pH Of Sol Research Articles

Mesoscopic structure modeling of silica aerogels using cluster‐cluster aggregation

AbstractSilica aerogels are nanostructured materials known for their low density, high porosity, and excellent thermal insulation properties. Among silica aerogels, organosilane‐derived aerogels have received considerable interest for their additional chemical functionalities such as hydrophobicity and flexibility. This work investigates the mesoscopic modeling of such aerogels, extending an aggregation based model developed for conventional silica aerogels. The pH of sol–gel polymerizations is one of the most critical reaction and processing parameters in determining the porosity, density, strength, and transparency of the resulting gels. Achieving optical transparency in aerogels depends on the presence of homogeneous mesoporous network structures. To account for the effect of pH, a relationship between pH and adhesion probability was incorporated into a three‐dimensional cluster‐cluster aggregation (CCA) model, providing insight into the gelation process. In addition, size‐dependent diffusivities are considered in this study. By incorporating different factors into the CCA model, the gelation kinetics are evaluated. The obtained mesoscopic structure is compared with experimental characterizations, together with preliminary mechanical simulations.

Effect of sol impregnation and changes in sol pH on mechanical properties of 3D printed alumina ceramics

This paper reports the successful preparation of high-strength 3D-printed alumina ceramic cores using stereolithography (SLA) and vacuum sol impregnation. Zirconia, alumina, and silica sols (ZS, AS and SS) were chosen as impregnating agents for alumina ceramics. The effects of different types of sols, various ratios of alumina sol to silica sol, and different pH values of sols on the mechanical properties of the ceramics were investigated. The flexural strength of the samples increased significantly after silica sol impregnation, reaching a maximum of 63.51 ± 3.67 MPa, which is 2.06 times higher than that of the unimpregnated samples (UN). Silica particles fill the original pores of the ceramics, and after high-temperature sintering, mullite is formed to increase the density and strength of the ceramics. The flexural strength of alumina ceramics decreases and then increases as the percentage of silica sol in the alumina-silica mixed sol increases. The optimal impregnation ratio for the mixed sols was found to be 1:4, which led to a flexural strength of 62.2 ± 2.09 MPa for the alumina ceramics. In addition, the pH of the sol plays a crucial role in maintaining stable sols. The silica sol is more susceptible to gelation as the pH of the sol increases within the range of 3.5–5.5, which can have a negative impact on its impregnation effectiveness. At a pH of 6.5 in the silica sol, the alumina ceramics exhibited the highest flexural strength of 92.57 ± 2.43 MPa, which is 3.01 times higher than the flexural strength of the unimpregnated samples. The research of impregnation process parameters suitable for 3D printing of alumina ceramics aim to enhance the material's strength, offering a novel solution for applications as high-performance components in the energy sector.

A study on preparation and properties of fly ash-based SiO2 aerogel material

Using fly ash acid leaching residue as the silicon source, sodium silicate solution was produced by alkali leaching and the wet gel was obtained by the sol-gel method. Hexamethyldisiloxane (HMDSO) was used to modify the surface of the wet gel, thereby reducing the capillary tension during the atmospheric pressure drying process, and finally preparing a silica aerogel material with hydrophobic properties. The effects of different alkali leaching conditions, different sol pH, HMDSO dosage on the aerogel density and the changes of aerogel material properties and composition during the preparation process were investigated, and the reaction mechanism of silica aerogel preparation by atmospheric pressure drying was described. The results showed that the optimum conditions for alkali leaching were 20 wt% NaOH concentration, 2 h reaction time and 100 °C, and the desilication rate was 81.72%; the lowest Silica aerogel density of 108 mg/cm3 at pH 5 to 6; the lowest density of silica aerogel was 110 mg/cm3 at a modifier to wet gel volume ratio of 1:1.4.

