for Boron-Phosphorous Chemicals Treated Wood-based MaterialsHyun Jeong Seo,Jeong Min Jo,Wuk Hwang,Min Chul Lee
P245: Development of an oxygen-hydrocarbon torch for liquid rocket engine ignitionJiaqi Zhang,Qinglian Li
P233: Bio-Alcohols Electrosprays for Practical Propulsion SystemsOhood AlNuaimi,Dimitrios C. Kyritsis
P174: MILD Combustion of Grape Marc as a Source of Renewable EnergyManabendra Saha,Giovanni Gitto,Bassam Dally
10:10 P187: A Numerical Study of Flame Instability and Cell Dynamics of Opposed Nonpremixed Tubular Flames near Radiation-Induced Extinction LimitHyun Su Bak,Chun Sang Yoo
P133: A sub-grid scale combustion model based on thickened-flame method and REDIM chemistry tableLiang Xu,Ping Wang,Qian Yu,Tian-zeng Hou
P194: The Effect of After Injection on In-Cylinder Soot Particulates in a Small Bore Diesel EngineL. Rao,Y. Zhang,D. Kim,S. Kook,K.S. Kim,C.-B. Kweon
P257: Numerical investigation of thermal and chemical effects of nanosecond repetitively pulsed discharges on a laminar premixed counterflow flameSylvain Heitz,Jonas P. Moeck,Anne Bourdon,Deanna A. Lacoste
P108: A Comparison of Complex Chemistry Mechanisms for Hydrogen Methane Blends Based on the Sandia / Sydney Bluff-Body Flame HM1H. H.-W. Funke,N. Beckmann,S. Abanteriba
P166: Lewis number effect on the flame height of circulation-controlled firewhirlsDehai Yu,Peng Zhang
P147: Mode coupling due to the non-uniformly distributed heat release in combustion instabilitiesLei Li,Liangliang Xu,Guoqing Wang
P234: Burning of Two Arbitrary Sized n-Heptane Droplets Suspended in a Grid Generated Turbulent Jet Flow FieldP Senthil Kumar,Gunamani Nath,V Raghavan,T Sundararajan
P181: On the Use of Sparse-Lagrangian MMC-LES for Simulation of a Piloted Coal JetL.F. Zhao,M.J. Cleary,O.T. Stein,A. Kronenburg
Room LT-1040 CS-1050 LT-1130 CS-1060 CS-1170 CS-2140 CS-2150 CS-2090 CS-208010:30 P188: A Study on
Measurement of Laminar Burning Velocity and Cellular Instability of SNG Fuel with 3% Hydrogen in Spherical Propagating FlamesDong Chan Kim,Jun Ho Song,Kee Man Lee
P144: Experimental Analysis of the Effect of Fuels on the Flame Describing Function of a Swirl-Stabilized Premixed FlameFrancesco Di Sabatino,Thibault F. Guiberti,Jonas P. Moeck,William L. Roberts,Deanna A. Lacoste
P024: Experimental Study of Spray Characteristics, Engine Performance and Emission Levels of Acetone-Butanol-Ethanol Mixture-Diesel Blends in a Diesel Engine.Sattar Jabbar Algayyim,Andrew P. Wandel,Talal Yusaf,Ihsan Hamawand,Saddam Al-Wayzy
P317: Two typical effects of microsecond plasma on flow rate disturbance premixed swirl flamesWei Cui,Yihua Ren,Shuiqing Li
P130: Rheological properties and ageing of bioslurry fuels prepared from crude glycerol/methanol/bio-oil blend and biochar for stationary combustion applicationsWenran Gao,Mingming Zhang,Hongwei Wu
P220: Firewhirl dynamics : what we know and what we don’tA. Y. Klimenko,F. A. Williams
P247: Numerical and experimental studies on the gas generator with separated air for mixing and coolingXinchen Liu,Jiaqi Zhang,Qinglian Li,Jianjun Zou
P241: Combustion Characteristics of Multi-staged Burner with Mixed FuelsMinjun Kwon,Daehae Kim,Yongmo,Kim,Sewon Kim
P198: On-line product analysis of coal and corn co-pyrolysis using photoionization mass spectrometryJun-Jie Weng,Yue-Xi Liu,Ya-Nan Zhu,Yang Pan,Zhen-Yu Tian
11:20 P189: Effect of H2 and CO Dilution on NO Formation in Coflow CH4/air Diffusion FlamesYe Y,Jianfei X,Zhongzhu G,Haiyang A,Xianpeng Z
P493: Effect of Spark Gap on Turbulent Facilitated Ignition through Differential DiffusionS.S. Shy,M.T. Nguyen,S.Y. Huang,C.C. Liu
P202: Influence of Injection Timing on In-Cylinder Flow and Combustion Performance in a Spark-Ignition Direct-Injection (SIDI) EngineL.G. Clark,S. Kook,Q.N. Chan,E.R. Hawkes
