bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Laser Formed Superalloys
Authors: Mahapatra S.K. , Khanna A.S. , Gasser A.
Published: October 2022

This work investigates the effect of processing parameters on the microstructure and composition of Ni-base alloys produced by laser forming, an additive technique also known as direct metal deposition. The parameters assessed in the study include powder flow rate, traverse speed, laser power, and spot size. In all experiments, a melt pool diameter of 0.3 mm was maintained. The results show that laser formed alloys are similar in structure to conventional wrought alloys with additional peaks formed as a result of the oxidation of active alloying elements. The complex compounds observed on the surface of the laser formed samples disappeared after polishing. Paper includes a German-language abstract.
Verschleiß- und Korrosionsschutz bei Leichtmetallen mittels schweißtechnischer Verfahren (Wear and Corrosion Prevention for Light Metals by Means of Welding Methods)
Authors: Gebert A. , Wocilka D. , Bouaifi B. , Schütz M.
Published: October 2022

The aim of this investigation is to increase the corrosion and wear resistance of magnesium (Mg) alloys. This paper explains how various coatings applied via plasma powder (PTA) and laser deposition welding processes affect the wear properties of two Mg alloys. It is shown that coating quality depends on the type of Mg used, the composition of the filler materials (matrix and carbides), and welding parameters. The best results for Mg alloys AM50 and AZ31 were obtained with a coating consisting of a composite matrix (AlSi12) with boron carbide additions. Paper text in German.
Characterization of Roughened Substrate Surface on Bond Strength of Thermal Spray Deposits
Authors: Fukanuma H. , Xie R. , Ohno N. , Fujiwara Y. , Kuroda S.
Published: October 2022

Although substrates are often grit blasted prior to thermal spraying to improve coating adhesion, the relationship between surface roughness and bond strength is not well understood. This paper proposes a new method for characterizing the surface roughness of substrates on the hypothesis that mechanical friction between the coating and substrate primarily determines adhesive strength. The authors explain how they measure 3D surface profiles using a confocal scanning microscope and develop the necessary math to calculate friction forces and coefficients. They also present experimental results comparing the roughness of stainless steel and aluminum substrates with the adhesive strength of plasma-sprayed Al203 layers. Paper includes a German-language abstract.
Residual Stress Determination in Near-Net Shape Formed Specimens Obtained by Thermal Spraying
Authors: Markocsan N. , Fogarassy P. , Dehelean D. , Manescu A. , Rustichelli F.
Published: October 2022

The aim of this work is to develop a finite element model that predicts the residual stresses in plasma sprayed parts formed on conical mandrels and removed by various means. The theoretical analyses and mathematical models are confirmed by X-ray diffraction measurements on plasma-sprayed zirconia samples freed from shaped mandrels by means of cooling, melting, and chemical dissolution. Based on test results, the mandrel-cooling removal method produced the highest internal stresses. Paper includes a German-language abstract.
Investigation of the Microplasma Spraying Processes
Authors: Borisov Y. , Sviridova I. , Voynarovich S. , Lugscheider E. , Fischer A. , Zhao L.
Published: October 2022

Microplasma spraying has the potential to expand the range of applications for plasma spraying, particularly for the production of functional coatings. The low heat input on the substrate material allows small and thin-walled components to be coated without risk of overheating or deformation and with less powder loss due to the small plasma jet. This paper investigates the influence of various process parameters on the spraying of molybdenum, stainless steel, WC-Co, zirconium dioxide, and aluminum oxide using a microplasma system. Material consumption, plasma jet size, and layer structure are measured along with various aspects of particle behavior in the plasma jet. Paper includes a German-language abstract.
Interactions Between High-Velocity Particles and Substrates During Cold Spraying
Authors: Papyrin A.N. , Kosarev V.F. , Klinkov S.V. , Alkhimov A.P.
Published: October 2022

A number of studies have been conducted over the past few years with the aim of modeling high-speed particle-substrate interactions during cold spraying. This paper summarizes the work conducted and some of the more important findings. Based on experimental measurements and dynamic deformation modeling, it is shown a radial jet of metal forms at the contact zone during cold spraying. The effect is similar to that observed in explosive welding and it leads to corona-shaped ejection of metal at the periphery of the contact zone. Paper includes a German-language abstract.
Effect of Nozzle Geometry on Cold Spray Process
Authors: Sakaki K. , Huruhashi N. , Tamaki K. , Shimizu Y.
Published: October 2022

Cold spray nozzles can have a significant impact on particle behavior and coating quality depending on their shape and size. This study investigates the influence of nozzle geometry on the cold spray process. Simulations show that particle velocities are highest at the outlet of de Laval type nozzles and that convergence pipe nozzles achieve the highest particle temperatures. Paper includes a German-language abstract.
Characterization of Tribological Quasicrystalline Composite Coatings
Authors: Román A. , Agüero A. , de Miguel C. , García de Blas F.J. , Longo F. , Muelas R. , Sánchez A.
Published: October 2022

Quasicrystalline (QC) alloys constitute a family of materials with low coefficient of friction, high hardness, and high yield strength under compressive stress. This paper examines the characteristics of QC composite coatings deposited by LPPS and HVOF spraying. It compares the coatings based on phase distribution and microstructure. Both compositions studied are extremely wear resistant, but their friction properties require further development. Paper includes a German-language abstract.
Einsatz der PIV-Technik zum Bestimmen des Einflusses unterschiedlicher Düsengeo- metrien auf den Lichtbogenspritzprozess (Particle Image Velocimetry (PIV) as a Tool to Investigate the Influence of Nozzle Configuration and Spray Parameters on the Arc Spray Process)
Authors: Bach Fr.-W. , Copitzky T. , Tegeder G. , Prehm J.
Published: October 2022

