Degradation Behavior of Tungsten in Molten Aluminum

2011 ◽  
Vol 415-417 ◽  
pp. 2262-2266
Author(s):  
Hong Feng Luo ◽  
Jing Wu ◽  
Yu Deng ◽  
Wei Ping Chen
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Intermetallic Compound ◽  
Corrosion Rate ◽  
Thermal Stresses ◽  
Molten Aluminum ◽  
Intermetallic Layer ◽  
Degradation Behavior ◽  
Static Immersion

Corrosion of tungsten in molten aluminum was investigated by static immersion tests at 700, 750 and 800°C temperature for 8-120 h. In all cases, the Al3W intermetallic compound was formed. The intermetallic layer broke up as long as it grew due to thermal stresses and dispersed in the molten aluminum. The weight-loss of tungsten varied linearly with time. The corrosion rate increased with temperature and the activation energy was nearly 87.92 kJ mol-1.

Corrosion Behavior of Molybdenum in Molten Aluminum

2012 ◽  
Vol 155-156 ◽  
pp. 969-973
Author(s):  
Hong Feng Luo ◽  
Jing Wu ◽  
Zhe Liu ◽  
Wei Ping Chen
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Thermal Stresses ◽  
Molten Aluminum ◽  
Intermetallic Layer ◽  
Static Immersion

Corrosion of molybdenum in molten aluminum was investigated by static immersion tests. The layer formed between aluminum and molybdenum was consist of Al4Mo at 700°C, Al8Mo3 at 750°C, Al4Mo and Al8Mo3 at 800°C range for periods varying from 8 to 120 h . The intermetallic layer broke up as long as it grew due to thermal stresses and dispersed in the molten aluminum. The weight-loss of molybdenum varied linearly with time. The corrosion rate increased with temperature and the activation energy was nearly 88.4 kJ mol-1.

scholarly journals Corrosion Inhibition of Mild-Steel in 0.5 M HCl using some prepared 1,2,3-Triazoles Derivatives

2019 ◽  
Vol 9 (4) ◽  
pp. 290-304 ◽  
Author(s):  
Hawraa Kareem Dhaif ◽  
Ekhlas Q . Jasim ◽  
Zena A. Muhajjar ◽  
Ashwaq A. Shanta
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Corrosion Rate ◽  
Mild Steel ◽  
Langmuir Isotherm ◽  
Mixed Type ◽  
Inhibition Efficiency ◽  
Temperature Impact ◽  
The Impact ◽  
Hcl Solution

The Weight loss was employed to investigate the impact of triazole on mild-steel dissolution in 0.5 M HCl solution. The inhibitor’s inhibition efficiency was seen to increase with concentration yielding (81.61%,82.61%,88.29%,91.64%,94.32%) of (T9, T8, T6, T4, T1) at concentration 1×10-4 M HCl, at a temperature of 25°C for 240 min. At a temperature range from 25–45°C, we studied the temperature impact on the corrosion behavior, wherein the results demonstrated decrease in inhibition efficiency with rising in temperature to achieve (61.7%, 52.26%, 63.1%, 72.11%, 75.77 %) of (T9, T8, T6, T4 and T1) at a concentration of 1×10-4 M, at a temperature 45°C for 240 min. A study was also performed regarding the impact of temperature on the corrosion rate in the presence and absence of triazole. The activation energy and Kinetic parameters were calculated and discussed. Polarization curves revealed that the studied inhibitors represent a mixed – type inhibitors. Adsorption of inhibitors was found to obey Langmuir isotherm and was isotherm physisorption type.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

Thermogravimetric devolatisation behavior of agricultural residue for generation of syngas

2021 ◽  
pp. 1-17
Author(s):  
Praveen Kumar ◽  
P.M.V. Subbarao ◽  
L.D. Kala ◽  
V.K. Vijay
Keyword(s):  
Activation Energy ◽  
Pearl Millet ◽  
Proximate Analysis ◽  
Thermochemical Conversion ◽  
Degradation Behavior ◽  
Ozawa Method ◽  
Thermogravimetric Method ◽  
Agricultural Residue ◽  
Tg Analysis ◽  
Tg And Dtg

Abstract The thermal degradation characteristics of eucalyptus, pearl millet cob, and corncob were investigated using non-isothermal thermogravimetric method. This investigation was performed with the objective of carrying out thermochemical conversion for obtaining syngas. TG and DTG analysis were carried out to understand thermal devolatisation behavior and estimation of various thermophysical properties of the biomasses. The degradation behavior was analysed in the light of lignocellulosic composition that was found to have definitive influence on degradation outcomes. TG analysis has been utilized to obtain proximate analysis of biomass. Activation energy using Flynn-Wall-Ozawa method have been estimated and found to be 201, 150 and 68 kJ mol−1 for eucalyptus, pearl millet cob, and corncob respectively. The TG analysis and activation energy together indicated that corncob is easiest for thermochemical conversion amongst the three biomasses. The TG curve also confirms the same.

