bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue and Mechanical Properties of Nanostructured vs. Conventional Titania (TiO2) Coatings
Authors: Ibrahim A. , Lima R.S. , Marple B.R. , Berndt C.C.
Published: August 2022

Nanostructured and conventional titania (TiO2) powders were thermally sprayed using APS and HVOF processes. The fatigue and mechanical properties of the coatings investigated. Coatings were characterized using SEM to investigate the microstructural features and Vickers indentation to determine the hardness. SEM analyses were also carried out on the fracture surfaces of fatigue-tested samples to assess crack nucleation and to study the mechanisms of deformations. The fatigue strength of coatings deposited onto low-carbon steel (AISI 1018) showed that the nanostructured titania coated specimens exhibited significantly higher fatigue strength compared to the conventional titania
Investigation of Ceramic and Hardmetal Coatings in an Oscillating Sliding Wear Test
Authors: Zieris R. , Berger L.-M. , Schulz I. , Martens S. , Enžl R.
Published: August 2022

The present study was carried out within the scope of a project oriented toward the evaluation of applicability of different materials as thermally sprayed coatings for gear flank protection. Investigations were made on APS deposited oxide coatings, such as Cr2O3 and Magnéli phases of different systems, as well as on hardmetal coatings based on WC, Cr3C2 and TiC deposited by HVOF. All coating microstructures were investigated by optical microscopy, with selected samples studied additionally by SEM. Phase composition, hardness, Young’s modulus and fracture toughness were other basic coating properties studied. An oscillating sliding wear test was used as the main tool for preliminary evaluation before more laborious testing. The wear resistance in this test was investigated against 100Cr6 for all materials as well as against sintered silicon nitride and sintered WC-Co for oxide and hardmetal coatings, respectively. Hardmetal coatings based on WC and TiC showed the best results and were selected for further testing.
Wet Spray Coatings for Heavy Equipment Industry
Authors: Revankar G.
Published: August 2022

The paper presents a wet spray method as an alternative to the thermal spray process when post-spray fusion of the coating is required to improve coating density and obtain a metallurgical bond to the substrate. The relatively new wet process [1] has been successfully used to apply alloy metal powders to ferrous substrates such as steels, grey and ductile iron, and other iron alloys. Since a majority of wear parts used in the heavy equipment industry are made of steels and irons the technology is found applicable to a large number of ferrous parts for reducing wear and extending life. The process has advantages over the thermal spray process in that it is much less expensive and can be applied to a much greater thickness without concern for pre-fusion coating stress and spalling. In this work, a commercially available iron based alloy powder was applied to several heavy equipment parts to produce wear and corrosion resistant coatings that were evaluated through laboratory and field tests. Many of these parts are now in production. The paper gives the process details and its current status, presents test data, and discusses its advantages and limitations over the thermal spray process.
Statistical Modeling of Thermal Spray Welding of Steel-Shaft Materials for Wear Resistance
Authors: Jawwad A. , Al-Bashir A.
Published: August 2022

Thermal spray processes are widely used in industries to compensate for worn surfaces of different power transmission steel shafts. These include plain carbon, alloyed and stainless steels. This comes as a means of saving the worn parts by reusing them after they have been thermally sprayed by suitable wear-resistant coatings. As there are several factors to be controlled in this process, this makes it necessary to get the best combination of process parameters to provide the required level of wear resistance and, hence part life. In this study the oxy-fuel process is applied to 4140 alloy steel. Process parameters have been varied using a 2k experimental design. The Pin-on-Disc test was used to estimate the wear resistance of the different material-coating-parameters combinations. The data were analyzed and a statistical model, explaining the effect(s) of different parameters as well as their interaction, was obtained.
Full Mechanised Cladding of 3-Dimensional Components in Constrain Position with the PPAW-Process
Authors: Wilden J. , Bergmann J.P. , Trommer M.
Published: August 2022

The industrial set of PPAW-cladding has gained a higher importance in the last few years. The process is characterised by high quality layers of about 1-2 mm with a low dilution of about 5 % and without intermediate layers. The great amount of different alloys, which can be processed as powders, opens a wide range for industrial applications. Manually PTA-cladding can be performed in different working positions. Presently the full mechanised PTA-cladding process is carried out in horizontal position. Thus the components have to be moved relative to the plasma arc. In order to improve operating efficiency and flexibility when processing wear and corrosion resistant coatings it is necessary to enlarge the working area and to set strategies for cladding in constrain position. The effect of the gravitation force leads in this case to a very difficult governing of the pool, which flows downwards and affects the quality of the coating. Basic knowledge of the mechanised process depending on the cladding position, for example with industrial robots, is not available at the moment, even if this is necessary when cladding huge heavy components. The present work shows coating strategies as well as the influence of process parameters while cladding steel with corrosion and wear resistant powders in constrain position (bottom-up and top-down). Investigations with Ni- and Co-based alloys were examined and the suitability for constrain position was evaluated. Through an optimisation of the heat input it was possible to influence positively the melt flow and to carry out successfully coatings. Finally the transferability was successfully proven on a complex three dimensional component.
Manufacture and Properties of Segmented Thermal Barrier Coatings
Authors: Vaßen R. , Szulc M. , Guo H. , Stöver D.
Published: August 2022