Arc spraying is an economical method for applying metallic layers due to its high spray rates and uniform melting of spray particles. The main disadvantage is the difficulty in achieving sufficient particle velocity to ensure good layer adhesion. This study investigates the influence of nozzle geometry, arc power, and gas pressure on the size and velocity of particles in an arc spray jet. The experiments were conducted using particle image velocimetry (PIV) to measure the spatial and velocity distribution of particles in flight. For X45Cr13 steel, particle velocities were found to be between 85 and 95 m/s at a gas volume flow of around 1 m3/min. Velocities of up to 150 m/s were ultimately achieved, but at the expense of higher atomizer gas consumption. Paper text in German.
Self-Strengthening of the Adhesion of HVOF Sprayed MCrAlY Coatings
Authors: Li C.-J. , Li W.-Y. , Matsunaga Y. , Nakagawa K.
Published: October 2022

This paper assesses the effect of different annealing treatments on the adhesion strength of NiCrAlY coatings. The coatings were HVOF sprayed on superalloy substrates using widely available powders. It was found that the annealing atmosphere has no significant influence on adhesion, indicating that the coatings self-reinforce when subjected to high temperatures. The observed effect is due to the diffusion of elements, forming a metallurgical bonding layer at the coating-substrate interface. Test results show that, in an ambient atmosphere at 1000 °C, this bonding layer becomes stronger with time, more than doubling the adhesion strength of HVOF NiCrAlY coatings on Inconel 738 substrates. Paper includes a German-language abstract.
Properties of Ceramic Coatings Prepared by HVOF and Plasma Spraying of Titanium Suboxide Powders
Authors: Vuoristo P. , Määttä A. , Mäntylä T. , Berger L.-M. , Thiele S.
Published: October 2022

This work investigates the influence of powder characteristics on thermal spray coatings produced from titanium suboxide powders. The powders used were prepared from commercially fused and ground titanium dioxide reduced in a mixture of hydrogen and argon gas. Two particle sizes were produced and subsequently applied by atmospheric plasma and HVOF spraying. Originally melted and crushed powder fractions served as a reference. All deposits showed high wear resistance, particularly the HVOF-sprayed layers. Paper includes a German-language abstract.
Improved Corrosion Resistant Coatings Prepared Using a Modified Diamond Jet HVOF Spraying System
Authors: Sturgeon A.J.
Published: October 2022

This paper reports on a modified diamond jet HVOF spray gun, which makes it possible to produce layers of stainless steel and nickel alloys with very low levels of oxide and porosity. The corrosion behavior of these layers is compared with that of coatings produced with a conventional HVOF gun. Cross-sectional examinations carried out before and after corrosion testing show where and when corrosion attacks occur. Paper includes a German-language abstract.
Einfluss der Düsenkontour auf atmosphärisch DC-plasmagespritzte AL2O3-Schichten (Nozzle-Design Effects on the Quality of APS-Alumina Coatings)
Authors: Schwenk A. , Nutsch G. , Gruner H.
Published: October 2022

This paper investigates the influence of nozzle design on the quality of Al2O3 coatings produced by atmospheric plasma spraying. It compares the thermal and deposition efficiency of different plasma guns along with the porosity and adhesion strength of the resulting coatings. The intent of the study is the application of convergent-divergent nozzles as an economic alternative to the nozzles typically used for atmospheric plasma spraying. Paper text in German.
Hastelloy C-276 Parameter Study using the Axial III Plasma Spray System
Authors: Burgess A.W.
Published: October 2022

In this paper, Hastelloy C-276 layers are produced using the Axial III plasma spray method and assessed based on oxide content and microhardness. Test results show that Hastelloy coatings with low hardness can be achieved in different atmospheres with appropriate adjustments in process parameters. Paper includes a German-language abstract.
Mechanische Bruchuntersuchungen zur Ermittlung der Haftfestigkeiten von WC-Co-Schichten auf Metallsubstraten (Fracture Mechanics Testing to Determine the Adhesion Strength of WC-Co Coatings on Metal Substrates)
Authors: Sauer H. , Weiß H. , Kern E. , Schwabe O.
Published: October 2022

In this investigation, the concepts of fracture mechanics are put to use to determine the adhesion strength of WC-Co coatings on metal substrates. The paper explains how test samples are produced and describes the procedures used to obtain fracture mechanics data. Adhesion strength is determined based on local energy release rates (crack closure integral method) and is verified using a finite element model of the test sample. With this approach, the spraying parameters for WC-Co can be more precisely tuned than would be possible with a frontal pull test. Paper text in German.
Fast Quality Control of Spray Powders
Authors: Dvorak M. , Schmid H.G. , Fischer F.
Published: October 2022

Metallurgical powders can be characterized by different techniques including image analysis, laser particle size analysis, and various forms of sieve analysis. This paper evaluates a new method that uses a high-resolution slide scanner in combination with automated image analysis. The results obtained with this system are comparable to powder analysis via laser scattering and classical sieving techniques, but are more sensitive to changes in powder quality. Paper includes a German-language abstract.
Densification of Thermal Sprayed Coatings with Spark Plasma Sintering (SPS)
Authors: Prawara B. , Yara H. , Miyagi Y. , Fukushima T.
Published: October 2022

