bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastoplastic Characterization of Thermal Spray Coatings using Instrumented Indentation
Authors: Gouldstone Andrew , Prchlik Lubos , Kulkarni Anand , Sampath Sanjay
Published: July 2022

Instrumented indentation is well-suited as a technique for probing mechanical behaviour of coatings; it requires minimal specimen preparation, can be performed multiple times on a single specimen, and can measure behaviour over various length scales, by recourse to appropriate indenter tip selection. However, the complex nature of the deformation fields under the tip, coupled with complex (e.g. anisotropy, nonlinearity) coating properties necessitates robust means of interpretation in order to extract stress-strain behaviour. Here we present a simple method, based on empirical work by Tabor, for converting coating indentation force-depth data to stress-strain curves. Using this method, results of indentation can thus be used to quantify mechanical behaviour of coatings deposited by different processes, and subjected to post-processing treatments, providing a powerful supplement to microstructural characterization. In addition, we show how anisotropic elasticity of coatings, measured via indentation, can qualitatively identify the existence of different microstructual features. Finally, we explore subsurface strain mapping as a technique to quantitatively compare elastoplastic behaviour of coatings to bulk, isotropic materials.
Study of the Influence of Microstructure on Electric Properties of Plasma-Sprayed Alumina Coatings using the Scanning Electron Microscope Mirror Effect (SEMME) Method
Authors: Beauvais S. , Guipont V. , Jeandin M. , Juve D. , Treheux D. , Robisson A. , Saenger R.
Published: July 2022

Pure alumina coating obtained by thermal spraying can find applications as electrical insulating layer. Thermally-sprayed ceramic coatings exhibit a complex lamellar structure with a network of interconnected pores, inter-lamellar and intra-lamellar cracks. In this work, the influence of the microstructure on electric properties for plasma-sprayed alumina coatings was investigated. Coatings have been sprayed with different pressures and gases using a CAPS (‘Controlled Atmosphere Plasma Spraying’) as well as different alumina feedstock powders. Detailed quantitative image analysis of cross-section views allowed to select six microstructures with different porosity levels and cracks orientation distributions. In order to assess the behaviour of the electrical insulation and the influence of local defects on electric properties, the so-called Scanning Electron Microscope Mirror Effect (SEMME) method has been applied on outer surfaces and on cross-sections of the different selected alumina coatings. This method, originally developed to study the ability of a bulk insulating material in trapping of charges from an electron beam irradiation in a SEM, revealed to be successfully feasible for porous materials such as thermally-sprayed ceramic coatings. It has been shown that cracks orientation modified both propagation and trapping of charges and therefore the electric properties of plasma-sprayed alumina coatings.
Measurement of a Low Power Plasma Jet by the Enthalpy Probe
Authors: Gao Yang , An Lian-Tong , Sun Cheng-Qi , Yan Zhi-Jun
Published: July 2022

The effects of the plasma gas composition (Ar-N2, Ar-H2), arc current and voltage on the temperature and velocity of a low power (5 kW) plasma torch in the arc field free region have been investigated using an enthalpy probe. Coatings of Al2O3-13TiO2 were deposited under different conditions. The results show that in the Ar-N2 plasma, the enthalpy, temperature and velocity change little with arc current and voltage when regulating the nitrogen proportion in the plasma gas, and the hardness of the resulting coatings is 800-900 HV. For Ar-H2 plasma, however, increasing the H2 content in the gas mixture remarkably enhanced the velocity and heat transfer of the plasma jet with the result that the coatings showed the high hardness up to 1200 HV.
Nanostructured Aluminum Coatings Produced Using Cold Spraying Technology
Authors: Mondoux J. , Jodoin B. , Ajdelsztajn L. , Schoenung J.M. , Kim G.E.
Published: July 2022

A mathematical model was developed and used to design and optimize a supersonic nozzle for a cold spray system. The objective was to spray 20 micron-size aluminum particles. Conventional and agglomerated nanostructured powders were used and successfully sprayed using a radial injection port. The microstructure of the coatings revealed that the nanocrystalline structure is preserved. An increase of 100% of the coating hardness was found for nanostructured coatings compared to conventional coatings. Further work needs to be done to improve the porosity of the coatings by changing some of the process parameter.
Maximization of Silica Loading in Ball-Milled Composite Powders for HVOF-Sprayed Multi-scale Polymer/Silica Composite Coatings
Authors: Saenz A. , Knight R. , Twardowski T.
Published: July 2022