Effect of alkylated diphenylamine on thermal-oxidative degradation behavior of poly-α-olefin

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Mian-Ran Chao ◽  
Wei-Min Li ◽  
Li-Li Zhu ◽  
Hai-Hong Ma ◽  
Xiao-Bo Wang
Keyword(s):  
Activation Energy ◽  
Oxidative Stability ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Degradation Behavior ◽  
Thermal Oxidative Stability ◽  
Zinc Dialkyl Dithiophosphate ◽  
Dialkyl Dithiophosphate

AbstractAn oil-soluble antioxidant, alkylated diphenylamine (ADPA), was prepared by alkylation of diphenylamine. The influence of ADPA on the thermal-oxidative stability of poly-α-olefin (PAO8) was evaluated by thermogravimetry (TG). For comparison, the thermal-oxidative stability of PAO8 with zinc dialkyl dithiophosphate (ZDDP) was also investigated. Activation energy (E

Corrosion Behavior of Duplex Stainless Steel in Industrial White Liquor

CORROSION ◽  
10.5006/2558 ◽  
2017 ◽  
Vol 74 (5) ◽  
pp. 543-550 ◽  
Author(s):  
Luiza Esteves ◽  
Mônica M.A.M. Schvartzman ◽  
Wagner Reis da Costa Campos ◽  
Vanessa F.C. Lins
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Corrosion Rate ◽  
Duplex Stainless Steel ◽  
Corrosion Behavior ◽  
Extrapolation Method ◽  
White Liquor ◽  
Duplex Steel ◽  
Kraft Mill ◽  
Lower Corrosion Rate

Specimens of lean duplex and duplex stainless steel were exposed at 200°C in industrial white liquor from a Brazilian kraft mill using an autoclave to simulate the same conditions of digester processing. Tafel extrapolation method and weight loss were used to evaluate corrosion behavior of duplex steel in white liquor. The higher alloy steel, although presenting a lower corrosion rate than the lean duplex, presents a more severe selective attack on ferrite, at 200°C and 1.8 MPa, after Tafel extrapolation method in industrial white liquor.

scholarly journals Influence of sodium carbonate addition on weight loss of bagasse alkaline black liquor during pyrolysis

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2428-2441
Author(s):  
Xusheng Li ◽  
Jinlong Wang ◽  
Derong Yan ◽  
Yongjun Yin ◽  
Shuangfei Wang
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Sodium Carbonate ◽  
Black Liquor ◽  
Reduction Reaction ◽  
Loss Ratio ◽  
N2 Atmosphere ◽  
Microscopic Morphology ◽  
Weight Loss Ratio

To understand the effects and the mechanism of sodium carbonate (Na2CO3) addition on the bagasse alkaline black liquor (BABL) pyrolysis, the reaction variables such as temperature, heating rate, and amount of Na2CO3 addition into BABL-solids were investigated under N2 atmosphere from 50 °C to 1000 °C by thermogravimetic analysis (TGA). Scanning electron microscopy (SEM) and the Coats–Redfern method (CRM) were employed for surface microscopic morphology observations and kinetic analysis, respectively. The results showed that Na2CO3 plays an inhibiting and promoting role during devolatilization (200 °C to 650 °C) and the reduction stages (650 °C to 1000 °C), respectively. Adding Na2CO3 into BABL-solids tends to increase the thickness of the salt layer covering the BABL-solids surface, which increases the activation energy and reduces the weight loss ratio of BABL-solids pyrolysis within 200 °C to 650 °C. Adding Na2CO3 into the BABL-solids tends to increase the number of alkaline compounds or the active site of the reduction reaction, which reduces the activation energy and increases the weight loss ratio of BABL-solids pyrolysis within 650 °C to 1000 °C. The role of Na2CO3 as an additive could be well understood by studying the influence mechanism of Na2CO3 on BABL-solids pyrolysis.

Research on the Influence of Salt Fog Corrosion Behavior of 6005A Aluminum Alloy Welded Joints by Environment Humidity

2013 ◽  
Vol 662 ◽  
pp. 251-257
Author(s):  
Ning Xia ◽  
Zhi Min Zhu ◽  
Hui Chen
Keyword(s):  
Weight Loss ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Relative Humidity ◽  
Corrosion Rate ◽  
Environmental Humidity ◽  
Welding Joints ◽  
Salt Fog Corrosion ◽  
Salt Fog

