High Vanadium Content Research Articles

Vanadyl acetylacetonate anchored onto amine-functionalised clays and catalytic activity in the epoxidation of geraniol

The parent clays laponite (Lap) and K10-montmorillonite (K10) and those functionalised with (3-aminopropyl)triethoxysilane (APTES) were used as supports to immobilise vanadyl(IV) acetylacetonate ([VO(acac) 2]). All the materials were characterised by elemental analysis, XRD, TG-DSC, nitrogen adsorption isotherms at −196 °C and IR spectroscopy. The K10-based materials were also characterised by XPS. In the case of K10-based materials, higher vanadium content was obtained for the APTES-functionalised K10, showing that the clay functionalisation enhanced the complex anchorage. In Lap-based materials the opposite tendency was observed, with a higher vanadium loading being obtained for direct complex immobilisation onto the parent clay. This is probably due to clay particles aggregation (resultant from the delaminated nature of Lap) provoked by functionalisation with APTES. Furthermore, FTIR data pointed out that in the amine-functionalised clays, the VO(IV) complex was anchored by Schiff condensation between the carbonyl groups of the acetylacetonate ligand and the amine groups from the grafted APTES, whereas the direct immobilisation of the complex onto the parents clays took place mostly through covalent bonding between the metal centre and the clay surface hydroxyl groups. The [VO(acac) 2]-based materials were tested in the epoxidation of geraniol using t-BuOOH as oxygen source and reused several times repeatedly. The [VO(acac) 2]APTES@K10 material was the most efficient and stable catalyst upon reuse (5 cycles), among the four materials tested, with a substrate conversion and 2,3-epoxygeraniol regioselectivity comparable to the homogeneous phase reaction; the organofunctionalisation of K10 was also quite advantageous in the catalytic reaction since it passivated some active sites of the K10 support. In the case of Lap-based materials, the [VO(acac) 2]@Lap was more catalytically efficient than [VO(acac) 2]APTES@Lap.

A Study of the Processes Related to Coagulation of Asphaltenes by Electronic Spin Resonance

Abstract Coagulation of asphaltenes in crude oil has been studied by electronic spin resonance (ESR). Free radicals in asphaltenes with the content of vanadium less than 0.1 mass% are found to recombine when asphaltenes precipitate. Polyaromatic fragments are shown to be localized in the inner part of the asphaltene molecules. A possibility of the formation of diamagnetic compounds between vanadyl (VO2+) complexes and free radicals of asphaltenes is investigated. Introduction The study of asphaltenes from crude oil is a matter of special interest and research in oil chemistry. The constantly increasing share of heavy crude oil and bitumen in total oil production has lead to the increasing importance of studies in this area. High concentrations of asphaltenes, resins, vanadium and sulphur are characteristic for most of the heavy crude oil and bitumen deposits. That makes oil production and refining more complicated. Petroleum asphaltenes are the highest molecular species among components of petroleum and asphaltenes only —the basic carriers of oil paramagnetysm. Basically, paramagnetic components in oils are free stable radicals and vanadyl (VO2+) complexes. The behaviour of asphaltenes under reservoir conditions, and in the preparation and transportation of crude oil, is strongly related to the interactions between paramagnetic fragments in the structure of asphaltene aggregates. There is a hypothesis that asphaltene molecules, especially the large ones, are not necessarily two-dimensional flat disks but they have the capacity, owing to the presence of long polymethylene bridges, to fold upon themselves into a complex three-dimensional globular conformer with an internal structure(1). In other works, however, it has been shown it is possible for the molecules containing alkyl fragments up to C24 (paraffins, ceresines, etc.) to co-precipitate together with asphaltenes(2,3). Hypothetical structures of the asphaltene molecules have been presented(4,5). They have a different type: polyaromatic fragments are in the centre of the molecules whereas naphtene-aliphatic groups are located on the periphery. By way of explanation of the characteristics of crude oil and bitumen, the most significant model was proposed by Juan Murgich(6) to describe asphaltenes from different crude oils. According to the model, all asphaltenes are two types: A-type and S-type. A-type asphaltenes have 15 to 20 condensed aromatic rings (in the centre), alkyl substitutes and heteroatoms on the periphery. Asphaltenes of this type are flat. S-type asphaltenes have several aromatic parts (2 to 5 rings) which are connected with each other by alkyl and sulphide bridges. The molecules are almost spherical. The aromatic parts are located on the outer surface of the asphaltene molecules. In the work by Galtsev et al.(7), a conclusion is made about the low mobility of the vanadyl complexes/ asphaltene system. This conclusion is based on the reverse correlation between the relaxation characteristics of electrons in crude oil. On the basis of the time of spin-spin relaxation, the concentration of an agent responsible for widening of the signal associated with free radicals, i.e., vanadyl complexes, is calculated. The concentration of vanadyl complexes derived from the integral intensity of the signal in a spectrum is lower than that derived based on the time of spin-spin relaxation.

