Effect of Graphite Content on Corrosion Resistance of Zirconia Graphite Materials

2014 ◽  
Vol 1033-1034 ◽  
pp. 873-877
Author(s):  
Fan Qian ◽  
Wen Gang Yang ◽  
Jian Bin Yu ◽  
Tian Fei Ma ◽  
Guo Qi Liu
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Test ◽  
Liquid Slag ◽  
Reaction Rate ◽  
Induction Furnace ◽  
Reaction Rate Constant ◽  
Corrosion Layer ◽  
Graphite Content ◽  
Slag Line ◽  
Result Show

The effect of graphite content on formation of decarbonization layer and corrosion resistance of zirconia graphite materials were studied by the corrosion test in induction furnace, and the effect of decarbonization layer on corrosion of zirconia graphite materials was also analysed by the kinetic models for the corrosion of SEN in mold, the result show that Thickness of decarbonization layer of slag line is decreasing with the increase of graphite content. Corrosion of zirconia graphite materials in steel liquid / slag interface is characterized by the features of consecutive reaction:original layer→decarbonization layer→corrosion layer, and k1, and k2 are their reaction rate constant respectively.when we adjust graphite content, k1 and k2 will be change in opposite directions, so graphite content with well corrosion resistance depend on the condition of continuous casting

Formation of Decarbonization Layer and its Effect on Corrosion Resistance of Zirconia Graphite Materials

2011 ◽  
Vol 399-401 ◽  
pp. 336-342
Author(s):  
Fan Qian ◽  
Hong Xia Li ◽  
Guo Qi Liu
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
High Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Graphite Content ◽  
Slag Line ◽  
Mold Fluxes ◽  
Result Show ◽  
Hot Surface

The effect of graphite content on formation of decarbonization layer and corrosion resistance of zirconia graphite materials were studied by the corrosion test in induction furnace, and the effect of decarbonization layer on corrosion of zirconia graphite materials was also analysed by the kinetic models for the corrosion of SEN in mold, the result show that: (1) Thickness of decarbonization layer of slag line is decreasing with the increase of graphite content. When the mold fluxes for high carbon steel is used, decarbonization layer is thin and graphite content has little effect on corrosion resistance of zirconia graphite materials, and 10wt%graphite is better. When the mold fluxes for low carbon steel is used, decarbonization layer is thick and 14wt% graphite is the best. (2) Corrosion of zirconia graphite materials in mold is characterized by the features of consecutive reaction:original layer (k1) decarbonization layer (k2) corrosion layer . If k1<<k2, there is no decarbonization layer forming and decarbonization is the key step for the corrosion; If k1>>k2, there is decarbonization layer on the hot surface of zirconia graphite materials and the corrosion of the layer is the key step. Graphite content is too high or too low is all harmful for the corrosion resistance of zirconia graphite materials.

Study of a Ceramic Thermocouple for Al Production

2007 ◽  
Vol 546-549 ◽  
pp. 2195-2198
Author(s):  
L.C. Feng ◽  
Liang Zhen ◽  
Wen Zhu Shao ◽  
N. Xie
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Response Time ◽  
Linear Relationship ◽  
Corrosion Test ◽  
Aluminum Electrolysis ◽  
Corrosion Layer ◽  
Temperature Test ◽  
Holding Temperature ◽  
Better Than

A ceramic thermocouple (CTC) was assembled using SiC as the cathode and MoSi2 as the anode for the temperature test of the aluminum electrolysis. The NiFe2O4 was sprayed on the surface of SiC cathode for increasing the corrosion resistance ability in the cryolite. The corrosion behavior of NiFe2O4 in the cryolite was investigated. The results of the corrosion tests show that the NiFe2O4 has a very low corrosion rate in the cryolite, and a corrosion layer was formed during the corrosion test. The mechanisms of the NiFe2O4 corrosion are reactive corrosion and particles flaking. The thermo emf of SiC-MoSi2 CTC was tested from 25 °C to 1300 °C in air. The results show that thermo emf has a linear relationship with the temperature dependence, and reached 350 mV at 1300 °C. The CTC which consists of SiC-MoSi2 prepared in the same batch has a preferable interchangeability. By holding temperature at 1300 °C, the deviation of thermo emf is 0.5 %, which is better than the criterion of industry thermocouple, 0.75 %. The CTC response time was also analyzed.