PH sensitive in-situ gel for ophthalmic delivery of ofloxacin and dexamethasone sodium phosphate: Formulation, development, and evaluation

Ofloxacin and dexamethasone sodium phosphate will be used to create a gel-forming ocular medicine delivery system and examine its efficacy. Conventional dose forms have a number of drawbacks, including inadequate routes for drug transport to the posterior portion of ocular tissue, poor ocular drug bioavailability, and pulse-drug entry following topical administration and systemic exposure due to nasolacrimal duct outflow. Ofloxacin and Dexamethasone were obtained from Trimed Life Science Pvt. Ltd. Mumbai India. HPMC E50, Carbopol 930 was obtained from MET’s Institute of Pharmacy, Nashik. The developed formulation showed sustained drug release for 480 Minutes. While compared with marketed eye drop which shows drug release within 80 Minutes. The formulations were evaluated for different parameters like Clarity, pH of Sol, Gelling pH, Viscosity of Sol, Viscosity of gel, drug content, and Percentage Cumulative Drug Release. From these studies, formulation gives good clarity and satisfactory gelling pH along with good gelling capacity. The in situ gelling systems of Ofloxacin and Dexamethasone Sodium Phosphate were successfully developed. It also showed increased residence time with good gelling capacity at physiological pH and sustained drug release.

Facile sol-gel preparation of amorphous TiO2 nanoparticles under pH of 8 for synergistic adsorption-photocatalytic degradation of tetracycline

In this work, an amorphous TiO2 nanoparticle (8-AT) was prepared via the sol-gel route in which the pH of sol was facilely adjusted to 8 with ammonia. The characterization results of physicochemical properties revealed that as-prepared 8-AT had the particle size of 20–24 nm and specific surface area of 365.68 m2/g. The degradation of 8-AT for 20 mg·L−1 tetracycline (TC) aqueous solution achieved 93.9% within 30 min dark reaction and 60 min visible light irradiation, which was 1.3 and 2.0 times higher than that of anatase TiO2 and P25. Moreover, 8-AT can maintain a degradation capacity of 82.7% for the concentrations up to 50 mg·L−1 of TC, and the degradation rate decreased slightly by 11.86% after five cycles. Based on the synergistic adsorption-photocatalytic activity of 8-AT catalyst, the possible degradation mechanism of TC was proposed. This work provided a facile method for obtaining amorphous TiO2 through adjustment of pH and a new idea for developing efficient photodegradation catalyst.

An efficient amine-modified silica aerogel sorbent for CO2 capture enhancement: Facile synthesis, adsorption mechanism and kinetics

At present, how to develop an economical and efficient solid adsorbent for CO2 capture at low temperature still remains a challenge. In this work, amine-modified silica (SiO2) aerogels were achieved by grafting with 3-(Aminopropyl) triethoxysilane (APTES) through a simple ambient pressure drying process, and verified as efficient adsorbents for CO2 capture. The effects of sol pH value and APTES concentration on the microstructure and CO2 adsorption property of as-prepared amine-modified silica aerogels (AMSAs) were investigated in detail. A double exponential model was proposed to reveal the kinetics adsorption mechanism of the AMSAs for the first time. It demonstrated that the as-prepared AMSAs were amorphous with a three-dimensional network structure composed of nanoparticles. And the AMSAs presented a high CO2 adsorption capacity of 3.37 mmol·g−1 at 70 °C. After 10 adsorption-desorption cycles, the AMSAs still kept 87.6% of the original capacity, exhibiting long cycle stability. Moreover, the kinetic adsorption behavior could be well simulated by the double exponential model, and the CO2 diffusion process was the speed-controlling step in the whole CO2 adsorption process. The diffusion active energy of AMSAs on CO2 capture was also calculated. This synthesis method is facile and environmental-friendly, which is of great significance to the large-scale production of SiO2 aerogel, and may provide a novel reference for the preparation of CO2 low-temperature adsorbents with high adsorption performance and good cycle stability.

Synthesis and Optimization of Superhydrophilic-Superoleophobic Chitosan-Silica/HNT Nanocomposite Coating for Oil-Water Separation Using Response Surface Methodology.