Physico-chemical study of impregnated Cu and V species on CeO2 support by thermal analysis, XRD, EPR, 51V-MAS-NMR and XPS

CuVCe oxides were prepared by impregnation of copper and/or vanadium precursors on ceria support. The solids freshly prepared were calcined under air between 400 and 700 °C. Physico-chemical properties of these oxides were then studied using different techniques: Thermal Analysis (DSC/TG), X Ray Diffraction (XRD), Electron Paramagnetic Resonance (EPR), 51V Magic Angle Spinning Nuclear Magnetic Resonance (51V-MAS-NMR) and X-Ray Photoelectron Spectroscopy (XPS). X-ray diffraction and thermal analysis revealed cerium orthovanadate phase formation during the calcination of the 1Cu1V10Ce solid. This CeVO4 phase is not observed for the 10Cu1V10Ce sample. The EPR study revealed two well-resolved copper signals: the first corresponds to isolated Cu2+ species and the second to Cu2+ dimers. The 51V-MAS-NMR confirmed the presence of CeVO4 phase for 1Cu1V10Ce sample and revealed polymeric V–O–V chains in interaction with a copper ceria matrix for 10Cu1V10Ce sample. Finally, the XPS study indicated high vanadium content on the solid surface. This phenomenon is enhanced by the copper content in the solid and could explain the absence of the CeVO4 phase in 10Cu1V10Ce sample. Thus the ceria orthovanadate phase formation is inhibited by the presence of a high copper content in the solid.

Mechanism and Kinetics of Plasma Nitriding of the Nb-Alloyed PM Tool Steel

The aim of this work was to describe the mechanism and kinetics of plasma nitriding of a Nb-containing PM (powder metallurgy) tool steel. Material containing 2.5 wt.% C, 3.3% Si, 6.2% Cr, 2.2% Mo, 2.6% V, 2.6% Nb and 1.0% W was prepared by nitrogen melt atomization and hot isostatic pressing. Heat-treated steel (quenching from 1100 °C, triple tempering at 550 °C for 1h) was plasma nitrided at temperatures ranging from 470 °C to 530 °C / 30 - 180 min. Light microscopy, TEM, SEM and WDS were used to study the nitrided steel. It has been shown, that nitriding at 470°C leads to the formation of thin layers composed only of a diffusion zone containing nitrogen-rich martensite and fine nitride precipitates, no layer of nitrides is formed on the surface. Nitriding is probably controlled by the nitrogen diffusion in martensite to the material or by the processes in the nitriding atmosphere at this temperature. Nitriding at the temperature of 500°C and more leads to the formation of a continuous layer of nitrides and carbonitrides on the surface that limits further nitrogen diffusion. Niobium, as a prospective element in tool steels, was not found to play a role in the formation of the nitrided layer directly. Niobium replaces vanadium in very thermodynamically stable primary MC carbides. This results in higher vanadium content in others less stable carbides and in the matrix. Due to this effect, higher portion of vanadium can precipitate as VC carbides and VN nitrides during heat treatment and nitriding, respectively.

Vanadium–Al 2O 3 nanostructured thin films prepared by pulsed laser deposition: Optical switching

The formation and optical response of VO x nanoparticles embedded in amorphous aluminium oxide (Al 2O 3) thin films by pulsed laser deposition is studied. The thin films have been grown by alternate laser ablation of V and Al 2O 3 targets, which has resulted in a multilayer structure with embedded nanoparticles. The V content has been varied by changing the number of pulses on the V target. It is found that VO x nanoparticles with dimensions around 5 nm have been formed. The structural analysis shows that the vanadium nanoparticles are oxidized, although probably there is not a unique oxide phase for each sample. The films show a different optical response depending on their vanadium content. Optical switching as a function of temperature has been observed for the two films with the highest vanadium content, at transition temperatures of about −20 °C and 315 °C thus suggesting the presence of nanoparticles with compositions V 4O 7 and V 2O 5, respectively.