6005A aluminum alloys were welded at different relative humidity conditions. The effects of relative humidity on the salt fog corrosion of the welding joints were researched. The results showed that the weight loss of the joints after 14 days corrosion was higher than that corroded after 7days, but the corrosion rate was lower. The corrosion rate first increased then declined with the increase of environmental humidity for the joints corroded for 7days. However, when the environmental humidity was 80%, corrosion rate achieved the maximum, when environment humidity was 70%, corrosion rate was the lowest. After corroded for 14 days, corrosion rate was the maximum when the environmental humidity was 50%, and it was the lowest when the environmental humidity was 90%. The tensile strength declined obviously after corrosion.

scholarly journals Effect of Degassing Treatment on the Interfacial Reaction of Molten Aluminum and Solid Steel

2017 ◽  
Vol 17 (2) ◽  
pp. 227-239 ◽  
Author(s):  
T. Triyono ◽  
N. Muhayat ◽  
A. Supriyanto ◽  
L. Lutiyatmi
Keyword(s):  
Electron Microscope ◽  
Intermetallic Compound ◽  
Scanning Electron Microscope ◽  
Interfacial Reaction ◽  
Immersion Time ◽  
Molten Aluminum ◽  
Furnace Lining ◽  
Brittle Phase ◽  
Crucible Furnace ◽  
Scanning Electron

AbstractThe gas porosity is one of the most serious problems in the casting of aluminum. There are several degassing methods that have been studied. During smelting of aluminum, the intermetallic compound (IMC) may be formed at the interface between molten aluminum and solid steel of crucible furnace lining. In this study, the effect of degassing treatment on the formations of IMC has been investigated. The rectangular substrate specimens were immersed in a molten aluminum bath. The holding times of the substrate immersions were in the range from 300 s to 1500 s. Two degassing treatments, argon degassing and hexachloroethane tablet degassing, were conducted to investigate their effect on the IMC formation. The IMC was examined under scanning electron microscope with EDX attachment. The thickness of the IMC layer increased with increasing immersion time for all treatments. Due to the high content of hydrogen, substrate specimens immersed in molten aluminum without degasser had IMC layer which was thicker than others. Argon degassing treatment was more effective than tablet degassing to reduce the IMC growth. Furthermore, the hard and brittle phase of IMC, FeAl3, was formed dominantly in specimens immersed for 900 s without degasser while in argon and tablet degasser specimens, it was formed partially.

Surface morphology studies and kinetic-thermodynamic characterization of steels treated in 5.0 M HCl medium: hot-dip galvanizing application

2018 ◽  
Vol 65 (2) ◽  
pp. 176-189 ◽  
Author(s):  
Younes El Kacimi ◽  
Mouhsine Galai ◽  
Khaoula Alaoui ◽  
Rachid Touir ◽  
Mohamed Ebn Touhami
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
Potentiodynamic Polarization ◽  
Phosphorus Content ◽  
Surface Heterogeneity ◽  
Protective Film ◽  
Content Type ◽  
3D Profilometry ◽  
Adsorption Processes ◽  
Hcl Solution

Purpose The purpose of this paper is to study the effect of silicon and phosphorus content in steel suitable for galvanizing on its corrosion and inhibitor adsorption processes in steels/cetyltrimethylammonium bromide combined and KI (mixture)/5.0 M hydrochloric acid systems has been studied in relation to the temperature using chemical (weight loss), Tafel polarization, electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM) analysis and Optical 3D profilometry characterization. All the methods used are in reasonable agreement. The kinetic and thermodynamic parameters for each steels corrosion and inhibitor adsorption, respectively, were determined and discussed. Results show that the adsorption capacity for Steel Classes A and B are better than Steel Class C surfaces depending on their silicon and phosphorus content. Surface analyses via SEM and Optical 3D profilometry was used to investigate the morphology of the steels before and after immersion in 5.0 M HCl solution containing mixture. Surface analysis revealed improvement of corrosion resistance of Steels Classes A and B in the presence of mixture more than Classes C. It has been determined that the adsorbed protective film on the steels surface heterogeneity markedly depends on steels compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content. Design/methodology/approach The effect of silicon and phosphorus content in Steels Classes A, B and C on its corrosion and inhibitor mixture adsorption processes in 5.0 M HCl solution has been studied by weight loss, potentiodynamic polarization, EIS and surface analysis. Findings The inhibition efficiency of mixture follows the order: (Steel Class A) > (Steel Class B) > Steel Class C) and depends on their compositions in the absence of mixture according on their silicon and phosphorus content, that is, the corrosion rate increases with increasing of the silicon and phosphorus content. A potentiodynamic polarization measurement indicates that the mixture acts as mixed-type inhibitor without changing the mechanism of corrosion process for the three classes of mild steels. Originality/value Corrosion rate mild steels in 5.0 M HCl depends on their compositions in the absence of mixture according to their silicon and phosphorus content, that is, the corrosion rate increases with increasing silicon and phosphorus content. The adsorbed protective film on the steels surface heterogeneity markedly depends on steels class’s compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.

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