This paper examines the effects of spark plasma sintering (SPS) on flame-sprayed zirconia coatings. It describes how the zirconia layers were produced, treated, and tested. The combination of heating and loading increased coating hardness and adhesion strength by a factor of three and caused a significant reduction in porosity. It also led to phase transformations which, in some cases, had an offsetting effect on coating properties. Paper includes a German-language abstract.
Spark Plasma Sintering (SPS) of Plasma Sprayed YSZ Electrolyte for Solid Oxide Fuel Cell (SOFC) Application
Authors: Khor K.A. , Yu L.-G. , Chan S.H. , Chen X.J.
Published: October 2022

Plasma spraying is a fast and inexpensive process for fabricating YSZ electrolyte for SOFCs. In this investigation, free-standing plasma sprayed YSZ disks are treated by spark plasma sintering at different temperatures, soak times, and loading cycles. SEM examination shows that the lamellar microstructure of the as-sprayed zirconia is converted to a predominantly granular structure with no significant phase changes as per XRD analysis. Microhardness and laser flash diffusivity measurements show that the SPS treatments also improve YSZ layer density, tensile modulus, and thermal conductivity. Paper includes a German-language abstract.
Production and Characterization of Surface Preparation of Ni-base Alloy Substrates for Plasma-Sprayed Thermal Barrier Coatings
Authors: Scrivani A. , Groppetti R. , Rossi A. , Tedeschi F. , Rizzi G. , Bardi U. , Niccolai F.
Published: October 2022

Thermal barrier coatings typically consist of a ceramic topcoat and a metallic bond coat that promotes adhesion and protects the substrate from corrosion. This study evaluates surface preparation processes used prior to the application of the bond coat layer. In the experiments, NiCrAlY bond coats are plasma sprayed onto Inconel substrates prepared by various methods, including dry and wet blasting and solid CO2 cryogenic cleaning. At different points in the process, samples are extracted and characterized based on surface roughness, subsurface hardness, morphology, adhesion, interface contamination, and coating thickness and structure. Paper includes a German-language abstract.
Performance of Graded, Duplex and Triplex Thermal Barrier Coatings Exposed to Cyclic Oxidation
Authors: Waheed A. , Azzam A.H. , El-Awadi G. , Abdel-Sammad A. , Rassoul E.-S.A.
Published: October 2022

This paper evaluates the effect of bond coat oxidation on the coating life of graded, duplex, and triplex TBC systems deposited on Inconel 617 and 738 substrates by vacuum plasma spraying. In oxidation experiments, the triplex system had the lowest number of cycles to failure. The graded system was found to be superior to the duplex system in terms of oxidation resistance, but inferior in terms of hot corrosion resistance. It was also found that the various TBC systems are more durable on Inconel 738 than on Inconel 617, particularly the graded systems. Paper includes a German-language abstract.
Salt Fog Corrosion Resistance of HVOF WC-10Co-4Cr Coated and Electrolytic Hard Chrome Plated AerMet 100 and 300M Steel Alloys
Authors: Dudzinski D. , Au P. , Legoux J.-G. , Simard S.
Published: October 2022

This paper compares the corrosion resistance of electrolytic hard chrome plating and HVOF-sprayed WC-Co-Cr on two steel alloys used in landing gears. Test samples were evaluated by means of salt spray testing and electrochemical measurements. Post-test metallographic examinations were conducted to investigate the failure mode of the coatings. Test results are presented along with relevant findings and observations. Paper includes a German-language abstract.
The Corrosion Behavior of High-Velocity Oxyfuel (HVOF) Sprayed NiCrSiB Coatings
Authors: Shrestha S. , Sturgeon A. , Hodgkiess T. , Neville A.
Published: October 2022

In this paper, the corrosion characteristics of two HVOF-sprayed coatings made with self-fluxing NiCrSiB powders are assessed in the as-sprayed condition. One of the coatings is also investigated after post-spray treatment with polymer sealing and after vacuum furnace fusion. It was found that cracking at lamellar boundaries dominates the corrosion behavior of the layers in the as-sprayed and sealed states, while pitting corrosion resulting from the failure of hard phases plays the main role in the melted layer. Paper includes a German-language abstract.
Development of Functionally Graded Thermal Spray Coatings for Polymer Substrates
Authors: Ivosevic M. , Knight R. , Twardowski T.E. , Kalidindi S.R. , Kim D.Y. , Sutter J.K.
Published: October 2022

In this paper, WC-Co reinforced polymer matrix coatings are sprayed on preheated steel and carbon-fiber reinforced substrates, producing relatively dense, adherent coatings. The particle morphology of the feedstock materials and the microstructure of the HVOF sprayed coatings are characterized and the thermal properties of the polymer powder and coatings are compared. It was found that the deposition and build-up of the polymer coating was only successful when substrates were preheated to the curing temperature of the thermosetting polyimide powder used. Layered coatings of varying polyimide and WC-Co content have been successfully deposited, showing that it is possible to produce graded composite coatings consisting of pure polymer at the substrate and pure WC-Co on the surface. Paper includes a German-language abstract.
Titanium Carbide-Based Powders and Coatings – Compositions, Processability and Properties
Authors: Berger L.-M. , Thiele S. , Vuoristo P. , Mäntylä T. , Keller H. , Proß E. , Scholl R.
Published: October 2022