Thermal barrier coatings (TBCs) made of yttria stabilized zirconia (YSZ) are frequently used in gas turbines to improve their efficiency. Coatings typically applied on combustion chamber parts with a thickness of more than about 500 mm often contain segmentation cracks. This type of cracks considerably improve the thermal cyclic life of the thick TBCs. Segmentation cracks can be directly introduced into the coatings during the plasma-spraying process. The influence of the most important process parameters as substrate temperature and passage thickness on the segmentation crack density will be described in detail. In addition to the coatings with thickness values of about 1 mm also thin coatings with segmentation cracks have been developed. This type of coating might also be favourable for an application on blades and vanes of gas turbines. The thermal cycling performance of all coatings was tested in gas burner test facilities. The thick, segmented TBCs almost reached the performance of conventionally sprayed thin TBCs. The thin, segmented TBCs showed an excellent performance at surface temperatures above 1300°C which was considerably better than that of conventionally sprayed thin TBCs. Possible explanations for the observed improvement of the thermal cycling behaviour by the introduction of segmentation cracks will be given. Abstract only; no full-text paper available.
Surface Modification Induced by the Pulsed Nd-YAG Laser Irradiation in the PROTAL Process
Authors: Li H. , Costil S. , Coddet C. , Barnier V. , Oltra R.
Published: August 2022

In the PROTAL process, a pulsed (10ns) laser irradiation is introduced to prepare the surface simultaneously to the thermal spraying process. The purpose of the laser pre-treatment is to eliminate the contaminants and generate a surface condition favorable to the coating adhesion. This study aims at clarifying the fundamental aspects of laser irradiation effects on metallic substrates. The broad technical applications, which involves various surface conditions, may lead to different phenomena and hence limit our comprehensive understanding of the laser-material interaction. Therefore, all specimens were mechanically polished to a mirror state before the laser treatment, which allows the same surface state. Both morphological and chemical surface modifications were investigated by optical microscopy, SEM observation, roughness measurements. Formation of dispersed craters, which takes place at the superficial defects location, dominates the surface modifications due to localized laser ablation.
Non Destructive Resting of the Coating-Subsrate Interface of Thermally-Sprayed Industrial Parts Non Destructive Testing of the Coating-Substrate Interface of Thermally-Sprayed Industrial Parts
Authors: Ducos M. , Bossuat B. , Walaszek H. , Canal B.
Published: August 2022

The present work deals with the application to actual in industrial conditions of the promising results of the study on adhesion, as presented at the previous edition of ITSC’2004 in Osaka, Japan. These industrial parts were typical of those produced in workshops for aircraft-aerospace, petro-chemical, printing works industries etc…. Thermal spray processing of industrial parts tested in this study are numerous, primarily air plasma spraying (APS), HVOF and conventional flame spray with or without remelting. Ultrasonic NDT facilities are now installed in an actual industrial workshop and show the reliability of the testing method and related results. For every tested part, digital ultrasonic testing was carried out to be compared to results from conventional adhesion tests according to EN 582 standard. U.T. results were quite in keeping with those from EN 582 testing. However, in addition, ultrasonic testing exhibited the any heterogeneity when existing, (local weak zones) at the coating-substrate interface. This resulted in easy discriminating of adhesive areas from cohesive areas. Results of this work obtained in a real workshop environment leaves promising expectations for ultrasonic testing to meet results from conventional EN 582 adhesion testing when applied to industrially-produced parts. Ultrasonic testing results in a low-cost NDT method which should compete with current high-cost control. Moreover, ultrasonic NDT looks more reliable in so far as the whole part can be controlled due to scanning of the whole surface.
Modern Gas Supply Concepts for Thermal Spraying
Authors: Krömmer W. , Heinrich P. , Rickfält C.
Published: August 2022

The gas industry not only offers the most effective gas for all thermal spray processes, it also provides a variety of supply concepts and hardware with which maximum profitability can be achieved. The operator of the thermal spray equipment is responsible for ensuring that sufficient gas quantities are available at all times, comparable to the logistics involved in spray material management. Linde is now offering a fully automatic gas supply concept, including everything from consultancy and installation, through to the types of gases which can be used. The customer can therefore choose to manage his stocks himself as before, or to have the gas delivered and the bundles replaced by the supplier. With a minimum of time and effort, this electronic aid enables a reliable and fail-safe gas supply
Thermal Spray Particulate and Its Challenges for Dust Collection Equipment
Authors: Abelson J.
Published: August 2022

Thermal spray particulate presents unique challenges for in-plant dust collection. Regulations about particulate level emissions are becoming increasingly stringent. This paper will discuss the thermal spray environment and technologies that can be useful in the mitigation of airborne particulate. First, a discussion of basic filtration concepts - The many methods that are used to collect particulate (diffusion, inertial impaction, interception, and sieving) and an explanation of each with an understanding of when each methodology is used. We will also explore the properties of the typical thermal spray particulate - particle size analysis of typical resultant thermal overspray process dust including actual test data and scanning electron microscope photos. The structure of the filter media is vital to achieve superior filtration performance. A unique filter media technology for this application will be discussed, including media construction and characteristics of its use. Finally, the filter media must function within a system. A brief discussion of dust collection technology and the dust collection system will describe a solution to the problems of thermal spray particulate.
The Development of a High Efficiency Supersonic Plasma System
Authors: Zhang P. , Liang Z. , Wang H. , Xu B. , Zhu S.
Published: August 2022

