Immersion In Acid Solution Research Articles

Highly stable self-cleaning antireflection coatings from fluoropolymer brush grafted silica nanoparticles

Self-cleaning antireflection coatings have potential applications in outdoor conditions and have been the subject of intense study. However, self-cleaning antireflection coatings are commonly prepared via grafting of small hydrophobic molecules, which are susceptible to detachment from the coatings due to hydrolysis, leading to considerable degradation of the self-cleaning functionality in practical applications. Here, we create fluoropolymer brush grafted silica antireflection coatings that demonstrate long-term self-cleaning performance. Fluoropolymer brush grafted silica nanoparticles were synthesized via surface initiated atom transfer radical polymerization and then coated on glass substrates to form antireflection coatings. The brush grafted coatings exhibited excellent transmission, with nearly 100% transmittance at a desired wavelength. The fluoropolymer brushes rendered the coatings hydrophobic, with water contact angle of 122°. Owing to their hydrophobicity, the brush grafted coatings exhibited excellent self-cleaning functionality. A notable advantage of the brush grafted coatings was their stable self-cleaning functionality. The brush grafted coatings remained their hydrophobicity after immersion in acidic solution, with water contact angle being constant at 122°, which were more stable than the small molecule modified hydrophobic coatings. This work opens a new avenue to create highly stable self-cleaning antireflection coatings that will find applications in harsh conditions.

Fabrication of a biomimetic hierarchical superhydrophobic Cu-Ni coating with self-cleaning and anti-corrosion properties

Many attentions have been attracted to prepare superhydrophobic coatings on the metal surfaces for their prominent properties, especially the self-cleaning and anti-corrosion properties. In this work, a facile electrodeposition method was applied to fabricate hierarchical Cu-Ni coating on the 316 L stainless steel, and the followed myristic acid modification was used to lower the surface energy. The water droplet would remain spherical on this coating, and measured water contact angle and sliding angle were 161.27° and 7.8°, respectively. The contaminants on the coating surface could be easily carried away by the closed water droplets. In addition, the coating could effectively hinder the deposition of salt solution. Besides, the coating could endure long-term acid solution immersion and natural placement. Moreover, it was verified that this superhydrophobic Cu-Ni coating formed a robust barrier to block the transmission of chlorine ions, thus corrosion damage to steel surface could be effectively relieved. This superhydrophobic Cu-Ni coating provides a novel strategy and promising applications for preventing various metal surfaces from being contaminated and corroded.

Chemical Resistance of Nano Silica Added Concrete

This study investigated the effects of nano silica on acid and sulphate resistance of concrete. The changes in mass and compressive strength of the concrete specimens for different immersion periods were determined. It was observed that, M 30 grade concrete produced with 0 %, 1 %, 2 %, 3 % nano silica have shown mass loss of 11.24 %, 9.01 %, 5.10 % and 3.59 % respectively at 56 days of immersion in acid solution. M 40 grade concrete produced with 0 %, 1 %, 2 %, 3 % nano silica have shown mass loss of 9.36 %, 8.71 %, 4.98 % and 3.56 % respectively at 56 days of immersion in acid solution. M 30 grade concrete produced with 0 %, 1 %, 2 %, 3 % nano silica have shown mass loss of 2 %, 1.55 %, 1.26 % and 0.91 % respectively at 56 days of immersion in sulphate solution. M 40 grade concrete produced with 0 %, 1 %, 2 %, 3 % nano silica have shown mass loss of 1.63 %, 0.82 %, 0.43 % and 0.29 % respectively at 56 days of immersion in sulphate solution. Similarly, the reduction in compressive strength after immersion in acid and sulphate solution was observed with the addition of nano silica. Among the two chemical environments, sulfuric acid was found to be most dangerous for all concrete mixes. Concrete mixes produced with nano silica showed superior durability.