This paper provides a short summary of the information that can be found in the literature on the preparation and structure of titanium carbide (TiC) wettable powders. From the work that has been done, it can be concluded that TiC-based coatings can be tailored for applications where complex stress profiles are encountered. Paper includes a German-language abstract.
Tribological Features of Self-Lubricated Coatings Obtained by Atmospheric Plasma Spraying (APS)
Authors: Guilemany J.M. , Navarro J. , Lorenzana C. , Miguel J.M.
Published: October 2022

This study analyzes the tribological behavior of nickel-graphite and aluminum-silicon-polyester thermal sprayed coatings and the effect of non-metallic compounds. Self-lubricating coating composites based on a metallic matrix with ceramic or polymeric filler phases show potential applications requiring high wear resistance and thermal stability at low cost. In some cases, the nickel-graphite layer may eliminate the need for external lubricants or lubricating systems. Paper includes a German-language abstract.
Damage Mechanism of Functionally Graded Thermal Barrier Coatings in Thermal Cycling
Authors: Ohki M. , Mutoh Y. , Takahashi M. , Ishibashi T.
Published: October 2022

This paper presents the results of long-term thermal cycling tests on plasma-sprayed thermal barrier coatings, including coating samples produced with functionally graded materials. The role of oxidation is also considered based on the results of elemental analysis. The authors explain how the coatings were produced and tested and present and analyze the test results. The thermal barrier coatings formed with functionally graded materials were found to be relatively unaffected after the long-term thermal cycling test and showed no signs of oxidation. Paper includes a German-language abstract.
Marine Corrosion Performance of HVOF Sprayed Alloy Coatings: Comparison of Field Exposure Test and Laboratory Test
Authors: Kuroda S. , Fukushima T. , Kawakita J. , Kodama T.
Published: October 2022

This study examines stainless steel and Hastelloy C coatings sprayed using commercial HVOF equipment. Porosity and oxygen content have been measured under various spray conditions and laboratory corrosion tests have been carried out using electrochemical techniques. The report first summarizes major results obtained in the laboratory evaluation, then presents the results of marine exposure testing for up to six months. It concludes with detailed comparisons between the two. Paper includes a German-language abstract.
Effect of Substrate Temperature and Roughness on Coating Formation
Authors: Mehdizadeh N.Z. , Chandra S. , Mostaghimi J.
Published: October 2022

Though a large literature exists on thermal spray coating, there have been few attempts to directly observe molten droplets as they land on a substrate, freeze, and coalesce into a solid layer. In this study, investigators photograph the impact of tin droplets landing on stainless steel surfaces at high speeds. They also measure the effect of substrate temperature and surface roughness on deposition efficiency, the fraction of coating material that adheres to the surface. The paper describes the apparatus used to create the tin droplets and record their impact with the target. It also provides a detailed review of the test results and discusses the practical implications of the study. Paper includes a German-language abstract.
Microstructure of FeAl Binary Alloy Coatings from Detonation Gun Spraying
Authors: Xin G. , Gao Y. , Yan Y.G.
Published: October 2022

In this investigation, binary FeAl layers are produced by detonation spraying and examined by means of microscopy and X-ray diffractometry. The examinations show that the layers have a lamellar structure consisting of FeAl and Fe4Al13 phases with a small amount of alumina. It is observed that with increasing amounts of fuel gas and decreasing detonation frequency, the proportion of FeAl phases decreases and variations in microhardness throughout the coating become irregular. Paper includes a German-language abstract.
Relationship Between Splat Morphology and Cohesion-Adhesion Strength of Coatings
Authors: Oki S.
Published: October 2022

This study investigates the relationship between splat morphology and adhesion strength in plasma sprayed coatings. The shape and size of the splats are examined and found to differ, in some cases significantly, depending on whether the splats are in the center or on the periphery of the spray pattern. Splats in the center of the pattern are formed by particles with higher temperature and velocity than those on the periphery and they tend to produce higher quality layers. In an experiment in which alumina layers are sprayed through a graphite slit filter, coating adhesion is shown to be superior, as expected. Paper includes a German-language abstract.
Tribological Properties of Carbide Coatings by Plasma and HVOF Spraying
Authors: Żórawski W.
Published: October 2022

This paper assesses the abrasion resistance of plasma and HVOF sprayed WC-Co and Cr3C2 coatings under dry friction conditions. It is observed that WC-Co layers produced by HVOF spraying have the most regular layer structure, the best abrasion resistance, and the highest hardness. Paper includes a German-language abstract.
Drawbacks in Corrosion Resistance of Thermal Spray Coatings in Aggressive Aqueous Media
Authors: Guilemany J.M. , Fernández J. , Delgado J. , Benedetti A.V.
Published: October 2022

The growing use of thermal spray technology in manufacturing is increasing the need for knowledge regarding the behavior of thermal spray coatings in aggressive environments. Due to the different characteristics of the spraying processes and materials used, the mechanisms of attack can vary greatly from layer to layer depending on the application. This paper presents a detailed investigation of corrosion mechanisms at room temperature and their effect on a wide range of thermally sprayed metals and ceramic-metal (cermet) composites. Paper includes a German-language abstract.
Structure and Tribological Characteristics of HVOF Coatings Sprayed from Powder Blends of Cr3C2-25NiCr and Metallic Alloys
Authors: Määttä A. , Männikkö U. , Vuoristo P. , Mäntylä T. , Laitinen K.
Published: October 2022

