scholarly journals Insights on the Influence of Surface Chemistry and Rim Zone Microstructure of 42CrMo4 on the Efficiency of ECM

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2132
Author(s):  
Alexander Schupp ◽  
Oliver Beyss ◽  
Bob Rommes ◽  
Andreas Klink ◽  
Daniela Zander
Keyword(s):  
Mixed Oxide ◽  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Material Removal ◽  
Chemical Elements ◽  
Nitrate Solution ◽  
Electrochemical Machining ◽  
Process Efficiency ◽  
Negative Effect ◽  
Sodium Nitrate Solution

The electrochemical machining (ECM) of 42CrMo4 steel in sodium nitrate solution is mechanistically characterized by transpassive material dissolution and the formation of a Fe3−xO4 mixed oxide at the surface. It is assumed that the efficiency of material removal during ECM depends on the structure and composition of this oxide layer as well as on the microstructure of the material. Therefore, 42CrMo4 in different microstructures (ferritic–pearlitic and martensitic) was subjected to two ECM processes with current densities of about 20 A/cm2 and 34 A/cm2, respectively. The composition of the process electrolyte was analyzed via mass spectrometry with inductively coupled plasma in order to obtain information on the efficiency of material removal and the reaction mechanisms. This was followed by an X-ray photoelectron spectroscopy analysis to detect the chemical composition and the binding states of chemical elements in the oxide formed during ECM. In summary, it has been demonstrated that the efficiency of material removal in both ECM processes is about 5–10% higher for martensitic 42CrMo4 than for ferritic–pearlitic 42CrMo4. This is on one hand attributed to the presence of the cementite phase at ferritic–pearlitic 42CrMo4, which promotes oxygen evolution and therefore has a negative effect on the material removal efficiency. On the other hand, it is assumed that an increasing proportion of Fe2O3 in the mixed oxide leads to an increase in the process efficiency.

scholarly journals Oxide Formation during Transpassive Material Removal of Martensitic 42CrMo4 Steel by Electrochemical Machining

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 402
Author(s):  
Daniela Zander ◽  
Alexander Schupp ◽  
Oliver Beyss ◽  
Bob Rommes ◽  
Andreas Klink
Keyword(s):  
Sodium Nitrate ◽  
Mixed Oxide ◽  
Material Removal ◽  
Nitrate Solution ◽  
Electrochemical Machining ◽  
Metal Dissolution ◽  
Oxide Formation ◽  
Current Densities ◽  
Sodium Nitrate Solution ◽  
Anodic Metal Dissolution

The efficiency of material removal by electrochemical machining (ECM) and rim zone modifications is highly dependent on material composition, the chemical surface condition at the break through potential, the electrolyte, the machining parameters and the resulting current densities and local current density distribution at the surfaces. The ECM process is mechanistically determined by transpassive anodic metal dissolution and layer formation at high voltages and specific electrolytic compositions. The mechanisms of transpassive anodic metal dissolution and oxide formation are not fully understood yet for steels such as 42CrMo4. Therefore, martensitic 42CrMo4 was subjected to ECM in sodium nitrate solution with two different current densities and compared to the native oxide of ground 42CrMo4. The material removal rate as well as anodic dissolution and transpassive oxide formation were investigated by mass spectroscopic analysis (ICP-MS) and (angle-resolved) X-ray photoelectron spectroscopy ((AR)XPS) after ECM. The results revealed the formation of a Fe3−xO4 mixed oxide and a change of the oxidation state for iron, chromium and molybdenum, e.g., 25% Fe (II) was present in the oxide at 20.6 A/cm2 and was substituted by Fe (III) at 34.0 A/cm2 to an amount of 10% Fe (II). Furthermore, ECM processing of 42CrMo4 in sodium nitrate solution was strongly determined by a stationary process with two parallel running steps: 1. Transpassive Fe3−xO4 mixed oxide formation/repassivation; as well as 2. dissolution of the transpassive oxide at the metal surface.

scholarly journals Crown Ether-Immobilized Cellulose Acetate Membranes for the Retention of Gd (III)

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3978
Author(s):  
Oana Steluta Serbanescu ◽  
Andreea Madalina Pandele ◽  
Madalina Oprea ◽  
Augustin Semenescu ◽  
Vijay Kumar Thakur ◽  
...  
Keyword(s):  
Cellulose Acetate ◽  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Separation Efficiency ◽  
Membrane Surface ◽  
Nitrate Solution ◽  
Cellulose Acetate Membrane ◽  
Retention Performance ◽  
Easy Method ◽  
Cellulose Acetate Membranes

This study presents a new, revolutionary, and easy method of separating Gd (III). For this purpose, a cellulose acetate membrane surface was modified in three steps, as follows: firstly, with aminopropyl triethoxysylene; then with glutaraldehyde; and at the end, by immobilization of crown ethers. The obtained membranes were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), through which the synthesis of membranes with Gd (III) separation properties is demonstrated. In addition, for the Gd (III) separating process, a gadolinium nitrate solution, with applications of moderator poison in nuclear reactors, was used. The membranes retention performance has been demonstrated by inductively coupled plasma mass spectrometry (ICP-MS), showing a separation efficiency of up to 91%, compared with the initial feed solution.