P356: Electro-hydrodynamic instability of premixed flames under manipulations of DC electric fieldsYihua Ren,Wei Cui,Shuiqing Li
P131: Combustion of bioslurry and its fractions: different contributions to PM10 emissionChao Feng,Wenran Gao,Hongwei Wu
P275: A Comparative Study of a Novel Multi-swirl Lean Direct Injection and Conventional Single Swirl Gas Turbine Burner for Reduced Emissions and Combustion InstabilityV. Deepika,S.R. Chakravarthy,T.M. Muruganandam,N. Raja Bharathi
P255: PDF-PBE for Particle Dispersion in a Turbulent Round JetFatemeh Salehi,Matthew J. Cleary,Assaad R. Masri,Andreas Kronenburg
P216: Effects of humidity on the aging of the pyrotechnic compositions ZPP and THPPJuyoung Oh,Anirudha Ambekar,Yoocheon Kim,Jai-ick Yoh
11:40 P190: Ion chemistry investigation in rich methane premixed flamesHaoyi Wang,Bingjie Chen,Jie Han,Heng Wang,Nils Hansen,S. Mani Sarathy
P155: Evolution of Surface Elements of Premixed Flames in TurbulenceAbinesh Mohan,Himanshu L.Dave,Swetaprovo Chaudhuri
P205: The Influence of Swirl Flow on Soot Formation Processes inside the Piston Bowl of a Small-bore Diesel EngineY. Zhang,D. Kim,L. Rao,S. Kook,K.S. Kim,C.-B. Kweon
P374: Characteristics of Liftoff and NOx Emission in Microwave Enhanced Methane Micro-Jet FlamesYoung Hoon Jeon,Eui Ju Lee
P175: Application of N-doped Fly Ash Materials with Enhanced Working Capacity for Post-combustion CO2 CapturePeng Wang,Chuanwen Zhao,Yafei Guo,Junjie Yan,Ping Lu
P303: Verification of Beating Phenomenon by Measuring of Pilot Flame Behavior in a Dual Swirl CombustorJaehyeon Kim,Munseok Jang,Keeman Lee
P263: An Experimental Study on Heavy Fuel Oil Droplet CombustionAbdulrahman Alkhateeb,Paolo Guida,Eid Barakati,Alaaeldin Dawood,Ayman M. Elbaz,William L. Roberts
P259: Experimental Study of Spherical Turbulent Flame Propagation of Pulverized Coal Particles Cloud in O2/N2 AtmosphereKhalid Hadi,Ryo Ichimura,Nozomu Hashimoto,Osamu Fujita
Invited Review: Fire & Rescue NSW’s Fire Research Program: A partnership approach to improving community safety through the application of fire researchAssistant Commissioner Jeremy Fewtrell,Assistant Commissioner Operational Capability,Fire & Rescue NSW
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사각형
11th Asia-Pacific Conference on Combustion, The University of Sydney, NSW Australia 10th -14th December 2017.
Effects of humidity on the aging of the pyrotechnic compositions ZPP and THPP
1Department of Mechanical and Aerospace Engineering, Seoul National University
Seoul, 151-742, South Korea
Abstract
This paper studies the effects of humidity and aging period on two pyrotechnic initiators viz. titanium hydride potassium perchlorate (THPP) and zirconium potassium perchlorate (ZPP) subjected accelerated aging. Knowing the combined aging effects for these pyrotechnic initiators are important because they are connected to the performance, lifetime, and safety of the materials. Experiments were carried out using a Differential Scanning Calorimeter (DSC), and the heat flow for each sample was measured over the designated temperature range. In addition, thermal behavior parameters such as the heat of reaction and peak temperature were obtained by using the AKTS software program. These parameters were compared for various aging periods and relative humidity levels. The results clearly show the different effects of humidity levels and aging duration on each sample. Additionally, Laser Induced Breakdown Spectroscopy (LIBS) was used to investigate the mass gain phenomenon of ZPP. Therefore, humidity aging is seen to be an important factor in aging research of common pyrotechnic initiator compositions namely ZPP and THPP.