A high efficiency supersonic plasma spray system (HEPJet) was successfully developed with a maximum power of 80 kW and a maximum working gas flow of 6 m3/h. It can be used to spray metallic, carbide and oxide powders. The supersonic plasma spraying gun has a single-anode, internal feeding structure. The development of 80 kW inverse power supply with 20 kHz PWM IGBT circuit solved the problems of high output voltage, high output current and strong interference of high frequency. The production cost of this system is only equivalent to that of ordinary plasma systems. The average velocity of Al2O3 particles in the plasma jet measured with a Oseir Spray Watch system reached 740m/s, and the coatings show high quality, good bonding strength and low porosity. The Co/WC coatings deposited by HEP Jet avoided the degradation from WC to W2C which should be attributed to the strong adjustability of the system for jet temperature and jet velocity.
Irregularity Parameter and Sphericity of Plasma Sprayed Nickel Powders
Authors: Selvarajan V. , Kumar S.
Published: August 2022

Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration of the powder particles, impact and bonding with the substrate. Feedstock powders of thermal spray applications have to meet several requirements. Particle shape, size and its distribution, powder flow characteristics and density are the important factors to be considered in order to ensure high spray efficiency and better coating properties. For smooth and uniform feeding of powders into the plasma jet, the powder particles have to be spherical in shape. In the present investigation powder particles are fed into the thermal plasma and spheroidized. The plasma was generated in a dc atmospheric plasma spray torch operating in non-transferred mode. Plasma processed powders were allowed to cool in atmospheric air inside a plasma reactor. The particle while free fall and cooling got spheroidized by surface tension forces. The feedstock powders were in the size range from 40 to 100 microns. The processed powders were analyzed through XRD, SEM/ Optical microscopy and irregularity parameter (IP) and roundness factor were determined. The same parameters were determined through theoretical methods and compared with experimental results.
Thermal Fatigue Testing of Ceramic Coatings Produced by Water-Stabilized Plasma Gun
Authors: Jakubov M. , Ctibor P.
Published: August 2022

Plasma sprayed coatings, thanks to their specific structure, are considered for applications with thermal shocks. Alumina, Alumina-Titania as well as less common spraying materials like mullite, forsterite and ilmenite were selected for testing. Carbon steel coupons were used as substrate. Flame-sprayed bond coats of Ni-Cr and Ni-Al under plasma sprayed ceramic coating were applied for comparison in selected cases. Two different regimes were used to simulate high and low temperature thermal cycling. Before the test and after given number of cycles coating's adhesion was tested by a standard tensile test (EN 582). After the test also the microstructure of samples was observed to evaluate the damage mechanism. It has been proved that Titania addition to Alumina improves the adhesion of coatings under thermal cycling, especially for the coatings without any bond coat. All materials had higher adhesion after each given number of cycles with bond coat than without. Cracking occurred dominantly on the boundary with the base in the case of pure Alumina and mullite while a cohesive cleavage is preferred in ilmenite and combination of both types is typical for other tested materials.
Performance Comparison of Various Sensor Systems and Plasma Spray Torches
Authors: Gevelber M. , Vattiat B. , Cui C. , Pollard L. , Barker W. , Harter D. , Jelovich J.
Published: August 2022

This study evaluates the performance characteristics of three different torches. A variety of different sensor systems were used to determine how each system resolves the differences in torch spray conditions. Torch performance characteristics include the long term drift behavior in terms of spray pattern and coating profile, the ability to control the particle state, and each torches nonlinear characteristics such as bifurcation (sudden jumps) and on/off repeatability. Sensors include commercially available particle sensors (Tecnar’s DPV 2000, Oseir’s Spraywatch, and Inflight’s IPM), as well as monitoring of plume intensity, acoustic emission, and high frequency voltage/current. Torches include Praxair’s SG 100 (internal injection), Sulzer Metco’s 9MB, and Progressive Technologies 100 HE. The study focused on spraying YSZ under each torches typical operating conditions. Abstract only; no full-text paper available.
Relationship between the Elastic Modulus and Microstructure in Vacuum Plasma Sprayed Structures
Authors: Salimijazi H.R. , Azarmi F. , Coyle T.W. , Mostaghimi J.
Published: August 2022

The structure of thermally sprayed deposit consists of individual lamellae formed from melted and re-solidified particles, along with unmelted and partially melted particles, pores, microcracks, and splat boundaries. The elastic modulus of a vacuum plasma sprayed Ti-6Al-4V alloy parallel to the splat plane determined by standard uniaxial tensile testing was found to be approximately 30% lower than that of conventionally processed materials with the same level of porosity. The relationship between the elastic modulus and the microstructure was studied using an in-situ tensile testing stage in an optical microscope combined with analytical and finite element models. An idealized microstructure was used for the analytical model, which yielded an estimate of the modulus higher than that measured. The finite-element program OOF was also used to compute the elastic modulus based on micrographs of polished and etched surfaces and predicted a reduction of about 37% in the modulus.
Preliminary Study on Plasma Spraying of Ion Conducting Oxides on Bi2O3 Base
Authors: Glazek W. , Pawlowski L. , Vannier R.-N. , Zdanowski J.
Published: August 2022