Elemental status of the adult able-bodied population of the Republic of Buryatia

2019 ◽  
pp. 308-313
Author(s):  
Inna Yu. Tarmaeva ◽  
Anatoliy V. Skalny ◽  
Olga G. Bogdanova ◽  
Andrey R. Grabeklis ◽  
Alexandr I. Belykh
Keyword(s):  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Federal District ◽  
Significant Degree ◽  
Electrolyte Imbalance ◽  
Scientific Development ◽  
Inductively Coupled ◽  
Elemental Status ◽  
The Republic ◽  
The Impact

Introduction.The study of the elemental status of the population of individual regions of the Russian Federation with the purpose of scientific development and implementation of measures for elimination of revealed elementosis is a promising direction for preventive medicine.The aim of the studyis to study the elemental status of the adult able-bodied population of the Republic of Buryatia, which was part of the Siberian Federal district (SFD) until 2018.Materials and methods.The analysis was performed by inductively coupled plasma mass spectrometry (ICP-MS) on the basis of the accredited laboratory of “Center of biotic medicine”. (Moscow; ISO 9001: 2008 certificate 54Q10077 from 21.05.2010). The content of chemical elements in the hair of 130 adults (102 women and 28 men) aged 25–50 years was studied. This indicator serves as an indicator in assessing the impact of the environment on the human body. Methods of nonparametric statistics were used for mathematical processing of the data.Results.For women living in the Republic of Buryatia, the maximum values of Zn, increased levels of Cu, Li, Si were revealed; for men — the maximum values of Mg, Cr, Si, increased levels of P, Li, Se, V, Pb. Minimum values were found for P, Fe, V. Elemental status indicates a significant degree of prevalence of essential trace element deficiencies and electrolyte imbalance. The obtained data can be used as reference values for the content of chemical elements in the hair of adults living in the Republic of Buryatia.Conclusions:Elemental analysis of the population of the Republic of Buryatia indicates imbalances among the adult working-age population.

Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation

2020 ◽  
Vol 11 (2) ◽  
pp. 43-50
Author(s):  
Yusup Hendronursito ◽  
Muhammad Amin ◽  
Slamet Sumardi ◽  
Roniyus Marjunus ◽  
Frista Clarasati ◽  
...  
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Silica Content ◽  
X Ray ◽  
Concentration Variation ◽  
Leaching Process ◽  
Hcl Concentration ◽  
Granite Powder

This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

scholarly journals Deposition of Zinc Oxide Coatings on Wood Surfaces Using the Solution Precursor Plasma Spraying Process

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 183
Author(s):  
Ghiath Jnido ◽  
Gisela Ohms ◽  
Wolfgang Viöl
Keyword(s):  
Zinc Oxide ◽  
Ftir Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Color Change ◽  
Uv Light ◽  
Beech Wood ◽  
Nitrate Solution ◽  
Ftir Spectra ◽  
Solution Precursor ◽  
Wood Surfaces

In the present work, the solution precursor plasma spray (SPPS) process was used to deposit zinc oxide (ZnO) coatings on wood surfaces using zinc nitrate solution as precursor to improve the hydrophobicity and the color stability of European beech wood under exposure to ultraviolet (UV) light. The surface morphology and topography of the wood samples and the coatings were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of ZnO was detected with the help of X-ray photoelectron spectroscopy (XPS) and by Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra of the coated samples showed the typical Zn–O band at 445 cm−1. According to the XPS analysis, the coatings consist of two different Zn-containing species: ZnO and Zn(OH)2. Variation of the deposition parameters showed that the most significant parameters affecting the microstructure of the coating were the solution concentration, the deposition scan speed, and carrier gas flow rate. The wettability behaviors of the coated wood were evaluated by measuring the water contact angle (WCA). The coatings that completely covered the wood substrates showed hydrophobic behaviors. UV-protection of wood surfaces after an artificial UV light irradiation was evaluated by color measurements and FTIR spectroscopy. The ZnO-coated wood surfaces were more resistant to color change during UV radiation exposure. The total color change decreased up to 60%. Additionally, the FTIR spectra showed that the wood surfaces coated with ZnO had more stability. The carbonyl groups formation and C=C-bonds consumption were significantly lower.

