Absolute Porosity Research Articles

Geochemical modelling of formation damage risk during CO2 injection in saline aquifers

This study provides an understanding of the impact of geochemical reactions during and after CO2 injection into a potential storage site. The results of calculations of geochemical reactivity of reservoir rock and of cap rock during and after CO2 injection were performed using a geochemical simulator, with the calculations showing that for these conditions up to 0.5 mol of CO2 can be dissolved per kg of water. The risk of dissolution of primary cements was considered and identified. In addition, the potential of carbonation reactions to permanently sequester CO2 was considered, although these reactions were shown to be very slow relative to other processes. The implications for security of storage are that while dolomite nodules exist in the sandstone formation, these do not contribute significantly to the overall rock strength, and hence the risk of dissolution of the formation or caprock causing significant leakages pathways is very low. Further calculations were performed using a commercial reservoir simulation code to account for brine evaporation, halite precipitation and capillary pressure re-imbibition. The impact on injectivity was found not to be significant during continuous and sustained injection of CO2 at a constant rate. Capillary pressure effects did cause re-imbibition of saline brine, and hence greater deposition, reducing the absolute porosity by up to 13%. The impact of the halite deposition was to channel the CO2, but for the configuration used there was not a significant change in injection pressure.

Geophysical assessment of potential hydrological units in hydrologically challenged geomaterials of Makurdi, Benue State, Nigeria

A geo-electric survey employing the Vertical Electrical Sounding (VES) was carried out in order to access the distributions of electrical and hydraulic parameters of hydro-geologic units in some locations of Makurdi where groundwater resources are difficult to tap. A total of fifteen geo-electric soundings were acquired. The contour maps were generated using the results. From the bulk aquifer resistivity and water resistivity values, the formation factor was calculated and it ranges from 4.12 to 10.07. The porosity with a range of 24.58 to 39.36% and hydraulic conductivity with a range of 0.85 to 45.1 m/day were estimated. The porosity values confirm that hydro-geologic units in the study area consist mainly of sandstone. The high resistivity in the northern part of the study area is due to high water quality while the southern part has lower resistivity due to the presence of argillaceous materials. It is also observed that the areas with low resistivity have high porosity. The observed low resistivity zone with high porosity is believed to have poor interconnected pores, the condition for high total or absolute porosity in argillaceous materials. The analyses of the geophysical data constrained by geological and borehole information revealed that potable water can be extracted within the depth of 35 to 50 m in the study area. Key words: Porosity, formation factor, hydraulic conductivity, aquifer resistivity, Makurdi, geo-electric survey.

Diagenesis and reservoir quality evolution of the Eocene sandstones in the northern Dongying Sag, Bohai Bay Basin, East China

The Eocene sandstones in the northern Dongying Sag, Bohai Bay Basin, China, are reservoirs for large accumulations of hydrocarbons. The sandstones are mainly lithic arkoses and feldspathic litharenites, texturally and compositionally immature. These sandstones have a wide range of porosity (0.4–37%) and permeability (0.004–6969 mD) and show an overall decrease in reservoir quality from 1500 m to 5000 m below sea level. The reduction in reservoir quality is a product of several digenetic processes; these include compaction, precipitation of dolomite and calcite in eodiagenetic stage; compaction, feldspar dissolution, precipitation of quartz cements and clays (kaolin and illite) and precipitation of ferrocalcite and ankerite in mesodiagenetic stage.Mineral distribution pattern and isotopic composition suggest carbonate cements in sandstones originate from sources outside the sandstones. Carbonate cementation, together with compaction reduced the sandstones’ porosity and permeability significantly. In a sandstone bed, marginal sandstones with distance to sandstone/mudstone interface less than one meter always have lower porosity than central sandstones. As burial depth exceeds 4000 m, marginal sandstones have very low porosities (<5%), indicating that thin sandstone beds (<2 m) were totally destroyed by cementation and compaction, and only thick sandstone beds (>2 m) can be potential effective reservoirs.Feldspar dissolution and precipitation of clays and quartz cements have little impact on absolute porosity. Mineral distribution pattern and quantitative data show that leached feldspars are the internal source of authigenic quartz and clays in sandstones, and the volume difference between feldspar secondary porosity and related authigenic cements is generally less than 0.25%. However, although there is little or no net import of matter to the sandstones, the pore architecture changes dramatically. Primary macropores are lost as clays and quartz precipitate while the proportion of microporosity increases, occurring mainly between clay crystals. The overall result is that permeability is significantly degraded.

