NaCl Vapor Research Articles

Chlorine-induced high-temperature corrosion of the Pt-modified aluminide coating in simulated marine environment

The corrosion behavior of a single phase Pt-modified aluminide coating in the marine environment was investigated through a novel cyclically alternate corrosion test. The results showed that the multilayer oxide scale with loose structure was formed on the coating. NaCl and water vapor were verified to play important roles in enhancing the aggressivity during the corrosion test, in which the presence of NaCl increased cracking and spallation tendency of the oxide scale, and the addition of water vapor accelerated the oxidation rate and promoted internal oxidation to the coating.

Formation of Balloon with Porous Structures in NaCl Vapor Assisted by Amphiphilic Polymer for Stent Delivery System

Recently, bioabsorbable vascular stents (BVSs) are actively studied owing to their ability to dissolve within the human body. However, despite their advantages, BVSs often dislodge from the expandable balloon‐based delivery system when transported to the lesion site. In this study, a novel methodology aiming at increasing the retention force between the stent and the delivery system is presented. The breath‐figure method is adopted to form a porous structure and enhance adhesion. Additionally, numerical and experimental methods are used to evaluate the effect of surface tension between two immiscible fluids (polymeric solutions and droplets). To control the interfacial tension between the solution and droplets, an amphiphilic polymer and NaCl‐added vapor are used. By selecting the appropriate parameters, a sponge‐like structure is prepared on the stent delivery system. To verify its applicability, the two types of structures presented in this study are experimentally compared. These findings provide valuable guidelines for understanding the mechanism of breath‐figure patterns. Thus, the innovative methodology developed in this study demonstrates simplicity and scalability for large‐area production, making it potentially applicable to industrial technologies and offering new insights into biomedical engineering.

Reaction mechanisms underpinning the removal of Cs from simulated Cs-contaminated ash during thermal treatment with NaCl or KCl

The vaporization mechanism of cesium (Cs) in simulated Cs-contaminated ash during thermal treatment with the addition of NaCl or KCl was systemically examined in a laboratory-scale horizontal electrical-heating furnace. A thermodynamic equilibrium calculation was performed to predict the distribution of Cs and Cl in the solid and gas phases under different experimental conditions. The results indicated that Cs vaporized following heat treatment of the simulated ash with the addition of NaCl or KCl. The vaporization ratio of Cs increased as the reaction temperature. As the content of NaCl or KCl was increased, the vaporization ratio also increased at > 1000 °C; whereas, it initially increased but then decreased at 900 °C. Both NaCl and KCl underwent direct vaporization and decomposition via chemical reactions with silicate/aluminosilicates in the ash, thus releasing HCl/Cl2. The interactions between Cs and solid Cl-bearing species (e.g. NaCl, Na2AlCl6, and KCl) formed CsCl and were responsible for the vaporization of Cs. Nevertheless, the release of HCl/Cl2 from the decomposition of NaCl and KCl had an insignificant effect on the vaporization of Cs. Compared to an air atmosphere, N2 facilitated the vaporization of Cs because the vaporization and/or decomposition of NaCl, Na2AlCl6, and KCl were delayed under the N2 atmosphere, which in turn enhanced the chlorination of Cs. By comparing the effect of adding NaCl, KCl, CaCl2, or MgCl2 on the vaporization of Cs, alkali chlorides (NaCl and KCl) were found to exhibit the best performance.

VACUUM HIGH-TEMPERATURE REFINING OF CARBON MATERIALS USING NaCl VAPORS AS A TRANSPORT AND REACTION MEDIUM

One of the main requirements to carbon materials is their purity. The authors have proposed and experimentally tested a new method for vacuum-thermal refining of carbon materials using NaCl vapor as an activator. It is experimentally confirmed that this method allows increasing the refining process efficiency and decreasing the energy consumption. The proposed method can be an alternative to modern methods of chlorine- and fluorine thermal refining that permits to exclude the use of hazardous reagents.

Enhanced oxidation and corrosion inhibition of 1Cr11Ni2W2MoV stainless steel by nano-modified silicone-based composite coatings at 600°C

Silicone-based composite coatings modified by ZrO2 nanoparticles were applied on the 1Cr11Ni2W2MoV steel. Their oxidation and corrosion performances were evaluated in air and an environment containing solid NaCl and water vapor at 600 °C, respectively. The coating with 20 wt.% ZrO2 exhibited better oxidation resistance than those with 10 and 30 wt.% ZrO2, while the coating with 20 or 30 wt.% ZrO2 exhibited better resistance against the corrosion induced by water vapor and solid NaCl deposits than those with 10 wt.% ZrO2.