The powders of Bi2O3 and Bi2WO6 were prepared by calcination, sintering and crushing. Their sizes were screened out to be in the range from 50 to 150 µm. The initial spray parameters were optimised using numerical codes simulating the behaviour of powders in plasma jet. Spray experiments onto metallic substrates were carried out using commercial plasma torch SG-100, equipped in an external powder injector. The spraying of coatings was carried out by varying electric power input to plasma, distance of spraying and the geometry of injector. The morphology of sprayed coatings was investigated using scanning electron microscope (SEM). X-ray Diffraction (XRD) of Bi2O3 coatings revealed the α-Bi2O3 phase, present in the initial powder, and also β-Bi2O3 in some of the samples. Reduction of oxide into metallic Bi at spraying process was not discovered using XRD and Differential Thermal Analysis (DTA). Bi2WO6 powder was crystallized in an orthorhombic phase that transformed into tetragonal one at spraying. Finally, the X-ray Photoelectric Spectroscopy (XPS) investigations revealed a possible presence of Bi(OH)3 phase in the coatings sprayed using Bi2O3 powder.
Effect of Spray Parameters on the Cracking and Spalling Behavior of WC-17% Co Cermet Coatings
Authors: Legoux J.-G. , Bouaricha S. , Sauer J.
Published: August 2022

WC thermal spray based powders are now frequently used as chrome replacement alternatives for a wide range of industrial and aeronautical applications. In numerous cases, the carbide materials outperform the hard chrome in many property evaluations However, its usage on highly stressed parts, especially in fatigue loading, can be limited by spalling resistance of the coating. While HVOF is being used on many flight critical parts, stringent applications like the carrier based landing gear components are still under investigation. This work, on WC-17%Co, relates the processing history of different HVOF processes used at a variety of industrial sources for hard chrome replacement to the coating microstructure and mechanical properties. The thermal history of the WC particles was monitored using a DPV-2000. The mechanical properties of the coatings were assessed following an instrumented four-point bend test as well as uniaxial cyclic loading. The coating microstructures were characterized using X-Ray diffraction and electron microscopy in order to investigate the phase content and nature. In particular, the cracks generated during the bend test were measured using SEM on samples cross sections to measure characteristics such as spacing and crack penetration to the substrate. The goal of the investigation was to better understand the interaction of processing parameters with the cracking/spalling resistance of the varied coating deposits. Abstract only; no full-text paper available.
HVOF Deposition of SOFC Interconnect Materials
Authors: Wang Y. , Garcia E. , Coyle T.
Published: August 2022

One of the tubular cell designs for solid oxide fuel cells is based on a closed-end tube made from the cathode material, with an electrolyte layer coating the outside of the cathode tube, and the anode coating the electrolyte layer. The outer anode layer of one tubular cell is connected to the inner cathode layer of the next tube by the interconnect material. High density is required in the interconnects to prevent mixing of the air and fuel gases. The fabrication of interconnect strips in tubular fuel cell stacks by DC-arc plasma spray deposition has been demonstrated in the past, both in air (APS) and in low pressure (vacuum) conditions (VPS). The High Velocity Oxy Fuel (HVOF) spray deposition technique typically yields among the highest density coatings of all common thermal spray techniques due to the high gas and particle velocities achieved, and therefore would appear to be an excellent method for depositing the interconnects if the powder could be sufficiently melted during spraying. The most common material choice is a doped LaCrO3, a ceramic material with a good thermal expansion coefficient match with the other components of the cell and an acceptable electrical conductivity. The microstructure, phase and chemical composition, and electrical properties of doped LaCrO3 deposited on (La,Sr,Mn)2O3 cathode tubes by HVOF was examined as a function of deposition conditions. Abstract only; no full-text paper available.
Modeling of Combustion Assisted Thermal Spray Processes
Authors: Xia C. , Shamim T. , Mohanty P.
Published: August 2022

The combustion assisted thermal spray systems are being used to apply coatings to prevent surface degradation. They offer a highly attractive way to modify the surface properties of the substrate to extend the product life. The quality of combustion assisted thermal spray coating depends greatly on the flow behavior of reacting gases and particle dynamics. The present study investigates the effect of gas phase and its interaction with particles through the nozzle of a thermal spray gun by developing a comprehensive mathematical model. The objective is to develop a predictive understanding of various design parameters of combustion assisted thermal spray systems. The model was developed by considering the conservation of mass, momentum and energy of reacting gases. The particle dynamics was decoupled from the gas phase dynamics since the particle loading in the spray process is very low. The developed model was employed to investigate the influence of various design parameters on the coating quality of thermal spray process.
Computer Simulation of Injected Particle Behavior During Cold Spray Process
Authors: Kwon E.H. , Han J.W. , Lee C.H. , Kim H.J.
Published: August 2022

