Scanning Electron Microscope With Energy Dispersive Spectrometer Research Articles

Carbonate salt based composite phase change materials for medium and high temperature thermal energy storage: A microstructural study

We investigated the microstructures and their formation mechanisms of carbonate salt based composite phase change materials (CPCMs). Such materials typically consist of a carbonate salt as the phase change material (PCM), a thermal conductivity enhancement material (TCEM) and a ceramic skeleton material (CSM) for structure stabilisation, and are mainly for medium and high temperature thermal energy storage applications. Two carbonate salt based composites were studied with one being eutectic NaLiCO3 and the other Na2CO3. MgO and graphite flakes were used respectively as the CSM and TCEM for fabricating the composite modules. A scanning electron microscope with energy dispersive spectrometer (SEM-EDS) was used to observe the microstructures and the salt distribution and redistribution within the composite structures during repeated melting-solidification cycles. The results showed salt migration within the composite structure during the thermal cycling. Such a microscopic motion led to a more homogenous distribution of not only the salt but also the CSM and TCEM. At a low graphite flake loading, breakage of the graphite flake was observed, suggesting stress generation during thermal cycling. The extent of the breakage reduced with increasing graphite flake loading, suggesting the stress generation be related to microscopic motion. The MgO based CSM particles were likely to be sintered, forming a porous structure. Such a structure reduced the swelling effect partially due to the use of graphite on which the salts had a poor wettability.

Low-friction behaviors of Ag-doped γ-Fe2O3@SiO2 nanocomposite coatings under a wide range of temperature conditions

In this paper, Ag-doped γ-Fe2O3@SiO2 nanocomposite coatings have been prepared by sol–gel method and deposited on steel substrate. The microstructure, surface topography, and high-temperature tribological properties of these coatings were measured and investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope with energy- dispersive spectrometer (SEM/EDS), transmission electron microcopy (TEM), and a high-temperature tribometer. The results show that the γ-Fe2O3 core is coated with an amorphous SiO2 shell and Ag nanoparticles are evenly distributed in the γ-Fe2O3@SiO2 nanocomposites. The tribological properties of the coatings against ZrO2 balls have been investigated by a tribometer at room temperature (RT), 100, 300, 500, and 600 °C, respectively. It is found that the nanocomposite coatings exhibit low and stable coefficients of friction (CoF) (in the range from 0.25 to ~0.06) from RT to 600 °C, respectively. CoF of the friction pair decreases with the increase of temperature. XRD, Raman spectroscopy, and SEM measurements show that the antifriction behaviors of nanocomposite coatings are owing to the soft phases of metal Ag and γ-Fe2O3. The presence of γ-Fe2O3 with high-temperature plasticity is beneficial to form low-shear interface and to achieve low and stable friction at high temperature. The core–shell microstructure of the nanocomposite coatings inhibits the soft γ-Fe2O3 phase, changing it into the α-Fe2O3 phase.

Influence of sodium gluconate and cetyltrimethylammonium bromide on the corrosion behavior of duplex (α-β) brass in sulfuric acid solution

Abstract The present research focuses on the corrosion inhibition of a two phases (α-β) brass in 0.5 M H2SO4 solution containing sodium gluconate (SG) and cetyltrimethyl ammonium bromide (CTAB) at different temperatures. The inhibition effect was studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM-EDS), Inductively Coupled Plasma Spectrometry (ICPS) and Density Functional Theory (DFT). Experimental results revealed that the corrosion inhibitors exerted a strong effect on brass corrosion and found to be less effective at a long immersion time (24 h). A concentration of 10−3 M of SG in combination with 5 ppm CTAB (SG/CTAB) can cover up to 89% of the brass’ surface, which provides very good protection against corrosion, reducing the corrosion rate from 49 mA cm−2 to 5.5 mA cm−2. The study also showed that the inhibition efficiency of SG/CTAB was slightly decreased at higher temperatures and their adsorption on brass surface was found to follow the Langmuir adsorption isotherm. The SG/CTAB acted as cathodic type corrosion inhibitors with insignificant changes in the anodic reaction. Electrochemical impedance spectroscopy (EIS) studies revealed that addition of 5 ppm CTAB to different concentrations of SG considerably increases the corrosion resistance of brass. The synergistic effect of SG and CTAB is also discussed. The SEM-EDS and ICPS analyses support the experimental results. Furthermore, quantum chemical calculations were used to understand the electronic properties of SG and CTAB.

