Resin Paint Research Articles

Nature-Friendly Water-Based Resin Paints with SiO2 Nanoparticles for Electrostatic Spraying

ABSTRACT This study presents an environment-friendly and less toxic approach to electrostatic spraying using novel water-based resin paints enhanced with SiO2 nanoparticles. Addressing the environmental and health concerns of traditional toxic solvent-based coatings, our research emphasizes the development and application of these paints on anodized aluminum substrates. Our experimental procedure involves formulating water-based paints; applying them via electrostatic spraying; and analyzing their stability, coverage, and adhesion properties. The findings demonstrated that the paints maintained stability and showed improved adhesion and uniformity without using a toxic solvent-based resin, particularly on substrates with extended anodizing treatment. This study highlights the potential of using water-based resin paints in industrial applications, offering a sustainable, efficient, and high-performance alternative to conventional coatings, paving the way for future research into their broader application and environmental impact.

Simulation-Guided Preparation of Copper Chalcogenide Nanoparticle-Based Transparent Photothermal Coating with Enhanced Deicing Performance.

In this investigation, transparent photothermal coatings utilizing plasmonic copper chalcogenide (Cu2-xS) nanoparticles were designed and fabricated for the deicing of glass surfaces. Cu2-xS nanoparticles, chosen for their high near-infrared (NIR) absorption and efficient photothermal conversion, were analyzed via finite difference time domain (FDTD) simulations to optimize nanoparticle morphology, thus avoiding costly trial-and-error synthesis. FDTD simulations determined that Cu2-xS nanorods (Cu-NRs) with an optimal aspect ratio of 2.2 had superior NIR absorption. Guided by FDTD simulations, the composite coating composed of Cu-NRs in clear acrylic resin paint was brush-coated to glass, achieving 62.4% visual transmittance and over 95% NIR absorbance. Photothermal conversion tests exhibited a significant temperature increase, with the coating reaching 65 °C under NIR irradiation within 6 min. The dynamic deicing process of ice beads on the coating at -20 °C completed within 220s, in contrast to the frozen state on glass coated with clear acrylic resin paint. Furthermore, heat transfer simulations in COMSOL illustrated melting initiation at the ice-coating interface and subsequent progression through the ice layer. This simulation-driven synthesis method and photothermal testing offer a design framework for the fabrication of photothermal deicing coatings with applications for automobiles, buildings, and aircraft in cold environments.

Evaluating the Deicing Performance of Copper Sulfide Nanoparticle-Infused Transparent Photothermal Coatings on Glazing: An Integrative Experimental and Simulation Study

This study presents an efficient approach to fabricating photothermal coatings using copper sulfide (CuS) nanoparticles for effective deicing on glass. The influence of nanoparticle shape on light absorption was economically evaluated using Finite Different Time Domain (FDTD) simulations, identifying CuS nanorods as the optimal choice in terms of light absorption and heat generation. Simulation results guided the fabrication of transparent photothermal coatings incorporating CuS nanorods and transparent acrylic resin paint. Deicing tests under 808 nm illumination demonstrated efficient active deicing potential of the developed coating covered with a 3mm-thick ice layer, raising the surface temperature from-20.0 °C to 42.5 °C within 400s. This combined simulation guidance and test validation approach introduces a cost-effective method for designing high-performance deicing coatings embedded with photothermal nanoparticles.

Intercalation of decanoate anions (C10) in layered double hydroxide Mg[sbnd]Al and its application as controlled-release corrosion inhibitor of steel

This study focuses on the preparation and characterization of a novel anticorrosion pigment based on decanoate anions (C10‐) intercalated within layered double hydroxide (LDH) MgAl. The LDH-NO3, LDH-C10 were synthesized by a simple co-precipitation method and analyzed by XRD, infrared spectroscopy, thermogravimetry and electronic microscopy. The LDH-C10 pigment with a basal distance of about 20 Å was consistent with the arrangement of C10 anions in bilayer. The inhibition efficiency of the LDH-C10 pigment in electrolyte and in alkyd resin paint was studied by electrochemical impedance spectroscopy and potentiodynamic techniques. The pigments act as a C10− nanocontainer, which release the C10− anions in contact with chloride ions that lead to the formation of a passive layer on steel. In alkyd resin, the LDH-C10-enriched organic coating exhibit very interesting anticorrosive performance in NaCl electrolyte during 40 days of immersion.