1 Introduction
Pyrotechnic compositions or propellants are generally composed of three main components: fuel, an oxidizer, and a binder. The safety aspects of these are very important because they are widely used in military or defense industries. However, these are prone to degradation of performance by environment elements such as temperature, humidity, vibration effects [1].
When these materials are aged during storage or transportation, chemical structure difference can occur over small features such as cracks of the particle surface. Although, they may seem to be trivial, but such changes have been known to cause enormous accidents since the past. [2]
Titanium hydride potassium perchlorate (THPP) and zirconium potassium perchlorate (ZPP) are commonly used as pyrotechnic initiators. THPP consists of potassium perchlorate as an oxidizer, titanium hydride as fuel, and a Viton binder. ZPP is composed of zirconium as metal fuel, potassium perchlorate as an oxidizer and a Viton binder. They are generally found in the defense, aerospace, automotive industries. Therefore, it is important to know how their properties and reaction kinetics when accelerated aging or humidity aging was applied.
Several studies on the effects of aging on pyrotechnic materials or propellants have been reported previously. Wang et al. [2] investigated the influences of combinative effect of temperature and humidity on the thermal stability of pyrotechnic
mixtures. By analysing the thermal behavior of each compositions and calculating the critical temperature of thermal explosion, it was possible to find the correlation between relative humidity and thermal stability. Also, they found the pyrotechnic composition with maximum thermal stability.
Analysing the thermal behavior is a suitable technique for observing the aging phenomena and other characteristics of the pyrotechnic mixtures. Generally, thermal behavior as well as thermal decomposition characteristics of pyrotechnic compositions consisting of fuel and an oxidizer can be obtained by DSC or thermos gravimetric analysis (TGA) [3, 4]. Although there have been many studies on the aging characteristics of pyrotechnic compositions, there are few studies dealing with humidity aging. In addition, there have been no investigations on humidity and accelerated aging for THPP and ZPP. Therefore, the aim of this study is to analyse the reaction changes of THPP and ZPP affected by humidity and aging period by using DSC.
2 Experimental
2.1 Sample preparation
A total of 10 samples were tested in this study and as listed in Table 1.
Sample type
Humidity and temperature conditions
for aging
Duration of aging n
THPP
75 ℃ and RH 90 % 20 days 1
75 ℃ and RH 0 % 0 day 2
14 days 3 42 days 4
ZPP
75 ℃ and RH 90 % 20 days 5
75 ℃ and RH 80 % 20 days 6 40 days 7
75 ℃ and RH 0 % 0 day 8
14 days 9 42 days 10
Table 1: All samples used in this study
The THPP and ZPP samples subjected to accelerated aging at 75 ℃ were sorted according to the relative humidity and finally classified by the aging duration. Henceforth, each sample will be referred by the serial number (n) instead of the name. The THPP mixture was composed of 32% TiH2, 63% KClO4 and 5 % Viton b. ZPP consists of 52% Zr, 42% KClO4, 5% Viton b, and 1 % graphite.
All samples were tested by using the DSC-3 instrument from Mettler Toledo. This calorimetry device can measure enthalpy changes in samples due to changes in their physical and chemical properties as a function of temperature and time. The net heat generated for each sample and the reaction rate were obtained by using the AKTS software program for the experimental results.
DSC analysis was performed at a heating rate of 2 ℃/min in temperature range of 30 ℃ to 600 ℃ under nitrogen atmosphere (85 ml/min). The mean mass of the samples used in this experiment has been listed in Table 2. Nearly all samples were tested more than twice. Especially, test with sample 7 was repeated five times. Here, mb is the net average mass of the sample before the experiment and ma indicates the average mass of the sample after the experiment. Samples were sealed in 40 μm standard pierced aluminum pan.
