Mixture Of Na2SO4 Research Articles

Influence of alternating electric current on the process of heat accumulation in a mixture of Na2SO4·10H2O–Na2S2O3·5H2O

One of the most critical tasks of modern energy is accumulating thermal energy due to the inefficient use of thermal energy during the underloading of power systems in which heat-accumulating materials are used. Therefore the paper studies the effect of alternating electric current on the heat-accumulating properties in a mixture based on Na2SO4·10H2O. It is established that the AC effect leads to an increase in the melt crystallization temperature of Na2SO4·10H2O and Na2S2O3·5H2O and also contributes to the return of heat. The selection of the treatment mode of the Na2SO4·10H2O–Na2S2O3·5H2O (50: 1 wt.) mixture by the AC was carried out. It was shown that the latent heat of melting of 329 kJ/kg is achieved at 500000 Hz frequency.

Hot corrosion behaviour of constant and pulsed current welded Hastelloy X in Na2SO4, V2O5, and NaCl salt mixture at 900 °C

The high-temperature corrosion behavior of constant current gas tungsten arc (GTA) and pulsed current gas tungsten arc (PCGTA) welded Hastelloy X with different filler wires (C263 and ERNiCr-3) are studied for 50 cycles at 900 °C. Molten salt I (MS I) (75% Na2SO4 + 25% V2O5) and molten salt II (MS II) (75% Na2SO4 + 20% V2O5 + 5% NaCl) were coated on the welded specimens. MS II coated substrate shows the highest weight gain than MS I with a parabolic constant for GTA ERNiCr-3 as 21.440 × 10–6 mg2/(cm4.s). Whereas PCGTA C263 welded sample with MS I, revealed parabolic constant (lowest) of 0.008 × 10–6 mg2/ (cm4.s). Based on the results, an increasing pattern of hot corrosion resistance of substrates is arranged as GTA ERNiCr-3 < GTA C263 < PCGTA C263 < PCGTA ERNiCr-3. PCGTA shows more refined grains, higher grain boundary volume, better corrosion resistance, and more protective phases like Cr2O3, NiO, NiCr2O4, CoCr2O4, Al2O3, NiFe2O4, NbO than GTA weldment. But phases such as Fe2O3, MoO3, and Cr2S3 (non-protective phases) decrease corrosion resistance due to acid fluxing of alloying elements that promote the oxide scale exfoliation, spallation, chipping, and cracking. This study observed that PCGTA with C263 filler in MS I and MS II environment provides good corrosion resistance at high temperatures.

Hot corrosion product and corrosion layer evolution of La2(Zr0.75Ce0.25)2O7 coating exposed to vanadate-sulfate salts at 1050 °C

In this work, plasma-sprayed La2(Zr0.75Ce0.25)2O7 (LCZ) coatings were submitted to hot corrosion tests at 1050 °C in different molten salts: single V2O5 and V2O5 + Na2SO4 mixtures. Several analyses, including XRD, SEM and EDS were employed to characterize the corrosion product and corrosion layer. The hot corrosion behavior of LCZ coating depended on the molten salt. In single V2O5 molten salt, LCZ coatings were corroded for different durations. It was found that (La, Ce)VO4 and m-ZrO2 were formed on the coating surface, independent on duration. The thickness of the corrosion layer increased with increasing duration and then remained unchanged in single V2O5 molten salt. In the mixed V2O5 + Na2SO4 molten salts, the LCZ coating surface was partially corroded and only (La, Ce)VO4 was formed. The morphologies of (La, Ce)VO4 particles have an important relationship with Na2SO4 content. Moreover, the corroded zone can be divided into three layers based on the microstructure and chemical composition. A model which well described the formation mechanism was proposed. These results demonstrated that single V2O5 was more corrosive to LCZ coating than mixed V2O5 + Na2SO4 molten salts.

Phase-Changing Glauber Salt Solution for Medical Applications in the 28-32 °C Interval.