Hot-Gas Corrosion Resistance of DD9 Single Crystal Superalloy

2016 ◽  
Vol 849 ◽  
pp. 463-467
Author(s):  
Zhen Xue Shi ◽  
Shi Zhong Liu ◽  
Xiao Guang Wang ◽  
Jia Rong Li
Keyword(s):  
Corrosion Resistance ◽  
Single Crystal ◽  
Corrosion Test ◽  
Middle Layer ◽  
Corrosion Layer ◽  
Single Crystal Superalloy ◽  
X Ray ◽  
Hot Gas ◽  
Sulfide Layer ◽  
Gas Corrosion

The hot-gas corrosion resistance of DD9 single crystal superalloy at 900°Cwas investigated in the present study. The composition and the morphology of corrosion layer were characterized by energy dispersive X-ray analysis spectroscope (EDS) and scanning electron microscopy (SEM). The results show that DD9 single crystal superalloy has excellent hot-gas corrosion resistance and basically obeys parabolic rate law during corrosion test for 100 h at 900 °C. The irregular and prismatic morphology of NiO tightly piles each other on the surface after 100 h corrosion test. The corrosion products possess three layers, outer layer is predominate NiO with a little of Al2O3, middle layer is mixed oxide, and inner layer is sulfide. It was found that flake shaped NiS phase formed in the sulfide layer.

scholarly journals Effect of Oxide Scale Microstructure on Atmospheric Corrosion Behavior of Hot Rolled Steel Strip

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 517
Author(s):  
Bin Sun ◽  
Lei Cheng ◽  
Chong-Yang Du ◽  
Jing-Ke Zhang ◽  
Yong-Quan He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Oxide Scale ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Corrosion Test ◽  
Atmospheric Corrosion ◽  
Corrosion Mechanism ◽  
Type I ◽  
Rust Layer ◽  
Hot Rolled

The atmospheric corrosion behavior of a hot-rolled strip with four types (I–IV) of oxide scale was investigated using the accelerated wet–dry cycle corrosion test. Corrosion resistance and porosity of oxide scale were studied by potentiometric polarization measurements. Characterization of samples after 80 cycles of the wet–dry corrosion test showed that scale comprised wüstite and magnetite had strongest corrosion resistance. Oxide scale composed of inner magnetite/iron (>70%) and an outer magnetite layer had the weakest corrosion resistance. The corrosion kinetics (weight gain) of each type of oxide scale followed an initial linear and then parabolic (at middle to late corrosion) relationship. This could be predicted by a simple kinetic model which showed good agreement with the experimental results. Analysis of the potentiometric polarization curves, obtained from oxide coated steel electrodes, revealed that the type I oxide scale had the highest porosity, and the corrosion mechanism resulted from the joint effects of electrochemical behavior and the porosity of the oxide scale. In the initial stage of corrosion, the corrosion product nucleated and an outer rust layer formed. As the thickness of outer rust layer increased, the corrosion product developed on the scale defects. An inner rust layer then formed in the localized pits as crack growth of the scale. This attacked the scale and expanded into the substrate during the later stage of corrosion. At this stage, the protective effect of the oxide scale was lost.

scholarly journals Determination of exothermic batch reactor specific model parameters

2019 ◽  
Vol 292 ◽  
pp. 01063
Author(s):  
Lubomír Macků
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Specific Model ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Model Parameters ◽  
Reactor Model ◽  
First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

Performance of Photocatalytic Microfiltration with Hollow Fiber Membrane

2007 ◽  
Vol 544-545 ◽  
pp. 95-98 ◽  
Author(s):  
Jong Tae Jung ◽  
Jong Oh Kim ◽  
Won Youl Choi
Keyword(s):  
Heavy Metals ◽  
Humic Acid ◽  
Rate Constant ◽  
Hollow Fiber ◽  
Reaction Rate ◽  
Hollow Fiber Membrane ◽  
Membrane Surface ◽  
Reaction Rate Constant ◽  
Operational Parameters ◽  
Tio2 Particles

The purpose of this study is to investigate the effect of the operational parameters of the UV intensity and TiO2 dosage for the removal of humic acid and heavy metals. It also evaluated the applicability of hollow fiber microfiltration for the separation of TiO2 particles in photocatalytic microfiltration systems. TiO2 powder P-25 Degussa and hollow fiber microfiltration with a 0.4 μm nominal pore size were used for experiments. Under the conditions of pH 7 and a TiO2 dosage 0.3 g/L, the reaction rate constant (k) for humic acid and heavy metals increased with an increase of the UV intensity in each process. For the UV/TiO2/MF process, the reaction rate constant (k) for humic acid and Cu, with the exception of Cr in a low range of UV intensity, was higher compared to that of UV/TiO2 due to the adsorption of the membrane surface. The reaction rate constant (k) increased as the TiO2 dosage increased in the range of 0.1~0.3 g/L. However it decreased for a concentration over 0.3 g/L of TiO2. For the UV/TiO2/MF process, TiO2 particles could be effectively separated from treated water via membrane rejection. The average removal efficiency for humic acid and heavy metals during the operational time was over 90 %. Therefore, photocatalysis with a membrane is believed to be a viable process for humic acid and heavy metals removal.