Condensation of KCl(g) under varied temperature gradient

Homogenous nucleation or heterogeneous condensation of gaseous alkali salts commonly occurs in biomass-fired power plants, and is mainly responsible for forming fine particles and triggering deposition or corrosion on tubes. This work aims to investigate the influence of surface temperature and exposure time on the initial condensation characteristics of KCl(g) in air atmosphere. It includes both experiment and simulation calculation to qualitatively and quantitatively study the condensation and gas-to-solid conversion of KCl(g) under different temperature gradients. Experiments were carried out in an electrically heated vertical tubular furnace, in which a defined evaporating source of KCl(g) was designed. A sampling probe equipped with a temperature controlled Fe-Cr-Ni alloy condensation surface, was inserted into the furnace to capture KCl(g). For each case, the morphology of condensed salt on the probe surface was analyzed via using Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS). The results showed significant differences in morphologies of the condensed salts which were respectively observed at the condensation surface temperature of Fe-Cr-Ni alloy of 673.15, 793.15 and 873.15 K. At the same tubular furnace temperature, due to the appearance of dendritic structure, the condensation rate of KCl(g) of 3.28 × 10−6 kg/m2·s at the surface temperature of 793.15 K was greater than that obtained at 673.15 K. The calculation of gas-to-solid conversion found that condensed KCl particles whose diameter is larger than 1 μm could not be formed only relying on the mechanism of nucleation and coagulation, when the gas temperature decreased from 1073.15 K to 673.15/793.15/873.15 K, respectively. The faster the cooling rate is, the smaller the size of formed particles is, and the more the number concentration of ultra-fine particles is. In addition, severe corrosion and cracks of surface material of the condensation surface were clearly observed at 793.15/873.15 K, which may be induced by couple attacks of condensed salts, thermal stress and molecular oxygen.

Effects of Cetyltrimethylammonium bromide on the Corrosion Inhibition of a Lead-free α-Brass by Sodium Gluconate in Sulfuric Acid

The inhibition performance of sodium gluconate (SG), cetyltrimethylammonium bromide (CTAB) and their mixture (SG/CTAB) on the corrosion behavior of α-brass in 0.5 M H2SO4 solution has been investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM-EDS), Inductively Coupled Plasma Spectrometry (ICPS) and molecular dynamics (MD) simulation techniques. The results reveal that SG with 5ppm CTAB, noted SG/CTAB, acts as a good corrosion inhibitor and its inhibition efficiency reached 89% after 24 h immersion in sulfuric acid solution, but slightly decreased at higher temperatures. The polarization curves displayed that SG/CTAB acts as a cathodic-kind inhibitor. Electrochemical impedance spectroscopy (EIS) studies revealed that the addition of 5ppm CTAB to different concentrations of SG considerably increases the corrosion resistance of α-brass. The SEM-EDS and ICPS analyses support the experimental results. Further, molecular dynamics (MD) simulations were used to understand the adsorption profiles of SG/CTAB on Cu(111) and Zn(111) surfaces.

Improving coal flotation using the mixture of candle soot and hydrocarbon oil as a novel flotation collector

Abstract An effective flotation collector determines the flotation performance and efficiency of fine coal particles. Generally, hydrocarbon oils, such as diesel and kerosene are widely applied in the flotation circuit in coal preparation plants. However, hydrocarbon oils are not effective enough for difficult-to-float coals, such as low rank coal and difficult to float coking coal. In this study, the mixture of candle soot and hydrocarbon oil (dodecane) was used as a novel flotation collector in the flotation of coking coal and low rank coal. X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to indicate the surface properties of candle soot. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) and attachment time measurer were used to show the adsorption of candle soot on coal particle surface. XPS and contact angle results showed that the candle soot was very hydrophobic. SEM/EDS results showed the candle soot consisted of plenty of carbon nanoparticles which could attach and adsorb on the coal particle surface and hence shortens the attachment time of coal particle and bubble. The flotation recovery of both coking and low rank coals using the mixture of candle soot and dodecane as a collector were higher than that using solo dodecane as collector. The adsorption of candle soot and other ultra-fine particles on coal particle surface enhanced the surface hydrophobicity and floatability of coking and low rank coal particles.