An antifouling epoxy coated metal surface containing silica-immobilized carbonic anhydrase supraparticles for CO2 capture through microalgae

Carbonic anhydrase (CA) has a promising application as a green and efficient biocatalyst for CO2 capture, and many successful cases of immobilizing CA have been reported. However, CA antifouling coatings on metal for CO2 sequestration have rarely been reported. Herein, dimeric CA from Sulfurihydrogenibium azorense (SazCA) with a ferritin tag, which was prepared by low-speed centrifugation with high yield, was adopted as a free enzyme and encapsulated in the sol-gel silica. The silica-immobilized CAs were dispersed into the commercialized metal-antifouling epoxy resin paint to obtain CA coated nickel foams, which had excellent stability, with 90 % and 67 % residual activity after 28 days of incubation at 30 °C and 60 °C, respectively. The CA coated nickel foams remained 60 % original activity after 6 cycles of use within 28 days. Then, a CA-microalgae carbon capture device was constructed using the CA coated nickel foams and Chlorella. The growth rate of Chlorella was significantly increased and the biomass of Chlorella increased by 29 % compared with control after 7 days of incubation. Due to the simple and cost-effective preparation process, sustainable and efficient CO2 absorption, this easy-to-scale up CA coated nickel foam has great potential in CA assisted microalgae-based CO2 capture and carbon neutrality.

Application of pulsed laser ablation thermal model in nanosecond pulsed laser removal of the epoxy resin paint film

The effect of laser surface paint removal depends on the mechanism of paint removal. The mechanism of nanosecond laser removal of epoxy resin paint film on aluminum alloy surfaces was studied theoretically and experimentally. Firstly, a laser thermal paint removal model was established based on the heat conduction equation, Hertz-Knudsen equation, and Hooke's law. The adsorption relationship between the paint film and the aluminum alloy substrate molecules and the adsorption force between the paint film and the substrate were analyzed and calculated. A laser thermal paint removal model was solved using COMSOL finite element software. By analyzing the changes in temperature and thermal stress with laser fluence, we obtained the theoretical threshold for laser paint removal. Subsequently, experimental research was conducted on laser paint removal. Through theoretical and experimental studies, it was found that the paint removal threshold of nanosecond pulse laser is 0.47 J/cm2. The primary mechanism of nanosecond laser paint removal is thermal stress stripping. When the laser fluence is low, the nanosecond pulse laser can only ablate the paint on the surface, and the thermal stress between the paint film and the substrate makes it difficult to remove the paint film. As the laser fluence increases, the nanosecond laser will ablate the surface paint film, and the thermal stress between the paint film and the substrate will cause the stripping of the underlying paint film and the substrate. The primary mechanism of laser paint removal is stripping.

Simulation and Experimental Study on Continuous Wave Fiber Laser Removal of Epoxy Resin Paint Film on the Surface of 6061 Aluminum Alloy

Paint removal is an essential process in the industrial field. Laser technology provides an effective method of paint removal to replace traditional mechanical and chemical methods. This paper establishes a continuous wave (CW) laser thermal paint removal model based on heat conduction theory and Arrhenius’ law. The paint stripping process of epoxy paint film on the surface of 6061 aluminum alloy via CW laser was studied through simulation and experiment. We found that the carbonization of the paint film during the CW laser paint removal process will inhibit the laser paint removal process. Therefore, the paint removal efficiency of the CW laser is limited. The depth of CW laser paint removal increases linearly with the CW laser power density. However, during the CW laser paint removal process, due to the pyrolysis of the paint film and the reflection of the laser by the substrate, the surface temperature of the material first increases and then decreases. In addition, after laser paint removal, the surface roughness of the material after paint removal is reduced due to the melting of the base material. The model established in this article can provide a theoretical reference for studying the CW laser paint removal process.