In this current study, facile, one-pot synthesis of functionalised nanocomposite coating with simultaneous hydrophilic and oleophobic properties was successfully achieved via the sol–gel technique. The synthesis of this nanocomposite coating aims to develop a highly efficient, simultaneously oleophobic-hydrophilic coating intended for polymer membranes to spontaneously separate oil-in-water emulsions, therefore, mitigating the fouling issue posed by an unmodified polymer membrane. The simultaneous hydrophilicity-oleophobicity of the nanocoating can be applied onto an existing membrane to improve their capability to spontaneously separate oil-in-water substances in the treatment of oily wastewater using little to no energy and being environmentally friendly. The synthesis of hybrid chitosan–silica (CTS-Si)/halloysite nanotube (HNT) nanocomposite coating using the sol–gel method was presented, and the resultant coating was characterised using FTIR, XPS, XRD, NMR, BET, Zeta Potential, and TGA. The wettability of the nanocomposite coating was evaluated in terms of water and oil contact angle, in which it was coated onto a polymer substrate. The coating was optimised in terms of oil and water contact angle using Response Surface Modification (RSM) with Central Composite Design (CCD) theory. The XPS results revealed the successful grafting of organosilanes groups of HNT onto the CTS-Si denoted by a wide band between 102.6–103.7 eV at Si2p. FTIR spectrum presented significant peaks at 3621 cm−1; 1013 cm−1 was attributed to chitosan, and 787 cm−1 signified the stretching of Si-O-Si on HNT. 29Si, 27Al, and 13H NMR spectroscopy confirmed the extensive modification of the particle’s shells with chitosan–silica hybrid covalently linked to the halloysite nanotube domains. The morphological analysis via FESEM resulted in the surface morphology that indicates improved wettability of the nanocomposite. The resultant colloids have a high colloid stability of 19.3 mV and electrophoretic mobility of 0.1904 µmcm/Vs. The coating recorded high hydrophilicity with amplified oleophobic properties depicted by a low water contact angle (WCA) of 11° and high oil contact angle (OCA) of 171.3°. The optimisation results via RSM suggested that the optimised sol pH and nanoparticle loadings were pH 7.0 and 1.05 wt%, respectively, yielding 95% desirability for high oil contact angle and low water contact angle.

Novel synthesis of ultrafiltration membranes by crosslinking metal (II)-Alginate hydrogels with hexamethylene 1,6 -Diisocyanate in inert solvent: Application for remediation of wastewater by removal of toxic pollutants

Hexamethylene 1,6- diisocyanate (HDI) crosslinking agent has been used for novel synthesis of ultrafiltration (UF) membranes from polysaccharide derivatives as natural polymers for the first time. This process takes place by crosslinking the soft membranes of Cu (II)-alginate hydrogels (Cu-Alg2)n with 9 % of (HDI) in dryness acetone (DA) for obtaining its corresponding (CCu-Alg2)n as UF membranes. These new crosslinking membranes can be used for uptaking the toxic metal ion contaminants from wastewater in purification of drinking water. The pore size in such membranes can be controlled by varying the pH of the alginate sol using either NaH2PO4 or Na2HPO4 simple salts. The formed crosslinking membranes (CCu-Alg2)n were characterized by the elemental, FTIR and SEM/EDAX analyses. The experimental results of the crosslinking membranes (CCu-Alg2)n in its hydrogen form (CH2-Alg2)n showed high affinity for removal of some divalent metal ions such as Cu2+, Ni2+, Co2+, Cd2+ and Pb2+ ion pollutants at the pH s 2–6. Also, they revealed high selective separation of some tested metal ions such as Ag+ and Cu2+ from electrolyte mixtures involving these metal ions with other divalent metal ions (0.1–0.5 mmole /L) at 25 °C. Again, such crosslinking membranes of (CCu-Alg2)n has proven high capability for isolation the Serratia marcescens Grahams-negative fine bacterium from contaminated media. The nature of geometrical configuration for chelation of Cu (II) ions with the alginate functional groups (–COO– and –OH) in its non-crosslinked (Cu-Alg2)n and crosslinked with HDI membranes (CCu-Alg2)n were suggested and discussed.

Physicochemical Properties of Mesoporous Organo-Silica Xerogels Fabricated through Organo Catalyst.