Optimisation of chemical composition of high speed steel with high vanadium content for abrasive wear using an artificial neural network

The wear weight loss were measured by pin-disk abrasive wear machine after high speed steels with V = 5–10% and C = 1.66–3.3% were quenched at 1050 °C, and tempered at 550 °C. By the use of back propagation (BP) network, the non-linear relationship between the wear weight losses ( W) and carbon contents, vanadium contents ( C, V) has been established on the base of dealing with the experimental data. The results show that the well-trained BP neural network can predict the wear weight loss precisely according to carbon contents and vanadium contents. The prediction results show the optimal V and C contents for abrasive wear are 9–10% and 3–3.4%, respectively. And the prediction values have sufficiently mined the basic domain knowledge of relationship between abrasive wear property and chemical composition of alloys. Therefore, a new way of optimising chemical composition for wear of materials has been provided by the authors.

Characteristics of vanadium-substituted mesoporous silica with wormhole framework structure: effects of vanadium content

Vanadium-substituted wormhole framework structure (V-WMS) mesoporous silicas (V-WMS) with various Si/V ratios in the range of 15 and 200 were prepared at ambient temperature by neutral surfactant templating pathway. The materials were synthesized by using dodecylamine as a template and tetraethylorthosilicate as a silicon source. They were characterized by energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), N2 adsorption–desorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared absorption spectroscopy (FT-IR) and ultraviolet-visible absorption spectroscopy. V-WMS samples shown characters of larger framework wall thickness, small crystallite domain sizes, and complementary textural mesoporosities in comparison with M41S materials. These mesoporous V-WMS samples exhibited irregularly shaped mesoscale fundamental particles which aggregated into larger particles. They also demonstrated better thermal stability than MCM-41. An absorption band of FT-IR at ca. 960 cm−1 was assigned to the vibration of Si–O–V linkages. These samples also showed one strong UV–visible absorbance with overlapping maxima at about 255 nm. The results show that vanadium was incorporated into the structure of wormhole mesoporous silica (WMS). However, for V-WMS with high vanadium content (Si/V < 25), a broad shoulder in XRD pattern was observed at about 3–4°, suggesting the presence of impurity phase of vanadium species in the sample. The efforts in preparing V-WMS specimens by neutral-template synthesis route had led to new mesoporous silica molecular sieves with catalytically active vanadium centers.

Polyfunctionality of DeNO x catalysts in other pollutant abatement

The total oxidation of o-dichlorobenzene over differently loaded V 2O 5/TiO 2-based catalytic materials was studied. A series of vanadium-supported catalysts have been prepared, by incipient wetness impregnation, on different commercial supports (bare TiO 2, TiO 2/WO 3 and TiO 2/WO 3/SiO 2). The prepared materials were characterized by XRD, H 2-TPR, Raman spectroscopy and surface area measurements. All the catalysts exhibited high oxidation activity and the content of vanadium in the system was demonstrated to be important in controlling the catalyst activity and selectivity. Isolated and well-dispersed vanadium sites resulted beneficial for o-DCB conversion. Thus, in spite of the lower ability of SiO 2 to spread metal oxides the higher resistance to sintering of silica-containing materials also at high vanadium content, favors VO x dispersion and leads to superior catalytic performance. Nevertheless, the presence of tungsten on the support and of high amount of vanadium also lead to the formation of partial oxidation products. In particular, dichloromaleic anhydride was formed and its production seems to be connected to the distribution of acidic sites.

06/02094 Production of hydrogen by thermal decomposition of methane in a fluidized-bed reactor - effects of catalyst, temperature, and residence time: Dunker, A. M. et al. International Journal of Hydrogen Energy, 2006, 31,(4),473–484.

