Modified phosphate coatings applied to steel by cold method

The deposition of phosphate coatings occurs on the surface of the product when it is immersed in a solution containing phosphoric acid. The formation of a film on the metal surface occurs during the deposition of insoluble two- and three-substituted phosphates of iron, manganese, and zinc from a solution. To speed up the process and conduct phosphating at low temperatures, nitrates, nitrites, and fluorides of active metals are introduced into the solution. Organic compounds, such as glucose, glycerin, Trilon A, and Trilon B, are buffer additives to maintain the pH of phosphating solutions in the range of 2.6-3.2. It was found that 10-15 minutes at a process temperature of 20-25 °C are sufficient for the formation of a protective phosphate coating from solutions containing modifiers. The content of zinc phosphates in the modified phosphate coatings is increased. Additives in cold phosphating solutions have a positive effect on the quality and protective properties of the resulting phosphate films. Modified phosphate coatings obtained by the cold method have a fine-crystalline structure, a smooth surface and low porosity.

Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.

Nanomagnetite Extraction from Iron Sand Prepared by Mechanical Alloying Method

In this paper, the magnetic properties of Aceh iron sand was studied. The iron sand was collected from the Syiah Kuala coastal area, Banda Aceh and obtained by mechanical alloying method using planetary ball milling. The mineral compositions were investigated by XRD and XRF analysis tests. The XRF test showed that the sand mostly contain magnetite, Fe3O4 (85.80%) in association with other impurities of SiO2, TiO2, Al2O3 and some others minor minerals. Compare to XRD results, the phase compositions were mainly magnetite (Fe3O4). So, it is consistent with the XRF data. The electron microscopy observation (SEM) showed the fine crystalline structure and the main morphology was micro-crystalline in agglomerate forms. Furthermore, the magnetic properties after 20 hours milling showed the increasing in the coercivity (Hc) and remanent (Br), while the magnetic saturation (Ms) was decreased. This behavior can be explained that nano-Fe3O4 phase after the milling process plays an important role in the magnetic properties of iron sand.

Wear-Resistant Materials Synthesized in A Solar Furnace

The influence of technological modes of the Big Solar Furnace on the process of synthesis of materials from the melt is studied. It is shown that for the synthesis of materials with a set of specified properties, it is necessary to optimize the density and nature of the energy distribution of concentrated solar radiation in accordance with the degree of blackness, absorption coefficient, melting temperature and thermal conductivity of the charge. It is shown that the remelted state and a homogeneous fine-crystalline structure with an optimal combination of crystalline and amorphous phases, which leads to increased wear resistance of the material.

Wear-Resistant Materials Synthesized in A Solar Furnace

The influence of technological modes of the Big Solar Furnace on the process of synthesis of materials from the melt is studied. It is shown that for the synthesis of materials with a set of specified properties, it is necessary to optimize the density and nature of the energy distribution of concentrated solar radiation in accordance with the degree of blackness, absorption coefficient, melting temperature and thermal conductivity of the charge. It is shown that the remelted state and a homogeneous fine-crystalline structure with an optimal combination of crystalline and amorphous phases, which leads to increased wear resistance of the material

Solid Solutions Formation Mechanism in Cordierite-Mullite Glass Materials During Ceramization

Relevance of the development of high-strength glass-ceramic coatings obtained by resource-saving technology for protective elements has been established. Structure formation mechanism in magnesium aluminosilicate glasses during heat treatment has been analyzed. Selection of the system was substantiated, model glasses and glass-ceramic materials on its base have been developed. Patterns of structure regularity and formation of the phase composition of glass-ceramic materials during their ceramization have been investigated. It was established that the presence of crystalline phase of mullite after melting leads to formation of the primary crystals and allows the formation of the fine crystalline structure under conditions of the low-temperature heat treatment at the nucleation stage. Developed high-strength glass ceramic materials can be used as a base in creating protective elements for special-purpose vehicles by energy-saving technology.