Simulation and Experimental Study of Nanosecond Pulse Laser Removal of Epoxy Paint on 6061 Aluminum Alloy Surface

Laser paint removal is a new cleaning technology that mainly removes paint through thermal ablation and mechanical stripping mechanisms. This paper established a thermal-mechanical coupling laser removal model of paint based on the heat conduction equation, Newton’s second law, and Fabbro’s theory. The removal process of epoxy resin paint film on an aluminum alloy surface via a nanosecond pulsed laser was studied using finite element simulations and experimental measurements. The simulation and experimental results show that the nanosecond pulse laser’s primary paint removal mechanism is the mechanical stripping caused by thermal stress and plasma shock. The laser paint removal threshold is 1.4 J/cm2. In addition, due to the different generation times of plasma shock and thermal stress, the mutual superposition of stress waves occurs in the material. This results in a discrepancy between the actual and thermal stress differences. Moreover, the thermal stress difference causes the maximum actual stress difference to fluctuate. The simulation model established in this paper can provide a reference for studying the thermal-mechanical coupling process of laser paint removal.

Superhydrophobic bilayer coating for passive daytime radiative cooling

Abstract Passive radiative cooling is an energy-free cooling method by exchanging thermal radiation with the cold universe through the transparent atmospheric window. Spectrum tailoring of the radiative cooler is the key to daytime radiative cooling in previously reported works. In addition, radiative coolers with large-scale fabrication and self-cleaning characteristics should be further developed to improve their industrial applicability. Herein, we propose a bilayer radiative cooling coating with the superhydrophobic property and a scalable process, by covering TiO2/acrylic resin paint with a silica/poly(vinylidene fluoride-co-hexafluoropropylene) (SiO2/P(VdF-HFP)) composite masking layer. The strong Mie scattering in TiO2/acrylic resin paint contributes to high solar reflection, while the SiO2/P(VdF-HFP) masking layer is responsible for superhydrophobicity and synergetic solar reflection in the ultraviolet band, resulting in an effective solar reflectivity of 94.0 % with an average emissivity of 97.1 % and superhydrophobicity with a water contact angle of 158.9°. Moreover, the as-fabricated coating can be cooled to nearly 5.8 °C below the temperature of commercial white paint and 2.7 °C below the local ambient temperature under average solar irradiance of over 700 W m−2. In addition, yearly energy saving of 29.0 %–55.9 % can be achieved after the coating is applied to buildings in Phoenix, Hong Kong, Singapore, Guangzhou, and Riyadh.

基于金刚烷和二苯甲酮修饰的醇酸树脂漆的制备及其性能研究

基于金刚烷和二苯甲酮修饰的醇酸树脂漆的制备及其性能研究

Effect of applied stress on corrosion properties of Q235 steel with multi-layer epoxy coating

Organic coating is one of the most effective, economical and universal methods for corrosion resistance of metal at a small, but the stability of the coating is highly dependent on the applied stress. In the study, a comprehensive experiment was conducted to investigate the corrosion progress of Q235 steel sheets in 3.5% NaCl solution and 10% H2SO4. The effect of applied stress on the corrosion as well as the corresponding adhesion characteristics of Q235 steel are examined and quantitatively analyzed. Results indicate that, compared with the NaCl solution, the H2SO4 solution has aggressive corrosion on the Q235 steel sheets, and the corrosion would be largely aggravated with increasing applied stress. Additionally, the decreased adhesion grade of the epoxy coating is a synergic result of the immersion time and the stress, and the continuous dissolution of the coating would lead to the aggravation of corrosion, which side-fact indicates that the prepared epoxy resin paint could show efficient anti-corrosive properties. Therefore, the stress has a direct influence on the adhesion ability of the prepared epoxy resin coating, which would decrease the anti-corrosion properties of the coating.