High temperature gasification has been considered as one of the most promising routes for the clean and efficient utilization of high-sulfur petroleum coke (petcoke). However, petcoke usually contains high content of vanadium (V). It has been proven that V element in petcoke can lead to fouling or corrosion problems in the process of combustion, which captures the attention to the fate of V during petcoke gasification. In this paper, thermodynamic equilibrium calculations based on the FactSage were used to investigate the reaction mechanism of V with the main associated mineral elements (Si, Ca, Al, Fe, Ni and Na) during petcoke gasification. The influence of gasification temperature and atmospheres on the V species equilibrium composition was also evaluated. The results indicate that V reacts with the mineral elements of Ca, Fe and Na to form V-containing species (CaO)3V2O5(s), FeV2O4(s), (Na2O)3V2O5(s) and (Na2O)2V2O5(l), respectively. The presence of H2S(g) suppresses the reactions of V with Ca and Fe due to the formation of sulfides (CaS and FeS). In addition, it is verified that V does not participate in the reactions with Si, Al and Ni. However, the associated mineral elements may have remarkable co-effects on V species equilibrium composition. Ca reacts with Si or Al easily to form the Ca-containing minerals (CaSiO3(s), Ca3Si2O7(s), Ca2SiO4(s), CaAl4O7(s), CaAl2O4(s)), impeding the formation of (CaO)3V2O5(s). Na combines with Al to generate Na-containing minerals (NaAlO2(s), Na2Al12O19(s)), inhibiting the formation of (Na2O)3V2O5(s) and (Na2O)2V2O5(l). When all of the main associated mineral elements are present, the V-containing species formed in the whole process of gasification are V2O3(s), FeV2O4(s) and a small amount of VO2(g).

Pentavalent vanadium induces hepatic metallothionein through interleukin-6-dependent and -independent mechanisms

Metallothionein (MT) is a low-molecular-weight cysteine-rich protein which has a high affinity for metals. The synthesis of MT is induced by heavy metals such as cadmium and zinc. However, little is known about the induction of MT by tetravalent or pentavalent metals. We investigated the induction of MT synthesis by a pentavalent vanadium compound in mice. Hepatic MT concentrations were increased by subcutaneous injection of ammonium metavanadate (AMV) dose-dependently, and to the similar levels as those induced by zinc chloride. However, accumulation of vanadium in the liver was very low, while high concentrations of vanadium were detected in the kidney. High performance liquid chromatography/inductively coupled argon plasma-mass spectrometry (HPLC/ICP-MS) chromatogram of the liver cytosol of AMV-treated mice revealed that the major metal bound to MT was not vanadium, but zinc. The chromatogram of the liver cytosol of MT null mice demonstrated the existence of a low-molecular-weight vanadium-binding protein that is different from MT. A time-course study showed that concentrations of serum interleukin-6 (IL-6) and serum amyloid A (SAA), an acute-phase protein, increased after the AMV injection. To confirm the involvement of IL-6 in MT induction by AMV administration, IL-6 null and wild-type mice were injected with AMV. In IL-6 null mice, hepatic MT induction by AMV administration decreased significantly to about a half of wild-type mice. These data suggest that both IL-6-dependent and -independent mechanisms are involved in MT induction by vanadium compounds in mice.

Naphthalene oxidation over vanadium-modified Pt catalysts supported on γ-Al2O3

Alumina-supported platinum catalysts modified by vanadium were synthesised and tested for the complete oxidation of naphthalene. The catalysts were characterised by BET, pulsed CO chemisorption, powder X-ray diffraction, laser Raman spectroscopy and temperature-programmed reduction. Whilst BET and CO chemisorption results showed that the addition of vanadium modified both the textural properties of the support and the distribution of Pt, XRD and TPR data suggested the presence of V2O5 on catalysts with higher V loadings. TPR data showed that the concentration of V2O5 and possibly some other vanadium species increased as the V loading increased. Only 0.5%V was found to promote the activity of the 0.5%Pt/γ-Al2O3 catalyst. The activity enhancement has been related to the presence of a more easily reducible vanadium species coupled with the enhanced number of surface Pt sites. On the other hand, the reduced activity demonstrated by catalysts with higher vanadium content (1 – 12%) has been attributed to the presence of crystalline V2O5.