Multidisciplinary Approach on the Corrosion Behavior of Welded Nickel-free and Nickel-containing Stainless Steel Orthodontic Wires

The oral environment is responsible to the degradation of metal wires, with consequent release of metal ions in the oral cavity during corrosion, and welded joints are known as areas that are particularly susceptible to corrosion. The aim of the study was to achieve the corrosion behavior of welded Ni-free and Ni-containing stainless steel (SS) orthodontic wires. The morphology and the topography of the laser welded samples were investigated by scanning electron microscopy and atomic force microscopy. The electrochemical measurements calculated the values for corrosion potential, corrosion current and corrosion rate, for different pH values. Immersion in acidic solution had minimal effect on the corrosion on the joint regions. Ni-free SS wires proved to have a better corrosion resistance, improved by laser welding. Ni-containing SS wires are positive influenced by laser welding, relative to the corrosion behavior.

Enhanced mechanical properties and durability of coal gangue reinforced cement-soil mixture for foundation treatments

High-speed railways with high load capacity and long-term performance have been developed by the aid of high-performance construction materials for foundation treatments. The mechanical properties and durability of new cement-soil mixture reinforced by local sourced waste coal gangue aggregate were investigated in this study. Extensive experiments were carried out to analyse the effects of coal gangue on compressive strength, elastic modulus, stress-strain curve and anti-corrosion of cement-soil mixture. The results show that incorporation of coal gangue significantly improve the strength, stiffness and anti-corrosion ability of cement-soil mixture. Strength improvements up to 81.8% was achieved, but the ductile failure model shited to brittle failure with more than 42% coal gangue reinforcements. Except for the declining segment of the stress-strain curve, the ascending segment of the stress-strain curve can be fitted by the existing models. From the microstructural characterization, coal gangue can reduce acid solution permeation compared to the soil. For the cemented soil with coal gangue, the mass-loss rates only reach 4–7% after 140 days acid solution immersion. Therefore, this new clean production of high-performance cement-soil mixture through waste coal gangue reinforcement has great potential for railway foundation treatments.

Analysis of iron FC 250 microstructure under the effect of phosphoric acid corrosion

The study of the prevention of metals corrosion by phosphoric acid has been increasing, due to its vast use in industrial processes such as the production of fertilizers and food products. About 5% of the profits of industrialized nations are spent to prevent corrosion. Several studies have been carried out to determine the corrosive behavior of cast iron in acidic and basic medium, but the resistance to corrosion in phosphoric acid has not yet been studied. The present work analyses the effects of phosphoric acid (H3PO4) on the corrosion of FC 250 cast iron, in its structure and properties, using mass loss analysis and scanning electron microscopy (SEM). The studies were performed after samples immersion in acid solutions with concentrations of 1, 2 and 3% of content for 86,400 and 424,800 s at room temperature and in a solution of 3% at 323,15 K and 373,15 K, for 21,600 and 43,200 s. The main losses were found in the percentage of 3%, at higher temperatures and lower immersion time. H3PO4 promotes the oxidation state in gray cast irons, which can compromise their structure and properties. The higher percentage of the acid causes greater mass losses, the temperature reacts in an analogous way and, in longer exposure times, the loss is sustained.

Study of effect acidic solution (HCl) and (EP/Al2O3 & EP/ TiO2) hybrid on thermal conductivity of epoxy resin.

This research studies the effect of adding micro, nano and hybrid by ratio (1:1) of (Al2O3,TiO2) to epoxy resin on thermal conductivity before and after immersion in HCl acid for (14 day) with normality (0.3 N) at weight fraction (0.02, 0.04, 0.06, 0.08) and thickness (6mm). The results of thermal conductivity reveled that epoxy reinforced by (Al2O3) and mixture (TiO2+Al2O3) increases with increasing the weight fraction, but the thermal conductivity (k) a values for micro and Nano (TiO2) decrease with increasing the weight fraction of reinforced, while the immersion in acidic solution (HCl) that the (k) values after immersion more than the value in before immersion.