Characterisation of lactose powder and granules for multivariate wet granulation modelling

Granulation and size enlargement of particulate materials is a complex process with broad application in industry. For better understanding of the governing mechanisms, we aim to develop a multivariate population balance model to describe granulation. For meaningful model design we require physical characteristics of real materials undergoing granulation. In this work, α-lactose monohydrate powder was investigated as a representative substance due to its broad use in the pharmaceutical industry for tablets. Powder and granules resulting from a high-shear granulation process are characterized with respect to size, shape, porosity and strength using various analytical methods. Particle size distributions are obtained by static image analysis, laser scattering and sieving. Granule porosities are determined using μCT and mercury intrusion porosimetry. Lactose granules show absolute porosities increasing from 30% to 40% along the size classes. The μCT derived visual information of larger granules shows internal pore structures with denser cores and porous shell parts. AFM, SEM and μCT are used for surface characterisation, yielding a maximum value for model particle roughness up to 0.7μm. The strength of the product granules measured via uniaxial compression testing follows a logarithmic decrease with size from 1.2 to 0.2MPa. The multivariate data set was then used for model performance analysis and parameter fitting. The size and porosity prediction performance of the computer model could be improved using the newly available data. The rate of coagulation was found to be the most dominant simulation parameter. Comparison with the experiment revealed limitations, for example in PSD shape predictions.

Statistical Analysis of the Added Value by Intelligent Well Application under Reservoir Uncertainty

Downhole control valves and sensors enable intelligent wells to monitor and control production in real time resulting in added value of the project and flexibility in petroleum production. However, noteworthy challenges remain in the development of optimized control strategies for intelligent wells, especially regarding the incorporation of the reservoir uncertainty. The aim of this work is to examine the influence of optimized intelligent strategies on the probability distribution functions of cumulative oil, water, and gas production and well net present value under reservoir uncertainty. The conceptual reservoir model used in this study contains a heterogeneous high permeable longitudinal channel with uncertainty in absolute permeability and porosity distribution, and there is also uncertainty in the available fault transmissibility. Having implemented intelligent well control strategies, an evident improvement in well net present value has been acquired especially for a reactive control. The optimized reactive strategy of control valves is able to react properly under reservoir uncertainty. Moreover, the reactive strategy does not need to be optimized and customized to each possible reservoir realization; as long as it provides a thorough and practical control strategy for the base case model, it is robust over a range of reservoir uncertainty.

Titanium foam with coarser cell size and wide range of porosity using different types of evaporative space holders through powder metallurgy route

Ti-foams were made using different evaporative types of space holders such as acrowax and ammonium bicarbonate with a wide range of porosities (55–89%) through powder metallurgy technique. Cold compaction pressure was varied from 100 to 200MPa in order to examine the effect of cold compaction pressures on the absolute porosities of the foams. The cell size, cell wall thickness and porosities of the foams were characterised as a function of cold compaction pressures and type of space holders. Empirical correlation has been established to predict foam porosities from compaction pressures and volume fraction of space holder. The sintered foams were found to be free from residue of the space holder. However, approximate 8–10% of titanium oxidized during sintering. The foam made with acrowax, as space holder attains slightly higher strength, modulus and energy absorption.

Towards Reaching the Theoretical Limit of Porosity in Solid State Metal Foams: Intraparticle Expansion as A Primary and Additive Means to Create Porosity