Hot corrosion of Ni, Cr, and 80Ni20Cr in the presence of NaCl and water vapor at 750 °C

The hot corrosion of Ni, Cr, and 80Ni20Cr in the presence of NaCl and water vapor at 750 °C was studied. The results indicated that no significant oxidation or corrosion effect of Ni was found in this case. However, a severe damage caused by the synergistic effect of NaCl deposit and water vapor on Cr was found. Both theoretical and experimental results have shown that Cr could react with NaCl or water vapor and form corrosive Cl2 or HCl, accelerating the corrosion of Cr by chlorination and oxidation. The element Ni in 80Ni20Cr alloy was accelerated corroded by means of reactions among Cr and solid NaCl as well as water vapor.

微量NaCl蒸気を含む空気中におけるNi-5, -8, および-10 at％Al合金の高温腐食

微量NaCl蒸気を含む空気中におけるNi-5, -8, および-10 at％Al合金の高温腐食

Reducing Effect of a Slight Amount of NaCl Vapor on Pest Oxidation of Ta–75at%Al at High Temperature

High temperature oxidation behavior of Ta–75at%Al was investigated by thermogravimetry at 800 and 900 °C in oxygen with NaCl vapor of 7.2, 32.1 and 123 volume ppm. Without NaCl vapor, pest oxidation took place and the aluminide crushed into particles at both temperatures from earlier stage. In contrast, with a slight NaCl vapor, the pest oxidation was effectively reduced to achieve very small mass gain values. For samples without pest oxidation, there formed a thin Al2O3 outer filmed scale and Al2O3 scale along the grain boundaries inside the alloy. The reducing mechanism of pest oxidation by NaCl vapor was considered from the viewpoint of thermodynamics. Namely, it was considered that NaCl vapor reacts with oxygen in the atmosphere at high temperatures to produce chlorine gas, and this Cl2 selectively chlorinates Al than Ta, which produces Al2O3 on the gas/scale interface where the oxygen potential is higher. This Al2O3 was thought to construct a protective film.

NaCl–H2O-assisted preparation of SrTiO3 nanoparticles by solid state reaction at low temperature

An environmentally friendly NaCl–H2O system was developed to synthesize monodisperse strontium titanate (SrTiO3) nanoparticles from commercially available raw materials (SrCO3 and rutile) by solid state reactions. The formation rate of SrTiO3 was accelerated by the addition of NaCl and water vapor. Single phase SrTiO3 was obtained by calcination at 700°C for 2h in water vapor (H2O flow rate of 2.0mL/min) by the addition of 50wt% NaCl, although 900°C and 750°C for 2h were required to complete the reaction by calcinations in air and air by the addition of 50wt% NaCl, respectively. The results demonstrate that both NaCl and H2O played vital roles to accelerate the formation of SrTiO3 nanoparticles at relatively low temperature. On the basis of experiments and analysis, a rational growth mechanism has been proposed and discussed.

Corrosion behavior of thermal sprayed WC cermet coatings containing metallic binders in saline environment

A series of electrochemical and long-term corrosion tests were carried out in a neutral saline (5% NaCl) vapor of 35 °C on thermal sprayed WC cermet coatings containing different kinds of metallic binders in order to examine the effect of composition of binder materials on the corrosion behavior. The experimental results revealed that the overall corrosion resistance of WC-Co coating was inferior to that of WC-Co-Cr coating. For the coatings without Cr, WC-Co, general corrosion occurred in binder materials in addition to galvanic corrosion between WC particles and metallic binders in the neutral environment. By contrast, the formation of passive film in the form of surface oxide in the coatings containing Cr, WC-Co-Cr, suppressed the binder and metallic binders to be eroded. It is found that the chemical composition of metallic binder materials is one of the important factors influencing the corrosion resistance of HVOF sprayed WC cermet coatings in the neutral vapor.