The physicochemical properties of organo-silica xerogels derived from organo catalyst were pervasively investigated, including the effect of one-step catalyst (citric acid) and two-step catalyst (acid-base), and also to observe the effect of sol pH of organo-silica xerogel toward the structure and deconvolution characteristic. The organo-silica xerogels were characterized by FTIR, TGA and nitrogen sorption to obtain the physicochemical properties. The silica sol–gel method was applied to processed materials by employing TEOS (tetraethyl orthosilicate) as the main precursor. The final molar ratio of organo-silica was 1:38:x:y:5 (TEOS:ethanol: citric acid: NH3:H2O) where x is citric acid concentration (0.1–10 × 10−2 M) and y is ammonia concentration (0 to 3 × 10−3 M). FTIR spectra shows that the one-step catalyst xerogel using citric acid was handing over the higher Si-O-Si concentration as well as Si-C bonding than the dual catalyst xerogels with the presence of a base catalyst. The results exhibited that the highest relative area ratio of silanol/siloxane were 0.2972 and 0.1262 for organo catalyst loading at pH 6 and 6.5 of organo-silica sols, respectively. On the other hand, the organo-silica matrices in this work showed high surface area 546 m2 g−1 pH 6.5 (0.07 × 10−2 N citric acid) with pore size ~2.9 nm. It is concluded that the xerogels have mesoporous structures, which are effective for further application to separate NaCl in water desalination.

Sol pH-induced zinc–titanium mixed-oxide multi-phase composite and its photocatalytic properties

ZnO-TiO2 nanocomposites were synthesized via sol–gel technique in varying sol pH and the effects of pH on the composites’ properties studied. The variation of crystallinity with pH was determined using the X-ray diffraction (XRD), particle morphology by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. UV–Visible diffuse reflection spectroscopy (DRS) and photoluminescence (PL) were used for the optical characterization whereas the Fourier transform infrared was used to determine the chemical bonds. Nitrogen adsorption–desorption was used for the textural properties. The obtained crystallite sizes ranged between 16.7–28.5 nm with the largest sizes at pH 4 while SEM and TEM images revealed particles of different morphologies observed at different pH levels. For the ZnO-TiO2 catalyst synthesized at pH1, a mixture of rod-like particles with trace agglomerations composed much smaller particles were formed. In all the other pH values, varied sizes of spherical particles were seen. The optical properties divulged band gaps that were governed by the obtained crystallite sizes. It was noted that the smallest Eg was recorded at pH 4 and was well-matched with the highest intensity of PL emission. Photocatalytic tests conducted also confirmed that by direct control of the crystallite sizes and the bandgap by varying the sol pH, photodegradation rate can be increased. The highest rate was obtained at pH 4 attributed to higher crystallinity and strong porosity as compared to the other pH levels.

PH-Dependent Morphology Control of Cellulose Nanofiber/Graphene Oxide Cryogels.

The precise control of the ice crystal growth during a freezing process is of essential importance for achieving porous cryogels with desired architectures. The present work reports a systematic study on the achievement of multi-structural cryogels from a binary dispersion containing 50 wt% 2,2,6,6-tetramethylpiperidin-1-oxyl, radical-mediated oxidized cellulose nanofibers (TOCNs), and 50 wt% graphene oxide (GO) via the unidirectional freeze-drying (UDF) approach. It is found that the increase in the sol's pH imparts better dispersion of the two components through increased electrostatic repulsion, while also causing progressively weaker gel networks leading to micro-lamella cryogels from the UDF process. At the pH of 5.2, an optimum between TOCN and GO self-aggregation and dispersion is achieved, leading to the strongest TOCN-GO interactions and their templating into the regular micro-honeycomb structures. A two-faceted mechanism for explaining the cryogel formation is proposed and it is shown that the interplay of the maximized TOCN-GO interactions and the high affinity of the dispersoid complexes for the ice crystals are necessary for obtaining a micro-honeycomb morphology along the freezing direction. Further, by linking the microstructure and rheology of the corresponding precursor sols, a diagram for predicting the microstructure of TOCN-GO cryogels obtained through the UDF process is proposed.

Synthesis and characterization of MgAl2O4 spinel precursor sol prepared by inorganic salts

Magnesium aluminate (MgAl2O4) spinel precursor sol was prepared using aluminum nitrate and magnesium nitrate as the precursors for alumina and magnesia, respectively. The obtained sol owned a translucent, homogenous, and stable appearance with a density of 1.19 g/cm3, and at the temperatures above 60 °C, converted to a soft and clear gel. The measured pH of sol was in the range of 3–4, and at the calcination temperature of 1000 °C, the solid content of 6% was reached. TGA/DSC analysis was utilized to study the thermal behavior of the sol. Fourier transforms infrared spectroscopy (FTIR) was applied to recognize the existing bounds in the dried and calcined sol. X-ray diffraction patterns revealed the formation of single-phase MgAl2O4 up to 600 °C. According to the FESEM images, the grain size for the sol calcined at 1000 °C was estimated at around 50 nm.