Industrial wastewater advanced treatment via catalytic ozonation with an Fe-based catalyst

An Fe-based catalyst was used as a heterogeneous catalyst for the ozonation of industrial wastewater, and key operational parameters (pH and catalyst dosage) were studied. The results indicated that the Fe-based catalyst significantly improved the mineralization of organic pollutants in wastewater. TOC (total organic carbon) removal was high, at 78.7%, with a catalyst concentration of 200 g/L, but only 31.6% with ozonation alone. The Fe-based catalyst significantly promoted ozone decomposition by 70% in aqueous solution. Hydroxyl radicals (·OH) were confirmed to be existed directly via EPR (electron paramagnetic resonance) experiments, and ·OH were verified to account for about 34.4% of TOC removal with NaHCO3 as a radical scavenger. Through characterization by SEM-EDS (field emission scanning electron microscope with energy-dispersive spectrometer), XRD (X-ray powder diffraction) and XPS (X-ray photoelectron spectroscopy), it was deduced that FeOOH on the surface of the catalyst was the dominant contributor to the catalytic efficiency. The catalyst was certified as having good stability and excellent reusability based on 50 successive operations and could be used as a filler simultaneously. Thereby, it is a promising catalyst for practical industrial wastewater advanced treatment.

Effects of attrition on coarse coal flotation in the absence of collectors

Samples of clean coarse coal particles (0.5–0.25mm) were used and the flotation process was conducted in the absence of collectors. Scanning electron microscope with energy dispersive spectrometer (SEM/EDS) was used to indicate the elementary composition on coal particle surface as well as particle shape. The attrition process was conducted in a flotation cell with a varied period of stirring process prior to the flotation process. Throughout this paper, it was found that the content of carbon element on coarse coal surface was reduced after attrition whereas the contents of aluminium and silicon elements were increased. A small part of organic matters could release from coarse coal surface by attrition. The attrition process rounded the edges of the coal particles. The flotation performance of coarse coal particles with round corner was worse than that of coal particles with sharp corner. A long period of attrition process could be conducive to obtain a low ash concentrate.

Solidification/stabilization of chromite ore processing residue using alkali-activated composite cementitious materials

Chromite Ore Processing Residue (COPR) produced in chromium salt production process causes a great health and environmental risk with Cr(VI) leaching. The solidification/stabilization (S/S) of COPR using alkali-activated blast furnace slag (BFS) and fly ash (FA) based cementitious material was investigated in this study. The optimum percentage of BFS and FA for preparing the alkali-activated BFS-FA binder had been studied. COPR was used to replace the amount of BFS-FA or ordinary Portland cement (OPC) for the preparation of the cementitious materials, respectively. The immobilization effect of the alkali-activated BFS-FA binder on COPR was much better than that of OPC based cementitious material. The potential for reusing the final treatment product as a readily available construction material was evaluated. X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS) analysis indicated that COPR had been effectively immobilized. The solidification mechanism is the combined effect of reduction, ion exchange, precipitation, adsorption and physical fixation in the alkali-activated composite cementitious material.

Characterization of the Thermo-Microstructural Analysis of Raffia Palm Fibers Proposed for Roofing Sheet Production

Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual frond leaf is taken off to create a long thin fiber. They are usually waste materials which cause a great environmental degradation. The characterization of Raffia palm fibers/ particles was investigated through X-ray diffractometer (XRD), thermogravimetric analysis (TGA/DTA), Fourier transform infrared spectrometry (FTIR), Scanning electron mi croscope with energy dispersive spectrometer (SEM/EDS) and Atomic force microscope (AFM). The various results obtained are equivalent to those of other agro-waste materials generally used in roofing sheets composites production. Hence, this work shows that Raffia palm fibers/particles can be a useful material for cement mortar composites production which can be used for production of roofing sheets.