Antifouling activity of isonitrosoacetanilides against microfouling and macrofouling.

Biofouling is responsible for structural and economic damage to man-made surfaces. Antifouling paints with biocides have been applied to structures to avoid organism adhesion; however, they have high toxicity and are not able to prevent all biofouling processes, necessitating the periodic mechanical removal of organisms and paint reapplication. Thus, there is an urgent demand for novel, effective, and environmentally friendly antifouling alternatives. As isonitrosoacetanilide is the precursor for many compounds with antibacterial activity, we believe that it could have antifouling activity against microfouling and, consequently, against macrofouling. The aim of this work was to investigate the antifouling potential of six isonitrosoacetanilide compounds and their toxicity. The compounds were employed at different concentrations (0.625-1.25-2.5-5-10µgmL-1) in this study. The biofilm and planktonic bacteria inhibition and biofilm eradication potential were evaluated by crystal violet assay, while Amphibalus amphitrite barnacle settlement was evaluated by cyprid settlement assay. Toxicity evaluation (LC50 and EC50) was performed with A. amphitrite nauplii II and cyprid larvae. At least one of the tested concentrations of 4-Br-INA, 4-CH3-INA, and 2-Br-INA compounds showed nontoxic antifouling activity against microfouling (antibiofilm) and macrofouling (antisettlement). However, only 4-CH3-INA and 2-Br-INA also showed biofilm eradication potential. These compounds with antibiofilm activity and nontoxic effects could be combined with acrylic base paint resin or added directly into commercial paints in place of toxicant biocides to cover artificial structures as friendly antifouling agents.

Analysis of Influence of Insulating Resin Paint Film on Enameled Wire Properties Based on Molecular Simulation

As one of the varieties of magnet wire, the enameled wire has excellent mechanical properties, heat resistance, ageing resistance, dimensional stability and chemical stability. This is one of the keys affecting the development of the electrical industry, especially the development of new motors. Different varieties of enameled wire insulating varnishes have advantages and disadvantages, in addition to their general properties. In order to improve the service life and reliability of the electrical coil of the motor, it is necessary to select the appropriate enameled wire reasonably according to different purposes. Molecular simulation technology can play a guiding role in the relationship between the molecular structure and properties of resins, help to understand the microscopic mechanism, shorten the experimental period, improve efficiency and save costs. In this paper, based on density functional theory (DFT) and molecular dynamics (MD), the microscopic properties of four insulating resins, polyamide–imide (PAI), polyester (PET), polyesterimide (PEI), and polyimide (PI), were studied. We also studied the influence mechanism of the insulating resin microstructure on the macroscopic properties of enameled wires, including adhesion, insulating properties and flexibility. The calculation results show that the polyester insulating enameled wire paint has good insulation performance and flexibility, the polyamide–imide paint has the best adhesion, and the polyimide insulating paint has very reliable insulation performance and flexibility. The performance research in this paper lays a foundation for the preparation of insulating resin coatings with better comprehensive properties. The performance research in this paper lays a foundation for preparing insulating resin paint with excellent comprehensive performance.

Synthesis and characterisation of cerium doped bismuth titanate proficient UV shielding and NIR reflective reddish brown pigment by citrate autocombustion synthesis

A new series of Bi4-xCexTi3O12 (0.25, 0.50, 0.75, 1.0, 1.25)] reddish brown to dark yellow NIR reflectance pigments with UV shielding properties have been synthesised via citrate auto combustion synthesis. The doping of Ce ions tunes the colour of the bismuth titanate from ivory to reddish brown. The reddish brown Bi3.75Ce0.25Ti3O12 pigment shows NIR reflectance of around 71.79%. All the synthesized pigments shows equally proficient UV absorbance value 1.271 at 274 nm. The increasing Ce ion concentration changes the colour from darker to lighter reddish shades. This reddish brown pigment was used in thermosetting acrylic resin paint and the ability of its heat resistance was analysed. The higher thermal stability and desirable optical properties of the synthesised pigments enables them as cost effective, environmental friendly NIR reflective reddish brown cool pigments and good alternative to the toxic pigments of the same colour.