Osmotic Virial Coefficients of Hydroxyethyl Starch from Aqueous Hydroxyethyl Starch–Sodium Chloride Vapor Pressure Osmometry

Hydroxyethyl starch (HES) is an important industrial additive in the paper, textile, food, and cosmetic industries and has been shown to be an effective cryoprotectant for red blood cells; however, little is known about its thermodynamic solution properties. In many applications, in particular those in biology, HES is used in an aqueous solution with sodium chloride (NaCl). The osmotic virial solution thermodynamics approach accurately captures the dependence of osmolality on molality for many types of solutes in aqueous systems, including electrolytes, sugars, alcohols, proteins, and starches. Elliott et al. proposed mixing rules for the osmotic virial equation to be used for osmolality of multisolute aqueous solutions [Elliott, J. A. W.; et al. J. Phys. Chem. B 2007, 111, 1775-1785] and recently applied this approach to the fitting of one set of aqueous HES-NaCl solution data reported by Jochem and Körber [Cryobiology 1987, 24, 513-536], indicating that the HES osmotic virial coefficients are dependent on HES-to-NaCl mass ratios. The current study reports new aqueous HES-NaCl vapor pressure osmometry data which are analyzed using the osmotic virial equation. HES modifications were measured after dialysis (membrane cut off: 10,000 g/mol) and freeze-drying using vapor pressure osmometry at different mass ratios of HES to NaCl for HES up to 50% and NaCl up to 25% with three different HES modifications (weight average molecular weights [g/mol]/degree of substitution: 40,000/0.5; 200,000/0.5; 450,000/0.7). Equations were then fit to the data to provide a model for HES osmotic virial coefficient dependence on mass ratio of HES to NaCl. The osmolality data of the three HES modifications were accurately described over a broad range of HES-to-NaCl mass ratios using only four parameters, illustrating the power of the osmotic virial approach in analyzing complex data sets. As expected, the second osmotic virial coefficients increase with molecular weight of the HES and increase with HES-to-NaCl mass ratio.

ChemInform Abstract: Corrosion Behavior of Metals or Alloys with a Solid NaCl Deposit in Wet Oxygen at Medium Temperature

AbstractReview: 27 refs.

The influence of sodium chloride on the melting temperature of collagen crystalline region in parchments

In order to observe the influence of sodium chloride on the melting temperature of collagen crystalline region in three new parchments, samples were soaked in water (blanks) and NaCl solutions of different concentrations, then removed, dried in air and measured by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The melting temperature of crystalline region of collagen, Tm, was determined as the minimum of the endothermal peak in the range 200–250 °C and as the inflection point of the decrease of storage modulus, respectively. There was observed a decrease in melting temperature of the salt-treated parchments compared to the samples soaked in water, sometimes significant (~20 °C) at certain concentrations of NaCl. Simultaneous TG/DTG/DSC thermal analysis (STA) was also applied for the determination of the amount of sodium chloride in salt-treated parchments, by calculating the mass loss due to the vaporization of NaCl, which occurs above 800 °C. By plotting Tm determined by DSC and DMA versus the NaCl content of the samples, an apparent minimum is observed. Additional information regarding the structural features was also obtained through X-ray diffraction (XRD) and attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR). XRD data put in evidence the preservation of collagen crystalline region in all salt-treated samples, while FTIR measurements did not showed significant modification of collagen. By removing the sodium chloride from the salt-treated parchments through washing with water, there is a return of the melting temperatures to the values of blank samples, demonstrating the reversibility of this phenomenon.

Corrosion behavior of metals or alloys with a solid NaCl deposit in wet oxygen at medium temperature

The corrosion of metals or alloys under solid NaCl deposit in wet oxygen (water vapor and oxygen) at medium temperature 400–700°C causes serious damage and has received considerable attention in recent years. Series of mechanistic studies have revealed synergistic interactions between solid NaCl and water vapor, which accelerates the corrosion process. In addition, the overall corrosion process comprises both chemical reactions (oxidation) and electrochemical reactions and their mutual interactions depend on the system of interest. Interestingly, the wet oxygen environment was found to modify the reactions of the element Cr, which plays a useful role in corrosion protection in this special environment.

Cyclic Corrosion Behavior of Pt/Ru-Modified Bond Coatings Exposed to NaCl Plus Water Vapor at 1050°C

In the present investigation, Pt/Ru-modified bond coating consisted of 2 μm Pt+2 μm Ru was deposited on a nickel-based superalloy by electroplating method and followed by conventional Al pack cementation. The cyclic corrosion behavior of Pt/Ru-modified bond coating exposed to NaCl plus water vapor has been investigated under atmospheric pressure at 1050°C. The result shows that the cyclic corrosion life of Pt/Ru-modified bond coating is longer than that of the conventional Pt-modified aluminide coating in the presence of NaCl plus water vapor. The addition of Ru makes the coating possess the increased strength and suppress the rumpling behavior. The absence of rumpling may be responsible for the improved corrosion resistance of Pt/Ru-modified aluminide coating.