Mechanical and surface properties analysis of restorative materials submitted to erosive challenges in situ.

Objective:This study aims to evaluate the effect of acidic solutions (AS) on surface roughness (Ra) and microhardness of restorative materials (RM).Materials and Methods:Eight volunteers wore intraoral palatal devices (IPD) containing samples of RM: Ketac Nano (KN); Ketac Nano + Biscover LV (KN-B); Esthet-X (EX); Esthet-X + Biscover LV (EX-B); Supreme XT (SXT); Supreme XT + Biscover LV (SXT-B); and bovine enamel. The samples were submitted to three phases: (1) immersion in 0.01M hydrochloric acid (HCl) – 10 min, three times/day (14 days); (2) immersion in soft drink (Sprite®) – 10 min, three times/day (14 days); and (3) keeping in saliva (14 days). Changes in Ra/microhardness were measured before/after the three phases.Statistical Analysis:ANOVA (α = 0.05) and Fisher's test.Results:Materials sealed with Biscover LV (B) presented lowest values in all periods. KN glass ionomer cement showed highest Ra values after exposure in AS. Application of B did not reduce the Ra for the composites studied, except for EX after immersion in HCl. AS promoted changes in Ra/microhardness of RM, except for sealed materials.Conclusions:The acids used were able to change the Ra and microhardness of RM, except of the sealed materials. The resin-modified GIC showed the most significant changes after immersion in AS; and the composites sealed with B, even after immersion in acidic solutions (AS), showed the lowest Ra values and the least degradation in microhardness, especially when subjected to low pH solutions.

Corrosion of laser-welded stainless steel orthodontic wires

PurposeFabricating orthodontic appliances using laser welding has the clinical advantage of biocompatibility, because the welded joint does not require soldered alloy. The purpose of this study was to investigate the corrosion of laser-welded stainless steel wires in acidic environments. Materials and methodsLaser welding of stainless steel wires with a 0.021×0.025 in cross-section was performed at an energy output ranging from 0.5 to 1.3kW. A control sample was prepared using conventional soldering. The samples were immersed in 1% lactic acid aqueous solution for 7 days. After immersion, the concentrations of metallic ions in solution were measured using inductively coupled plasma atomic emission spectroscopy. Tensile loading tests were carried out with and without lactic acid immersion. Scanning electron microscopy was used to examine the microstructure of laser-welded samples. ResultsThe concentrations of metallic ions detected in solution for laser-welded samples were significantly lower than that for soldered sample. There was no significant difference among the mean tensile strengths with and without immersion for laser-welded samples. The penetration depth and the localized region fused by laser irradiation increased with energy output, and ductile fractures were observed in the fused region of laser-welded samples. ConclusionLaser welding of stainless steel orthodontic wires should be acceptable for clinical use, because the joints showed sufficient strength and the original structure was not significantly altered. Immersion in acidic solution had minimal effect on the mechanical performance at the joint regions, and showed minimal acceleration of metallic ion release.

Microhardness of different esthetic restorative materials: Evaluation and comparison after exposure to acidic drink