scholarly journals Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

2018 ◽  
Vol 2 (4) ◽  
pp. 80 ◽  
Author(s):  
Mir Molaie ◽  
Ali Zahedi ◽  
Javad Akbari
Keyword(s):  
Surface Roughness ◽  
Specific Energy ◽  
Material Removal ◽  
Normal Force ◽  
Tangential Force ◽  
Process Efficiency ◽  
Multiwall Carbon Nanotube ◽  
Ultrasonic Vibrations ◽  
Mql Grinding ◽  
Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

scholarly journals Seasonal variations in PM10 inorganic composition in the Andean city

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rasa Zalakeviciute ◽  
Katiuska Alexandrino ◽  
Yves Rybarczyk ◽  
Alexis Debut ◽  
Karla Vizuete ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Large Fraction ◽  
Urban Pollution ◽  
Optical Emission ◽  
High Elevation ◽  
Water Soluble ◽  
Wet Season ◽  
Soluble Ions

Abstract Particulate matter (PM) is one of the key pollutants causing health risks worldwide. While the preoccupation for increased concentrations of these particles mainly depends on their sources and thus chemical composition, some regions are yet not well investigated. In this work the composition of chemical elements of atmospheric PM10 (particles with aerodynamic diameters ≤ 10 µm), collected at the urban and suburban sites in high elevation tropical city, were chemically analysed during the dry and wet seasons of 2017–2018. A large fraction (~ 68%) of PM10 composition in Quito, Ecuador is accounted for by water-soluble ions and 16 elements analysed using UV/VIS spectrophotometer and Inductively Coupled Plasma—Optical Emission Spectroscopy (ICP-OES). Hierarchical clustering analysis was performed to study a correlation between the chemical composition of urban pollution and meteorological parameters. The suburban area displays an increase in PM10 concentrations and natural elemental markers during the dry (increased wind intensity, resuspension of soil dust) season. Meanwhile, densely urbanized area shows increased total PM10 concentrations and anthropogenic elemental markers during the wet season, which may point to the worsened combustion and traffic conditions. This might indicate the prevalence of cardiovascular and respiratory problems in motorized areas of the cities in the developing world.

scholarly journals Decolorization of Methylene Blue by Ag/SrSnO3 Composites under Ultraviolet Radiation

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Patcharanan Junploy ◽  
Titipun Thongtem ◽  
Somchai Thongtem ◽  
Anukorn Phuruangrat
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Uv Radiation ◽  
Photoelectron Spectroscopy ◽  
Separation Process ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Negative Effect ◽  
Uv Visible

SrSn(OH)6 precursors synthesized by a cyclic microwave radiation (CMR) process were calcined at 900°C for 3 h to form rod-like SrSnO3. Further, the rod-like SrSnO3 and AgNO3 in ethylene glycol (EG) were ultrasonically vibrated to form rod-like Ag/SrSnO3 composites, characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy (EM), Fourier transform infrared (FTIR) spectroscopy, and UV-visible analysis. The photocatalyses of rod-like SrSnO3, 1 wt%, 5 wt%, and 10 wt% Ag/SrSnO3 composites were studied for degradation of methylene blue (MB, C16H18N3SCl) dye under ultraviolet (UV) radiation. In this research, the 5 wt% Ag/SrSnO3 composites showed the highest activity, enhanced by the electron-hole separation process. The photoactivity became lower by the excessive Ag nanoparticles due to the negative effect caused by reduction in the absorption of UV radiation.

Preparation and Characterization of SnO2/WO3/MWCNT Nanocomposite Thin Film for NO2 Gas Sensor

2010 ◽  
Vol 129-131 ◽  
pp. 99-103
Author(s):  
Wei Lin ◽  
Shi Zhen Huang ◽  
Wen Zhe Chen
Keyword(s):  
Thin Film ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Surface Composition ◽  
Chemical Elements ◽  
Film Material ◽  
Nanocomposite Thin Film ◽  
Oxide Compound ◽  
Thin Film Material

A novel nanocomposite thin film material of SnO2/WO3 metal oxide compound doped by multi-walled carbon nanotubes (MWCNT) and its corresponding gas sensor were prepared by radio frequency (RF) reactive magnetron sputtering. The surface composition and chemical elements of the thin film material were respectively analyzed and validated by X-ray diffraction (XRD) and photoelectron spectroscopy (XPS). The influencing factors of gas sensing properties were studied and the test results of gas sensor were analyzed. The results indicated that the detection using the composite material gas sensors for low concentration NO2 toxic gas could be greatly improved by MWCNTs which were doped on the mixed oxides matrix. A possible mechanism explaining the behaviour of the thin film gas sensor was introduced.

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