(1) Background: The field of medicine requires simple cooling materials. However, there is little knowledge documented about phase change materials (PCM) covering the range of 28 to 40 degrees Celsius, as needed for medical use. Induced mild hypothermia, started within 6 h after birth, is an emerging therapy for reducing death and severe disabilities in asphyxiated infants. Currently, this hypothermia is accomplished with equipment that needs a power source and a liquid supply. Neonatal cooling is more frequent in low-resource settings, where ~1 million deaths are caused by birth-asphyxia. (2) Methods: A simple and safe cooling method suitable for medical application is needed for the 28 to 37.5 °C window. (3) Results: Using empirical experiments in which the ingredients in Glauber salt were changed, we studied the effects of temperature on material in the indicated temperature range. The examination, in a controlled manner, of different mixtures of NaCl, Na2SO4 and water resulted in a better understanding of how the different mixtures act and how to compose salt solutions that can satisfy clinical cooling specifications. (4) Conclusions: Our Glauber salt solution is a clinically suited PCM in the temperature interval needed for the cooling of infants suffering from asphyxia.

Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Phosphorus rich sewage sludge ash is a promising source to produce phosphorus recycling fertilizer. However, the low plant availability of phosphorus in these ashes makes a treatment necessary. A thermochemical treatment (800–1000 °C) with alkali additives transforms poorly plant available phosphorus phases to highly plant available calcium alkali phosphates (Ca,Mg)(Na,K)PO4. In this study, we investigate the use of K2SO4 as additive to produce a phosphorus potassium fertilizer in laboratory-scale experiments (crucible). Pure K2SO4 is not suitable as high reaction temperatures are required due to the high melting point of K2SO4. To overcome this barrier, we carried out series of experiments with mixtures of K2SO4 and Na2SO4 resulting in a lower economically feasible reaction temperature (900–1000 °C). In this way, the produced phosphorus potassium fertilizers (8.4 wt.% K, 7.6 wt.% P) was highly plant available for phosphorus indicated by complete extractable phosphorus in neutral ammonium citrate solution. The added potassium is, in contrast to sodium, preferably incorporated into silicates instead of phosphorus phases. Thus, the highly extractable phase (Ca,Mg)(Na,K)PO4 in the thermochemical products contain less potassium than expected. This preferred incorporation is confirmed by a pilot-scale trial (rotary kiln) and thermodynamic calculation.

EFFECT OF HOT CORROSION AND OXIDATION ON COBALT - BASE SUPERALLOYS COATED BY ALUMINUM WITH PRESENCE OF THERMAL BARRIER ZRO2 AND MIXTURE OF (NACL) AND (NA2SO4) STEAMSALTSAT HIGH TEMPERATURES

The aim of the study was to investigate the Mechanisms properties of thermal barrier coatings (TBCs) to enhance of performance evaluation characteristics and develop TBCs.Cobalt –base superalloy has been used as a substrate and zirconium stabilized Aluminum as ceramic topcoat , in addition the study include degradation behavior of system during thermal cycling (3hr per cycle in furnace) the failure of the aluminized was due to thermally grown oxide (TGO) interface. The fractures propagatethrough the interface and produce a deformation of the bond coating . the effect of cycle will result a spallation failure of the TBCsand this is also corresponding to a slightdegradation .The steam of salt (Nacl)and(Na2So4) mixture will affecton the coating lifetimes .The high temperature have a strong effect thermally grown oxide (TGO) which consistent with a first order growth of scale failer variation.

Superheater deposits and corrosion in temperature gradient – Laboratory studies into effects of flue gas composition, initial deposit structure, and exposure time

The heterogeneous nature of the ash chemistry of biomass fuels gives rise to challenges in predicting the deposit melting, sintering, and enrichment of corrosive ash species. An experimental method has been developed to study the evolution of ash deposit chemistry and morphology in temperature gradients simulating the conditions of real superheater deposits. The method is based on applying synthetic ash mixtures on an air-cooled corrosion probe, which is inserted into a tube furnace. The focus has been on how the melting behavior of alkali salt-rich deposits, i.e., KCl–K2SO4–NaCl–Na2SO4 mixtures, affects the chemistry and morphology. Intradeposit vaporization-condensation of alkali chlorides has been of interest. The interaction of reactive gas components (H2O + SO2), with the deposits, was also studied. The vaporization-condensation mechanism leads to enrichment of alkali chlorides in crevices and voids within deposits, leading also to build-up of chlorides on the steel surface, which causes accelerated corrosion, due to the formation of low-melting FeCl2 mixtures. Liquid phase sintering and temperature gradient zone melting (TGZM) were the main mechanisms for the supersolidus sintering of the deposits. Iron and nickel oxides were found within the deposits and at the outer edge of deposits, due to the TGZM mechanism.