n Sample
mass (mg)
Total mass - mb
(mg)
Total mass - ma
(mg)
Mass loss (%)
1 1.00 50.88 50.88 0.00
2 1.31 51.02 50.86 12.21
3 1.25 51.09 50.92 13.60
4 1.21 51.20 51.09 9.09
5 1.36 51.35 51.26 6.62
6 1.07 50.89 50.83 5.18
7 1.29 50.88 51.02 -11.41
8 0.99 50.75 50.61 13.56
9 1.25 51.09 51.89 14.87
10 1.20 50.92 50.74 15.29
Table 2: Mass and mass loss data of all samples
The phenomenon of mass increase of the ZPP composition during the DSC experiment was analyzed by using LIBS technique. A Q-switched Nd:YAG laser was used in the LIBS system (RT-250Ec, Applied Spectra Inc.) that operates at 1064nm, 4-7 ns pulse duration. The pulse energy of the laser range was from 25 mJ to 30 mJ. This spectrometer has 6 channels to improve the resolution and can cover the wavelengths from 190 nm to 1040 nm as detected spectrum range. The resolution of the spectrometer is less than 0.1 nm from ultraviolet to visible range and 0.12 nm from visible to near infrared range. The gate delay was 0.5 μs gate and the gate width was set as 1.05 ms. The pressure in the chamber was maintained at 760 Torr. The ZPP samples were exposed 10 times to the laser beam.
2.3 Reaction rate calculation
As shown in Fig.1, the baseline could be obtained by involving the tangent lines superposition on each side of the exothermic peak of the DSC signal. The reaction rate at the time can be determined by dividing heat flow value which is the difference between the DSC signal of the sample and the base line to the heat generation in the entire process. [5] The values of reaction rate, baseline, and heat of reaction were obtained by using AKTS software program.
Figure 1: The example of the DSC signal line and base line of the THPP sample aged at 75 ℃-RH 90% for 20 days
3 Results and discussion
3.1 Experimental results
Table 3 shows the heat of reaction, peak temperatures, and onset temperature for four THPP samples. Fig. 2 shows the effects of the humidity and aging period on the THPP samples. Here, n is the sample number, △H is the heat of reaction, Tp indicates peak temperature, and To is onset temperature of reaction. As the aging days increased, the heat of reaction tended to decrease.
Sample type n △H (J/g) Tp (℃) To (℃)
THPP
1 3847.60 418.80, 515.11 335.60
2 5175.16 409.70, 517.10 353.07
3 4814.49 418.27, 519.24 310.13
4 4568.55 420.43, 518.43 310.13
Table 3: Heat generation data of THPP samples
Figure 2(a) shows two curves for THPP samples which were subjected to accelerated aging and humidity aging (sample 3, sample 1). The sample 3 as well as sample 1 displayed two exothermic peaks. The peak temperatures for the sample 1 were observed to be similar to that of sample 3. Therefore, it can be seen that humidity aging does not affect the peak temperature. The onset temperatures of sample 1 was higher than that of sample 3. On the other hand, heat of reaction of sample 1 was lower than sample 3. In the case of reaction rate, sample 1 was higher than sample 3 initially and lower for the second exothermic peak. Therefore, the effect on moisture itself could be found in reaction of heat, reaction rate and onset temperature.
Figure 2(b) shows samples with accelerated aging. The curves in this graph represent the non-aged sample (sample 2) and the samples aged at 75 ℃ for 14 days and 42 days (sample 3, sample 4). In this case, the longer the period of aging days of the sample, the higher the first peak temperature and the reaction rate. Also, heat of reaction decreased with the aging period.
Figure 2: Reaction rate of THPP samples (a) humidity effect, (b) aging period effect except relative humidity
Table 4 shows the heat of reaction, peak temperature, and onset temperature for six ZPP samples. When humidity aging or accelerated aging was applied to the ZPP sample, the heat of reaction tended to be lower than that of the original value. Also, the longer the aging period, the lower the heat of reaction. Under the effect of humidity aging, when the number of days of aging was the same, higher relative humidity resulted in, lower heat release.
Sample type n △H (J/g) Tp (℃) To (℃)
ZPP
5 2190.64 415.77 328.20
6 2449.06 413.83, 483.83 345.00
7 2010.80 473.33, 511.50 325.73
8 2629.81 448.10, 504.20 345.27
9 2529.75 374.43, 444.61, 504.80
312.20
10 2107.88 374.10, 449.10, 503.83
310.67
Table 4: Heat generation data of ZPP samples
Figure 5(a) shows three curves for the ZPP samples. Two of them are samples with different relative humidity (80%, 90%) which were aged at 75 ℃ for 20 days (sample 6, sample 5). The remaining sample was aged at 75 ℃ for 14 days (sample 9).
Each sample had a different number of peaks. Sample 9, 6 and 5 displayed the number of 3, 2 and 1 exothermic peak respectively. As the moisture content increased the number of exothermic peaks decreased. The main exothermic peak temperature and the heat released in the case humidity aged samples were lower than the 0% humidity sample, but main reaction rate was higher.