Study on relative wear resistance and wear stability of high-speed steel with high vanadium content

In this work, a new concept of wear stability was put forward by authors, and it was quantitatively expressed by factor of wear stability. Different hardness, impact toughness and retained austenite content high-speed steel with high vanadium content samples were obtained by varying heat treatment conditions. The effects of hardness, impact toughness and retained austenite content on relatively wear resistance and wear stability were studied under abrasive wear condition. Results show that relative wear resistance increases with increasing hardness or decreasing impact toughness, whereas the wear stability rises with the increasing of hardness or impact toughness. The analyzing results reveal that mechanical behaviors are only apparent factors to influence wear behaviors. Relative wear resistance substantially depends on retained austenite content (Ar). At retained austenite content of about 30 vol.%, the relative wear resistance is optimal. However, wear stability is scarcely influenced by retained austenite content, which depends on the maximum changing amount of retained austenite under certain condition (ΔAr) in essence. With increasing ΔAr, wear stability linearly decreases.

Selective oxidative activation of isobutane on a novel vanadium-substituted bimodal mesoporous oxide V-UVM-7

New vanado-silicates with a bimodal mesoporous system (V-UVM-7) and high vanadium contents (Si/V ≥ 7) have been prepared by a modification of the so-called atrane method. Its morphology consists of aggregation of nano-particles with V-MCM-41 structure, creating a second broader porous system in their interparticle space. Its structure allows to incorporate a high V contents into tetrahedral sites of the framework while keeping vanadium dispersion. V-UVM-7 catalysts are very active and selective for the direct transformation of isobutane to isobutene and methacrolein. Total conversion and methacrolein-to-isobutene ratio in the products increased with increasing vanadium contents. The catalytic performance comparison with homologous V-MCM-41 catalysts revealed an influence of the channel length on the products distribution.

Doping effect on the optical, electro-optic, and photoconductive properties of Bi12MO20 (M = Ge, Si, Ti)

The doping effect on the optical, electro-optic, and photoconductive properties of Czochralski-grown Bi12MO20 (M = Ge, Si, Ti) sillenite-structure single crystals was studied. The dopants were introduced into the growth charge in the form of oxides. Bi12TiO20 crystals were doped with V, Zn, Cu, P, and Nb; and Bi12SiO20 crystals were doped with Cd and Mo. The results indicate that the doping level has a significant effect on the photoconductivity of the Bi12TiO20〈Zn〉, Bi12TiO20〈Cu〉, Bi12SiO20〈Cd〉, and Bi12SiO20〈Bi24CdMoO40〉 crystals, which may exceed that of undoped crystals at low doping levels and may be substantially lower than it, down to zero, at increased dopant concentrations. Niobium doping of bismuth titanate has no effect on its photosensitivity and electro-optic properties. Phosphorus and vanadium enhance the photosensitivity of bismuth titanate over the entire composition range studied but have little effect on its electro-optic coefficient r41. A slight increase in r41 was only observed at high vanadium concentrations. The axial impurity distribution in the crystals is shown to be nonuniform, which reflects in their photoresponse: the photoconductivity of the copper-doped crystals near the seed end is 3 times that near the tail end.

Effect of silica on the catalytic destruction of chlorinated organics over V2O5/TiO2 catalysts

In the present work, the contribution of silica doping to the catalytic activity of V2O5/TiO2 based catalysts in the decomposition of chlorinated organic materials and on the formation of possible by by-products was investigated. The influence of vanadium loading on surface structures of differently supported materials has been systematically investigated by XRD, BET, Raman spectroscopy and H2-TPR. These studies demonstrated that the V2O5 supported on either TiO2/WO3 or TiO2/WO3/SiO2 is very active for the oxidation of o-DCB, a probe molecule for aromatic compounds which is present in flue gas. Silica was found to form a highly dispersed amorphous phase on the support surface, which strongly affects the structural degradation phenomena, delaying the collapse of surface area, that is particularly significant at high vanadium content. The presence of silica on the support influences the distribution of VOx species. Since it was demonstrated that support surfaces predominantly covered with highly dispersed vanadium lead to high activity, in spite of the lower ability of SiO2 to spread metal oxides, the higher stability of silica containing materials, while preserving surface area, favors vanadium dispersion and leads to superior catalytic performance.

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

This paper describes a new route for the preparation of V2O5–SiO2 mixed oxides with high vanadium content and high surface area by the sol–gel processing method. Dry samples were characterized by powder X-ray diffraction, electron paramagnetic resonance, Fourier-transform infrared, and energy dispersive X-ray spectrometry. Our results show that the incorporation of vanadium pentoxide into the silica matrix was obtained by intimate mixing of the two different inorganic polymers (Si–O and V–O based polymers), and the overall structure is held together by a Si–O–Si network interpenetrated with V–O–V polymeric chains. The catalytic activity of the V2O5–SiO2 mixed oxides was evaluated in the oxidation of the cyclooctene and styrene in liquid phase.