In this study, Cr3C2+25NiCr hardmetal powder is mixed with small amounts of NiCr and CoCr powder and sprayed on steel substrates with a high-velocity oxyfuel torch. High-temperature friction tests are used to assess tribological performance and investigate the formation of tribolayers. The results of the study show that the friction coefficient of HVOF sprayed hardmetal coatings can be reduced by adding small amounts of low-friction powder to the feed stocks prior to spraying. The reduction in friction is the result of a tribochemical reaction that occurs on friction surfaces under contact conditions involving high temperature, pressure, and sliding speed. Paper includes a German-language abstract.
Wear Behavior of Hot Isostatically Pressed Thermal Spray Coatings
Authors: Stoica V. , Ahmed R. , Tobe S.
Published: October 2022

Hot isostatic pressing has been shown to be an effective post treatment for thermal spray coatings, improving hardness, density, and microstructure as well as metallurgical bonding between splats. In this study, the sliding wear resistance of as-sprayed and post-treated WC-Co deposited by HVOF is evaluated by means of ball-on-disk testing and the effects of HIPing are assessed based on SEM and XRD analysis, hardness measurements, and fracture toughness tests. Changes observed in the WC-Co layers, including the precipitation of carbides and the elimination of secondary phase W2C, are also discussed. Paper includes a German-language abstract.
3D Modeling of Substrate Temperature During Layer Build-up
Authors: Bolot R. , Imbert M. , Coddet C.
Published: October 2022

The modeling work presented in this paper is intended to simulate a plasma jet impinging on a flat surface and its influence on substrate temperature during layer build-up. In the first step, a two-layer model is incorporated into a commercial CFD code to express the turbulent plasma jet and the viscous sublayer that forms on the surface of the impact plane, or in this case, the substrate. In a subsequent step, heat dissipation in the substrate is expressed with a 3D volume model based on finite volume approximation of thermal exchanges. This two-step approach allows surface temperatures on the substrate to be determined as the plasma-sprayed layer grows. The influence of different substrate materials is also considered in this investigation, particularly in regard to transient surface temperatures. Paper includes a German-language abstract.
Plasma-Pulver-Auftragschweißen von Messern für die Lebensmittelindustrie (PTA Powder Cladding of Knives for Food Processing Industry)
Authors: Gebert A. , Heinze H.
Published: October 2022

The processing of frozen foods places high demands on the strength and edge retention of knives, which are typically made of chromium steels due to their corrosion resistance. In meat processing, in addition to cutting, the knives also assume a transport function, where enormous bending forces can occur. A trade-off between strength and ductility is thus required when choosing a material and heat treatment. This paper describes the implementation of a path-controlled build-up welding system for complicated flat contours and the special properties of a newly developed corrosion-resistant powder optimized for knife edges. Field tests indicate that, with the plasma transferred arc welding process and new powders, service life can be extended by a factor of five. Paper text in German.
Investigation of Composite Powders with Hard Lubricant Components for Thermal Spraying of Coatings
Authors: Ilyuschenko A. , Shevtsov A. , Azarova T. , Okovity V. , Smurov V. , Ignatiev M. , Kovalion E.
Published: October 2022

This paper presents the results of studies on powders used in wear-resistant thermal spray coatings. The work focuses on the influence of the shape, size, and structure of composite powders containing nickel, iron, and chromium mixed with TiC and dry lubricants such as MoS2 and CaF2. The powders are analyzed using SEM and metallographic methods along with X-ray diffraction. Paper includes a German-language abstract.
Performance of HVOF Nanostructured Titanium Diboride Composite Coatings
Authors: Wilden J. , Schnick T. , Wank A. , Schreiber F.
Published: October 2022

This study assesses the wear performance of HVOF-sprayed nanostructured TiB2 composite coatings and the use of mechanical alloying for powder preparation. In order to prevent the formation of undesired secondary borides, TiB2 particles are processed with a nickel-base self-fluxing matrix alloy. XRD analysis shows that the minimum average TiB2 crystal size is 22 nm after high-energy milling and only slightly larger and uniformly distributed after HVOF spraying. The resulting TiB2 layers are characterized based on morphology and wear behavior and are shown to hold promise for abrasive wear applications. Paper includes a German-language abstract.
Multipliers in weighted Sobolev spaces on the axis
Authors:   Astana IT University, Myrzagaliyeva A.
Published: October 2022

This work establishes necessary and sufficient conditions for the boundedness of one variable differential operator acting from a weighted Sobolev space W^l_p,v to a weighted Lebesgue space on the positive real half line. The coefficients of differential operators are often assumed to be pointwise multipliers of function spaces. The author introduces pointwise multipliers in weighted Sobolev spaces; obtains the description of the space of multipliers M(W_1 → W_2) for a pair of weighted Sobolev spaces (W_1, W_2) with weights of general type.
Forcing companions of Jonsson AP-theories
Authors:   Karagandy University of the name of academician E.A. Buketov, Yeshkeyev A.R. , Tungushbayeva I.O. ,   Karagandy University of the name of academician E.A. Buketov, Omarova M.T. ,   Karagandy University of the name of academician E.A. Buketov,   Karaganda University of Kazpotrebsoyuz
Published: October 2022

This article is devoted to the study of the forcing companions of the Jonsson AP-theories in the enriched signature. It is proved that the forcing companion of the theory does not change when expanding the theories under consideration, which have some properties, by adding new predicate and constant symbols to the language. The model-theoretic results obtained in this paper in general form are supported by examples from differential algebra. An approach in combining a Jonsson and non-Jonsson theories is demonstrated. In this paper, for the first time in the history of Model Theory. This will allow us to further develop the methods of research of Jonsson theories and expand the apparatus for studying incomplete theories.
New exact solutions of space-time fractional Schr¨odinger-Hirota equation
Authors:   Mersin University, Science and Letters Faculty, Mathematics Department, Ala V.
Published: October 2022

