Temperature distribution in a cylindrical lengthy workpiece under plasma electrolytic heating

The article focuses on developing a model of a stationary temperature field inside a semi-infinite cylindrical sample partly immersed in electrolyte. Temperature calculation is carried out by solving a heat transfer equation separately for the immersed and protruding parts of the sample. The heat flux is set on the outer area boundaries; meanwhile heat flux density for the immersed part is linearly dependent on the vertical coordinate. Within the framework of the model, vertical and radial temperature gradients are worked out both in protruding and immersed parts of the anode. It has been established that the vertical coordinate of the sign reversal point of the heat flux density in the immersed part depends on heat exchange conditions in the protruding part.

The Effect of Variations in Electrolyte Temperature and Current Strength on the Synthesis of Manganese Dioxide from Manganese Sulfate Precursors by Electrolysis Method

The development of science and technology today in the field of electronics, especially energy storage increases the demand for the use of lithium secondary batteries. The development of lithium batteries is focused on energy storage capacity by using manganese dioxide (MnO2) as a lithium battery cathode material. Manganese dioxide was chosen as the cathode material for lithium batteries because it has a high storage capacity of about 615 mAh/g compared to other materials such as graphite which has a storage capacity of 372 mAh/g and has a low toxicity of 0.14 mg/kg. MnO2 was synthesized by electrolysis method from manganese sulfate (MnSO4) precursor which was obtained from Trenggalek manganese ore leaching process. The electrolysis process was carried out for 5 hours using variations in electrolyte temperature of 30, 40, 50 and 60oC as well as variations in current strength of 2, 3, 4 and 5 A to determine the effect of electrolyte temperature and current strength on mass gain, structural polymorphy and morphology of MnO2 formed. The highest mass gain was obtained at the use of an electrolyte temperature of 60oC and a current of 5 A, which was 11.4 grams with the polymorphy structure of the MnO2 compound formed was α-MnO2 polymorphy. SEM image shows that the MnO2 particles have a spiny round shape and tend to agglomerate with particle diameter values ranging from 50 nm - 170 nm. Keywords: Electrolysis, MnO2, MnSO4, Electrolyte temperature, Current strength

Study on the Effect of Magnetic Field on Temperature Domain During Electrolytic Processing

A physical model, mathematical model and geometric model of multi-physical field (electric field, flow field, temperature field, magnetic field) were established to explore the influence of magnetic field on the temperature domain in the gap during ECM. The change law of temperature domain of ECM gap under different magnetic field design methods was studied by using COMSOL MULTIPHYSICS. The scheme is as follows: the magnetic field line is perpendicular to the electric field and the flow field is parallel; the magnetic field line is parallel to the electric field and the flow field is vertical; the electric field of the magnetic field is vertical and the flow field is vertical. The change law of the influence of the magnetic field on the electrolyte temperature is studied by simulation. The changes of current density under three magnetic field design methods and different electrolyte flow were studied. The simulation results show that when the magnetic field is perpendicular to the electric field and the flow field, the temperature change is relatively gentle, and the flow field changes uniformly under the action of the magnetic field volume force, so that the change of current density is relatively stable; The current density of anodic dissolution increases with the increase of voltage, resulting in the increase of electrolyte temperature and heat, further reducing the gap and machining gap, and the temperature in the gap will be greatly increased. Under the action of magnetic field, the electrolyte flow rate increases and the electrolyte temperature decreases greatly.

Template-Assisted Iron Nanowire Formation at Different Electrolyte Temperatures

We studied the morphology, structure, and magnetic properties of Fe nanowires that were electrodeposited as a function of the electrolyte temperature. The nucleation mechanism followed instantaneous growth. At low temperatures, we observed an increase of the total charge reduced into the templates, thus suggesting a significant increase in the degree of pore filling. Scanning electron microscopy images revealed smooth nanowires without any characteristic features that would differentiate their morphology as a function of the electrolyte temperature. X-ray photoelectron spectroscopy studies indicated the presence of a polycarbonate coating that covered the nanowires and protected them against oxidation. The X-ray diffraction measurements showed peaks coming from the polycrystalline Fe bcc structure without any traces of the oxide phases. The crystallite size decreased with an increasing electrolyte temperature. The transmission electron microscopy measurements proved the fine-crystalline structure and revealed elongated crystallite shapes with a columnar arrangement along the nanowire. Mössbauer studies indicated a deviation in the magnetization vector from the normal direction, which agrees with the SQUID measurements. An increase in the electrolyte temperature caused a rise in the out of the membrane plane coercivity. The studies showed the oxidation resistance of the Fe nanowires deposited at elevated electrolyte temperatures.

TYPE OF WEAR OF ALUMINIUM OXIDE LAYERS DEPENDING ON MANUFACTURING PARAMETERS

The article presents the type of wear of Al2O3 layers produced on the aluminium alloy EN AW-5251 depending on the production parameters. Oxide layers were produced by using DC anodizing in a ternary electrolyte at variable current density and electrolyte temperature. The layer scratch tests were carried out using a Micron- Gamma microhardness tester. The scratches of oxide layers were tested for the geometric structure of the surface using a Form TalySurf 2 50i contact profilograph. Contact thickness measurements were also made using a Dualscope MP40 device based on the eddy-current method. Using a scanning microscope (SEM), photos of the sample surfaces were taken to show and compare the surface morphology of the anodized layers in various parameters. Based on the research, it can be concluded that changes in the conditions of the production process of Al2O3 layers (electrolyte temperature and current density) have an impact on the type of tribological wear and changes in layer thickness. The largest thickness of the oxide layer (19.44 μm) was measured for Sample B produced at a current density of 3A/dm2 at an electrolyte temperature of 283 K, which was also characterized by the lowest value of the ratio of parameters f1 to f2 (0.584). The smallest thickness (5.32 μm) was measured for the Sample C anodized at 1 A/dm2 at 303 K, this sample had the largest ratio f1 to f2 (1.068) for the produced Al2O3 layers. Thanks to the parameters f1 and f2 and the calculation of their ratio, the wear process for Sample B was determined as scratching and microcutting, while for Sample C as grooving.