N-Containing Hybrid Composites Coatings for Enhanced Fire-Retardant Properties of Cotton Fabric Using One-Pot Sol–Gel Process

In this report, a unique methodology/process steps were followed using Sol–gel-based concept to deposit thin flame-retardant coatings on cotton fabric. Surface microstructure and compositional analysis of the coated cotton were carried out using scanning electronic microscope (SEM), which explored significant coverage of the fabric. The obtained samples were further analyzed through rupturing mechanism test and color check. Compositional investigation of the coated samples was carried through Attenuated total reflection Fourier transform infrared (ATR–FTIR) and energy-dispersive X-rays spectroscopy (EDS) analysis. Thermal analyses were carried out through Thermogravimetric analysis (TGA) and Vertical flame tests (VFT), which suggested higher resistance of the coatings obtained for 5 h and zero heat-treatment time on the cotton fabric. A 28.86% char residue was obtained for the same sample (ET–5h–RT) coupled with higher degradation temperature and excellent combustion properties

PHOTOCATALYTIC DEGRADATION KINETICS OF PESTICIDE RESIDUES IN DIFFERENT pH WATERS USING METAL-DOPED METAL OXIDE NANOPARTICLES

We report the dissipation behavior of pyrazosulfuron-ethyl under direct sunlight using iron-doped titanium dioxide nanoparticles (FeTiO2) as a catalyst. The test was carried out by reinforcement three varying aqueous pH solutions with pH~4.0,7.0 and 9.0 to make the homogeneous concentrations of T0 – untreated control, T1 – pyrazosulfuron-ethyl 70% WG @ 1 mg/L of pH water and T2 – pyrazosulfuron-ethyl 70% WG @ 2 mg/L of pH water. The fortified test samples were exposed to sunlight. The sampling occasions were 0, 1, 5, 10, 24, 48, 72 and 96th hours for all three different aqueous solutions having pH ~ 4.0 (acidic water), 7.0 (neutral water) and 9.0 (basic water). The acquired samples were quantified using validated high-pressure liquid chromatography with UV detection technique. The pyrazosulfuron-ethyl half-life (DT50) was calculated from the dissipation results by regression equation. The FeTiO2 nanoparticles were determined to be a wonderful decontaminating catalyst for pyrazosulfuron-ethyl in various water samples

Enhanced Thermal Properties of Zirconia Nanoparticles and Chitosan-Based Intumescent Flame Retardant Coatings

Zirconia (ZrO2)-based flame retardant coatings were synthesized through the process of grinding, mixing, and curing. The flame retardant coatings reinforced with zirconia nanoparticles (ZrO2 NPs) were prepared at four different formulation levels marked by F0 (without adding ZrO2 NPs), F1 (1% w/w ZrO2 NPs), F2 (2% w/w ZrO2 NPs), and F3 (3% w/w ZrO2 NPs) in combination with epoxy resin, ammonium polyphosphate, boric acid, chitosan, and melamine. The prepared formulated coatings were characterized by flammability tests, combustion tests, and thermogravimetric analysis. Finally, char residues were examined with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The peak heat release rate (PHRR) of the controlled sample filled with functionalized ZrO2 NPs was observed to decrease dramatically with increasing functionalized ZrO2 NPs loadings. There was an increase in the limit of oxygen index (LOI) value with the increase in the weight percentage of ZrO2 NPs. The UL-94V data clearly revealed a V-1 rating for the F0 sample; however, with the addition of ZrO2 NPs, the samples showed enhanced properties with a V-0 rating. Thermal gravimetric analysis (TGA) results revealed that addition of ZrO2 NPs Improved composite coating thermal stability at 800 °C by forming high residual char. The results obtained here reveal that the addition of ZrO2 NPs in the formulated coatings has shown the excellent impact as flame retardant coatings

(EDTA)4− supplements as superior modifier of the in-vitro-degradation properties of the magnesium alloy coated through discharge-assisted process

The (EDTA)4− organic substituents were supplemented with alkaline silicates electrolyte, however in varying concentration to explore the microstructure, chemical composition and subsequent effects on the biodegradation of the PEO coated Mg AZ91 alloy. From surface analysis-, carried out through SEM, samples with zero-(EDTA)4− were found-, lacking pancake structural features; however, supplementing electrolyte with (EDTA)4−, bulky and layered pancakes were obtained with minimum cracks and minimum porosity for EDT-1. From the phase and inner layer analysis, it was found that EDTA can significantly alter the surface layers composition and could act as a passivation agent-; however, individual polycrystalline phases were not found to form. The hardness value obtained for EDT-1 was ∼909.69 HV, the highest value found here which occurs with the shallowest indents found in this study. In-vitro degradation analysis was carried out using potentiodynamic polarization at room temperature, cyclic polarization at RT and high fever conditions (HFT ∼40 °C). The corrosion potential for coated AZ91 was obtained as a positive value of ∼ 0.1 V, for the first time in the PEO research; however, the results were not supported by the cyclic polarization tests at room temperature and at HFT. The post corrosion microstructural analysis confirmed the effective role of EDTA up to 1.0 g·L−1 and revealed the formation of thin films during the forward polarization at HFT