In this study, improved Bernoulli sub-equation function method (IBSEFM) is presented to construct the exact solutions of the nonlinear conformable fractional Schr¨odinger-Hirota equation (FSHE). By using the traveling wave transformation FSHE turns into the ordinary differential equation (ODE) and by the aid of symbolic calculation software, new exact solutions are obtained. 2D, 3D figures and contour surfaces acquired from the values of the solutions are plotted. The results show that the proposed method is powerful, effective and straightforward for formulating new solutions to various types of nonlinear fractional partial differential equations in applied sciences.
Stability of the time-dependent identification problem for delay hyperbolic equations
Authors:   Bahcesehir University, Ashyralyev A. ,   Peoples Friendship University of Russia,   Institute of Mathematics and Mathematical Modeling, Haso B. ,   Near East University,   Department of Mathematics, High School
Published: October 2022

Time-dependent and space-dependent source identification problems for partial differential and difference equations take an important place in applied sciences and engineering, and have been studied by several authors. Moreover, the delay appears in complicated systems with logical and computing devices, where certain time for information processing is needed. In the present paper, the time-dependent identification problem for delay hyperbolic equation is investigated. The theorems on the stability estimates for the solution of the time-dependent identification problem for the one dimensional delay hyperbolic differential equation are established. The proofs of these theorems are based on the Dalambert’s formula for the hyperbolic differential equation and integral inequality.
Estimates of singular numbers (s-numbers) for a class of degenerate elliptic operators
Authors:   M.Kh. Dulaty Taraz Regional University, Igisinov S.Zh. , Zhumaliyeva L.D. ,   M.Kh. Dulaty Taraz Regional University, Suleimbekova A.O. ,   M.Kh. Dulaty Taraz Regional University, Bayandiyev Ye.N. ,   M.Kh. Dulaty Taraz Regional University
Published: October 2022

In this paper we study a class of degenerate elliptic equations with an arbitrary power degeneracy on the line. Based on the research carried out in the course of the work, the authors propose methods to overcome various difficulties associated with the behavior of functions from the definition domain for a differential operator with piecewise continuous coefficients in a bounded domain, which affect the spectral characteristics of boundary value problems for degenerate elliptic equations. It is shown the conditions imposed on the coefficients at the lowest terms of the equation, which ensure the existence and uniqueness of the solution. The existence, uniqueness, and smoothness of a solution are proved, and estimates are found for singular numbers (s-numbers) and eigenvalues of the semiperiodic Dirichlet problem for a class of degenerate elliptic equations with arbitrary power degeneration.
Two theorems on estimates for solutions of one class of nonlinear equations in a finite-dimensional space
Authors:   Al-Farabi Kazakh National University, Koshanov B.D. ,   International University of Information Technology, Kakharman N. ,   Institute of Mathematics and Mathematical Modeling, Segizbayeva R.U. ,   Civil Aviation Academy, Sultangaziyeva Zh.B. ,   Al-Farabi Kazakh National University
Published: October 2022

The need to study boundary value problems for elliptic parabolic equations is dictated by numerous practical applications in the theoretical study of the processes of hydrodynamics, electrostatics, mechanics, heat conduction, elasticity theory and quantum physics. In this paper, we obtain two theorems on a priori estimates for solutions of nonlinear equations in a finite-dimensional Hilbert space. The work consists of four items. In the first subsection, the notation used and the statement of the main results are given. In the second subsection, the main lemmas are given. The third section is devoted to the proof of Theorem 1. In the fourth section, Theorem 2 is proved. The conditions of the theorems are such that they can be used in studying a certain class of initial-boundary value problems to obtain strong a priori estimates in the presence of weak a priori estimates. This is the meaning of these theorems.
Pengembangan Media Pembelajaran Macromedia Flash Berbasis Saintifik
Authors: Ependi Agustan , Purwasi Lucy Asri , Adha Idul
Published: October 2022

This study aims to develop scientific-based macromedia flash learning media on integer material for seventh grade junior high school students and determine the quality of learning media developed based on validity and practicality. This research is a development study using the ADDIE development model. The stages of the ADDIE development model consist of 5 stages, namely: Analysis, Design, Development, Implementation, Evaluation. The results of the study, from the results of the assessment analysis by the three experts namely: linguists, material experts, and media experts, the learning media developed met very valid criteria with an average score of 4.24. The results of the analysis of the practicality of the user questionnaire (teachers and students) met very practical criteria with an average score of 4.37. The characteristics of the developed media are 1) The material is in accordance with the competency to be achieved; 2) The learning objectives are clear; 3) There are clear instructions; 4) Language that is easily understood by students; 5) In accordance with the approach used is a scientific approach; 6) There is a section to motivate students; 7) Clear learning flow; 8) There are practice questions and discussion as well as evaluation questions; 9) Interactive; 10) Easy navigation; 11) Images, animations, text, and colors are presented in harmony and harmony. In conclusion, the development of scientific-based macromedia flash learning media meets valid and practical criteria for use by VII grade junior high school students in learning integer material.