Measuring impacts of microplastic treatments via image recognition on immobilised particles below 100\u2009\u03bcm

The treatment of samples for microplastic (MP) analysis requires purification steps that sufficiently reduce the non-MP content while preserving the targeted particles integrity. Besides their macromolecular structure this also encompasses their in situ numbers and sizes. However, any step of sample manipulation will come at a cost: particle loss, fragmentation, coagulation or degradation may lead to distorted results, predominantly in the smaller fraction of the MP size range. Therefore, the evaluation of MP resistivity against applied methods such as chemical digestions is a vital criterion for obtaining meaningful results on MP content of a sample. We developed a framework to test the applicability of MP purification methods and apply it to four protocols commonly used to prepare environmental samples for MP particle identification. The approach was designed for MP particles being too small to be handled manually (i.e. 10–70 μm). The evaluation consists of a two-tiered assay: a simple particle suspension approach is used to confirm a post-treatment qualitative recognisability of the target polymers by the analysis method of choice (here Raman and FTIR). In a following quantitative part, immobilised particles are used to evaluate the preservation of particle numbers and areas after the treatment on an individual particle level. A Python image analysis package was written that identifies, matches and measures particles on pairs of pre- and post-treatment images, and is available as open source software. Our results show that the chemical digestions using hydrogen peroxide, cooled Fenton’s and a combined alkaline / oxidative treatment using potassium hydroxide and sodium hypochlorite are suitable methods for preparing MP samples for a microspectroscopic analyses. Also acidic sodium polytungstate solution used for MP density separations and a pentane based protocol for lipid removal were found applicable for small sized MP. Certain degradative effects were found when acrylonitrile butadiene styrene is exposed to acidic treatments, as well as for MP from acrylate and epoxy based paint resins in strong oxidative regimes. Several paint resins tested here were spectroscopically not identifiable by polymer attributed bands even before treatment, indicating that these materials might slip through analyses of environmental samples and consequently being underreported. We conclude that evaluating chemical treatment procedures on MP < 100 μm is feasible, despite limitations of the current methodology which we discuss. Our results provide more certainty on the tested methods for MP studies specifically targeting small sizes and should be extended for more protocols used in MP laboratory practises.

Preparation of autoxidative water-reducible alkyd resins from waste polyethylene terephthalate.

In this paper, the waste polyethylene terephthalate (PET) was glycolysed by trimethylolpropane with zinc acetate as catalyst. The effects of different content glycolysis product of waste PET on the appearance, viscosity, particle size and molecular weight of autoxidative water-reducible alkyd resins and the corresponding film adhesion, flexibility, impact resistance, gloss, hardness and chemical resistance were studied. Meanwhile, experimental results were compared with commercial water-reducible alkyd and water-reducible alkyd without the glycolysis product of waste PET. The results show that the maximum concentration of PET in autoxidative water-reducible alkyd resins can reach 8.5 wt%, and the molecular weight, particle size and viscosity of water-reducible alkyd resin do not change much with the increase of PET concentration. The introduction of PET resulted in the viscosity of water-reducible alkyd resins being greater than that of water-reducible alkyd resin without PET; this is mainly because PET contains harder terephthalic acid monomer units. However, the particle size of water-reducible alkyd resins with waste PET is significantly lower than that of the water-reducible alkyd resin without PET; this is due to PET-free water-reducible alkyd resin containing more pentaerythritol with greater steric hindrance. In addition, the hardness of the water-reducible alkyd resin paint film (PET content is 8.5%) reaches 1H, which is higher than the hardness (HB) of the water-reducible alkyd resin paint film without PET and the commercial alkyd resin paint film, while the physical properties and chemical resistance of the former are comparable to those of the latter two kinds of paint films. Therefore, the use of waste PET in water-borne coatings systems not only reduces the cost of coatings, but also opens up a new market for recycled PET, which may contribute a promising method for management of waste PET.