Reaction rate constant of SO3+ NH3in the gas phase

1990 ◽  
Vol 95 (D9) ◽  
pp. 13981 ◽  
Author(s):  
Gaunlin Shen ◽  
Masako Suto ◽  
L. C. Lee
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant

Photocatalytic Degradation of Methyl Orange by TiO2/Schorl Photocatalyst: Kinetics and Thermodynamics

2015 ◽  
Vol 713-715 ◽  
pp. 2789-2792
Author(s):  
Huan Yan Xu ◽  
Xue Li ◽  
Yan Li ◽  
Ping Li ◽  
Wei Chao Liu
Keyword(s):  
Methyl Orange ◽  
Reaction Rate ◽  
Reaction Kinetic ◽  
Kinetic Studies ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Solution Ph ◽  
Kinetics And Thermodynamics ◽  
Hoff Equation ◽  
Degradation Of Methyl Orange

An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

Reduction Kinetics of Mill Scale Briquettes by Using A3 Fine Coal as a Reductant

2021 ◽  
Vol 21 (4) ◽  
pp. 2563-2567
Author(s):  
Nguyen Hoang Viet ◽  
Pham Ngoc Dieu Quynh ◽  
Nguyen Thi Hoang Oanh
Keyword(s):  
Reaction Rate ◽  
Reduction Process ◽  
Reduction Reaction ◽  
Reaction Rate Constant ◽  
Reduction Degree ◽  
Furnace Temperature ◽  
Time Duration ◽  
Mill Scale ◽  
Fine Coal ◽  
Kinetics Of

In this work, a mixture of mill scale with 5 wt% molasses as binder was pressed under pressure of 200 MPa to prepare briquettes. The reduction process was performed at the temperature of 1000, 1050, 1100, 1150 and 1200 °C in the bed of A3 fine coal as the reductant. The degree of reduction was evaluated at time duration of 15, 30, 45, 60, 90 and 150 minutes, after the furnace temperature reached the predetermined reduction temperature. The highest reduction degree is 94.7% at the reduction process temperature of 1200 °C. Reaction rate constant (k) increased from 4.63×10-4 to 5.03×10-3 min-1 when the temperature increased from 1000 to 1200 °C. The apparent activation energy of the reduction reaction (Ea) is about 95.6 kJ/mole.

Prediction of Chemical Reaction Yield in a Microreactor and Development of a Pilot Plant Using the Numbering-Up of Microreactors

2010 ◽  
Author(s):  
Shigenori Togashi ◽  
Yukako Asano ◽  
Yoshishige Endo
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Chemical Reaction ◽  
Rate Constant ◽  
Pilot Plant ◽  
Reaction Rate ◽  
Main Product ◽  
Reaction Rate Constant ◽  
Reaction Yield ◽  
Production Scale

The chemical reaction yield was predicted by using Monte Carlo simulation. The targeted chemical reaction of a performance evaluation using the microreactor is the consecutive reaction. The main product P1 is formed in the first stage with the reaction rate constant k1. Moreover, the byproduct P2 is formed in the second stage with the reaction rate constant k2. It was found that the yield of main product P1 was improved by using a microreactor when the ratio of the reaction rate constants became k1/k2 >1. To evaluate the Monte Carlo simulation result, the yields of the main products obtained in three consecutive reactions. It was found that the yield of the main product in cased of k1/k2 >1 increased when the microreactor was uesd. Next, a pilot plant involving the numbering-up of 20 microreactors was developed. The 20 microreactor units were stacked in four sets, each containing five microreactor units arranged. The maximum flow rate when 20 microreactors were used was 1 × 104 mm3/s, which corresponds to 72 t/year. Evaluation of the chemical performance of the pilot plant was conducted using a nitration reaction. The pilot plant was found to capable of increasing the production scale without decreasing the yield of the products.

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