Keywords: Integer, Macromedia Flash, Scientific, Development of Learning

                 Media
Pengembangan Perangkat Pembelajaran Berdasarkan Problem Based Learning terhadap Peningkatan Kemampuan Pemahaman Konsep Siswa
Authors: Sinaga Wita , Purba Tuty Novelinda , Telaumbanua Folala , Simanjuntak Ruthmayasari
Published: October 2022

This study aims to develop learning tools in the form of lesson plans and worksheets based on Problem Based Learning mathematics on comparative material for seventh grade junior high school students oriented to the ability to understand concepts. The quality of the developed products is assessed based on aspects of validity, practicality, and effectiveness. The learning device development procedure refers to the 4-D development model, namely Define, Design, Develop, and Disseminate. Due to the limitations of the researcher, the research was carried out until the develop stage. The subjects of this study were students of class VII ASMP Negeri 2 Dolok Pardamean, totaling 34 people. The results of the research, namely: 1) the resulting learning tools, in the form of: lesson plans, student activity sheets and concept understanding tests have met the criteria; 2) the effectiveness of learning tools is concluded based on the percentage of students who understand the concept of at least moderate is 85.29% of the 34 students who take the test and the achievement of the ideal percentage of time for each category of student and teacher activity. In conclusion, the development of learning tools in the form of lesson plans and worksheets based on Problem Based Learning on comparative materials for grade VII junior high school students proved to be effective and able to improve students' conceptual understanding.

Keywords: Ability to understand concepts, Learning tools, Problem Based Learning
Pengaruh Strategi React dengan Media Pembelajaran Berbasis Prezi terhadap Kemampuan Komunikasi Matematis
Authors: Vanka Fany Aviola , Kurniasih Meyta Dwi
Published: October 2022

This study aims to determine whether or not there is an effect of using the REACT strategy with Prezi-based learning media on mathematical communication skills. This type of research is quantitative using a quasi-experimental research method. The population in this study were all seventh grade students at SMP Negeri 194 Jakarta for the 2020/2021 academic year. The sample used was 66 students from class 2 class. Sampling using simple random sampling technique. The research instrument is in the form of a description question. The results of the normality test showed that the experimental class data were normally distributed and the control class data were not normally distributed. Hypothesis testing using a non-parametric test, namely the Mann Whitney test with a significant level of 5%, the value z_table=z_0.5(1-0.05) =z_0.475=1.96; because the value of z_count = 5.40. So that in determining the test criteria, the acceptance of Ha is: z_hitung>z_table. The results of this study can be concluded that there is an effect of REACT strategy with Prezi-based learning media on students' mathematical communication skills.

Keywords: REACT Strategy, Prezi Learning Media, Students’ Mathematical Communication
Efektivitas Pembelajaran Kontekstual dalam Meningkatkan Kemampuan Siswa Menyelesaikan Soal Matematika Berbasis HOTS (Higher Order Thinking Skill)
Authors: Supratman Moh
Published: October 2022

This study aims to determine the effectiveness of contextual learning in improving students' ability to solve math problems based on HOTs (Higher Order Tinking Skill). This type of research is experimental research, the research design uses a one group pretest-posttest design. The research subjects were students of class VIIA SMP Negeri 2 Praya Timur, totaling 42 students. The data collection instrument used a written test in the form of an essay (essay), and data analysis used the t test. Based on the results of descriptive statistical analysis, it shows that the pretest results of students in solving HOTs-based questions are still low with an average of 31.07, and after being given treatment by applying a contextual learning approach, students' ability to solve HOTs-based questions based on the posttest average increased to 84 .57 with very high category. While the results of the t-test with a test-value of 65 obtained tcount = 15.515, for a significance value of 0.000. In conclusion, the contextual learning approach is effective in improving students' ability to solve HOTs-based questions.

Keywords: Contextual Learning, HOTS-Based Questions
Synthesis of Some Organic Ammonium Formate Salts and Study of Their Antifungal Properties
Authors: Ali Bawa Ramadan
Published: October 2022

This work is concerned with the preparation of a number of organic ammonium formate salts (or ionic liquids; ILs) throughout a reaction between the formic acid and some aliphatic and aromatic amines including the ammonia. Five organic ammonium formate salts were formed, some of them were in the form of solid salts and others were as the ionic liquids (ILs) at room temperature. The yields of the prepared organic salts ranged from (21%) to (79%). However, some attempts towards the preparation of other fifteen organic salts were not successful. The resulting five organic ammonium formate salts/ionic liquids were characterized using a number of spectroscopic techniques such as the infrared (IR), the nuclear magnetic resonance spectroscopy (1HNMR) and the mass spectrometry (ms). The collected spectroscopic data confirmed the formation of theses organic ammonium formate salts. The antifungal properties of the prepared organic ammonium formate salts were investigated against the aspergillus niger (A. niger), and the antifungal results were compared with the antifungal effect of the commercially available antifungal agent Daktarin, which was used as a reference in this study.
Pseudo-Subdural Collection on Ultrasound: A Mirror Image Artefact
Authors: Saba Khalaf
Published: October 2022

Teaching point: -Extra-calvarial subcutaneous or subgaleal collection can mimic as subdural collection on ultrasound due to mirror image artefacts.
Tricuspid regurgitation and left ventricular eccentricity as a measure of heart failure in the newborn patient with a vein of Galen malformation: illustrative case
Authors: Yarden Jeremy A. , Hauck Lily I. , Athavale Kamlesh V. , McCrary Andrew W. , Campbell M. Jay , Hauck Erik F.
Published: October 2022

BACKGROUND

Successful management of a vein of Galen malformation (VoGM) in the newborn patient requires a highly coordinated team approach involving neonatologists, pediatric cardiologists, pediatric neurologists, neurosurgeons, and interventionalists. Indication and timing of catheter intervention are topics of ongoing debate.

