• Title, Summary, Keyword: solution combustion

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Covalently-Bonded Solid Solution Formed by Combustion Synthesis

  • Ohyanagi, Manshi;Munir, Zuhair A.
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.250-257
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    • 2000
  • The feasibility of synthesizing SiC-AlN solid solution by field-activated combustion synthesis was demonstrated. At lower fields of 8-16.5V/cm, composites of AlN-rich and SiC-rich phases were synthesized, but at fields of 25-30 V/cm, the product was a 2H structure solid solution. Combustion synthesis of the solid solution by nitridation of aluminum with silicon carbide under a nitrogen gas pressure of 4-8 MPa was also investigated. The maximum combustion temperature and wave propagation velocity were found to be influenced by the electric field in the field-activated combustion synthesis, and by the green density and nitrogen pressure in the combustion nitridation. In both cases the formation of solid solutions is complete within seconds, considerably faster than in conventional methods which require hours.

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Characterization of LaCrO$_3$ Powders Synthesized by Combustion Process with Different Heating Methods (가열방법에 따른 LaCrO$_3$ 연소합성분말의 특성)

  • 정층환;박홍규;오석진;박지연
    • Journal of the Korean Ceramic Society
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    • v.35 no.10
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    • pp.1078-1084
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    • 1998
  • lanthanum chromite(LaCrO3) powder was synthesized by the combustion of a solution of metal nitrates La(NO3).6H2O and Cr(NO3)3.9H2O and urea. The pH of solution affected a yield of the combustion products but did not influence the morphology of the products. When the pH of the solution was in the range of 0.7-4, the yield of the combustion products was more than 90% The morphology of the combustion products was af-fected by heating methods for the solution. The hot-plate induced heating of the solution yielded powders hav-ing two-dimensionally interconnected agglomerates whereas microwave-induced heating produced a fine and non-agglomerated powders. The specific surface area(BET) of the combustion products using microwave-in-non-agglomerated powders. The specific surface area(BET) of the combustion products using microwave-in-duced heating method were larger(25~32m2/g) than that of hot plate heating method(10-14m2/g)

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Synthesis of Lanthanides Doped $CaTiO_3$ Powder by the Combustion Process

  • Jung, Choong-Hwan;Park, Ji-Yeon;Lee, Min-Yong;Oh, Seok-Jin;Kim, Hwan-Young;Hong, Gye-Won
    • The Korean Journal of Ceramics
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    • v.6 no.1
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    • pp.47-52
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    • 2000
  • Lanthanides such as La, Gd and Ce have recognized as elements of high level radioactive wastes immobilized by forming solid solution with $CaTiO_3$. For easy forming solid solution between $CaTiO_3$and lanthanides, the combustion synthesis process was applied and the powder characteristics and sinterability were investigated. The proper selection of the type and the composition of fuels are important to get the crystalline solid solution of $CaTiO_3$and lanthanides. When glycine or the mixtures of urea and citric acid with stoichiometric composition was used as a fuel, the solid solution of $CaTiO_3$with $La_2O_3$or $Gd_2O_3$or $CeO_2$was produced very well by the combustion process. The combustion synthesized powder seemed to have a good sinterability with the linear shrinkage of more than 25% up to $1500^{\circ}C$, while that of the solid state reacted powder was less than 10% at the same condition.

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Numerical Simulation of Self-excited Combustion Oscillation in a Dump Combustor with Bluff-body (둔체를 갖는 연소기에서 자려 연소 진동에 관한 수치해석)

  • Kim, Hyeon-Jun;Hong, Jung-Goo;Kim, Dae-Hee;Shin, Hyun-Dong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.9
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    • pp.659-668
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    • 2008
  • Combustion instability has been considered as very important issue for developing gas turbine and rocket engine. There is a need for fundamental understanding of combustion instability. In this study, combustion instability was numerically and experimentally investigated in a dump combustor with bluff body. The fuel and air mixture had overall equivalence ratio of 0.9 and was injected toward dump combustor. The pressure oscillation with approximately 256Hz was experimentally obtained. For numerical simulation, the standard k-$\varepsilon$ model was used for turbulence and the hybrid combustion model (eddy dissipation model and kinetically controlled model) was applied. After calculating steady solution, unsteady calculation was performed with forcing small perturbation on initial that solution. Pressure amplitude and frequency measured by pressure sensor is nearly the same as those predicted by numerical simulation. Furthermore, it is clear that a combustion instability involving vortex shedding is affected by acoustic-vortex-combustion interaction. The phase difference between the pressure and velocity is $\pi$/2, and that between the pressure and heat release rate is in excitation range described by Rayleigh, which is obvious that combustion instability for the bluff body combustor meets thermoacoustic instability criterion.