Monolithic and transparent sol-gel derived lithium-mica nano-glass-ceramic for optical applications

The objective of the present research is to demonstrate the possibility of fabricating a transparent monolithic lithium-mica nano-glass-ceramic by a sol-gel route. The transparent bulk glass-ceramic was successfully prepared using the drying control chemical additive (N,N-dimethyl formamide) along with an appropriate heat treatment schedule (final heating temperature = 662°C) for the LiMg3AlSi3(1+x)O10+6xF2 (x=0.66) glass-ceramic with MgF2 content of 6.95 wt%. The transparency of the dried gel depended on the synthesis conditions such as sol pH and the amount of added water as well as solvents. The results also revealed that the pH range of 2-3.5 is optimal to provide transparent gel. Moreover, at this pH range, the crack-free dried gel was acquired at the water to chemicals molar ratios of 6 to 8. In such conditions, the molar ratios of solvents to chemicals were determined 25 to30.

The synergistic role of pH and calcination temperature in sol–gel titanium dioxide powders

Titanium dioxide (TiO2) nanoparticles were prepared by the sol–gel method starting from a volume of 1.5 mL of titanium tetraisopropoxide (TTIP) dissolved in 10 mL of ultrapure water milliQ grade (pH 5). The pH of the solution was adjusted by adding HNO3 and NaOH to reach an acidic and basic character of the sol, respectively. A wide pH range from 1 to 10 was explored. The prepared TiO2 nanopowders were annealed at three different calcination temperatures, 100, 450 and 800 °C for 3 h. The synergic effect of pH and calcination temperature on the structural and morphological properties of TiO2 nanoparticles was investigated by XRD and Raman analyses. At the lowest (100 °C) and highest (800 °C) calcination temperatures, we observed the dominance of anatase and rutile phases, respectively. A mixture of these phases was observed for the titania powders calcinated at 450 °C. In particular, the nanoparticles produced in strong acidic medium showed a coexistence of anatase and rutile with a dominance of rutile, whereas the anatase was the crystalline phase favored in alkaline medium environment.

AGRO-ECOLOGICAL SUBSTANTIATION OF THE MELIORATIVE ACTIVITIES TO IMPROVE THE STATE OF SOILS OF KALINOVSKY DISTRICT

Agricultural production is one of the factors for the deterioration of the agro-ecological state of the environment and the anthropogenic-man-made changes in all its components. After analyzing the results of the research, it can be argued that the soils of the Kalinovsky region are characterized as medium-provided with humus, an indicator in the range of 2.21-4.01%. The content in the topsoil of mobile phosphorus is 10.0 mg/100 g of soil, mobile potassium 8.3 mg./100 g of soil related to the well-being, salt pH is 5.9. To carry out reclamation measures and reduce the areas of soil acidity to neutral and close to them values, it is necessary to have highly acidic soils with pH of salt. 4.5 and Нr 5.4 mg.eq/100 g produce lime with a rate of 5.4 t/ha; average oxygen with pH of sol. 4.8 and Нr 4.7 mg.eq/100 g to lime with the norm of lime 4.7 t/ha and slightly acid with pH of salt 5.4 and Hr 3.1 mg. Eq/100 g – 3.1 t/ha.

Organic solvent-saving preparation of water glass based aerogel granules under ambient pressure drying

An organic solvent-saving method of preparing silica aerogel is reported. The silica aerogel was made from water glass (WG) and used as the solvent. Na+ was removed through ion exchange; prior to this ion exchange, concentrated hydrochloric acid (HCl) was added to the WG solution. The sol pH was adjusted to ~1 to suppress the condensation to the maximum extent. Ethanol was added to the sol after ion exchange. Surface modification was conducted with the assistance of hexamethyldisiloxane, which was catalyzed by HCl. The entire process can be finished in 6 h. The overall consumption of organic solvent is much lower than that in the previous preparation route. Characterization results indicate that the resulted silica aerogel has a uniform mesoporous structure and low thermal conductivity (0.0237–0.0245 W/m·K at 1 atm).