porosity has typically been limited to � 40%. These relatively low porosity levels (compared to liquid state processes) constrain the applications of metal foams produced via solid state foaming. To extend the capabilities of solid state foaming, we have developed an additive means of creating porosity by intraparticle expansion. The current limitation of solid-state expansion by gas entrapment is dictated by voids formed between solid particles during consolidation. In this model, the initial gas pressure and foaming temperature determine the resulting porosity. However, if the expanding gas is not limited to just that which is trapped between particles, but is also located within particles, solid state foaming may assume a character more akin to expandable polymers which foam from the constituent pellets. This concept is a paradigm shift in terms of the solid state foaming process and the achievable levels of porosity. On the basis of this simple, powder feedstock expansion, there is universal application to powder metallurgy methods for foaming. In this work, we examine the microstructure and morphology of a Cu–Sb alloy that expands to porosities of close to 40% within individual particles, resulting in absolute porosity of 69% in sintered samples. The Cu–Sb alloy powder was formed by mechanically alloying Cu and Sb (Alfa Aesar, 99.9 and 99.5%, respectively) at cryogenic temperature(� 196°C) for 4h using a modified SPEX 8000M Mixer/Mill. The elemental powders were combined to achieve 5 at% Sb in Cu. The as-milled powders contained no appreciable porosity. Ball milling was used as a means to intimately mix the elements and refine and distribute preexisting oxides. Although oxygen exposure was controlled during milling and storage of powders, the manufacturersupplied precursors did contain appreciable oxygen content. The importance of this will be detailed later. The alloyed powder was annealed at 600°C for a period of 1h under 3% H2 (bal. Ar). During annealing, the powders underwent pore formation and expansion. When annealing was done in the absence of H2, it did not produce any expansion. Microscopic examination of the loose powders was carried out using an FEI Nova Nano Lab 600 dual beam microscope using scanning electron microscopy (SEM). Cross-sectional analysis was performed using a focused ion beam (FIB). The grain size and grain orientations were measured using focused ion beam

Analytical Derivation of the Temperature Dependence of Absoltue Permeability of a Porous Medium

The ability of a porous medium to transmit its fluid content under an applied pressure gradient is what is called the absolute permeability when it is fully saturated with the flowing fluid. A number of publications have appeared in the petroleum literature that shows experimentally derived data on decreasing absolute permeability with temperature. By starting with the most widely cited empirical relationships between absolute permeability, porosity, irreducible water saturation and specific surface this paper has presented analytical equations first for permeability, porosity and irreducible water saturation and secondly for absolute permeability, porosity and specific surface relationship (Kozeny equation). Results of equations have been compared with published experimental work and have been found to perfectly explain observed experimental trends in absolute permeability dependence on temperature.

Karstification of reef-bank facies carbonate and its control on pore distribution: A case study of Upper Ordovician Lianglitage Formation in eastern Tazhong area, Tarim Basin, NW China

Abstract The karstification type and characteristics and its control on pore distribution in reef-bank carbonate rock in the Upper Ordovician Lianglitage Formation (O 3 l) in eastern Tazhong area were studied using cores, thin sections and well logging data. The area experienced two types of karstification: syndepositional karstification and early diagenetic karstification near surface. During the depositional stage of reef-bank complex, meteoric diagenetic lens with lots of selective dissolution pores were formed by the syndepositional karstification, they were developed in the middle and upper parts of reef-bank sedimentary cycles, and a single porous/cavity layer has a thickness of 10–30 m, increasing the absolute porosity by 3%–4%. After depositional stage, sediments were uplifted and exposed without experiencing burial diagenesis, the depositional topography was influenced by early diagenetic karstification near surface and turned into karst paleotopography and formed four karstification zones within 100 m below the top of the Upper Lianglitage Formation. The surface karstification zone and radial flow karsitifiction zone have favorable porous connectivity, increasing the absolute porosity by 4%-8%. These two types of karsitifiction are continuous in diagenesis stage and the formed porosity is successive in distribution. The favorable space-time coupling is the key reason for effective pores being largely developed in the O 3 l 3 –O 3 l 1 members.

Abstract 178: In-vitro Fluid Dynamic Investigation of a Novel Hyper Elastic-Thin Film Nitinol Stent and the Pipeline Embolization Device for Cerebral Aneurysm Treatment