Evidence for the occurrence of electrochemical reactions and their interaction with chemical reactions during the corrosion of pure Fe with solid NaCl deposit in water vapor at 600 °C

The results of this work prove that electrochemical reactions are involved in the whole corrosion process of pure Fe with a solid NaCl deposit in water vapor at 600 °C. The interaction of chemical and electrochemical reactions accelerates the corrosion rate of pure Fe significantly. The electrochemical reaction is coupled with a preceding chemical reaction process (ce), in which Fe first reacts chemically with NaCl and water vapor to generate HCl (g). And then, the electrochemical reaction proceeds via a one-electron electrochemical reduction to form H 2.

The Mechanism of Electrochemical Testing Method under Synergistic Effect of NaCl and Water Vapor at 600℃

The Mechanism of Electrochemical Testing Method under Synergistic Effect of NaCl and Water Vapor at 600℃

Fabrication and Properties of Porous SiC Sheets from Clutch Lining Wastes

During the production of friction sheets with their pack assemblies used in clutch for automatic transmission of motorcars, useless sheet fragments are formed and have to be disposed of, amounting to several tens of tons per a month. These wastes are composed of cellulose, diatomaceous earth, synthetic fibers, and carbon powder/fibers, impregnated with phenol resin as the bonding medium. When two types of these sheets are heated in an inert atmosphere at 600°C, they become porous and contain excess carbon formed by decomposition of the resin. The reaction of these porous sheets with a source of silicon such as tetra-ethoxy-silane or SiO at 1500°–1600°C results in the formation of porous silicon carbide (SiC) (∼80% porosity). If the porous sheets are impregnated with phenol resin and again reacted with SiO gas at 1500°–1600°C in Ar, SiC sheets with reduced porosity (<70%) are obtained. The surfaces and cross sections of the SiC sheets were observed by scanning electron microscopy, and their pore size distribution in the samples heated at 1600° and 1900°C in Ar was determined by mercury porosimetry. The oxidation and corrosion properties of the SiC sheets with 60% and 80% porosities were determined at 1200°C in Ar/O2 in the absence and presence of NaCl vapor.

Evaluation of cyclic oxidation of thermal barrier coatings exposed to NaCl vapor by finite element method

The cyclic oxidation of NiCrAlY + YSZ coating exposed to NaCl vapor has been investigated under atmospheric pressure at 1050 °C, 1100 °C and 1150 °C. The result showed that the cyclic oxidation life of NiCrAlY + YSZ coating in the presence of NaCl vapor was shortened compared with that in air. The failure of the TBC exposed to NaCl vapor occurred within the top coat and close to the YSZ/thermal growth oxide (TGO) interface. A finite element analysis was employed to analyze the stress distribution in the coatings. The computed result showed that maximum stresses occurred at the interface between the bond coat and TGO near the edge of the sample and the increased thickness of TGO caused the value of stress in TGO/YSZ interface to increase. The comparison of the maximum stresses indicated that the spinel TGO resulted in significantly higher stresses than Al 2O 3 TGO. This implies that the formation of spinel plays a dominant role in shortening the coating cycling lifetime.

Cyclic-Oxidation Behavior of Thermal-barrier Coatings Exposed to NaCl Vapor

A Ni–24Cr–6Al–0.7Y (NiCrAlY) coating was deposited on a nickel-base superalloy by low-pressure plasma spraying, and the top coating, ZrO2 partially stabilized with Y2O3 (7.5 wt%), was deposited on the NiCrAlY coating by air-plasma spraying. The cyclic-oxidation behavior of the NiCrAlY + YSZ coating exposed to NaCl vapor was investigated under atmospheric pressure at 1,050 °C, 1,100 °C and 1,150 °C. The cyclic-oxidation life of the NiCrAlY + YSZ coating in the presence of NaCl vapor was shortened compared with that in air. The higher the temperature is, the shorter the cyclic oxidation life. The oxide scale formed at the interface between the bond coat and the ceramic layer after exposure to NaCl vapor consisted of voluminous and non-protective NiO, Al2O3 and NiCr2O4 spinel. The failure of the TBC exposed to NaCl vapor occurs within the top coat and close to the YSZ/thermal growth oxide interface. The failure mechanism has been discussed based on the experimental results and thermodynamics.