Application of green surfactants to control barnacle recruitment

Green surfactants were evaluated for the determination of antifouling activity against barnacles on steel panels. Glyceryl laurate and 9,10-dihydroxy-octadecanoic acid were chemically synthetized, while rhamnolipid was obtained from Pseudomonas cepacia CCT6659 fermentation. The surfactants were incorporated into a natural resin paint formulation and were used in immersion tests for 90 days. The synthetic surfactant SDS was used as control. Glycerol laurate and hydroxylated oleic acid showed surface tensions of 22.22 and 34.65 mN/m and CMC of 200 and 400 mg/L, respectively. The biobased surfactants glyceryl laurate and hydroxylated oleic acid showed low toxicity against Artemia salina, i.e., LC50 of 163.80 and 191.03 mg/L, respectively, while the rhamnolipid biosurfactant showed a LC50 of 7200 mg/L. Carbon steel panels coated with rhamnolipid repelled only 2% of barnacles. The panels coated with SDS repelled 25% of barnacles, while panels coated with glyceryl laurate and hydroxylated oleic acid repelled 46% of the fouling. The results showed that values closer to or above the CMC of the surfactants influence the repellent action against fouling organisms. These finds demonstrate that green surfactants can be a more environmentally friendly alternative for barnacle control by replacing toxic commercial antifouling.

The synthesis and corrosion protection mechanisms of PANI/CNT nanocomposite doped with organic phosphoric acid

In this paper, PANI/CNT nanocomposites doped with organic phosphoric acid (PANI/CNT (HEDP)) with a PANI nanospheres adsorbed on the surface of CNT micromorphology were successfully prepared. The redox activity of PANI is extended to neutral effectively after compositing with CNT due to the interfacial π-π interaction between PANI and CNT. The resulting PANI/CNT nanocomposite has better dispersity in paint resin, causing a more compact nanocoating than polymeric coating revealed by the porosity measurement. The unique cathode suppression of PANI/CNT (HEDP) can be revealed with PANI/CNT (HCl) nanocomposites (doped by hydrochloric acid) as a control by polarization curve analysis on the scratch nanocoating sample. The results of electrochemical impedance and neutral salt spray test confirm that PANI/CNT (HEDP) nanocomposite has much better corrosion protection than PANI/CNT (HCl) nanocomposite. The corrosion protection mechanisms of PANI/CNT (HEDP) nanocomposite are proved to be the synergistic effect of Nanobarrier effect, Anode protection, Cathode suppression and Inhibitor role.

Digital analysis and prediction of the topography after pulsed laser paint stripping

In this study, a finite element model was established by using ANSYS to analyze the surface topography following the stripping of epoxy resin paint from the type 304 stainless steel. The nanosecond pulse laser was used to carry out the stripping process, while the “Birth & Death” method was used to simulate the resulting surface topography. The authors aimed to study the influences of various process parameters on the paint stripping process, including the laser fluence, scanning speed, and scanning interval. Furthermore, the surface topography following the plane scanning laser paint stripping was predicted, and the results obtained by using numerical simulations were verified experimentally. The results have shown that the cleaning threshold of single-pulse laser paint stripping is approximately 6.1 J/cm2. The ablation depth is inversely proportional to scanning speed and positively correlated with the laser energy density. The process was optimized by using a series of simulations. The optimal plane scanning results were obtained for the 58 μm ablation depth, the removal efficiency of ca. 11.55 cm3/min/kW at the laser fluence of 50 J/cm2, the scanning speed of 5000 mm/s, and the 70 μm scanning interval. Following the comparison with the experimental results, the digital topography analysis model was proposed, providing a reference for controlling the laser paint stripping process within an average error below 10 %.