Meanwhile, amongst the samples with different humidity levels, the first peak did not show a significant difference. However, the special point was found at the second peak. The second peak means the decomposition reaction of Potassium Perchlorate (KClO4). [6] The sample with 90% relative humidity had only first peak. Therefore, it could be assumed that KClO4 was affected by humidity level.
Figure 5(b) shows three curves, two of them are ZPP samples with different aging period (20 days, 40 days) aged at 75 ℃ and relative humidity 80% (sample 6, sample 7) and the last one is non-aged original ZPP sample (sample 8). All the samples in the graph displayed two exothermic peaks. In the case of heat of reaction, both of the humidity aged samples showed a lower heat value than the original sample. Especially, sample aged for longer period of time had the lower heat value.
A remarkable point was found in the sample 7, which was that the sample mass increased after the experiment. As seen in Table 2, every other sample showed the mass loss. However, the mass of sample 7 was observed to increase by 11.41% compared to the initial sample mass. One of the most likely reasons for the increase in mass was bonding of atmospheric oxygen molecules with the residual sample and increase the sample mass.
In order to confirm the degree of oxidation before and after the DSC experiment, LIBS experiments were performed on Sample 5, 6 and 7. In Fig. 3, the peak indicates the oxygen in ZPP samples. The large difference in oxygen intensity means increased oxidation of zirconium. In Fig. 4, the y-axis shows the difference in oxygen intensity between samples 5, 6, 7 before and after the DSC, and the x-axis shows the mass change of the samples before and after the DSC. The difference in oxygen intensity was noticeable when the number of days of aging increased compared to when humidity was increased. Thus, it could be seen that zirconium oxidation was affected by humidity but is more sensitive to aging period. As a result, due to the oxidative effect after the experiment, 20-day humidity aged samples shows reduced mass loss value compared to accelerated aged samples. Sample humidity aged for 40 days, which was aged longer than other samples, increased in mass.
Figure 3: Oxygen intensity peak of sample 5, 6, and 7
Figure 4: Oxygen intensity difference of sample 5, 6, and 7 with mass change
Figure 5: Reaction rate of ZPP samples (a) humidity effect, (b) aging period effect with relative humidity, (c) aging period effect except relative humidity
When accelerated aging was applied to ZPP samples at 75 ℃ in the case of Fig. 5(c), the first exothermic peak appeared at 374 ℃. The second peak and the third peak of the accelerated aged samples were approximately identical when compared to the original sample. Accelerated aged THPP also decreased the released heat with increasing aging days. Finally, the onset
temperature tended to decrease when accelerated aging was applied.
4 Conclusions
DSC experiments were conducted using THPP and ZPP samples corresponding to different humidity levels and aging periods. From the DSC data, thermal behavior parameters could be obtained and studied the effects of above conditions to the samples.
In the THPP sample, 90% relative humidity sample had lower heat of reaction and reaction rate. In other words, when aged under high humidity conditions, THPP may cause decreased heat released than the unaged sample. Therefore, humidity aging was deduced to be significantly affect the performances of THPP. In the case of where aging duration was increased, the reaction rate of the samples at the main exothermic peaks increased slightly with the duration of aging. Also, the first exothermic peak tended to shift to higher side, and lower side at the second peak.
The ZPP samples subjected to humidity aging for 20 days displayed a decreased heat of reaction when compared to the sample with 0% humidity. In addition, when the humidity increased, the heat value tended to decrease. Simultaneously, the main exothermic peak temperatures were observed to be decreased. This phenomenon corresponded to significant changes in the sample’s performance. In addition, it could be seen that when ZPP is aged at the humid environment, the aging period is more influential on the ZPP oxidation than the humidity.
The humidity aging study was conducted with a limited number of humidity levels, so it was difficult to obtain detailed changes in the chemistry of the initiators due to humidity. Future studies with more samples with larger parametric variation would yield a more accurate picture. However, the current study has established that observable changes in the performance of THPP and ZPP occur due to humidity aging. As humidity aging is an important factor in aging research of THPP and ZPP, further studies will be carried out.
5 Acknowledgment
Authors acknowledge the support from Hanwha Corporation for providing ZPP and THPP samples. Additional support came from Advanced Research Center Program (NRF-2013R1A5A1073861) contracted through Advanced Space Propulsion Research Center at Seoul National University.
References
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