Laboratory simulation of salt weathering under moderate ageing conditions: Implications for the deterioration of sandstone heritage in temperate climates

AbstractSalt weathering is a significant process affecting the deterioration and conservation of stone‐built heritage in many locations and environments. While much research has focused on the impact of salt weathering under arid or coastal conditions with characteristic climatic conditions and salt types, many sites found to be experiencing salt‐induced deterioration, such as sandstone rock‐hewn cave temples in Gansu Province, China and sandstone buildings in the northern UK, experience high humidities, moderate temperature ranges, and different salt types. To evaluate the impact of salt weathering on sandstone‐built heritage under such mild humid environmental conditions, a lab simulation experiment was designed. The experiment was carried out on three types of sandstone (used in the northern UK and Gansu Province, China) and utilized a realistic diurnal humidity and temperature cycle (85% RH/16°C + 60% RH/22°C), and three widespread damaging salts, that is, Na2SO4, MgSO4, and the mixture of Na2SO4–MgSO4. The nature and extent of deterioration was monitored by photography, weight loss, and the changes in petrophysical properties measured using hardness, ultrasonic pulse velocity (P‐wave velocity), water absorption coefficient by capillarity, open porosity, and apparent density. All three sandstones were found to be susceptible to MgSO4 and the mixture of Na2SO4–MgSO4, but weakly affected by Na2SO4 under mild humid environmental conditions.

Comparative investigation of oxidation behavior and hot corrosion behavior in NaCl–Na2SO4 mixture for a Ti2AlNb based alloy at 1023 K

Oxidation behavior of a Ti2AlNb based alloy (Ti–22Al–23Nb (at.%)) and hot corrosion behavior of this alloy coated with a salt mixture of NaCl–Na2SO4 at 1023 K were comparatively investigated. The results showed that the alloy possessed relatively good oxidation resistance while suffered severe hot corrosion attack. The mass gain of the hot-corroded alloy was much larger than that of the oxidized alloy. The oxide scale was mainly composed of TiO2. During the oxidation, the oxide scale could keep intact. In the corrosion product scale, TiO2 + Al2O3 layers and NaNbO3 layers existed alternately and Al2O3 was distributed in the lower parts of the TiO2 + Al2O3 layers. The formation of the TiO2 + Al2O3 layer and the NaNbO3 layer should promote each other by altering the acidity/basicity of the salt film, and thus the growth of the scale was accelerated. The escape of the gaseous chlorides, the fast growth of the scale and the coefficient of thermal expansion (CTE) mismatch between TiO2 and NaNbO3 resulted in serious cracking and spalling of the scale.

Hot corrosion of Gd2Zr2O7, Gd2Zr2O7/YbSZ, YSZ + Gd2Zr2O7/YbSZ, and YSZ thermal barrier coatings exposed to Na2SO4 + V2O5

Gd2Zr2O7 ceramic is considered as a potential candidate for thermal barrier coatings. Here we present hot corrosion behavior of single layer Gd2Zr2O7 (GZO), Gd2Zr2O7 + 50 wt% YbSZ (GZO/YbSZ), YSZ and double-layer YSZ/Gd2Zr2O7 + 50 wt% YbSZ (YSZ + GZO/YbSZ) coatings prepared by air plasma spraying on Inconel 625 substrates. Prior to hot corrosion the fracture toughness of the coatings was assessed by Vickers indentation showing a variation between 0.6 and 2.3 MPa.m1/2 where the GZO/YbSZ coating exhibited the highest fracture toughness. The hot corrosion test was conducted by exposing the coatings to an equimolar mixture of Na2SO4 and V2O5 at 750 °C. After the hot corrosion test, the type of phases, chemical composition, microstructure and crack formation were investigated. Formation of GdVO4 and YVO4 was observed as the corrosion products in the GZO containing coatings and the YSZ coating, respectively. All coatings showed the formation of monoclinic zirconia after the corrosion test. The Gd2Zr2O7 + 50 wt% YbSZ (GZO/YbSZ) coating showed the best hot corrosion resistance due to reduced reactivity and enhanced fracture toughness and represents a new composition with properties promising for TBC applications.