Effect of K2ZrF6 Concentration on the Two-Step PEO Coating Prepared on AZ91 Mg Alloy in Alkaline Silicate Solution

In this study, a two-step Plasma Electrolytic Oxidation (PEO) method with constant primary step parameters and varying K2ZrF6 concentration in the secondary electrolyte solution was carried out to obtain a hard and dense coating on AZ91D alloy. For lower concentrations of K2ZrF6, a mixture of granular and pancake structure with higher surface porosity was obtained. Increasing the concentration up to 6 g/L caused the granular structure to disappear and a significant decrease was observed in the surface porosity as well as inner layer damage. Due to the compact inner layer structure, significant improvement in the corrosion resistance and mechanical properties of the AZ91 was observed with K2ZrF6 concentration. Highest values of hardness and corrosion resistance, i.e., 1589.45 HV and 386.30 × 103 Ω cm2, respectively, were obtained for a 6 g/L K2ZrF6 concentration

Effects of Hybrid Voltages on Oxide Formation on 6061 Al-alloys During Plasma Electrolytic Oxidation

AbstractPlasma electrolytic oxidation (PEO) is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na2SiO3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration (XRD), scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current (DC) values (140-280 V) with constant alternate current (AC) amplitude (200 V). Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al2O3, γ-Al2O3 and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature

Influence of Zinc Oxide Nanoparticles and Char Forming Agent Polymer on Flame Retardancy of Intumescent Flame Retardant Coatings

Zinc oxide nanoparticles (ZnO NPs) were synthesized by a precipitation method, and a new charring–foaming agent (CFA) N-ethanolamine triazine-piperazine, melamine polymer (ETPMP) was synthesized via nucleophilic substitution reaction by using cyanuric chloride, ethanolamine, piperazine, and melamine as precursor molecules. FTIR and energy-dispersive X-ray spectroscopy (EDS) studies were employed to characterize and confirm the synthesized ETPMP structure. New intumescent flame retardant epoxy coating compositions were prepared by adding ammonium polyphosphate (APP), ETPMP, and ZnO NPs into an epoxy resin. APP and ETPMP were fixed in a 2:1 w/w ratio and used as an intumescent flame-retardant (IFR) system. ZnO NPs were loaded as a synergistic agent in different amounts into the IFR coating system. The synergistic effects of ZnO NPs on IFR coatings were systematically evaluated by limited oxygen index (LOI) tests, vertical burning tests (UL-94 V), TGA, cone calorimeter tests, and SEM. The obtained results revealed that a small amount of ZnO NPs significantly increased the LOI values of the IFR coating and these coatings had a V-0 ratings in UL-94 V tests. From the TGA data, it is clear that the addition of ZnO NPs could change the thermal degradation behaviors of coatings with increasing char residue percentage at high temperatures. Cone calorimeter data reported that ZnO NPs could decrease the combustion parameters including peak heat release rates (PHRRs), and total heat release (THR) rates. The SEM results showed that ZnO NPs could enhance the strength and the compactness of the intumescent char, which restricted the flow of heat and oxygen

Unravelling the Anisotropic Behavior of Nickel—Wires Prepared through External Magnetic Field Assisted Hydrazine Reduction Method

Ni wires, prepared through a hydrazine reduction, were exposed to external magnetic fields of different geometrical shape and configuration during the synthesis denoted as Ni-Non-Magnetic, Ni-Double, Ni-Single, Ni-Ring. Their effect on the wire morphology, magnetization and magnetic anisotropy was then investigated via various characterization techniques viz. X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (HR-FESEM), and vibrating sample magnetometer (VSM). The polycrystalline single phase of the Ni-wires with face centered cubic symmetry was confirmed through the analysis of XRD patterns. Analysis of HR-FESEM images revealed that the Ni-particles were aligned in form of wire-like morphology. The Ni-single sample formed the wires with minimum diameter compared to the parent sample. The magnetization measurements performed at 300 K and 50 K demonstrated the ferromagnetic behavior of all the samples. The room temperature saturation magnetization (MS) and anisotropy constant (K) of the Ni-wires were reduced upon providing the external field during synthesis. However, the low temperature (50 K) magnetization behavior was rather opposing, indicating enhanced values of MS and K. Among all, Ni-ring sample showed maximum anisotropy with a value of 3.84 × 104 erg/cm3 at 50 K. The ambiguous nature of the anisotropic constant and saturation magnetization ascribed partly to the variation in diameters of Ni-wires and to the intermittent spin-spin exchange interactions of unaligned/partially aligned particles during the synthesis. Briefly, in the present study, it was established that the morphology and magnetic anisotropy of the Ni-wires could be tailored through the external magnetic field assisted synthesis method