The cold spray process is a relatively new process using high velocity metallic particles for surface modifications. Metallic powder particles which are injected into a converging-diverging nozzle are accelerated to supersonic velocities. In this study two-dimensional temperature and velocity distributions of gas along the nozzle axis are calculated and the effects of gas pressure and temperatures on particle velocities and temperatures inside and outside of the nozzle are also investigated. It is found that the acceleration of the gas velocity takes place in the area of the nozzle throat and it increases and reaches maximum value at the nozzle exit. Due to compression shocks in the area after the nozzle, the gas jet properties show irregular shape and these result in the existence of the maximum particle velocity by the change of particle size at a given gas pressure and temperature.
Thermal Properties of Continuously Graded Thermal Barrier Coatings Deposited by Supersonic Plasma Spray
Authors: Wang H. , Xu B. , Han Z. , Zhou S.
Published: August 2022

Continuously graded yttria stabilized ZrO2(YSZ) /NiCoCrAlY coatings were prepared using a high efficiency supersonic plasma-spray system and the thermal shock properties of the coatings were studied. The specimens were so prepared that the two kinds of powders with different melting point were fed to the different regions of the plasma jet by using two powder feeders. The two powders melted perfectly at the same power, and the overheating of the powder with lower melting point was avoided. In this way, a continuously graded transition layer was obtained. The Results show that the continuous change of the coefficients of thermal expansion and thermal conductivity in the transition layer leads to a excellent thermal shock resistance of the totally 0.9mm thick TBCs. The thermal shock cycles of the specimens which underwent heating by oxygen-acetylene flam to 1200 and then quenching into water reached more than 200. The coatings’ surface was still perfect without any visible cracks after the thermal shock test. The analysis shows that the dense structure and the sufficient plastic deformation of the particles depressed the formation of TGOs, which, together with the continuously graded thermal expansion coefficient and thermal conduction coefficient, contributes to the long thermal shock resistance of the coatings.
Relationship between Process Parameters and Microstructure and Wear Characteristics of Plasma Sprayed Nanostructured Al2O3-TiO2 Ceramic Coatings
Authors: Ahn J. , Kim J. , Lee S.
Published: August 2022

The wear characteristics of plasma spray coated layer of Alumina-Titaina composite powder have been investigated, in this study, focusing on the effect of particle size of Alumina powder and parameters of plasma spray coating process. Alumina-Titania composite powders were artificially agglomerated into the size suitable for plasma spray coating process. The process condition for plasma spray coating has been optimized through a statistical data treatment method i.e. response surface analysis. Mechanical properties of coated layer have been measured as a function of the initial Alumina particle size. The structure of Alumina nano-powders in the coated layer was found to be affected by flow rates of Ar and H2 gases, and the power of plasma in a combinational way. The relationship between the wear characteristics of coated layer and process parameters and microstructure of the coated layer was elucidated, by measuring the size distribution, temperature, and velocity of traveling Alumina-Titania composite powder agglomerates. Abstract only; no full-text paper available.
Synthesis and Characterization of Nano-Size La0.8Sr0.2MO3-d Cathode Materials by Induction Plasma
Authors: Gitzhofer F. , Bouchard D. , Sun L. , Brisard G.
Published: August 2022

The synthesis of nanoscale particles has received considerable attention because of the potential for new materials and unique properties. The novel properties and the numerous applications of nanophase materials, especially ceramic nanopowders, have attracted many scientists and engineers to invent and explore the preparation methods of ceramic nanoparticles. Induction plasma is used to synthesize cathode materials for fuel cells. Solid oxide fuel cells (SOFCs) are very promising energy conversion systems. SOFCs are based on an oxide-ion conducting electrolyte and they offer a clean, low-pollution technology to electrochemically generate electricity at high efficiencies. These fuel cells provide many advantages over traditional energy conversion systems including high efficiency, reliability, modularity, fuel adaptability, and very low levels of SOx and NOx emissions. It has been found that La1-xSrxMO3-d, (M= Fe, Co etc) are perovskite materials widely considered as the Intermediate Temperature SOFC cathode materials of choice. In particular, La0.6Sr0.4Co0.2Fe0.8O3-δ is extensively used for IT-SOFCs because its thermal expansion coefficient is relatively close to that of the common electrolytes. In this paper, the nanopowders of SOFC cathode materials were synthesized by thermal plasma spray technique. The results of their structure, morphology and particle size distributions will be presented. Abstract only; no full-text paper available.
A Comprehensive Characterization of Industrially Manufactured Hard Chrome Platings and of Thermally Sprayed Alternatives
Authors: Bolelli G. , Cannillo V. , Lusvarghi L. , Soragni E. , Loreto A. , Valente T.
Published: August 2022