Pressed Composites Based on Gypsum and Magnesia Binders Modified with Secondary Resources

The results of the studies aimed at increasing the water resistance of the pressed building materials based on gypsum and magnesia binders due to their modification with active dispersed fillers from secondary resources are presented. The gypsum binder modification was carried out by the joint introduction of carbonate-containing sludge from it into the chemical treatment of thermal power plants and monoammonium phosphate, and of magnesia cement - silica fume and finely ground burnt mines. Physical and mechanical characteristics of the materials’ control samples were determined according to the standards and generally accepted methods. The increase in water resistance of the pressed modified composites was evaluated by changing the softening coefficient. It is shown that when using gypsum binders, an increase in the water resistance of products based on them can be achieved by changing the structure formation of the pressed material and the formation on the elements’ surface of its fine-crystalline structure of the sparingly soluble calcium phosphates’ screening protective films. The increase in water resistance of pressed products made of modified magnesia binders is explained by the appearance of insoluble hydro silicates, hydro aluminates and hydro aluminosilicates of magnesium, in the structure of the hardened artificial stone as well as the formation of a complex combined structure containing coagulation, condensation and crystallization phases. The technical characteristics of the materials obtained are sufficient for their use, in particular, in the building envelope. The possibility of replacing a significant amount of binders with secondary resources has been identified. This allows not only to increase the water resistance of the pressed products on the basis of the proposed modified binders, but also to reduce their cost, as well as free up the land allocated for dumps.

Modification of Magnesia Binder with Iron Ore Concentrate

On the basis of the experimental data, a method and mechanism for modifying magnesia binders with iron ore concentrate has been proposed. It consists in form of a material reinforced fine-crystalline structure with elongated magnesium oxychloride crystals, which improves its physical and mechanical characteristics. The components of iron ore concentrate and magnesia binder, having improved sorption properties, significantly accelerates the formation of such a structure.

STUDIES OF WATER FREEZING FEATURES IN ICE CREAM WITH STARCH SYRUP

The purpose of the study is to research the process of water freezing in new types of ice cream with starch syrup at certain stages of the technological process. Starch syrup as a degradation product of corn starch is characterized by different values of the dextrose equivalent (DE). Starch syrup is a source of solids, sweetener, cryoprotectants (at high DE) and thickener (for low values of DE). The starch syrups with fundamentally different functional and technological properties are chosen for the study: high glucose-fructose syrup HGFS-98 (DE = 98) and low-sugar starch syrup GFS-30 (DE = 30). To determine the size of ice crystals in ice cream, a light microscope of the brand XS-2610 with a cooling chamber is used for an increase of x600, and the cryoscopic temperature is measured by cryostat and Beckmann thermometer (TL-1) to calculate the content of frozen out water. The regularities of the process of water freez-out in ice cream with milk fat content of 3.5%, creamy fat content of 10% and filling with fat content of 15% in the temperature range from minus 6ºС to minus 40ºС are established. In particular, the content of frozenwater in ice-cream at certain stages of the technological process is determined. The results are used to optimize the prescription composition of ice cream with starch syrup. It is recommended to use hydrocarbon complexes consisting of HGFS-98 and GFS-30 in the ratio of 30:70 to 80:20 to reduce the content of frozen water in ice cream of different chemical compositions. The results of the study are of practical importance and allow to obtain in production conditions the fine-crystalline structure of ice cream with starch syrup.

The influence of sodium niobate addition on sintering and properties of zirconia ceramics

The study of sintering, microstructure and phase composition of zirconia ceramics containing the additive - sodium niobate. It is shown that the use of an additive helps to reduce the sintering temperature to 1,400 ° C. The obtained materials are characterized by a high content of the tetragonal phase, a fine-crystalline structure and high strength up to 440 MPa during bending. The developed low-temperature materials can be used in dentistry as ceramic crowns.