Acidic beverages, such as soft drinks (orange juice and cola), can produce erosion of resin composites. The aim of this in vitro study was to evaluate the effect of immersion in acidic drink on the Vickers microhardness (VK) of different esthetic restorative materials (one nanohybrid Ormocer-based composite, one nanoceramic composite, one nanofilled composite, and one microfilled hybrid composite). In this in vitro study, thirty specimens of each esthetic restorative material were divided into three subgroups (n = 10): specimens of group 1 were used as control, specimens of group 2 were immersed in 50 ml of acidic drink for 1 day, specimens of group 3 were immersed in 50 ml of acidic drink for 7 days. Data were analyzed by Shapiro-Wilk test to assess the normality of the distributions followed by nonparametric Kruskal-Wallis analysis of variance and Mann-Whitney U-test comparison test among groups. A significant level of α = 0.05 was set for comparison between the groups. Mann-Whitney U-test showed that each material showed lower microhardness values after immersion in acidic solution (P < 0.05). Paired t-test confirmed that microhardness for each composite did not change after immersion in distilled water (Control group) (P > 0.05). Significant changes were registered for all restorative materials after immersion in acidic solution for 1 day and 7 days (P < 0.05). The Filtek Supreme XTE, a nanofilled composite, and Admira Fusion, a nanohybrid ormocer-based composite, showed the best behavior. The Ceram X Universal (nanoceramic composite) although reached lower hardness values than the previous materials, but resisted well to the 1 week immersion in soft-drink. Finally, the Gradia Direct achieved the most disappointing results: Low microhardness values are justified by the nature of its filling (microfilled hybrid composite).

The effect of matrix type on ageing of thick vinyl ester glass-fibre-reinforced laminates

In this research, glass fibre reinforced composite laminate samples were manufactured with filament winding technique using four different vinyl ester resin systems to study ageing. The manufactured laminate samples were conditioned in an environmental cabinet (70°C, 95 RH%), water immersion (95°C), and in sulphuric acid solution immersion under pressure (5% H2SO4, 95°C, 15bar). After 6 and 12months of conditioning, the samples were tensile tested and the results were compared with the initial values. Regardless of the matrix type, conditioning in the environmental cabinet resulted in the lowest weight gain and least decrease in tensile properties: the decrease in the tensile strength values was 10–25% after 12months’ conditioning depending on the vinyl ester used. The water immersion was more detrimental to the samples than the 5% H2SO4 immersion causing the highest weight gain and the greatest decrease in tensile strength (up to 65%). However, when comparing the tensile performance, it was noted that the highest weight gain did not inevitably correlate with the strongest ageing effect. In water immersion, the ultimate strength deteriorates faster than the proof stress level leading to a decreasing damage tolerance of the vinyl-ester composite laminates.

Sorptivity and acid resistance of ambient-cured geopolymer mortars containing nano-silica

This study investigated the effects of nano-silica on flowability, strength development, sorptivity and acid resistance properties of fly ash geopolymer mortars cured at 20 °C. The changes in mass, compressive strength and microstructure of the specimens after immersion in acid solutions for different durations were determined. The microstructures were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. It was found that addition of nano-silica in geopolymer mortars based on fly ash alone or fly ash blended with 15% GGBFS or 10% OPC improved the compactness of microstructure by reducing porosity. Thus, the nano-silica reduced sorptivity and increased compressive strength of the mixes. The average mass loss after 90 days of immersion in acid solutions reduced from 6.0% to 1.9% by addition of 2% nano-silica. Similarly, significant reduction in strength loss after immersion in acid solution was observed in the specimens by using nano-silica.

Low-Permeability Poly(ether Ether Ketone)-Based Ampholytic Membranes.

Ion-exchange membranes based on sulfonated and sulfaminated poly(ether ether ketone) were prepared by a modified sulfamination route. In a first step, poly(ether ether ketone) was sulfonated. The sulfonic acid groups were then transformed into chlorosulfonic moieties by reaction with thionyl chloride. A proportion of the chlorosulfonic functionalities reacted with dimethylamine to give basic sulfonamide groups, whereas those remaining were hydrolyzed back to sulfonate moieties obtaining, after immersion in acidic solution, an ampholytic polymer. The thermal, mechanical, electrical, and permeability properties of these amphoteric membranes were characterized. These membranes exhibit good thermal and mechanical stability and ultra-low vanadium ion permeability. The type and value of ion conductivity can be adjusted by the choice of acidic or basic medium. The tunable ion conductivity and the low ion permeability are suitable characteristics for the development of high-performance separator membranes.