HVOF-sprayed coatings (WC-17Co, WC-10Co-4Cr, Co-28Mo-17Cr-3Si) have been compared with various kinds of industrially manufactured hard chrome coatings (HCC), whose substrate preparation, deposition process, post deposition treatments greatly affect their characteristics. Microstructure, micromechanical properties, tribological behaviour and corrosion resistance (electrochemical polarization tests and Corrodkote test) have been studied. HVOF-sprayed cermets are harder but less tough than HCC, Co-28Mo-17Cr-3Si are less hard than HCC. Splats detachment causes a comparable or higher mass loss in three-body abrasion than HCC coatings. Forming a uniform surface film, cermet coatings definitely overcome HCC in two-body sliding, while Co-28Mo-17Cr-3Si has insufficient hardness to display good sliding wear resistance. HVOF coatings show no passivation in corrosive media but cermets posses more noble corrosion potentials than HCC, and undergo generalized corrosion in HNO3 and HCl, with similar corrosion current densities (IC). HCC passivate and resist well in HNO3 0.1N, but undergo pitting corrosion in 0.1N HCl. Definitely different EC and IC are recorded for various HCC in HCl. HVOF-sprayed cermet coatings show lower IC in 0.1N HCl solution than several kinds of HCC. No visible damage occurs on HVOF-sprayed coatings after the Corrodkote test, while non de-hydrogenated HCC suffered pitting corrosion.
Effect of Surface Oxidation on Transition Temperature of Stainless Steel Substrate Upon Impact of Aluminum Particles
Authors: Pourmousa A. , Abedini A. , Chandra S. , Mostaghimi J.
Published: August 2022

Experimental studies involving aluminum particles sprayed onto polished AISI304L substrates using the Valuarc 200 wire arc previously showed that there exists a transition temperature from splash to disk splats. Increasing the substrate temperature above the transition temperature was seen to increase the number of disc splats, thus producing coatings of improved properties. XPS test results have shown that increasing the substrate temperature also results in increased oxygen content on the surface of the substrate. Experiments also show that prolonged heating of a substrate at a particular (fixed) temperature further promotes oxidation of the substrate surface, thus increasing the surface roughness (Ra). Samples generated on substrates that were held at or above 350°C (above Tt) for prolonged periods of time (over 20 minutes) were seen to promote splashing. This is in contrast to the previous findings that showed substrate temperatures above Tt further promoted disc type splats and improved adhesion between the splat and substrate. Samples generated in this study consistently showed that splashing can be seen at temperature well above the transition temperature, if the substrate has been heated for too long a duration. The cause of splashing is believed to be related to increased surface roughness resulting from prolonged oxidation of the substrate surface. Abstract only; no full-text paper available.
Topological Characterization of Wear Tracks in Thermally Sprayed Abradable Coatings
Authors: Seichepine J.-L. , Albertazzi S. , Nardin P. , Coddet C. , Sporer D.
Published: August 2022

Abradable coatings are located on the stationary parts of gas turbines, in front of blades, which cut a track in them. This has to be achieved with minimum wear of the blades, in order to control the over-tip leakage. These coatings are generally deposited by thermal spraying of composite powders comprising a metal base, a polymer filler generating porosities and a dislocator such as hBN. The very demanding properties are nowadays adjusted using rig tests, where samples are rubbed by the contact of a dummy, simulating actual working conditions in an aircraft engine. Several types of behaviour are usually described, but few numerical data are produced from these tests. Only the blade wear (or metal transfer) is generally measured. As the understanding of contact phenomena is fundamental for the development of predictive models allowing the design of more performing materials, a comprehensive characterization process of the rub path was developed. The study was based on a topological survey made by laser profilometry, giving three-dimensional maps. These maps were then processed by image analysis and several parameters were computed, like surface roughness and parameters giving information on the shape and orientation of the holes or grooves in the rubbed surface of the samples.
Characterization of Nano WC-Co Coatings Produced by Dynamic Powder Deposition
Authors: Kim H.J. , Hwang S.Y. , Lee C.H.
Published: August 2022

WC-Co powders with nano-sized WC were deposited by dynamic powder deposition process. Microstructural characterization and phase analysis of feedstock powders with different compositions and as-deposited coatings with various substrates were carried out by SEM and XRD. The results show that there is no detrimental phase transformation and/or decarburization of WC by dynamic powder deposition. It is also observed that nano-sized WC in the feedstock powder is maintained in the deposited coatings. It is demonstrated that it is possible to fabricate the nano-structured WC-Co coatings with low porosity and very high hardness by dynamic powder deposition.
Study of the Electrical Conductivity of Plasma-Sprayed 4.5mol% Yttria Stabilized Zirconia Coatings
Authors: Ning X.-J. , Li C.-X. , Li C.-J.
Published: August 2022