Introduction: Fusiform and wide-neck intracranial aneurysms (ICAs) can be challenging to treat with conventional endovascular or surgical means. Recently developed low porosity stents, such as the pipeline embolization device (PED), are designed to treat these ICAs by diverting flow away from the aneurysmal sac. However, low porosity stents rely on a dense metal mesh to divert flow, which reduces flexibility and increases the risk of perforator blockage. In this study, we compare fluid dynamic performance between the PED and a novel high porosity stent fabricated from Hyper Elastic-Thin Film Nitinol (HE-TFN). Methods: An idealized model of a sidewall ICA with a collateral branch, located immediately upstream of the aneurysm, was constructed from transparent silicone. A blood analog solution was circulated through the model at steady and pulsatile flow rates spanning a range of physiologic conditions. The PED and two HE-TFN stents, with pore densities of 8 and 21 pores/mm 2 for 500 and 300 υm pore meshes respectively, were deployed into the model. Each stent was placed across the aneurysm and collateral. Volumetric flow velocity data were acquired before and after stent placement using particle image velocimetry. Computational fluid dynamic (CFD) simulations were also conducted. Results: For both steady and pulsatile conditions, the 300 HE-TFN stent led to the largest drops in RMS Velocity Magnitude in the aneurysmal sac and in cross-neck flow. Under pulsatile conditions, the average drops in aneurysmal RMS Velocity Magnitude over the cardiac cycle, for the range of parent-vessel flow rates investigated, were 42.8-73.7% for the PED, 46.4-58.1% for the 500 HE-TFN, and 68.9-82.7% for the 300 HE-TFN. The largest drops were observed at lower parent-vessel flow rates and at peak systole. Examination of collateral flows showed that the PED led to the largest drops in collateral RMS Velocity Magnitude. Under pulsatile conditions, the average drops in collateral RMS Velocity Magnitude over the cardiac cycle were 38.3-46.1% for the PED, 14.0-25.9% for the 500 HE-TFN, and 34.5-40.8% for the 300 HE-TFN. For steady flow, both the aneurysmal and collateral performance metrics followed similar trends. Conclusion: The 300 HE-TFN stent led to larger reductions in cross-neck flow than the PED. This may be due to the higher pore density of the HE-TFN, which may be of greater importance for aneurysm occlusion than absolute porosity. Additionally, the ultra low profile, thin struts of the HE-TFN reduce perforator blockage as demonstrated by increased post-treatment collateral flows as compared to the PED. Overall, the 300 HE-TFN device performed best among the flow diversion devices examined by this study. CFD results characterizing the flow dynamics of each device will also be presented.

Evaluation of free porosity in shale gas reservoirs (Roseneath and Murteree formations case study)

Organically rich shale rocks represent a voluminous, long-term, global source of natural gas and could be referred to as shale gas. Unlike conventional gas reservoirs, shale gas reservoirs have very low effective porosity and permeability. Therefore, an evaluation of porosity in such a tight rock is a challenge. The Roseneath and Murtree shale formations in the Cooper Basin are believed to be potential shale gas reservoirs in SA. Core samples of Murteree and Roseneath carbonaceous shales from the Della–4 and Moomba–46 wells were collected to measure interstitial and intergranular porosity in these prospective shale gas reservoirs in the Nappamerri Trough. After initial preparation, the shale core samples were investigated to determine the pore size classification and effective free porosity using the mercury injection capillary pressure technique (MCIP). The focused ion beam/scanning electron microscopy (FIB/SEM) technique was then employed to obtain micro and nano scale images of the core samples. Then, helium porosimetry was used on the samples to measure their effective porosity. Finally, the pyknometry method was used on the crushed samples to measure their total intergranular porosity. MICP techniques revealed that the samples were mainly comprised of meso-porosity, with the pore throat diameters between 2–50 nanometres and an effective porosity of less than 2%. Helium porosimetry also showed an average porosity of less than 2%. Liquid pyknometry revealed an average absolute porosity of 30.5% for Murteree shale and 39% for the the Roseneath shale, which is much higher than the results from the MCIP technique and helium porosimetry. This is an indication of having very high isolated porosity and very low permeability. The findings were analysed and validated by the use of SEM images, displaying high amounts of isolated porosity, confirming the high porosity measurement from the pyknometry technique. The results achieved strongly emphasised that gas prone, over-mature, carbonaceous shales have very low effective but very high total porosity. Therefore, it is envisaged that total intergranular porosity holding compressed gas in over-mature source rocks cannot be evaluated using the helium porosimetry and mercury injection techniques. The pyknometry technique supported by the SEM images is an alternative method; however, this method can only measure total, rather than effective, porosity.

