Chandraambhorn, Walairat

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Alternative Name

Chandra-Ambhorn, Walairat

Chandra-ambhorn, Walairat

Chandra-Ambhorn, W.

Main Affiliation

School of Engineering

walairat.ch@kmitl.ac.th

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Reduction of chromium volatilisation from stainless steel interconnector of solid oxide electrochemical devices by controlled preoxidation
(2016-05-01)
Wongpromrat, Wichitra
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Berthomé, Grégory
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Parry, Valérie
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Chandra-ambhorn, Somrerk
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Chandra-ambhorn, Walairat
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Oxidation and volatilisation behaviour of a type 430 stainless steel coated by Mn-Co oxide by slurry method with pre-oxidation for SOFC interconnect application
(2021-07-15)
Chandra-ambhorn, Somrerk
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Homjabok, Wanna
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Chandra-ambhorn, Walairat
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Thublaor, Thammaporn
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Siripongsakul, Thamrongsin
An AISI 430 stainless steel was coated by Mn-Co spinel using a slurry method. Pre-oxidation before the coating helped reduce the oxidation rate of the coated steel at 800 °C in O<inf>2</inf>-5%H<inf>2</inf>O, relating to the formation of the continuous chromia layer which inhibited the outward diffusion of iron to the coating layer. It also helped reduce the mass flux of Cr loss due to the volatilisation. The combined molecular and Knudsen diffusion of the volatile species through the coating layer was suggested to explain the reduced volatilisation rate of the coated sample with pre-oxidation.
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Arsenic adsorption using the adsorbent synthesised from oyster shell
(2017-01-01)
Khownpurk, Pichnipa
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Wongpromrat, Wichitra
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Chandra-Ambhorn, Walairat
Ground oyster shells were calcined and used as an adsorbent to remove As (III) from contaminated water. Adsorption experiment was performed by batch tests. The effect of pH on the adsorption performance was investigated. The result showed that at the initial concentration of 100 mg/L, over the pH range of 5-11, the highest efficiency was obtained at pH 11. The experimental data better correlated with pseudo-second order model. The maximum adsorption capacity (q<inf>m</inf>) of approximately 195.5 mg/g was obtained at pH 11.
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Preparation and characterization of oyster shell powder-treated rice husk ash adsorbent pellet for As(III) removal
(2018-08-14)
Khownpurk, Pichnipa
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Chandra-Ambhorn, Walairat
The adsorbent pellet for As(III) removal was prepared from ground oyster shell and rice husk ash. The effects of particle size of oyster shell powder (OS) and the ratio between the OS and Treated rice husk ash (TRHA) on the stability of the adsorbent pellet were studied. The adsorbent pellet was characterized by XRD, XRF and SEM. The solubility and As(III) adsorption tests were performed. The results showed that the adsorbent pellet prepared from OS size <106 μm with OS:TRHA ratio of 0.7:0.3 could provide As(III) maximum adsorption capacity of approximately 26.20 mg/g. Furthermore, the XRD and SEM results indicated that the adsorbent pellet could consist of two parts i.e. CaO that could adsorb As(III) in the form of Ca-As-O and the CaSiO<inf>3</inf> and C-S-H compounds which behaved as a binder to bind the precursor powders to be stable adsorbent pellet without cracking.
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Advanced microstructural investigations of AISI 441 early stage oxidation in wet atmosphere
(2017-01-01)
Wongpromrat, Wichitra
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Parry, Valérie
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Chandra-Ambhorn, Walairat
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Chandra-Ambhorn, Somrerk
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Galerie, Alain
AISI 441 ferritic stainless steel is a good candidate for metallic interconnects in solid oxide fuel cells (SOFCs). The minor elements Ti and Nb are used to stabilize the ferritic matrix and also to reduce creep by a combination of solid solution strengthening and precipitation of intermetallic Laves phase particles along the grain boundaries. However their influence on the oxidation behavior is not well understood. This study focuses on the early stages oxidation (from 4 to 24 h) at 800°C of AISI 441 under 5% H<inf>2</inf>O in O<inf>2</inf>. A relatively smooth micro-crystallized oxide scale and Ti, Nb containing nodules are observed. The internal microstructure of these objects is studied by FIB tomography which allows computing cross sectional views in any direction of interest. FIB study reveals a complex microstructure and a development strongly linked to the presence of niobium and/or titanium in the substrate.
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Oxidation and Scale Adhesion of a Type 430 Stainless Steel in Ar–CO2 Gas Mixtures at 800 °C
(2023-04-01)
Wiman, Panya
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Muengjai, Angkana
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Srihathai, Padungaut
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Thublaor, Thammaporn
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Siripongsakul, Thamrongsin
