نشریه علم و مهندسی سرامیک
سال یازدهم شماره 4 (پیاپی 43، زمستان 1401)

Smart materials are those materials that can understand the environment and conditions around them and react to it. Magnetic memory alloys are a subset of smart materials whose shape and other mechanical properties change in response to magnetic and mechanical fields. Memory alloys in recent years due to their unique features such as high corrosion resistance, relatively high specific electrical resistance, relatively good mechanical properties, long fatigue, high plasticity and ability to adapt to the body in a wide range of Industries have been taken into consideration. These alloys are smart materials that can remember their original shape after being deformed. The purpose of presenting this article is to familiarize, use and examine the properties of magnetic memory materials. In fact, by presenting several studied models, structural equations, properties, their application in different fields and diagrams, we have tried to investigate these materials and addressed their existing challenges. One of the most important quantitative results of these materials is the magnetic memory effect of up to 6% increase in length, frequency response of 1-2KHZ, power density of 2Mpa, magnetic field smaller than 0.8T and Curie temperature of about 95-105℃, which is the necessity of using this material. It describes materials in different industries.

The aim of this study was to prepare titanium dioxide nanoparticles calcined at different temperatures to be used for adsorption of zinc ions from aqueous medium and then to investigate the kinetics and isotherms of the adsorption process. For this purpose, nanoparticles were synthesized using the sol-gel method and then calcinated at 450 °C and 800 °C. XRD, BET, FTIR, and SEM analyses were used to investigate the structural, surface, and chemical properties of the synthesized nanoparticles. Adsorption studies revealed that the solution containing zinc with an initial concentration of 10 mg/l had the highest adsorption efficiency under conditions of pH = 7, adsorbent concentration of 0.3 g/l, and temperature of 25 ° C. Under these conditions, adsorbents prepared at 450 °C and 800 °C achieved 99% and 92% adsorption efficiencies, respectively. Adsorption isotherm studies revealed that the Freundlich, Temkin, Langmuir, and Dubinin–Radushkevich isotherms had the best agreement with equilibrium sorption data, in that order. In addition, investigations on fitting into kinetic models revealed that the quasi-second-order, Elovich and the quasi-first-order equations had the best fit with experimental data, respectively.

Electrochemical capacitors have been considered for use in energy storage systems in recent years due to their high power density, high cycling stability, and optimal energy density. Binary metal oxides have been used by researchers to make electrodes due to their desirable morphological properties and better supercapacitive performance. In this study, manganese vanadate (Mn2V2O7) electrode was synthesized using two-step sol-gel and hydrothermal methods. Then, the characterization tests of XRD, FT-IR and SEM were used to determine the crystallographic and morphological properties. Characterization analyses showed that the electrode material of Mn2V2O7 was obtained with a hollow microbial morphology. Electrochemical tests of CV, GCD and EIS showed that the Mn2V2O7 electrode had excellent supercapacitive performance with a specific capacitance of 401 F/g at a current density of 1 A/g.

In this study, the electro catalytic properties of CoPSe nanostructured electrodes with different molar ratios of phosphorus to selenium in the electrode structure were investigated. These electrodes were synthesized by hydrothermal method on a nickel foam (as substrate) at 180 ° C for 5 hours in different molar ratios of phosphorus to selenium (0: 1, 2: 8, 4: 6, 1: 1 , 6: 4, 8: 2 and 1: 0) were prepared. Morphology of samples were synthesized by FE-SEM electron microscopy, atomic scattering of various elements in the structure were detected by element mapping analysis, element composition were detected by X-ray energy spectroscopy (EDS) technique, phase analysis and bond type Atomic samples were also examined by X-ray spectroscopy (XRD) and Fourier transform spectroscopy (FTIR). In order to determine the electrochemical quality performance, the electrodes were subjected to underwent cyclic polarization (CV), linear polarization (LSV) and electrochemical impedance (EIS) tests. According to the obtained data, the highest capacity and the sharpest reduction peak were in the cyclic polarization curve for CoPSe (6:4). The lowest over potential was in the linear polarization curve for HER at a current density of -20 mA/cm2 for CoPSe (6:4) and equal to -0.21 V. According to the electrochemical impedance test, none of the samples had capacitive properties and the lowest Rct was equal to (1.543 Ω) and belonged to the CoPSe (6:4) sample. Therefore, this sample was introduced as the best electrode synthesized in this study.

Carbon ion energy is a key factor in determining the amount of sp3 bonds in the structure of the amorphous carbon film and its like-diamond nature. In this study, the structural evolution of diamond-like carbon coating based on the mechanism of sp3 bond formation of amorphous carbon under the influence of the ion beam energy in the radio frequency ion-beam deposition process were investigated. For this purpose, the parameter of ion beam energy was 200, 300, and 400 eV ​​ for the deposition of DLC coatings. Raman and X-ray spectroscopy (XPS) analyzes were used to evaluate the structure and chemical composition of the coatings. Also, in order to determine the effect of ion beam energy on the surface roughness and thickness of the applied coatings, atomic force microscope (AFM) and field emission scanning electron microscope (FESEM) were used. Hardness and elastic modulus were measured by nanohardness test. According to the results of Raman analysis, the lowest value of ID/IG ratio was obtained in ion beam energy of 300 eV, which was equal to 0.66. The results of XPS analysis showed the lowest amount of sp2 bonds in the diamond-like carbon film at ion beam energy of 300 eV. Also, results of AFM analysis showed at ion beam energy of 300 eV, the surface roughness of diamond-like carbon coating has the lowest value. Due to the highest amount of sp3 bonds in the ion beam energy of 300 eV, the diamond-like carbon coating had the highest hardness and was equal to 10.6 GPa.

In this research, zirconia matrix composites stabilized by yttria with 7 and 14% by weight of nickel oxide were prepared by spark plasma sintering process. Investigation of phase changes by X-ray diffraction pattern showed the dominant peak of zirconia stabilized by yttria (YSZ) with tetragonal structure along with peaks with very low intensity of monoclinic phase of YSZ. Also, the addition of nickel oxide for composite samples led to the creation of nickel metal phase. The electron microscope images prepared from the polished surface of the samples showed relatively proper distribution of the nickel phase in the ground phase. Examining the physical and mechanical properties of the samples showed that the maximum fracture toughness (14.21 ± 0.19 MPa square meter), relative density (99.81% of theoretical density), bending strength (665 MPa) is related to the composite containing 14% by weight. It was nickel oxide. But regarding the Vickers hardness of the samples, the increase of nickel oxide in the composites led to a decrease in the hardness of the sample due to the formation of metallic nickel phase.

The production of nitrogen-doped graphene coating usually requires two or three time-consuming processes of graphene synthesis, nitrogen doping and deposition on substrate. In this study, nitrogen doped-turbostratic graphene-based material was synthesized and deposited on Nickel substrate by the cathodic plasma electrolysis process in one-step. The addition of urea, as nitrogen precursor, to ethanol electrolyte causes nitrogen doping of graphene structure and graphene formation by electrolytic plasma simultaneously. This process was carried out at the atmospheric pressure, under 800 V voltage within a very short time of one minute. The glow discharge optical emission spectroscopy showed the presence of nitrogen in coating. Also, studying the 2D band intensity and position at Raman spectrum confirmed the presence of multi-layer graphene nano-sheets. The 9cm-1 increase of G-band position at Raman spectrum, by addition of urea to electrolyte, confirmed the concentration of 1.4% nitrogen in coating. Thus, the cathodic plasma electrolysis can be a facile one-step method for the simultaneously production and doping of graphene nano-sheets coating on Ni surfaces.