Removal of Hg0 from a simulated flue gas by photocatalytic oxidation on Fe and Ce co-doped TiO2 under low temperature

Fe and Ce co-doped TiO2 composites were synthesized by a sol-gel method and subsequently employed as a photocatalyst to oxidize elemental mercury (Hg0) from a zinc smelting flue gas. Hg0 photo-oxidation were conducted under UV irradiation (253.7 nm). A series of influence factors have been investigated: calcination temperature, pH of the sol, amounts of Fe2O3 and CeO2, reaction temperature and flue gas components. Hg0 photo-oxidation efficiency as high as 95% at 30 °C was obtained over Fe5Ce5Ti synthesized at the sol pH = 6 as a result of the optimum optical absorption properties and maximum specific surface area (109.543 m2/g) of this material. Besides, O2 and SO2 contributed to favor photo-oxidation of Hg0 while NO exhibited inhibition. Based on UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) revealed a red-shifted absorption edge for Fe5Ce5Ti, which prevented the recombination of the photogenerated charge carriers and decreased the band gap width (2.34 eV). In addition, X-ray photoelectron spectroscopy (XPS) indicated that HgO was the main species of the mercury on the used Fe5Ce5Ti sample. This species was generated by photo-oxidation of Hg0 with Oβ, O2− and h+.

Deposition and characterization of spin-coated n-type ZnO thin film for potential window layer of solar cell

Spin-coating technique has been utilized to deposit ZnO thin films on ITO substrates. The dependence of the structural, optical, and electrical properties of the prepared films on both the sol–pH values and annealing temperatures has been investigated. X-ray diffraction analysis has revealed that the optimal sol–pH value was found to be 8 at annealing temperature 450 °C. At these conditions, the optical transmission and reflection data have also shown a clear enhancement in both the morphology and the grain size of the films. In addition, the analysis of I–V and C–V measurements of the Schottky Au/ZnO diode has shown a high agreement with both the investigated structural and optical properties. Furthermore, a new empirical method based on the calculated electrical parameters in the context of both the thermionic emission and Mott–Schottky models has been proposed to evaluate the approximate value of the electron effective mass in the conduction band of the ZnO (m* = 0.224 mo).

Direct production of lignin nanoparticles (LNPs) from wood using p-toluenesulfonic acid in an aqueous system at 80°C: characterization of LNP morphology, size, and surface charge

Abstract Lignin nanoparticles (LNPs) from renewable lignocelluloses can be a valuable building block for a variety of applications and could contribute to the economic development in rural agricultural communities. Current technologies for producing LNPs are not cost effective and use toxic solvents. In this study, LNPs were produced by fractionating poplar wood at ≤80°C with a recyclable hydrotrope p-toluenesulfonic acid (p-TsOH) in an aqueous system. The dissolved lignin was separated as LNPs simply by diluting the spent liquor (SL) to the minimal hydrotrope concentration (HCmin) of 11.5%. The p-TsOH, a solid acid, can be easily recycled by re-concentrating the diluted SL after lignin separation. The LNP size, morphology, and surface charge were controlled by the dilution ratio, speed, pH, and ionic strength of the LNP sol. The LNPs were analyzed by dynamic light scattering (DLS) and found to be fairly stable in terms of mean particle size and surface charge over a period of 2 weeks. Fractionation conditions also affected LNP properties.

Development of Alkoxide Precursors-Based Hybrid Coatings on Ti-6Al-4V Alloy for Biomedical Applications: Influence of pH of Sol

The Ti-6Al-4V alloy, widely used in biomedical applications, is associated with cytotoxic effects due to the release of aluminum and vanadium ions in the human body. One of the most effective ways to control the release of cytotoxic ions is through anti-corrosive coatings. Among them, the alkoxysilanes stand out for their good barrier properties and the absence of toxicity. Aiming to improve the clinical success rate of metallic implants, this study sets out to evaluate the influence of the pH of the sol on the physico-chemical, morphological, mechanical and electrochemical characteristics of hybrid films based on 3-(trimethoxysilylpropyl)methacrylate (MAP) and tetraethoxysilane (TEOS) applied to Ti-6Al-4V. The film was prepared by using the sol–gel method for pH values of 3, 4, and 5. The results indicated that maintaining the pH of the sol at 4 favors the hydrolysis rate of alkoxide precursors, which results in a uniform, dense and adherent film with excellent anti-corrosion performance.