Исследование стойкости к высокотемпературной газовой и солевой коррозии жаропрочного интерметаллидного титанового сплава ВТИ-4

We investigated high-temperature gaseous and salt corrosion resistance of heat-resistant intermetallic titanium VTI-4 (ВТИ-4) alloy samples by conducting accelerated cyclic laboratory testing in air, in a NaCl environment, and in a mixture of Na2SO4 and NaCl. While testing the VTI-4 (ВТИ-4) alloy in air, we observed corrosion of a chemical nature and pseudo-parabolic specific mass variation kinetics. After cyclic testing in a NaCl environment at 700 °C the surface of the VTI-4 (ВТИ-4) alloy was covered by a film consisting of two layers: a mixture of Al2O3 and (Ti, Nb)O2 oxides, and a (Ti, Nb)O2 layer. In a NaCl + Na2SO4 environment at temperatures of 650 and 700 °C a liquid ion conductor film may manifest on the alloy surface alongside the oxides, while corrosion becomes predominantly electrochemical, of the pitting type. Globular orthorhombic phase particles initiate the pitting process. We detected that the pit depth in the alloy after testing in a Na2SO4 + NaCl environment at 650 and 700 °C is twice that obtained in NaCl at 700 °C. At the temperatures of 650 °C in Na2SO4 + NaCl and 700 °C in NaCl and Na2SO4 + NaCl environments the specific mass variation becomes negative, which is due to the oxide film peeling and shedding as temperatures change. The corrosion rate for the VTI-4 (ВТИ-4) alloy in the Na2SO4 + NaCl environment at 650 °C is lower than those for the nickel alloys VV751P (ВВ751П) and VZh175-ID (ВЖ175-ИД)

Na2SO4 deposit‐induced hot corrosion of BN‐coated α‐SiC

AbstractBN coated α‐SiC was exposed to ~2.5 mg/cm2 of Na2SO4 for 0.75‐144 hours between 700°C and 1100°C in a 0.1% SO2‐O2 gaseous environment. A combination of SEM, EDS, ICP‐OES, XRD, and optical profilometry was used to determine that BN induced a previously unobserved form of Na2SO4 deposit‐induced hot corrosion of SiC below the melting temperature of Na2SO4 (Tm = 884°C). Above the melting temperature of Na2SO4 BN did little to alter the hot corrosion behavior of SiC, due to B2O3 volatility. Substrate attack below the melting temperature of Na2SO4 was found to result in rivulet recession features, whereas deep, localized pitting occurred above the melting temperature of Na2SO4. Initially, the mixture of Na2SO4 and BN led to the formation of a Na2O‐ and B2O3‐containing liquid silicate and accelerated corrosion which after prolonged exposure, resulted in the partial crystallization into a lath‐like tridymite and cristobalite mixture. Prolonged exposure resulted in a flattening of SiC consumption rates after exposure for several hours at 1000°C and after several days at 800°C, resulting in decreased SiC oxidation/corrosion kinetics.

Microstructures and cyclic hot corrosion behavior of laser deposited Inconel 718 alloy under different heat treatment conditions

In this research, the hot corrosion behavior of laser deposited Inconel 718 alloy under different heat treatment conditions (solution plus aging, direct aging and as-deposited) is investigated in a salt mixture of Na2SO4 (87.5 wt.%) + NaCl (5 wt.%) + NaVO3 (7.5 wt.%) at 650 °C. The weight changes of the Inconel 718 specimens that have experienced different heat treatments are measured during the hot corrosion experiments and the data of the weight changes are used to determine the kinetics of the hot corrosion. Field emission scanning electron microscope (FE-SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) are employed to characterize the corrosion products of the specimens, thus the corrosion mechanisms are analysed. It is shown that the hot corrosion kinetic of the as-deposited Inconel 718 alloy follows a parabolic law. The element mapping results of the corroded surfaces reveal that the corrosion products of as-deposited Inconel 718 include two distinct layers, of which the outermost layer is mainly composed of Ni2CrO4, Cr2O3 and Fe3O4, while the inner layer contains Ni3S2. The laser deposited Inconel 718 alloys with different heat treatments behave differently in the hot corrosion. The hot corrosion performance of the solution treated specimens is better than that of the directly aged specimens, while the latter has better hot corrosion resistance than the as-deposited specimens. According to the hot corrosion test results and theoretical analyses, the hot corrosion behavior of as-deposited Inconel 718 alloy with different heat treatments in the salt mixture solution is closely related to basic fluxing mechanism, sulphidation and oxidation as well.