The public health implications of farming cattle in areas with high background concentrations of vanadium

Forty-two adult Brahman-cross cattle farmed extensively in two groups, immediately adjacent to and 2 km from a vanadium processing plant respectively, were slaughtered over a 5 year period at a nearby abattoir. Cattle were being exposed to vanadium at close to no-adverse-effect levels. The dose of vanadium that cattle were taking in prior to slaughter was calculated for each animal from environmental and physiological data using a stochastic risk assessment model. The median exposure doses in the month prior to slaughter ranged from 0.55 to 2.73 mg vanadium/kg body weight/day. A range of tissues was taken from the cattle at slaughter for vanadium determination and tissue levels of vanadium in muscle, liver and kidney are reported. The concentrations of vanadium in the milk of cattle from the same farm sampled over 5 years are also reported. Concentrations were further modelled using a lognormal distribution function to look at possible extreme values that are likely to occur. The concentrations of vanadium in commonly consumed tissues ranged from <0.05 to 11.51 mg/kg (wet-mass basis). The median concentration of vanadium in milk was 0.23 mg vanadium/kg. People drinking milk were at highest risk. The potential oral daily intake of vanadium for people consuming these foodstuffs was modelled using a stochastic model. The model predicted that there is less than a 5% chance that the potential daily intake of vanadium from milk will be >0.44 μg/kg/day for adults. Based on this upper limit it was concluded from current knowledge of toxicity in humans that the tissue and milk residues from cattle should pose no health risk to the consumer.

Research on wear resistance of high speed steel with high vanadium content

Different microstructures and mechanical behaviors were obtained after vanadium and carbon contents of high speed steel were changed, and the abrasive wear property of which were studied. Results show that the wear resistance of high speed steel generally depends on the hardness and microstructures. At hardness of lower than HRC58, the wear resistance of the alloys mainly depends on its hardness. At hardness of higher than HRC58, the wear resistance of the alloys mainly depends on the amount, morphology and distribution of VC in the matrix. When vanadium and carbon content is up to 8.15–10.20% and 2.70–3.15%, respectively, the large amount of and uniformly distributed spherical or lumpy VC carbides can be obtained, which can resist the micro-cutting of Al 2O 3 abrasive, and minimizes width and depth of the furrow. This leads to the excellent wear resistance of high speed steel with high vanadium content.

Improvement of cyclic durability of BCC structured Ti–Cr–V alloys

Durabilities of Ti–Cr–V alloys were investigated using the cyclic hydrogen absorption–desorption test. The XRD pattern obtained for Ti 24Cr 36V 40 alloy after 100 cycles suggested the production of a highly distorted secondary phase. A temperature swing cyclic test was conducted and it became clear that the degradation of hydrogen transfer was caused by the decrease of total hydrogen content in the alloy. Vanadium content is an important factor in improving durability. High vanadium content prevents rapid degradation in the initial cycles. Floating zone melting is effective also for improving durability and the effect is remarkable for alloys with high vanadium content. Highly homogenized Ti 8Cr 12V 80 alloy made by floating zone melting shows only 1.4% degradation from the initial hydrogen capacity after 500 cycles. As a behavior different from other Ti–Cr–V alloys, the floating zone melted Ti 8Cr 12V 80 alloy shows an increase of the hydrogen absorption plateau pressure with the progression of cycles.

Corrosion behavior of Fe-Si metallic coatings added with NiCrAlY in an environment of fuel oil ashes at 700°C

Electrochemical potentiodynamic polarization curves and immersion tests for 300 h at 700°C in a furnace have been used to evaluate the corrosion resistance of Fe-Si metallic coatings added with up to 50 wt.% of NiCrAIY. The corrosive environment was fuel oil ashes from a steam generator. The composition of fuel oil ashes includes high content of vanadium, sodium and sulfur. The results obtained show that only the addition of 20 wt.% NiCrAlY to the Fe-Si coating improves its corrosion resistance. The behavior of all tested coatings is explained by the results obtained from the analysis of every coating using electron microscopy and energy dispersive X-ray analysis.