The high velocity oxy-fuel (HVOF) combustion spray technique has been shown previously to be an excellent solution for depositing crystalline matrix nano-reinforced polymer coatings. Dense polymer coatings can be produced by controlling both the particle dwell time in the HVOF jet and through substrate thermal management. In composite materials, it is often desirable to incorporate the maximum amount of reinforcing material into the polymer matrix to achieve optimum mechanical properties. The experiments described here were performed to determine the maximum amount of different scales of silica particles that could be incorporated into a nylon 11 matrix and the time required to do so. Ashing results indicated a maximum amount of silica that can be incorporated. Also, the maximum level of silica incorporation occurs in a shorter time than previously believed. Microscopy, however, indicated that other physical changes continued to occur within the powders when ball milling was allowed to continue beyond this time.
Erosion and Erosion-Corrosion Properties of HVOF Sprayed Tungsten Carbide (WC) Coatings with High Alloy Binders
Authors: Berget J. , Rogne T.
Published: July 2022

This paper describes results from investigations of tungsten carbide (WC) coatings with high alloy binders. Experimental powders were manufactured by agglomeration/sintering using pre-alloyed metal particles together with WC particles. Coatings were sprayed by the HVOF process and investigated with respect to microstructure, hardness, erosion and erosion-corrosion. For comparison coatings from commercial powder materials were sprayed and investigated. This and previous work has demonstrated the importance of having a corrosion resistant binder. A corrosion resistant binder is of major importance for constructions where maintenance is difficult for instance in constructions for oil and gas production from wells at large depths in the North Sea. Improved coating quality will lead to increased life time for coated components, improved safety conditions, fewer shut-downs and large reductions in maintenance costs.
Investigations of Corrosion Properties of Different Ceramic-Metallic Coatings Sprayed by the HVOF Process
Authors: Rogne T. , Berget J.
Published: July 2022

In corrosive media the wear resistance of ceramic-metallic coatings depends on the corrosion resistance of the metallic binder. Other factors influencing the coating deterioration are the corrosivity of the media and any galvanic interaction from the surrounding material. The corrosion resistance of the metallic binder should be comparable to the material of the rest of the system. This is especially important when the surrounding materials are corrosion resistant alloys such as stainless steels, where the coatings otherwise will act as an anode. This paper summarises results from corrosion tests of different ceramic-metallic coatings sprayed by the HVOF process. The corrosion properties of the coatings have been compared with results from corresponding tests obtained for stainless steel and some nickel based alloys. The corrosion compatibility and risk of galvanic corrosion is discussed.
Corrosion Resistance of Fe-Cr-Mo-(C,B,P) Amorphous Coatings Thermal Sprayed by HVOF and APS Processes
Authors: Otsubo F. , Shimoda A. , Era H. , Kishitake K.
Published: July 2022

Two kinds of Fe-16Cr-30Mo-(C,B,P) alloy powders of different composition were thermal sprayed onto mild steel using HVOF and APS processes. Perfect amorphous coating was formed by HVOF and APS processes in both powders. The corrosion potential of the amorphous coatings sprayed by HVOF process was higher and the passive current density was lower than that of the amorphous coatings sprayed by APS process in 1N HCl solution. The coatings of perfect amorphous phase were little corroded after one week immersion tests and the corrosion rates of the amorphous coatings showed a fairly less value of 0.03 mm/y compared with Inconel 625 plate in 5N HCl solution at room temperature.
Effect of Coating Thickness and Sealants on the Steam Oxidation Resistance of APS Ni-Cr Coatings
Authors: Sundararajan T. , Haruyama H. , Kuroda S. , Abe F.
Published: July 2022

In our earlier studies we reported the excellent steam oxidation resistance of 50Ni-50Cr coatings produced by high velocity oxyfuel (HVOF) spray process. The coating produced by atmospheric plasma spray (APS) for the thickness of 40 µm yielded the scale incorporation into the coating structure on the steam oxidation due to its porous structure compared to HVOF process. The steam could penetrate into the pores and resulted in the scale initiation at the coating-substrate interface. To improve the steam oxidation resistance of the coating, thick coatings (~450 µm) of 50Ni-50Cr with sealant layer were tested in the steam. The sealant layer was applied to fill the pores produced by the APS process. The results showed that the thick coating of 50Ni-50Cr with sealant was able to protect against the steam oxidation till 3000 hours of tested duration.
Metallographic Evaluation and Process Correlation of Thermally Sprayed Coatings
Authors: Lima Carlos Roberto Camello , Camargo Flávio , de Lima Carmo Roberto Pelliciari
Published: July 2022

Thermal sprayed coatings are widely used for industrial applications. One of the main characteristics that have to be evaluated in a coating is its microstructure that finally determines the coating performance. Several techniques and processes are available for coatings deposition and new materials have been incorporated in the long list of the available ones. Therefore, since microstructure is a key factor to be evaluated, its preparation has to follow some rules in order to inhibit incorrect statements that can arise from wrong interpretation of an incorrect sample preparation. In this work, a series of distinctive materials are thermally sprayed onto low carbon steel substrates. The metallographic preparation of samples for the different coatings is presented and the effects of correct or wrong sample preparation are discussed and correlated to coating microstructure and process characteristics. The coatings were applied by Air Plasma Spray (APS) and Electric Arc Spray.
Prediction of Plasma Sprayed Coating Properties by the Use of Neural Networks
Authors: Lugscheider E. , Seemann K.
Published: July 2022