The Inhibition of Sodium Oleate for Pitting Corrosion of Aluminum Alloy 2024 in 0.1 mol L-1NaCl Solution

The inhibition mechanism of sodium oleate (C17H33COONa) for pitting corrosion of aluminum alloy (AA) 2024 in 0.1 mol L-1 NaCl solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). C17H33COONa showed good inhibition effect on uniform corrosion of AA2024 in 0.1 mol L-1 NaCl solution by promoting surface passivity of aluminum alloy. But in NaCl solution with high concentration (3.5 wt.% NaCl), C17H33COONa could not promote passivity of aluminum alloy. C17H33COONa also suppressed the tendency of pitting initiation and reduced the pitting corrosion sensitivity of aluminum alloy. The addition of 0.1 g L-1 C17H33COONa showed good inhibition performance but further concentration increase had little effect on the inhibition efficiency. The C17H33COO− groups adsorbed on the surface of aluminum alloy by chemical adsorption effect, which promoted oxidation of the aluminum alloy surface.

Molecular Modeling of Acidic Treated PSTM-3T Polymer for Removal of Heavy Metal Ions by Experimental and Computational Studies

The synthesized poly[N,N′-bis(3-silsesquioxanilpropyl)-thiocarbamide] (PSTM-3T) was used and the surface morphology and microstructure of it were analyzed by scanning electron microscopy with energy dispersive spectrometer (SEM/EDS). The molecular structure change of the PSTM-3T polymer of the PSTM-3T after treatment by acidic solution with different pHs was revealed using FT-IR experiments andab initiocalculations with density functional theory method. The sorption efficiency of the heavy metal ions depends on the molecular structure change of PSTM-3T after treatment of different pH aqueous solutions. After the treatment of acidic solution (pH = 2) of PSTM-3T, the polymer formed the tautomer state to increase the sorption efficiency for chromate ion. For the increment of pH value for acidic solution, the PSTM-3T polymer was dissociated to increase the sorption efficiency for copper ion.

Effects of eggshell on the microstructures and properties of Al–Cu–Mg/eggshell particulate composites

The effects of eggshell particles (ES) on the microstructures and properties of Al–Cu–Mg/ES particulate composites have been studied. A total of 2–12wt.% ES particles were added. The microstructures of the Al–Cu–Mg/eggshell particulate composites produced were examined by a scanning electron microscope with energy dispersive spectrometer (SEM/EDS). The physical and mechanical properties measured included: density, tensile strength, hardness values and impact energy. The results revealed that the tensile strength increased by 8.16% at 12wt.% uncarbonized ES and 14.28% at 12wt.% carbonized ES, the hardness values increased by 10.01% at 12wt.% uncarbonized ES and 25.4% at 12wt.% carbonized ES with decrease in the density by 6.50% at 12wt.% uncarbonized ES and 7.4% at 12wt.% carbonized ES. The impact energy decreased by 23.5% at 12wt.% uncarbonized ES and 24.67% at 12wt.% carbonized ES particles, respectively. These increases in strength and hardness values are attributed to the distribution of hard phases of the ES particles in the ductile Al–Cu–Mg alloy matrix. These results showed that using the carbonized eggshell as reinforcement in the Al–Cu–Mg alloy gives better physical and mechanical properties as compared to uncarbonized ES particles. Hence addition of ES particles upto 12wt.% can be used as a low cost reinforcement for the production of metal matrix composites for engineering applications.

Acid corrosion resistance and mechanism of E-glass fibers: boron factor

Acid corrosion and stress corrosion characteristics of E-glass fibers with and without boron (B2O3 or B) were carefully studied, using 1 N H2SO4 acid at 96 °C and room temperature, respectively. The effect of boron on glass resistance to the acid attack is elucidated in conjunction with structural roles of B, Al, and Ca in the glass. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) characterization was performed on the selective fiber samples before and after the acid leaching. For high boron-containing fibers, the results showed the formation of alteration layer enriched in Si as a result of depletion of both Ca and Al. Chemical analysis of the high boron fibers before and after 24 h acid leaching and the solution after 24 h test further confirmed that B, Ca, and Al in the glass fibers preferentially dissolved in the acid solution. Glass fiber dissolution mechanisms were discussed with a proposal that acid corrosion attack in boron-containing E-glass is controlled by hydrolysis of aluminoborate complex species (less than 10 nm) separated from the silicate glass network, whereas the acid corrosion attack in boron-free E-glass is controlled by hydrolysis of the silicate network, where 4-coordinated aluminum in the network is locally charge compensated by Ca.