17. PENGARUH PENCELUPAN KARKAS AYAM PEDAGING DALAM LARUTAN ASAM SITRAT DAN ASAM ASETAT TERHADAP PENGHAMBATAN WAKTU PEMBUSUKAN The Immersion Effect of Broiler Carcass in Citric Acid and Acetic Acid On Spoilage Process Inhibition

The purpose of this research was to determine the immersion effect of chicken carcass in 3% citric acid, 3% acetic acid, and combination of 1.5% citric acid and 1.5% acetic acid on the spoilage time. A total of 36 broiler carcasses were divided into 4 treatment groups. The observation was conducted three times on 0, 4, and 8 hours. Broiler carcass in control group (K0) was without immersion in acid solution, while broiler carcass in first groups (K1), second groups (K2), and third groups (K3) were dipped in 3 % acetic acid, 3 % citric acid, and combination of 1.5 % acetic acid + 1.5 % citric acid, respectively. The data were analyzed using two way of analysis of variances. The average amount of spoilage chicken carcass in K0 vs K1 vs K2 vs K3 vs K4 on 0, 4, and 8 hours dipping were 0.0 vs 0.0 vs 0.0 vs 0.0, 1.0 vs 0.0 vs 0.33 vs 0.67, and 1.33 vs 1.33 vs 1.0 vs 1.33. The result showed that the immersion treatment was not significantly affect the spoilage time of the chicken carcass (P0.05), however the effect of treatment was significantly different between spoilage time (P0.05). The spoilage time were significantly differences (P0.05) between 0 and 4th hour (p= 0.008), 0 and 8th hour (p= 0.000), and 4th and 8th hour (p= 0.000). In conclusion, broiler carcass immersed in 3% acetic acid, 3% citric acid and their combination could inhibit spoilage time. ____________________________________________________________________________________________________________________ Key words: chicken carcass, citric acid 3%, acetic acid 3%, spoilage time

Acid Attack Resistance of Magnesium Phosphate Cement

Magnesium phosphate cements (MPC) had been used as repair materials for deteriorated Portland cement concrete structures. In this paper a new MPC was prepared and the basic properties including workability and compressive strength were tested. The acid attack resistance of MPC was investigated by immersing the MPC mortars in solutions at pH 3, 5, and 7, for 14d, 28d and 60d respectively. The compressive strength of MPC mortars after acid attack was tested and the microstructure of MPC were examined. The results showed that the compressive strength of MPC decreased after immersion in acid solution for 14d and 28d, however the strength of MPC with suitable materials mixture can recovered again after 60d immersion. The results indicated MPC has high acid attack resistance in static acid solution. The behavior of MPC in flowing acid solutions is need to be studied further.

STUDY OF THERMAL CONDUCTIVITY OF UNSTATURATED POLYESTER REINFORCED BY POLYPROPYLENE FIBERS

In this research has been manufacture of overlapping polymer of unsaturated polyester resin Reinforced by polypropylene fibers (PPF) with ratio weight , (0,4,6,8,10) gm from polypropylene fibers . And at room temperature it has been studied the thermal conductivity properties of this compound and identified practical results that the thermal conductivity in natural conditions decreases with increasing the ratio by mass of fibers of polypropylene in the compound, and the thermal conductivity values continue decreasing as ratio strengthened polyethylene fibers of polypropylene in the compound. Immersion and the solution of acid, the value of the thermal conductivity of all the samples increases with increasing duration of immersion in the acid solution, and when comparing the thermal conductivity values for samples with a period of immersion in the solution of acid with the dry state is evident that the difference in The increase in the value of thermal conductivity between the dry case and the case of immersion in acid solution increases whenever a period of immersion increased with the increase in the proportion of reinforcement fibers of polypropylene.