Validation of a Model Formula for Predicting the Long-Term Corrosion Rate of Carbon Steel Pipes in Freshwater

In Japan, conduits buried underground protect telecommunication cables, and it is desirable to continue to use these conduits as much as possible. Hence, it is important to grasp the deterioration in considering the use limit. There are several kinds of conduits, and carbon steel conduits are mainly utilized especially. Though the carbon steel conduits outer surface contacting with the soil is coated with asphalt jute or polyethylene, the inner surface is protected only with synthetic resin paint. Since the conduit inner surface is connected to the manhole, it may be filled with stagnant water such as groundwater or rainwater. Therefore, it is necessary to predict the long-term corrosion rate of carbon steel conduits in fresh water.We carried out a test to measure the average corrosion depth converted from the weight loss by immersing test pieces made from a carbon steel conduit in distilled water at 60 °C and in a manhole stagnant water as a sample. The test pieces were obtained by cutting the steel pipe into 50 mm, removing the coating film on the inner and outer surfaces, shaping it to a thickness of 3 mm, and applying a urethane coating film on the outer surface so that bare steel was exposed only on the inner surface. This test continued for about 1500 days, and test pieces were brought out every 45 days for the specimens immersed in distilled water and every 90 days for the specimens immersed in manhole. The corrosion products were removed using 10% ammonium dihydrogen citrate heated to 80 °C, and weight loss of each test piece was measured. Using this result, the applicability of the model equation proposed by Ozawa et al. in 2017 was considered. Ozawa et al. developed a model to predict the corrosion depth of carbon steel pipes in neutral static water based on temperature, salinity, and Larson Skold Index (LSI). The model assumes that the corrosion depth with time is determined by the initial corrosion rate, time and film resistance coefficient. Salinity and temperature determine the initial corrosion rate, and LSI and temperature determine the film resistance coefficient. In order to apply this model, the pH, chloride ion and sulfate ion of manhole stagnant water were measured by ion chromatography. The pH was 7.8, Cl- was 2.9 mg/l, and SO42- was 5.3 mg/l. The value of hydrogen carbonate ion has not been measured yet, and 207.5 mg/l, which is the average value measured in 1960 in Tokyo 45 manholes, is used. At this time, the film resistance coefficient becomes 2909.3. The temperature and salinity of the manhole reservoir water were 20 ° C and 0.05 ‰, respectively. The model was applied to distilled water with salinity of 0.01 ‰ and LSI with 1.The results of observed corrosion depth is shown on the vertical axis, and the results are shown in the log diagram with the predicted values obtained from the model equation of Ozawa et al. on the horizontal axis. The corrosion depth on day 45 after immersion in distilled water and the corrosion amount on day 90 after immersion in manhole reservoir water agree with the measured value predicted from the model equation, but the observed corrosion depth tends to be larger than the value derived from the model equation after that. The original model equation showed good agreement when compared with the test results at approximately 500 hours. It may be considered that this model equation is applicable in 45 days (1080 hours), but it is highly possible that the corrosion depth becomes larger than the model equation in the long term. In addition, the corrosion rate of the specimen immersed in the manhole deviates more from the model equation. Figure shows a photograph in which corrosion products were observed with an electron microscope on the test specimen as of 1321 days, and it can be seen that cracks of several μm in width were generated just above the base metal and at 150 μm to 300 μm positions, respectively. There is a possibility that the corrosion rate becomes faster than expected due to the influence of the cracks. In addition, though the stagnant water is presumed as still water in the usual time, the flow with the inflow of the water may be generated depending on the season. Considering these factors, it is possible to improve the long-term prediction accuracy of carbon steel conduits. Figure 1