Influence of absolute basicity and capillary porosity on carbonation of concrete

The single influence of capillary porosity and coupling effects of absolute basicity and capillary porosity on concrete carbonation were investigated. The experimental results showed that carbonation rate of concrete at a given absolute basicity (AB) increased moderately with the increase of the porosity ranging from 6.2% to 9.25%, and increased rapidly with porosity from 9.25% to 12.8%.The coupling effect mainly embodied in disappeared mutation point of capillary porosity, and the distributing regions of carbonation depth were clearly partitioned in the coupling influence of absolute basicity and capillary porosity. A design method on carbonation related durability of concrete based on the coupling effects was proposed.

Petrophysics laws as invariants of filtration model

In this paper the methods of Lie group analysis are used to investigate symmetry properties of differential equations that describe filtration of a two-phase liquid in a porousmedia. Lie algebra of operators of a group of equivalence transformations is calculated. Invariants with respect to a subgroup of the group of equivalence transformations are used for constructing the functional dependencies which define arbitrary parameters of the model. It is shown that one of the invariants of a subalgebra of operators of equivalence transformations is the Timur’s law, describing a relation between absolute permeability, porosity and residual water saturation.

Can carbon surface oxidation shift the pore size distribution curve calculated from Ar,N2 andCO2 adsorption isotherms? Simulation results for a realistic carbon model

Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbonsurface oxidation on the pore size distribution (PSD) curve determined from simulated Ar,N2 andCO2 isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton,and that all pores are accessible for studied molecules (i.e., only the effect of the change ofsurface chemical composition is studied). The results obtained show two important things,i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculatedfrom the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curvescalculated from simulated isotherms are to a greater or lesser extent affected by thepresence of surface oxides. The most reliable results are obtained from Ar adsorption data.Not only is adsorption of this adsorbate practically independent from the presenceof surface oxides, but, more importantly, for this molecule one can apply theslit-like model of pores as the first approach to recover the average pore diameterof a real carbon structure. For nitrogen, the effect of carbon surface chemicalcomposition is observed due to the quadrupole moment of this molecule, and thiseffect shifts the PSD curves compared to Ar. The largest differences are seen forCO2, and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms ofthis molecule contain artificial peaks and the average pore diameter is strongly influencedby the presence of electrostatic adsorbate–adsorbate as well as adsorbate–adsorbentinteractions.

Glutaraldehyde and oxidised dextran as crosslinker reagents for chitosan-based scaffolds for cartilage tissue engineering

Chitosan crosslinked with glutaraldehyde or oxidised dextran was studied as a potential scaffold material in tissue engineering for cartilage regeneration. By mixing two solutions of both components it became a gel, which was frozen. After lyophilization a scaffold was generated with interconnected pores with diameters ranging between 120-350 microm. The mechanical properties (yielding point, elastic and viscous moduli), absolute porosity, pore morphology were determined depending on the ratio of chitosan to crosslinker. ATDC5 (murine cell line) and bovine articular chondrocytes (primary cells) were cultured for 14 days on the scaffolds. Cultivation with ATDC5 cells and bovine chondrocytes showed no negative influence of glutaraldehyde on cell vitality and growth.

Asphaltene Cake Properties

One of the major problems encountered during the exploitation of the oil reservoir is the deposition of asphaltene in the porous rock near the wellbore. The crude oil asphaltene considerably reduces the rock permeability and, consequently, the oil production. The aim of this work is to propose a specific test to identify the relevant parameters controlling the damaging potential of asphaltene deposits. Our approach is to avoid the particle/porous media interactions to allow for the characterization of asphaltene-deposit-specific properties. To this end, a filtration process (carried out under static pressure) has been developed. First, experiments conducted on crude oil indicated that two parameters essentially characterize the asphaltene cake: the specific resistance and the delay of the cake growth depending upon the pressure drop. Overall, asphaltene cake shows intrinsic properties (specific resistances and porosities) similar to those of clay or sludge. The absolute porosity of the asphaltene deposit ...

Porosity determination of ceramic materials by digital image analysis - a critical evaluation

Measuring the porosity of materials by digital image analysis of micrographs is a well-established and convenient method for the testing of metallic samples. However, when applied to ceramic materials, this method has been shown to be much less reliable and poorly reproducible. The purpose of this present work is to clarify the reason for this deficiency, involving many porosity measurements, performed on plasma-sprayed zirconia, under systematically varied microscopic imaging conditions, and the porosities being calculated using various evaluation methods. Comparison between of the results has shown that the present state of the image analysis method is not satisfactory for absolute porosity measurements on ceramic materials. It can be useful as a convenient tool for comparative measurements, however, if the imaging conditions maintained in the microscope and the evaluation method are held to be exactly identical.