Y2O3 stabilized ZrO2 (YSZ) coating is widely applied to the electrolyte layer in solid oxide fuel cell. With regard to the application of YSZ coating to solid oxide fuel cell, the electrical conductivity of YSZ coating is of essential importance. In this study, YSZ coating was deposited by plasma spraying using a sinter-crushed powders containing 4.5mol% Y2O3. The electrical conductivity of the coating at both directions parallel and perpendicular to the coating surfaces was measured by a direct current approach. The measurement was carried out at a temperature range from 600 °C to 1000 °C. The effect of spray distance on the electrical conductivity was also examined. The test showed that 4.5YSZ layer yielded the electrical conductivities of 2.2 s·m-1 and 4.3 s·m-1 at a temperature of 1000 °C in both direction perpendicular and parallel to the coating surface, respectively. It is clear that the electrical conductivity of the coating was lower than the identical sintered bulk material. The electrical conductivity of YSZ coatings in this study was of one-fifth to one-fourth in perpendicular direction and about one-half in parallel direction compared with the sintered YSZ bulk. It was considered that the lower electrical conductivity of the coating compared with the identical sintered bulk results from the lamellar structure with the limited interface bonding.
Quality Management System Implementation in LERMPS Laboratory
Authors: Klein D. , Bocci T. , Lahoupe L. , Lamy S. , Coddet C.
Published: August 2022

LERMPS laboratory has been implementing a Quality Management System (QMS) for one year now. Only few Research organisms in the world have begun such process, which has up to now mostly been applied to industrial companies. Hence, the path leading to Quality excellence will be long, but LERMPS is on the way for at least certification, and some interesting results have already been achieved. This QMS implementation is mainly focused for the moment on characterisation team, which are the main support of Thermal Spray and PVD coatings activities in LERMPS. Nevertheless it slightly expands its application area to the whole activity of the laboratory, including administrative support processes. Abstract only; no full-text paper available.
DIVERSIDADE DE INVERTEBRADOS EM DIFERENTES USOS DO SOLO NA FLORESTA DA AMAZÔNIA
Authors: Marcílio Gonçalves dos Santos Arnoldo , Gatto Alcides , Pereira Oliveira Elisiana , Ribeiro Fabiana Piontekowski , Elias Reis Hodecker Bárbara , Pereira Bussinguer Angela , de Faria Ferreira Natália Cássia
Published: August 2022

O objetivo foi avaliar os efeitos de diferentes sistemas do uso da terra na qualidade do solo. O estudo foi realizado no Campo Experimental Confiança - Embrapa - RR. Foram avaliados oito usos da terra em parcelas de 50 x 50 m; floresta, capoeira, capoeira manejada, agrofloresta sem insumos, agrofloresta com insumos, pastagem alterada, pastagem manejada e um sistema de produção de pupunha/palmito. Em cada uso do solo projetou-se sobre um transecto na diagonal do terreno, para obtenção de cinco pontos amostrais, onde foram realizadas coletas de solo/serapilheira. A mesofauna foi obtida utilizando funil de Berlese-Tullgren, as amostras foram coletadas com sonda de 5 x 5 cm, introduzida no solo a 5 cm de profundidade. As amostras foram triadas adontando-se a chave de especialistas do grupo. Foram avaliadas: caracterização biológica da mesofauna e frequência e diversidade do grupo Collembola. Os ambientes apresentaram elevada diversificação de ordens de mesofauna, com as maiores frequências em ambientes com maior cobertura do solo. Houve destaque no uso do solo pupunheira/palmito, com alta diversidade de ordem e indivíduos, equivalentes aos ambientes de maior cobertura do solo. A diversidade de invertebrados do solo pode ser mais bem estudada e apresenta-se como bom indicador de qualidade do solo.
Palavras-chave: ação antrópica; manejo do solo; biodiversidade.
 
Land use on the diversity of soil invertebrates in the forest region of the amazon
 
ABSTRACT: The objective was to evaluate the effects of different land use systems on soil quality. The study was carried out at the Confiança Experimental Field - Embrapa - RR. Eight land uses were evaluated in 50 x 50 m plots; forest, capoeira (a kind of secondary forest), managed capoeira, agroforestry without using inputs, agroforestry using inputs, altered pasture, managed pasture and a peach palm/heart palm production system. Mesofauna was obtained using a Berlese-Tullgren funnel, samples were collected with a 5 x 5 cm probe, introduced into the soil at a depth of 5 cm. The samples were sorted using the group experts key. The following were evaluated: biological characterization of the mesofauna and frequency and diversity of the Collembola group. The environments showed high diversification of mesofauna orders, with the highest frequencies in environments with greater ground cover. The use of peach palm/heart palm soil stood out, with high diversity of order and individuals, equivalent to environments with greater soil cover. Invertebrates soil diversity can be better studied and is a good indicator of soil quality.
Keywords: human action; soil management; diversity.
AMINO ACID COMPOSITION AND SOME PHYSICOCHEMICAL PARAMETERS OF MULTI-FLORAL HONEY FROM MOUNTAINOUS REGIONS OF KYRGYZSTAN
Authors: Mazhitova Aichurok , Smanalieva Jamila
Published: August 2022