A Study on the Nanostructured W–Ti Thin Films Deposited on Si

The W(90%)–Ti(10%) wt% alloy target is prepared and the W–Ti thin films are deposited by the dc Ar+ sputtering on silicon substrates. The morphology, composition, and microstructure of the alloy and thin films were observed. The structure was undertaken using X-ray diffraction (XRD). The morphology was determined by scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and high-resolution transmission electron microscopy (HRTEM). The surface composition and chemical bonding of elements on the Ti-W thin films after deposition and exposed to air were analyzed by X-ray photoelectron spectroscopy (XPS). The results show the structure evolves from amorphous film to dual phase (bcc W and bcc Ti) followed by uniform β-phase solid solution with increasing sputtering power. The sputtering power and bias voltage also have great effect on the resistivity of the W–Ti thin films.

Estimation of firing temperature and ancient geomagnetic field intensity of archaeological potteries recently excavated from Tamilnadu, India

In the present study, fragmented pottery samples were collected from the recently excavated archaeological site named Salamankuppam near the famous Mahabalipuram in Chennai, Tamilnadu, India. An attempt was made to subject the samples to scanning electron microscope with energy dispersive spectrometer (SEM/EDS) and chemical analysis. Also porosimetry study was done. The result from the analysis provided the chemical composition of the potteries, the firing atmosphere and firing temperature achieved by the artisans at the time of manufacture. The results obtained from different analytical techniques provided information of the firing temperature of the pottery which lies in the range of 800 °C–950 °C in the oxidizing and reducing atmosphere. Mineral magnetic studies also were performed and proved that all samples were highly magnetically enhanced materials and paleointensity measurements by Thellier method yielded the field intensity value of 42.15 ± 2.0 μT. The age of the sample was around 150 BC.

Characterization of individual airborne particles in Taiyuan City, China

Taiyuan, the capital of Shanxi province, China, is one of the most polluted cities in the world. To characterize the ambient particulate pollution, samples of particulates with aerodynamic diameter less than 10 µm (PM10) were collected during a 6-day campaign. Individual particles were analyzed by Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM-EDS) to determine their chemical composition. Meanwhile, photomicrographs were obtained from SEM to aid in particles’ source identification. The lumped data from SEM-EDS were subjected to hierarchical cluster analysis (HCA) to sort out particle types chemically. HCA combined with SEM photomicrographs allowed us to identify 20 different particle types, namely (in order of particle frequency), soil/fly ash particles, coal-burning, sulfur-rich, and iron-rich particles, gypsum, syngenite, quartz, cement, silicon sulfide, siliconferro alloy, calcium-rich particles, ferrochromium alloy, ammonium sulfate and chloride, iron-zinc, ammonium chloride, molybdenum-rich, potassium sulfate, dolomite, lead sulfate, and copper-rich particles. Their possible origins and pathways are suggested. The majority of the particles seem to originate from coal combustion, which conforms to Taiyuan’s industrial structure.