Experimental Study of the Acid Corrosion Effects on an Intumescent Coating for Steel Elements

Acid corrosion may cause the deterioration of the fire resistance of the intumescent fire retardant coatings. This paper reported the results of an experimental study of degradation in fire protection performance of intumescent coating for steel elements after different times of immersion in the hydrochloric acid solution. The morphology, the equivalent thermal resistance, and the changes of the elements and groups contained on the surface of the coatings were investigated. The corrosion mechanism was as follows: when the coating was immersed in the acid solution, the ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) underwent the process of acid catalyzed hydrolysis, dissolution, and chemical reaction, which led the change of the content ratio of the compositions and caused the deterioration of the coating fire resistance. A prediction method of the remaining fire resistance property for the acid corrosion coatings was proposed, by comprehensively considering the physical and chemical characteristic changing trends of the corroded coating.

Dependence of the abnormal protective property on the corrosion product film formed on H2S-adjacent API-X52 pipeline steel

The dependence of the protective property on the corrosion product film formed on API-X52 pipeline steel was investigated using the electro-chemical hydrogen permeation method in acidic solution under various H2S partial pressures. The hydrogen permeation current is dependent on the H2S concentration and the corrosion product film. The hydrogen permeation current increases with the H2S partial pressure, and decreases with thickening the corrosion product film. The dense corrosion product films formed in 1.0 MPa H2S shows the obvious protective property against hydrogen permeation, while the delamination of the corrosion product film formed in 0.1 MPa H2S weakens the protective property. The hydrogen permeation current in 1.0 MPa H2S is lower than that in 0.1 MPa H2S after 200 h immersion in acidic solution and this is of great significance to the service life prediction and the prevention of hydrogen embrittlement in H2S-adjacent pipelines.

Pretreatments Effect in Drying Behaviour and Colour of Mature and Immature ‘Napolitana’ Sweet Cherries

The effect of different treatments on drying behaviour and colour of mature and immature cherries (Napolitana var.) has been studied. Drying was carried out at 70 °C with air at 4 m/s speed and 8 % relative humidity, and fruits were subjected to the following pretreatments: B (blanching), F (freezing), P (pitting), B + Dip1 (blanching and immersion in acid solution) and B + Dip1 + Dip2 (blanching and immersion in saline acid solution) which affected the drying behaviour and the colour retention of fruits for both maturity degrees. Regarding skin colour in terms of chroma and hunter a parameters, the anthocyanin retention and the evaluation of anthocyanin degradation index, both B + dip1 and B + dip1 + dip2 pretreatments led to better-quality dry products, mainly in mature cherries. Moreover, the incorporation of blanching in the combined pretreatments significantly reduced drying time. Lewis, Page and Logarithmic models were selected to represent in a simple way the thin-layer drying characteristics of pretreated cherries and to predict the process times required to reduce the moisture content to about 0.3–0.4 kg water/kg dm (aw ≤ 0.6). Logarithmic model provided the best fit to experimental data for each drying curve, based on the statistical tests used for evaluation.

The Nanomechanical and Tribological Properties of Restorative Dental Composites after Exposure in Different Types of Media

The aim of this study was to evaluate the effects of various acidic solutions on the surface mechanical properties of commercial resin composites with different microstructures (Filtek Z350 XT, TPH3, Durafill, and Superlux). Specimens were immersed in orange juice, cola, and distilled water for 5 days and the nanohardness, elastic modulus, and wear behavior of the samples were determined via the nanoindentation test and a reciprocating nanoscratch test. The nanoscratch morphology was observed using scanning electron microscopy (SEM) and the wear depth was recorded by scanning probe microscopy (SPM). The results indicate that the nanofilled resin composites had the greatest hardest and highest elastic modulus, whereas the microfilled composites exhibited the lowest nanohardness and elastic modulus values. SEM observations showed that all resin composites underwent erosion and surface degradation after immersion in acidic solutions. Furthermore, the wear resistance was influenced by the composition of the acidic solution and was correlated with the nanohardness and elastic modulus. The dominant wear mechanism changed from plastic deformation to delamination after immersion in acidic solutions.