Biogas is an alternative source of fuel potentially used to run solid oxide fuel cells (SOFCs). It mainly consists of CH<inf>4</inf> and CO<inf>2</inf> which can degrade the SOFC interconnect, which is typically made of stainless steel. To investigate the effect of each gas constituent, we focussed here on the effect of CO<inf>2</inf> on high-temperature oxidation behavior of and scale adhesion on the stainless steel interconnect, Type 430 stainless steel. The samples studied were oxidised in CO<inf>2</inf> at contents of 5–100% at 800 °C. The oxidation kinetics were found to be parabolic with the rate constant increasing when the CO<inf>2</inf> content increased. The scale adhesion was assessed using a tensile-test method. The scale formed in the atmosphere containing higher CO<inf>2</inf> content exhibited poorer scale adhesion, as indicated by a lower strain initiating the first spallation and a larger spallation percentage after the first spallation took place. The worsened scale adhesion relates to pores formed at the scale/steel interface. The adhesion energies were further quantified giving the values of about 40–100 J m–2. Oxidation mechanisms were suggested based on the dependence of the parabolic rate constant on the oxygen partial pressure and the inward diffusion of carbon-bearing species.
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Modification of a solar thermal collector to promote heat transfer inside an evacuated tube solar thermal absorbe
(2021-05-01)
Supankanok, Rasa
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Sriwong, Sukanpirom
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Ponpo, Phisan
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Wu, Wei
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Chandra-Ambhorn, Walairat
Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.
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Possible connection between nodule development and presence of niobium and/or titanium during short time thermal oxidation of AISI 441 stainless steel in wet atmosphere
(2015-01-01)
Wongpromrat, W.
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Parry, V.
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Charlot, F.
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Crisci, A.
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Latu-Romain, L.
AISI 441 ferritic stainless steel is a good candidate for metallic interconnects of solid oxide fuel cells (SOFCs). In this alloy, the minor elements Ti and Nb are used to stabilise the ferritic structure but their influence on steel durability is not well understood. This study focuses on the early stages of oxidation (24 h) at 800°C of AISI 441 under 5%H<inf>2</inf>O in O<inf>2</inf> following the cathodic SOFCs conditions. The typical duplex oxide scale, composed of a (Mn,Cr)<inf>3</inf>O<inf>4</inf> spinel top layer and a Cr<inf>2</inf>O<inf>3</inf> rich sublayer is observed, with oxide nodules growing in places. These objects, in the micrometre range in size, are studied by FIB tomography. The analyses reveal a complex structure and a development strongly linked to the presence of niobium and/or titanium compound(s) in the subjacent substrate.
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High temperature corrosion behaviour of aluminide-coated cast iron for an exhaust manifold application
(2020-01-01)
Kerdbua, Panya
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Bidabadi, Mohammad Hassan Shirani
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Chandra-Ambhorn, Walairat
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Chandra-Ambhorn, Somrerk
To reduce the pollution emission from vehicles, an improvement on the combustion process is expected, leading to increased exhaust gas temperature. As a result, the development of new materials for an exhaust manifold used at higher temperatures is required. A cost-effective cast iron exhaust manifold treated by aluminising pack cementation was developed in the present work to combat the high temperature corrosion. Its kinetics under cyclic oxidation in N<inf>2</inf>-12%O<inf>2</inf>-10%H<inf>2</inf>O at 850 °C was parabolic with the rate constant (kp) of 5.66 × 10-12 g2 cm-4 s-1, about two orders of magnitude lower than that of the bare cast iron, which indicated the protectiveness of the applied coating. These results relate to the protective alumina formation for the aluminised cast iron and the formation of the less protective iron oxides for the bare cast iron after oxidation, as evidenced by the XRD and Raman spectroscopy results. The addition of 10% water vapour to N2-12%O2 thickened the aluminide layer from 344 μm for the sample oxidised in dry atmosphere to 409 μm for the sample oxidised humidified one. It accelerated the oxidation rate of the aluminised cast iron as the kp value increased by 8.5 times, and also increased the hardness of the aluminised surface, as it was 364 HV for the sample exposed to dry atmosphere and 420 HV for the sample exposed to humidified one. The latter result implied the possibility of the hydrogen dissolution into the metal surface. The roles of hydroxyl ion and dissolved hydrogen on the oxidation and evolution of the aluminide layer after exposure to water vapour were proposed.
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Chromium vaporisation from AISI 441 stainless steel oxidised in humidified oxygen
(2013-06-01)
Wongpromrat, Wichitra
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Thaikan, Harit
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Chandra-Ambhorn, Walairat
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Chandra-Ambhorn, Somrerk
Chromium vaporisation from chromia-forming alloys when exposed to high temperatures can deteriorate the protective property of oxide scale. This problem affects the lifetime of solid oxide fuel cells and solid oxide electrolysers using chromia-forming alloys as interconnectors. In this work, AISI 441, a commercial grade stainless steel which chromium vaporisation investigation has not been reported so far, was chosen for study. Chromium vaporisation rates of bare AISI 441 and AISI 430 and AISI 441 and AISI 430 coated with Mn-Co spinel by electroplating method were measured in an atmosphere of 5 % H<inf>2</inf>O in O<inf>2</inf> over the temperature range of 650-900 C with the linear velocity of the humidified oxygen stream varied in the range of 0.8-3.0 cm s-1. For uncoated samples, AISI 441 showed a lower chromium vaporisation rate in comparison with that of AISI 430. Mn-Co spinel coating could reduce the chromium vaporisation rate from AISI 430 surface. However, on the contrary, the Mn-Co spinel coating could not only fail to suppress the chromium vaporisation, but it also promoted the chromium vaporisation from AISI 441 surface by 2 times. © 2013 Springer Science+Business Media New York.

Chandraambhorn, Walairat

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