Experimental study on thermal behavior of new mixed medium phase change material for improving productivity on salt gradient solar pond

Five identical cylindrical salinity-gradient solar ponds (SGSPs) with internal heat exchanger were constructed and operated. In order to optimize the performance of the SGSPs, mixtures of NaCl and Na2SO4 were used. Radiation flux, temperature of the zones, ambient temperature, inlet, and outlet temperature of the internal heat exchangers were measured. It was shown a controlled amount of Na2SO4 improves the thermal and salinity stability of the pond in the normal operation and heat extraction and lowers the pond temperature drop ratio to the water outlet temperature drop during the heat extraction, which means an improvement in the energy storage capacity. The pond with higher percentage of Na2SO4 requires less time to stabilize. Higher percentage Na2SO4 reduces the density gradient between the upper and lower convective zones of the pond and leads to rapid destruction of the upper layer. Maximum ability of heat extraction corresponds to the pond with 0.75% Na2SO4. In addition, to prevent the algae growth at higher percentage Na2SO4, spraying of HCl on the pond surface was used.

Ionic Strength Effect Alters the Heterogeneous Ozone Oxidation of Methoxyphenols in Going from Cloud Droplets to Aerosol Deliquescent Particles.

Methoxyphenols are one of the most abundant classes of biomarker tracers for atmospheric wood smoke pollution. The reactions of atmospheric oxidants (ozone, OH) with methoxyphenols can contribute to the formation of secondary organic aerosols (SOA). Here, for the first time, we use the well-established vertical wetted wall flow tube (VWWFT) reactor to assess the effect of ionic strength (I), pH, temperature, and ozone concentration on the reaction kinetics of ozone with acetosyringone (ACS), as a representative methoxyphenol compound. At fixed pH 3, typical for acidic atmospheric deliquescent particles, and at I = 0.9 M adjusted by Na2SO4, the uptake coefficient (γ) of O3 increases by 2 orders of magnitude from γ = (5.0 ± 0.8) × 10-8 on neat salt solution (Na2SO4) to γ = (6.0 ± 0.01) × 10-6 on a mixture of ACS and Na2SO4. The comparison of the uptake coefficients of O3 at different pH values indicates that the reaction kinetics strongly depends on the acidity of the phenolic group of ACS. The observed different reactivity of gas-phase ozone with ACS has implications for ozone uptake by the dilute aqueous phase of cloud droplets and by aerosol deliquescent particles loaded with inorganic salts, and it can affect the formation of SOA in the atmosphere.

Synthesis of thin alpha alumina platelets with a large aspect ratio

Since α-Al2O3 platelets with small thickness and large aspect ratio are needed in various applications, it is of great importance to control their morphology. In the present work, we successfully fabricated α-Al2O3 platelets with small average thickness below 100 nm and large average aspect ratio above 100 by molten-salt method, using Al2(SO4)3 as the raw material, eutectic mixtures of Na2SO4 and K2SO4 as the molten salt as well as TiO2 and SiO2 as the co-dopants. The effects of calcination temperature, seeds amount and seeds morphology on the final morphology of α-Al2O3 platelets were investigated. The growth mechanism of the α-Al2O3 platelets in molten salt was also discussed. A new growth mechanism of α-Al2O3 platelets in molten salt has been proposed, which is different from previous mechanism but can explain the two different phenomena caused by seeds with different sizes and quantity.

Shock effects of monovalent cationic salts on seawater cultivated granular sludge

Saline wastewater is commonly encountered in various industries, posing challenges to biological treatments. The application of seawater as a seed source provides a media of diverse halophilic organisms for rapid startup. However, effects of transitioning from a mixed salt source to monovalent salt solutions prevalent in industry remains unexplored. Hence, seed sludge was cultivated using seawater and later granulated under a mixed-salt synthetic medium comprising a mixture of NaCl, KCl and Na2SO4 at a combined concentration of 0.8 M (0.27 M each). The stable, acclimated granules were then tested against single salt media of 0.8 M NaCl, KCl, or Na2SO4. Shift to single salt media resulted in granule disaggregation, poor settling, sludge washout and development of fluffy or slimy flocs. Changes in exopolysaccharides composition after the single salt shift was the predominant reason for the large changes in sludge morphology. The impacts of KCl and Na2SO4 were more significant than the shift to NaCl. The resulting impacts also had a major influence on the treatment performance. A complex mechanism involving monovalent cation stimulation of proteins; ionic strength impacts on exopolysaccharides and morphology; solution density influence on sludge density and settling; and tonicity impacts on cell viability and treatment is described.