Preparations of PZT Ceramic by Solution Combustion Synthesis (용액연소합성방법에 의한 PZT세라믹의 제조)

  • 이상진;윤존도;권혁보;전병세
    • Journal of the Korean Ceramic Society
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    • v.39 no.1
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    • pp.74-78
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    • 2002
  • In this study, the solution combustion method was employed to synthesize perovskite PZT ceramics. Multicomponent oxides can be prepared by the solution combustion synthesis using redox exothermic reaction of precursor solutions. The results of DTA/TG showed exothermic peaks in 214$^{\circ}C$ and 350$^{\circ}C$. Those were caused by the differences of the thermal decomposition behavior of oxidizer and fuel. The combustion reaction was completed at 370$^{\circ}C$ during heating procedure, but the product was not transformed into perovskite. The thermal decomposition behavior of both oxidizer and fuel were considered during solution combustion process at 600$^{\circ}C$, which showed tetragonal single phase PZT ceramics with 50 nm crystalline size. The lattice constant a was 3.997 ${\pm}$ 0.001 ${\AA}$ and the lattice constant c was 4.147${\pm}$0.001 ${\AA}$.

Partial Preconditioning Approach for the Solution of Detailed Kinetics Problems Based on Sensitivity Analysis (효율적인 상세 반응 기구 해석을 위한 민감도 기반의 부분 음해법)

  • Kang, K.H.;Moon, S.Y.;Noh, J.H.;Won, S.H.;Choi, J.Y.
    • Journal of the Korean Society of Combustion
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    • v.13 no.1
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    • pp.17-22
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    • 2008
  • A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

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Facile Synthesis of Hydroxyapatite by Hydrothermal and Solvent Combustion Methods

  • Bramhe, Sachin N;Lee, Hyun Chul;Chu, Min Cheol;Ryu, Jae-Kyung;Balakrishnan, Avinash;Kim, Taik Nam
    • Korean Journal of Materials Research
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    • v.25 no.9
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    • pp.492-496
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    • 2015
  • Hydroxyapatite (HA), which is an important calcium phosphate mineral, has been applied in orthopedics, dentistry, and many other fields depending upon its morphology. HA can be synthesized with different morphologies through controlling the synthesis method and several parameters. Here, we synthesize various morphologies of HA using two simple methods: hydrothermal combustion and solution combustion. The phase purity of the synthesized HA is confirmed using X-ray diffractometry. It demonstrates that pure phased hydroxyapatite can be synthesized using both methods. The morphology of the synthesized powder is examined using scanning electron microscopy. The effects of pH and temperature on the final powder are also investigated. At $140^{\circ}C$, using the hydrothermal method, nano-micro HA rods with a hexagonal crystal structure can be synthesized, whereas using solution combustion method at $600^{\circ}C$, a dense cubic morphology can be synthesized, which exhibits monoclinic crystal structures.

Preparations of Nano-scale Mullite Powder from Solution Combustion Synthesis (용액연소합성에 의한 나노크기 물라이트 분말의 제조)

  • Lee, Sang-Jin;Yun, Jon-Do;Gwon, Hyeok-Bo;Jeon, Byeong-Se
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.797-801
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    • 2001
  • In this study, the solution combustion method was employed to synthesize stoichiometric mullite, and hence the attrition process was employed to prepare ultrafine mullite particles with nano size. The thermal decomposition behavior and partial pressure of equilibrium species of both oxidizer and fuel were considered during solution combustion process. The synthesized product was mullite phase with 40 nm crystalline size, and the alumina contents of the product by TEM/EDS quantity analysis was 3.12$\pm$04 mole. The result showed that the synthesized mullite was almost close to the it's stoichiometric composition. For attrition process, the dispersion behavior of the mullite suspension was controlled and was comminuted with the condition of 800 rpm for 4 hours using 0.3 mm zirconia ball media. As a result of comminution, the mean particle size was 80 nm.

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Determination of sulfur containing organic drugs by means of thin layer chromatography and flask combustion method (Thinlayer chromatography및 oxygen combustion flask method에 의한 유기유황약품의 분리정량)

  • 백남호;김박광
    • YAKHAK HOEJI
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    • v.13 no.2_3
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    • pp.84-87
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    • 1969
  • Microanalysis of organic sulfur compounds by means of combining thin layer chromatography and oxygen combustion flask method was attempted. The following procedure was found to be very simple and to give accurate results. The mixture of sulfa drugs was separated with T.L.C., and it was burned in a flask filled with oxygen, and the gas formed was absorbed in a dilute solution of sodium hydroxide. The solution was neuralized with hydrochloric acid and heated in a water bath. The sulfate ion formed was then treated with barium chromate solution and its absorbancy at 370 m.mu. was measured.

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Analysis of heavy metal in polymer materials by combustion ICP-AES Method (연소법 전처리에 의한 고분자 물질 중 중금속의 분석)

  • Lim, Heon-Sung;Lee, Bo-Reum;Lee, Sueg-Geun
    • Analytical Science and Technology
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    • v.23 no.6
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    • pp.615-618
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    • 2010
  • An oxygen bomb combustion procedure were studied for determination of heavy metal in polymer materials such as polyvinyl chloride and polypropylene by ICP-AES. This method is proposed as a rapid and simple sample preparation for decomposition of polymer containing certified contents of the analytes by teflon coated oxygen bomb combustion using different absorbing solution. The recoveries of metal were found to be 30~102% from absorbed solution by ICP-AES method using polypropylene certified reference material(PP CRM-As, Ba, Cd, Hg, Pb, Zn). The recoveries of metal using PVC CRM(Cd, Hg, Pb) was found to be 45 ~101% with same procedures.