Qualitative–Quantitative Analyses of the Influence of Depth and Lithological Composition on Lower Pontian Sandstone Porosity in the Central Part of Bjelovar Sag (Croatia)

Results of several tests (porosity–depth graphic relation, t-test, F-test, Pearson’s R), were used to analyse and interpret the regularity in porosity values of Lower Pontian oil-bearing sandstones from the central part of Bjelovar sag. Data came from 7 cored intervals within 5 wells in the Pepelana member and from 6 cored intervals (in 4 wells) in the Poljana member. The expected porosity decrease with increasing depth was checked against lithological variations. Sandstones are mostly fine-grained lithoarenites. The detritus is composed of quartz, various micas, carbonate fragments and feldspars. Across the study area, the depth range of the sandstones varies from 430 m (top of the Pepelana member near Šandrovac) to 2046 m (base of the Poljana member near Velika Ciglena). Cores included in the analyses vary between 2.75 to 15.5 m in length. Mean porosity and relative depth data were collected for two groups: Group 1 comprised wells Pav–1, Pav–2, Rov–1, Ša–5, Ša–35, and Group 2 included well VC–1. These groups were subdivided for analysis into two (litho)stratigraphic units (Pepelana and Poljana ss.). Porosity variation within each group is explained with reference to the silt or clay fraction. Differences between the porosities of the two groups (~10% lower absolute porosity near Velika Ciglena) is the result of compaction and other processes. Interval of 400 m thickness in particular sandstone member is set as minimum value for observing influence of compaction. Such statement is based on sandstone’s tops and bottoms comparison as well as graphical presentation of relation core porosity–relative depth interval. The analysis was improved by statistical calculation of Pearson’s R, t-test and F-test, which more precisely described the relationship between porosity and depth. Using these statistical tests and regression equitation, the depth difference is calculated as 621 m in the Pepelana and 667 m in the Poljana sandstones, as the limits when the influence of compaction in the porosity–depth relationship could be noticed. Compaction was observed, in the study area, when data from Velika Ciglena are compared to data from the other wells.

A review of NDE methods for porosity measurement in fibre-reinforced polymer composites

Low porosity levels are essential for ensuring the performance of carbon fibre-reinforced composite structures. Despite many attempts to measure absolute porosity levels as a process-control tool, the currently accepted methods often rely on relative measurements in comparison with a reference standard. However, newer low-cost manufacturing methods such as resin-transfer moulding (RTM) and resin film infusion (RFI) would benefit from a reliable absolute 'porosity meter.' This paper reviews the literature documenting NDE methods for porosity measurement in fibre-reinforced polymer composites. The majority of the papers have concentrated on ultrasonic methods to determine porosity levels, mainly for quality control purposes. A few workers have reported on the application of other NDE methods. The review concentrates on methods that have potential for use during composite manufacture. To date, no one NDE method has been able to provide a porosity measurement independent of both the pore morphology and the fibre and resin matrix materials.

Characterization of thermal barrier coatings with a gradient in porosity

A major problem in thermal barrier coatings (TBC) applied to gas turbine components is the spallation of ceramic coating under thermal cycling processes. In order to prevent spallation and improve the thermomechanical behaviour of the TBC, graded ceramic coatings can be produced. For this purpose we are developing a new concept of Thermal Barrier Coating (TBC) that consist of a conventional NiCoCrAlY bond coat and an atmospheric plasma sprayed ZrO 2–8 wt.%Y 2O 3 top coat graded in porosity on an Inconel 738 LC substrates. The aim of this work is to produce coatings with low thermal conductivity and better thermomechanical behaviour due to the gradient in porosity which reflects a gradient in the elastic properties. Absolute porosity was measured with a mercury porosimetry and by image analysis. The second technique was also used to estimate the porosity variation along the cross-section. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) were used to observe the morphology and coating microstructure. The microhardness was measured with a Vickers indenter and 0.981 N load. The microhardness has been evaluated for coatings in as-sprayed condition and after annealing at 1100 °C during 100 h. The results show a fast increase of the hardness after annealing. After thermal shock heating at 1000 °C, 1 h and quickly cooling in water no spallation was observed for 100 cycles.