Effect of nanotegnogenic high-alumina raw materials on the physical and mechanical parameters and phase composition of acid-resistant materials

The use of nanotechnogenic high-alumina (Al2O3 > 70 %) raw materials of petrochemical production ― the spent IM2201 catalyst in the production of acid-resistant materials based on unenriched kaolin clay makes it possible to obtain products with high physical, mechanical and chemical parameters in the range of firing temperatures of 1250‒1300 o C. Nanotechnogenic raw materials contribute to an increase in surface energy, which is the source of the sintering process. Studies have shown that in compositions based on unenriched kaolin clay and chamotte from it, which do not contain nanotechnogenic high-alumina raw materials, mainly mullite is formed, which mainly forms the operational properties of ceramic products. X-ray diffractometric analysis showed that the introduction of nanotechnogenic high-alumina raw materials into the compositions of ceramic masses contributes to the formation of corundum. IR spectroscopic analysis confirmed the data of X-ray studies. Corundum is characterized by high chemical resistance to acidic and alkaline reagents and gives acid-resistant materials high physical and mechanical properties. Ill. 4. Ref. 33. Tab. 5.

Effect of Heat Treatment on the Properties of Polyetheretherketone and its Composite

Polyetheretherketone (PEEK) is a semicrystalline thermoplastic polymer with high chemical resistance, thermal stability and excellent mechanical properties. In the present work, neat PEEK and 3% bioactive glass/PEEK composites were annealed at various temperatures (100 °C, 200 °C and 300 °C) for (30 and 60) min and characterized with mechanical and density tests, differential scanning calorimetery and Fourier transform infrared spectroscopy. Results manifested bioactive glass powder enhanced the properties of the PEEK matrix. Thermal annealing at (200 and 300 °C) had a positive influence on the mechanical properties and density owing to increase in the level of crystallinity, whereas annealing at (100 °C) had not effect on the properties.

Improving Water Resistance of Magnesium Binding Substances by the Introduction of Mineral Fillers

Magnesia binders provide strength to the stone, but have one drawback-low resistance and salt resistance. Increasing water and salinity tolerance, mechanical strength of the hardening magnesia binders can be achieved by introducing the system of micro-aggregates. The quality criteria that determine the activity of the micro filler are: high chemical resistance to water, aggressive media, high mechanical strength. Among the effective microfillers composite magnesia binders include diopside, wollastonite. It is shown that the introduction of 60-80 wt%. wollastonite or diopside with a specific surface of 2000-3500 cm2/g provides significant improvement in strength and water resistance that allows you to lengthen the lifespan and maintain the required quality of products based on composite of magnesia binders.

Properties of Polypropylene Yarns with a Polytetrafluoroethylene Coating Containing Stabilized Magnetite Particles

This paper describes an original method for forming a stable coating on a polypropylene yarn. The use of this method provides this yarn with barrier antimicrobial properties, reducing its electrical resistance, increasing its strength, and achieving extremely high chemical resistance, similar to that of fluoropolymer yarns. The method is applied at the melt-spinning stage of polypropylene yarns. It is based on forming an ultrathin, continuous, and uniform coating on the surface of each of the yarn filaments. The coating is formed from polytetrafluoroethylene doped with magnetite nanoparticles stabilized with sodium stearate. The paper presents the results of a study of the effects of such an ultrathin polytetrafluoroethylene coating containing stabilized magnetite particles on the mechanical and electrophysical characteristics of the polypropylene yarn and its barrier antimicrobial properties. It also evaluates the chemical resistance of the polypropylene yarn with a coating based on polytetrafluoroethylene doped with magnetite nanoparticles.

Passivation of chromium disilicide in acidic media

The anodic behavior of CrSi2 electrode in 0,5 M H2SO4, 0,5 M HClO4, 0,5 M HNO3 and 0,5 M HCl solutions has been studied by the methods of polarization, capacitance, and impedance measurements. It has been concluded that in the process of anodic oxidation at potentials from corrosion E to transpassivation E inclusive, an oxide film is formed on the surface of chromium disilicide in the studied media, which is close in composition to SiO2 (with a small content of chromium oxides). The presence of this film on the silicide surface determines its high chemical resistance in the studied solutions. The thickness of the oxide film on CrSi2 has been calculated depending on the potential and composition of the electrolyte. The growth constant of the oxide film has been determined.

Design of an ELC resonator-based reusable RF microfluidic sensor for blood glucose estimation

Design of a reusable microfluidic sensor for blood glucose estimation at microwave frequencies is presented. The sensing unit primarily comprises a complementary electric LC (CELC) resonator, which is made reusable by filling the test sample in a glass capillary before mounting it inside a groove cut in the central arm of the resonator. The use of glass capillary in the present situation to contain the blood sample actually eliminates the possibility of any direct contact of the sensor with the test sample, and hence wards off any coincidental contamination of the sensor. Usage of the capillary provides additional benefits as only microliters of the sample are required, besides offering sterile measuring environment since these capillaries are disposable. The capillary made of borosilicate glass is highly biocompatible and exhibits exceptionally high chemical resistance in corrosive environments. Apart from reusability, the novelty of the proposed sensor also lies in its enhanced sensitivity which is quite an essential factor when it comes to the measurement of glucose concentration in the human physiological range. The applicability of the proposed scheme for glucose sensing is demonstrated by performing RF measurements of aqueous glucose solutions and goat blood samples using the fabricated sensor.

High temperature and wear resistant materials with enhanced performance propertie

The results of studies of obtaining self-sintering refractory masses are presented. A new technology for their manufacture is proposed. The basis of the resulting masses are baritecontaining components (barite or viterite concentrates). High chemical resistance, refractoriness, mechanical strength, hardness and wear resistance determine the scope of their application ― the manufacture of refractory products, linings, putties and concrete.

Characteristics of a Fly Ash-Based Geopolymer Cured in Microwave Oven

Geopolymer is known as an alkaline alumino-silicate material that has many potential advantages to replace for cement-based materials. Geopolymer is a green material with low or non-CO2 emission technology, high strength and heat resistance, high chemical resistance, and low energy production. Geopolymer has synthesized from activated alumino-silicate resources in high alkaline conditions. After formed, the geopolymer samples are cured in different conditions such as room temperature, drying oven temperature (from 40°C to 150°C), high pressure and temperature conditions of autoclave equipment. In this study, the paper would like to introduce a new technique for curing the specimens. The geopolymer samples were cured in a microwave oven set by various regimes of curing time. After cured in microwave conditions, the samples were tested for engineering properties such as compressive strength (MPa), volumetric weight (kg/m3), and water absorption (kg/m3). This technology is a useful solution because of saving time for curing the geopolymer specimens in comparison with others (normally, it takes time for curing in 28 days). Microstructural characteristics of the fly ash-based geopolymer were analyzed and evaluated using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR).