Study of Thermal Dehydration of Sodium Orthophosphate Monosubstituted

Depending on the conditions of conducting the synthesis, it is possible to obtain polymeric phosphates of different composition and structure. The mixtures of polyphosphates, employed in the production of technological lubricants, are expedient to synthesize by the high-temperature dehydration of sodium orthophosphate monosubstituted. The temperature ranges, over which the thermochemical transformations of sodium orthophosphate monosubstituted with the formation of polyphosphates proceed, are established by the thermogravimetric method. The composition of polyphosphates is determined using the X-ray phase analysis. Quantitative composition of the mixtures of polyphosphates is determined by applying the original method of eluent ion-exchange chromatography. It is established that the basic products of thermal dehydration of sodium orthophosphate monosubstituted in the range of temperatures 200–650 °C are Na3Р3О9, Na2H2P2O7 and Na6P6O18. Thermochemical transformations of NaH2PO4 into Na6P6O18 at temperature 650 °C are accompanied by the side reactions of formation of Na3H2P3O10. We proposed the chemical scheme of the high-temperature dehydration of sodium orthophosphate monosubstituted. Kinetics of the isothermal process of obtaining the polymeric phosphates from sodium orthophosphate monosubstituted at different temperatures is examined.We established quantitative composition of the mixtures of inorganic polymeric phosphates depending on the duration of isothermal process of dehydration. The possibility of obtaining a salt mixture of polymeric phosphates of the assigned qualitative and quantitative composition is demonstrated. We proposed to use the mixture: 76 % Na6P6O18, 8 % Na2H2P2O7, 8 % Na3H2P3O10, 8 % NaH2PO4, obtained at 650 °C, as the basic phosphate component of technological lubricants for the hot rolling of pipes

Study of the Anticorrosion Effect of Polymer Phosphates on Steel at Elevated Temperatures

Technological greases based on polyphosphates of alkali metals have great prospects for application at high-temperature machining of steel. An important task is to study the anti-corrosive effect of polyphosphates on steel at elevated temperatures. Temperature ranges, in which phase transformations of metaphosphate and sodium tripolyphosphate, as well as interaction with iron oxide, occur, were established using a thermogravimetric method. Composition of products of interaction between metaphosphate and sodium tripolyphosphate and scale is determined employing an X-ray phase analysis. It was established that in the region of temperatures of hot steel deformation the iron oxides, contained in scale, are dissolved in molten metaphosphate and sodium tripolyphosphate. As a result of interaction between sodium metaphosphate and iron oxide, the mixed polyphosphates Na3Fe2(PO4)3 and Na9Fe2(P3O10)3 are formed. It is shown that sodium tripolyphosphate almost does not participate in the interaction with the iron oxide of scale. Comparison of the results of corrosion test of the steel surface, treated in the presence of a polyphosphate lubrication and sodium chloride, testifies to the high anti-corrosive effect of polyphosphates. Thus, the time before the emergence of first signs of corrosion in the presence of polyphosphates increased fourfold, while the degree of corrosion damage was reduced by 40 times. It was established that at the deformation treatment of steel at a temperature of 800 °C in the presence of a polyphosphate lubricant, corrosion resistance is due to the formation of a barrier film at the steel surface, consisting of mixed polymer phosphates

Research Into Effect of Propionic and Acrylic Acids on the Electrodeposition of Nickel

Nickel coatings are widely used in machine-building, electronics, automotive and aerospace industries. High requirements for environmental safety and operational performance of contemporary processes of electrochemical nickel plating predetermine the search for the new electrolytes. Electrolytes based on carboxylic acids are characterized by high buffer properties, ecological safety, and enhanced values of limiting current. Heuristic approach when fabricating comprehensive electrolytes, based on empirical data, does not make it possible to conduct predictable optimization of the formulations of nickel plating electrolytes. Solving this problem seems possible when using a quantum-chemical simulation. In this work, we performed quantum-chemical calculations for the propionate and acrylate complexes of nickel. It was established that coordination numbers of the propionate and acrylate complexes of nickel are equal to five and six, respectively. It is shown that electroreduction of the propionate nickel complex proceeds with the formation of an intermediate particle. The negative charge of this particle is localized on the intrasphere molecules of water. This may lead to the electroreduction of the latter and to an increase in the pH of a near-electrode layer. In the intermediate particle of the acrylate complex, localization of the charge occurs on the vinyl fragment of acrylate-ion. Electrochemical reaction of reduction of the coordinated water molecules in such a particle is not energetically favorable. It was established that the isolation of nickel from the acrylate complex proceeds with lower kinetic difficulties than from the propionate complex. An assumption was made that fewer insoluble hydroxide nickel compounds, which block the cathode surface, form in the acrylate electrolyte.Such an assumption is based on the fact that given close buffer properties of acids, electroreduction of the acrylate complexes does not imply the involvement of coordinated water molecules in the electrode process. The results obtained are very valuable for selecting the nature of carboxylic acid as a component for the complex nickel plating electrolyt

Research Into Corrosion and Electrocatalytic Properties of the Modified Oxide Films on Tin

Oxide films on tin, modified by titanium compounds, are non­toxic and serve as anticorrosion protection, material for gas sensors, photo­ and electrocatalysts. We investigated the process of anodic tin treatment in the presence of potassium metatitanate. It is shown that the two­stage technique for the formation of an oxide film at the electrode potentials of −0.3 V and 3.0 V makes it possible to substantially increase the content of titanium oxide compounds in the oxide mixture. The content of Ti(IV) reaches values of 14−15 % (mol). Films with a maximum content of titanium compounds and the largest corrosion resistance are formed at a concentration of potassium metatitanate above 1·10–3 mol/l. The time of self­activation of such films is 10 times longer than that of the unmodified films. We explored catalytic properties of the obtained films with mixed composition SnОх(TiОу). It is shown that an increase in the content of titanium oxide compounds in the film contributes to the acceleration of anodic oxidation of MTBE. It was established that this process takes place directly on the surface of the oxide film rather than during interaction with oxygen formed on the anode. The modified oxide films SnОх(TiОу) on tin with maximal corrosion resistance and electrocatalytic activity are formed from the solutions that contain 0.5M KOH