Micromorphological properties of salt affected soils in Northeast Thailand

A micromorphological study was carried out on salt affected soils from three locations on erosional terraces overlain by wash and alluvium under tropical savanna climate in Northeast Thailand where salinity problem has been acute. This aimed at providing detailed data for a better agricultural land use planning of the area. Five or six profiles at each location were sampled along a linear traverse that included the soils with highest and lowest levels of salt accumulation. Sixteen soil profiles were described, sampled and analyzed using physio-chemical, optical microscope and scanning electron microscope with energy dispersive spectrometer (SEM/EDS) techniques. The highest salt affected profiles show salt crusts, bare surfaces and halophytic plants and these soils have been left idle. All soils are deep, poorly drained, moderately to highly developed and with various salinity levels. They are fourteen Natraqualfs and two Endoaqualfs. Soil textures are sandy for location 1, clayey for location 2 and with a sandy topsoil and clayey subsoil for location 3. The soils at locations 1 and 2 mostly have high values of electrical conductivity (EC) and exchangeable sodium percentage (ESP). Soils at location 3 may have been affected by desalinization and alkalization as is indicated by low EC, high basic cations and high pH. Field morphology, optical micromorphology and SEM/EDS analysis results show clear accumulation of salt in some profiles. Their microstructures are different due to the difference in their texture. Compact grain and bridge grain structures are common in sandy-textured soil whereas channel and subangular blocky structures are common in the clayey soils. Quartz and runi-quartz grains are common as skeleton materials, but are present in different sizes and amounts. Halite occurs in voids in soils at locations 1 and 2 and is abundant in Pedons 1 and 6 where salt crusts exist. Calcite is present only in one profile (Pedon 1). Amorphous pedofeatures are manganiferrous impregnative nodules and iron and manganese oxide impregnated s-matrix. The EDS spectra indicate the presence of barite (BaSO 4) and sylvite (KCl) crystals in voids in some of the soils. The element composition of the soil matrix in a triangle graph of SiO 2: Al 2O 3: Fe 2O 3 is displaced from the ‘kaolin line’ towards the SiO 2 apex, indicating that very fine-grained quartz and/or a Si-rich clay mineral (s) is present in the matrix. The presence of Si-rich clay minerals is supported by XRD results that identified smectite in addition to kaolin and may be an evidence of the resilication process that can occur in salt affected soils. The data points near the Fe 2O 3 apex of the triangle graphs represent iron oxide nodules and their position on the matrix Al 2O 3/SiO 2 line indicates that induration of the matrix with iron oxide has occurred and that the nodules have formed in situ. The normalized element composition of the matrix in triangle graph between SiO 2: Al 2O 3: Na 2O + CaO + MgO indicates that in some instances the salts of Na, Ca and Mg have indurated the soil matrix as data points for salt-rich matrix fall on the clay matrix composition line.

The electrochemical behaviour of bronze in synthetic seawater

This paper reports a voltammetric study of bronze in synthetic seawater (SSW). The effects of buffering and deoxygenating were particularly visible in the transpassive region. The breakdown of the anodic passive film on bronze leads to a well-defined activation peak in the transpassive region typical of a nucleation and growth of pits. The breakdown potential of the passivity was shown to vary with the experimental conditions, namely, with buffering and deoxygenating. Buffering has shown to lead to more stable passive films and deoxygenating to higher oxidation currents. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) studies of bronze samples with 1-month exposure in non-deoxygenated buffered and non-buffered SSW under open circuit potential have shown significant differences in their morphology: a uniformly cracked surface and a surface showing large and spherical precipitates of about 50 μm uniformly distributed along the surface, respectively, for bronze coupons in buffered (pH 9) and in non-buffered SSW. The EDS technique has identified Cu, O, Cl and Na on the corrosion products of bronze in non-buffered SSW, whilst in buffered media, Sn was also identified. In non-buffered media, open circuit potentials have shown to be all the time less negative than in the buffered media. After 1-month exposure the E OCP of bronze samples in both media seem to converge to −0.131 and −0.155 V vs Ag|AgCl, respectively. This potential can be assigned to the formation of cuprite, Cu2O and nantokite, CuCl. The analysis of the SEM images after the removal of the corrosion products has shown descuprification with higher intensity on the surface from coupons in non-buffered SSW.

The influence of alloying elements on the corrosion behaviour of ferritic steels in simulated combustion atmospheres

AbstractThe low‐chromium steels (Cr content 0.7–1.4 wt.%) are usually being used in low temperature boiler applications where the environments are not so aggressive as in waste‐fire boilers. To improve their mechanical properties and corrosion resistance several alloying elements have been used. In the present study the new low‐chromium steels modified with Si, Ni and Ce have been investigated. These steels were compared with the common boiler steel – 2.25Cr1M.The multi‐sample exposure tests were made in moist air (8% O2 + 15% H2O) with and without 200 ppm SO2 or 2000 ppm HCl addition at the isothermal temperature of 500°C. Corrosion products were analysed by Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM/EDS) and XRD techniques. The results of the study show that addition of Ni and Si to the steels studied could improve their corrosion resistance, but only in moist air atmospheres. In SO2‐containing atmospheres the corrosion resistance seems to remain the same, when in HCl‐containing atmospheres Ni and Si additions seem to have a negative effect on the corrosion behaviour. As could by seen from SEM analysis, the scales formed, on the steels with above elements, are more adherent to the metallic core.The cerium was added to the studied materials mainly to improve their mechanical properties. This alloying element seems to increase the corrosion rate of materials, especially in atmospheres containing Cl.