Mountain animal food products are at the center of attention due to their intrinsic value and, as such, mountain beekeeping products deserve attention and effort for their valorisation. The work aimed at investigating the quality traits of mountain honey samples from Kyrgyzstan, giving particular emphasis on the amino acid profiles and their possible relationship with the other chemical-physical characteristics. The moisture content, acidity, pH, and diastase activity of honey samples were within the limits established by normative documents. The honey samples showed a higher diastase activity (26.34 – 77.9 Schade units), which demonstrates the high quality and superiority of mountain honey. The amino acid content of Kyrgyz honey was investigated for the first time. The major amino acids were proline (1553 mg/kg), followed by phenylalanine (805 mg/kg), lysine (349 mg/kg), and arginine (261 mg/kg). The sum of essential amino acids ranged from 675 to 4506 mg/kg and that of total amino acids from 1539 to 8958 mg/kg. Weak positive correlations were found between the altitude of the collection area and asparagine, glutamine, histidine, glycine, threonine, alanine, proline, valine, and total amino acids. The results form a basis for the establishment of quality standards for mountain honey.
Efficacy of Clavipectoral Fascia Plane Block as Analgesic Modality in Clavicle Fractures: Exploring New Horizons
Authors: Panse Neha A. , Deshpande Jyoti P. , Panse Neha A.
Published: August 2022

Clavicle fractures are commonly encountered in orthopedic outpatient department but are often managed conservatively. Yet some clavicle fractures need surgical intervention which in turn demand adequate anaesthesia and analgesia. Due to complex sensory innervation there is no sole regional anaesthesia technique which could provide adequate analgesia for clavicle fractures. With the advent of ultra-sonography (USG) and the description of clavipectoral fascia plane block (CPB) by Dr. Valde a lot was simplified. Administration of CPB provides intra as well as postoperative analgesia, maintains hemodynamics, reduces opioid consumption and improvises postoperative recovery of the patients undergoing clavicle surgeries.
Lectotype designations in the genus Sphenoptera Dejean (Coleoptera: Buprestidae)
Authors: Volkovich M.G. , Kalashian M.Yu.
Published: August 2022

Lectotypes of Sphenoptera antiqua (Ill.), S. coerulea Jak. and S. nox Jak. are designated.
A new species of the genus Chorebus from Moldova (Hymenoptera: Braconidae, Alysiinae)
Authors: Lozan A. , Tobias V.I.
Published: August 2022

Chorebus ioni sp. n. reared from Agromyzidae is described from Moldova. The new species belongs to the ovalis complex. It is related to Ch. iphias (Nixon), but differsmainly in the structure of mandibles, length of petiole, andpubescence of mesoscutum. It is alsosimilar to Ch. expansus Tobias from the Russian FarEast, but the latter differs in the lessdeveloped 3rd and 4th teeth of mandible andshorter radial cell of fore wing.
Hylobius futabae Morimoto new to the Russian fauna (Coleoptera: Curculionidae)
Authors: Korotyaev B.A. , Legalov A.A.
Published: August 2022

Hylobius futabae Morimoto, 1982, is for the first time recorded for Russian fauna from the Kunashir I.
Student Errors in Mathematics Word Problem: What Can Be Learned?
Authors: Nofrianto Adri , Gulo Albert D.C. , Amri Mira Amelia , Rafulta Elfa
Published: August 2022

This study aims to understand better student errors in solving mathematics word problems. A Word problem is a problem that has a story or arrangement based on sentences. The qualitative research approach was used. The data were collected by giving tests and interviewing two male high achievers senior high school students in mathematics. The student error analysis adopted the Newman error analysis system. The source triangulation was used to ensure the data validity. Based on the collecting data and data analysis, the decoding/reading error happened caused by students' common understanding or unfamiliarity of the mathematical terms used in the problem. The subjects showed inconsistency in interpreting problem sentences and misused mathematical symbols. Furthermore, the subject encountered difficulties with the arithmetic process, especially fractions and their operation. This research identified students' difficulties in solving problem mathematics word problems. Moreover, this research provides evidence that encourages further research on mathematical literacy, mathematical communication skills, students' arithmetic skills, and the evaluation process of the problem-solving activity.
Changes in the spatial structure of land use as a result of suburbanisation processes in rural areas surrounding the Tri-city agglomeration
Authors: Korwel-Lejkowska Barbara
Published: August 2022

Motives: For many years now, suburbanisation processes have been perceived as one of the most significant factors affecting changes in landscape structures. Numerous attempts are made to find appropriate methods and materials for a comparative analysis of land use changes in different periods of time and other indicators measuring the scale of this phenomenon. These studies result from the need to balance the suburbanisation process around the main service area of the Tri-City, the rapid pace of which causes development to enter areas that are not suitable for development due to environmental reasons. This implies the need for constant monitoring of this process.
Aim: The study is an analysis of changes in land use patterns that took place in some rural areas surrounding the Tri-City agglomeration in the period of 2012–2018, and an attempt to assess how suburbanisation processes may be perceived in the light of the 1985 concept of the Gdańsk agglomeration development. The analysis covers selected rural areas located in the closest vicinity to the central housing zones of the Tri-City agglomeration and areas of rural characteristics located within the administrative borders of the cities.
Results: Applying a synthetic indicator allowing to analyse convergence of structures made it possible to determine areas where the far-reaching changes are observed. The analysis covers some negative consequences of suburbanisation in relation to the natural environment, e.g. the unbalanced proportion between bioactive and built-up areas. In order to grasp current trends, the analysis refers to the data on the agglomeration development in the 1980’s. The methods of the research can be used in the analysis of other areas – regardless of administrative borders, for research where statistical data generalized at the commune level are insufficient.