Çevrimli ve İzotermal Sıcak Korozyonun Nikel Esaslı Süper Alaşım Malzemeye Etkisi

Nickel-based superalloys have a wide range of usage area such as gas turbines, nuclear reactors, generators. They are especially preferred in areas where mechanical strength and corrosion resistance are important. Hot corrosion is a highly corrosive type of damage in high temperature applications. In hot corrosion, molten salts easily react with reactive components, causing premature damage to the workpieces. In this study, Inconel 718 was subjected to hot corrosion tests as a nickel-based superalloy. 50% V2O5-50% Na2SO4 mixtures were used as corrosion salt. Cyclic and isothermal hot corrosion tests were carried out at 900 ° C for 18 hours. Corrosion products and microstructural changes formed in Inconel 718 were characterized by scanning electron microscopy (SEM), SEM-Energy Dispersive X-Ray (EDX), SEM-mapping and X-Ray Diffraction (XRD) analysis after hot corrosion tests. At the end of the isothermal and cyclic hot corrosion tests, Inconel 718, which has been subjected to cyclic hot corrosion, has been found to be more affected by the damage. Similar results were observed in terms of the corrosion products and the damage mechanism.

Magnetic Property Changes of CoNiCrAlY Coating Under Cyclic Oxidation and Hot Corrosion

In this paper, a non-destructive method for evaluation of a CoNiCrAlY coating applied to gas turbine blades has been studied. The specimens from cast Ni-base superalloy IN738LC were coated with Co–34Ni–18.6Cr–8.7Al–0.5Y by low pressure plasma spray (LPPS) technique. The XRD peaks indicated that CoNiCrAlY coatings are composed of β-NiAl and γ-Co (Ni, Cr) matrix with small amounts of Al2O3 and γ′-Ni3Al. The surfaces of the coated specimens were covered with thin salt mixture of Na2SO4 + l0 wt% NaCl. Afterward, the specimens were maintained at 850 °C for 24 h, cooled to room temperature (as one cycle) and then reintroduced in the furnace. The magnetic susceptibility of coating, as one of the magnetic properties, was periodically determined after each cycle. The results showed that the magnetic susceptibility of Co–34Ni–18.6Cr–8.7Al–0.5Y coating is related to the phase compositions and microstructures. The magnetic susceptibility typically increases with depletion of β-NiAl phase and decrease in the coating thickness during cyclic oxidation and hot corrosion. Therefore, measurement of magnetic susceptibility can be employed as a non-destructive test (NDT) method to estimate the thickness or residual lifetime of CoNiCrAlY coatings.

Sintering and hot corrosion of yttria silicate tablets in molten salts prepared by spark plasma sintering

Purpose This paper aims to study the microstructural hot corrosion behaviour of the sintered Y2SiO5 ceramic silicate under a Na2SO4 + V2O5 mixture at an engine representative temperature of 1150°C. Y2SiO5 is a promising candidate for thermal barrier coatings (TBC) due to its excellent chemical stability at high temperatures. As a continuous source of Y3+, it is expected that Y2SiO5 environmental barrier coating may prolong the lifetime of TBC systems by stopping the degradation caused by the loss of the Y2O3 stabilizer. Design/methodology/approach Two routes were chosen for the yttria silicate powder synthesis by sol-gel from TEOS and APTES precursors as the difference in Si source changed the ratio of Y2SiO5/Y2Si2O7 phases. Hot corrosion studies using Na2SO4 and V2O5 mixtures were conducted on both surfaces of APTES and TEOS tablets at 1150°C for 8 h in atmospheric air. The morphology and microstructure analyses of the silicate samples after hot corrosion tests were carried out using a SEM and X-ray diffraction analyse techniques. Findings Based on the degradation, the general status of the APTES tablet after hot corrosion presents a better hot corrosion resistance at a temperature of 1150°C than does that of the TEOS tablet. In the TEOS tablet, the crystal morphology of NaY9Si60O26 woodchip shapes with a size of 60 µm is developed on the surface for finally initiating some cracks. In the APTES case, the crystal morphology of rod-like shapes with a size of 100 µm is developed; hence, a dense thick layer predominately postpones the reaction of V2O5 and Na2SO4 with yttria silicate, and consequently, less damage is observed. Originality/value Coating yttria silicate preparation is very complicated; the problems of a high synthesis temperature, long production period and low yield still need to be solved. Under these perspectives, ceramics prepared via spark plasma sintering (SPS) can reach theoretical high densities and a fine grain size can be retained after the SPS process; hence, well resistance to the corrosion in molten salts is expected to obtain for the sintered yttria silicate tablets.