OBSERVATIONS

The authors highlighted two key echocardiographic markers believed to be practical indicators regarding the need for urgent catheter embolization in neonates with a VoGM. The first and preferred parameter was the tricuspid valve regurgitation (TR) gradient, an estimate of pulmonary artery hypertension. If the TR gradient exceeds systolic blood pressure (suprasystemic pulmonary hypertension [PH], i.e., >60 mm Hg), urgent intervention should be considered in eligible newborns. The second parameter was the left ventricular end-systolic eccentricity index (EI), a newly emerging echocardiographic marker and indirect correlate of PH. As an alternative to the TR gradient, an increased eccentricity index (>1.6) suggests severe right heart compromise, requiring emergency catheter embolization of the malformation. Postoperatively, the progressive reduction of both the TR gradient and the EI correlated with recovery.

LESSONS

In eligible newborns, urgent embolization of a VoGM is recommended in the presence of suprasystemic TR gradients and/or increased EI >1.6.
تقييم الإطار القانوني للإنتخابات في السودان
Authors:   International Institute for Democracy and Electoral Assistance (International IDEA), Abdelkarim Zeinab Elnour
Published: October 2022

يقدم تقرير تقييم الإطار القانوني للانتخابات في السودان نظرة ثاقبة وتحليلاً عميقاً للإطار القانوني الحالي للانتخابات في السودان. فهو يقارن الإطار الانتخابي القانوني في السودان بالقياس إلى الفهم الدولي المشترك للمبادئ والأعراف والالتزامات التي تحدد الانتخابات الديمقراطية الموثوقة. وليست الغاية من هذا التحليل إنتقاد العمليات الانتخابية الحالية في البلاد أو إصدار حكم عليها، وإنما الغاية هي تقديم تقييم غير متحيز للكيفية التي تهيأ بها قوانين الانتخابات الحالية في السودان وسياق القطر كبيئة مواتية أو غير مواتية لإجراء انتخابات حرة ونزيهة. و يقدم توصيات شاملة وبناءة لتعزيز التشريعات القائمة وتحسين النزاهة والتماثل والموثوقية والاتساق والمهنية في انتخابات السودان المستقبلية. تقيم هذه الورقة أيضاً حالة المبادئ والحريات الديمقراطية الأساسية التي توفر الأساس لإنتخابات ذات مصداقية، وتسلط الضوء على أي قيود تكتنف هذه الحقوق والحريات الأساسية بحيث يمكن أن تعرقل الانتخابات المقبلة في البلاد أو تؤخر انتقالها السياسي. وتدعو الورقة الحكومة الانتقالية إلى حماية حقوق المواطنين وحرياتهم ومنع الانتهاكات التي قد تؤثر على ثقة الجمهور وعلى نزاهة وشفافية العمليات الانتخابية وغيرها من العمليات الانتقالية. وأخيراً، تناقش هذه الورقة القضايا السياسية والاجتماعية والاقتصادية والقانونية التي تؤثر على خارطة طريق السودان نحو الانتقال الديمقراطي قبل الانقلاب العسكري في أكتوبر ٢٠٢١.
Prawna ochrona zwierząt w kontekście zwalczania epizootii i chorób odzwierzęcych
Authors: Gądzik Zuzanna , Wiak Krzysztof
Published: October 2022

Ochrona zwierząt w związku ze zwalczaniem chorób zakaźnych jest zagadnieniem złożonym. W razie wystąpienia takiego zagrożenia w kolizji pozostają ze sobą dwa rodzaje dóbr prawnych – życie i zdrowie ludzi oraz zwierząt, chronione przed rozprzestrzenianiem się choroby zakaźnej i wiążącymi się z tym zagrożeniami, oraz wolność zwierząt od zadawanego im bólu lub cierpienia. Ze względu na mogącą wystąpić szeroką skalę szerzenia się choroby zakaźnej zwierząt w ramach epizootii, ich uśmiercenie stanowi często jedyną szansę na przerwanie łańcucha epizootycznego i zatrzymanie dalszego rozwoju danej choroby. W konsekwencji ustawodawca przyznaje wyższy priorytet bezpieczeństwu zdrowotnemu osób i zwierząt przybywających na określonym terytorium w związku z zagrożeniem tego obszaru epizootią niż dobru pojedynczych osobników zwierząt. Niedopuszczalne jest jednak całkowite zrezygnowanie ze wszystkich aspektów ochrony humanitarnej zwierząt. Uzasadnione, ze względu na wystąpienie epizootii, uśmiercenie zwierzęcia nie eliminuje konieczności przeprowadzania takich czynności w sposób humanitarny.
Covid-19, vagus nerve and phrenic nerve: three sides to the same story
Authors: Labrou Dimitris
Published: October 2022

This article aims to prove that there is an intoxication of the vagus and phrenic nerves in cases of covid 19 that lead to symptoms of the disease. First of all, it should be noted that the virus affects the nicotinic receptor a7(a7nAchR), which is the main arm of those peripheral nerves, thus paralyzing the function of both the respiratory system and that of the heart, which is controlled by those nerves. Through our analysis, we support that there is no case of Central Nervous System(CNS) entry, rather the Severe Acute Respiratory Coronavirus 2(SARS-CoV-2) can have distal effects on the CNS, through the microbiome and vagus nerve paralysis. Also, the Angiotensin Converting Enzyme 2(ACE2) receptor upregulation is the key to having milder symptoms. Last but not least, the administration of cholinergic agents, antiepileptics, or even vagus and phrenic nerve stimulation is proposed to be an effective treatment of covid-19.