The number of parameters and noise factors that influence the plasma spraying process is huge, with over 200 known. Today, only a few parameters such as gas flow rate, current, voltage, spraying distance and substrate roughness can be controlled. In recent years, several particle diagnostic systems have been developed, which give the chance to control processes much better than at present. These techniques are now close to being introduced in industrial applications. In addition to the in-flight particle properties, the surface temperature of the substrate has a large influence on the coating quality. Statistical methods are widely used to quantify the influences of the particle and substrate characteristics. Neural networks provide a greater capability to analyse particle characteristics and substrate temperature data for coating quality control. In this work, the analysis of comprehensive process data and coating characteristics using neural networks is investigated and compared to established design of experiments (DOE) statistical methods.
Tribological Behavior of HVOF-Sprayed Cr3C2-NiCr and TiC-based Coatings under High- Temperature Dry Sliding Conditions
Authors: Berger L.-M. , Woydt M. , Zimmermann S. , Keller H. , Schwier G. , Enžl R. , Thiele S.
Published: July 2022

In the current study, the tribological properties of TiC-based coatings paired with polycrystalline alumina under unlubricated sliding conditions were investigated in order to demonstrate the technological and engineering potential of such coatings. (Ti, Mo)(C, N)-Co coatings were prepared from an agglomerated and sintered spray powder by HVOF spraying using JP-5000 equipment. Cr3C2-NiCr coatings were studied for comparison. Sliding wear tests were performed over the temperature range from 23°C to 800°C with sliding speeds in the range 0.3-3 m/s, a wear distance of 5000 m and a normal force of 10 N. Wear rates of coatings and sintered alumina counterparts were measured separately. Compared with Cr3C2-NiCr coatings, (Ti, Mo)(C,N)-Co coatings showed significantly lower total wear rates, corresponding to those found in the region of mixed/boundary lubrication. With few exceptions, the coefficients of friction were found to be lower for (Ti, Mo)(C,N)-Co coatings than for Cr3C2-NiCr coatings. After tests were performed, the coating microstructures were studied by optical microscopy and SEM. The oxide scales formed on the coating surfaces were investigated by SEM and X-ray diffraction. Comparison of the total wear rates of the couples consisting of sintered alumina and a (Ti, Mo)(C,N)-Co coating with those of other alumina-ceramic and hardmetal-hardmetal tribological systems demonstrates the immense potential of TiC-based coatings for sliding wear applications.
Optimization of Wear Protective Coatings for Heat Transferring Components
Authors: Wielage B. , Reisel G. , Wank A. , Gross U. , Barth G.
Published: July 2022

The laser-flash method is used to determine the thermal diffusivity of HVOF sprayed WC-Co(Cr) and Cr3C2-Ni20Cr as well as APS sprayed Cr2O3 and electroplated hard chromium coatings in the temperature range between RT and 600°C. Additionally bond and/or corrosion protective coatings like Ni5Al, Ni20Cr and 316L are characterized taking into account the different manufacturing methods twin wire arc spraying, HVCW and HVOF. With respect to the application example of drying rollers in paper industries the Taber-Abraser wear test is applied to evaluate the wear resistance. Finally the coatings are characterized concerning their corrosion resistance by salt fog test and by exposure to humid SO2 environment. For WC-CoCr feedstock the effect of carbide size and micro hardness on thermal, wear and corrosion properties are studied. WC-CoCr coatings with maximum micro hardness and fine carbides show the best thermal conductivity. The use of coarse carbide feedstock permits manufacturing of coatings with the highest resistance against dry abrasive wear, but the protective function depends severely on the processing conditions.
Finely Structured Ceramic Coatings Elaborated by Liquid Suspension Injection in a DC Plasma Jet
Authors: Delbos C. , Fazilleau J. , Rat V. , Coudert J.F. , Fauchais P. , Bianchi L.
Published: July 2022

This paper describes a study of a plasma spray process to deposit ceramic coatings with finer structures than those that can be produced by conventional DC plasma spraying. The structures are similar to those produced by plasma-enhanced chemical vapor deposition (PECVD), but with a very fast coating rate and the ability to produce a wide range of thicknesses (1 < e < 100 µm). The process involves injecting a ceramic suspension containing submicronic ceramic particles into a DC plasma jet. The goal is to develop the process so that it can be used for the production of such coatings as yttria stabilized zirconia (YSZ), Ni-YSZ, or perovskite (for solid oxide fuel cells) or YSZ, Al2O3-YSZ, or Pyrochlore (for thermal barrier applications). The research stage described in this paper is related to the study of the growth of YSZ coatings, to calculations of the dynamic and thermal plasma-particle transfers, linked to the effect on particle flattening of the various spray parameters (arc current intensity, particle collection distance, substrate temperature, plasma gas composition, and so on). It also describes the achievement of a multi layered coating of YSZ and alumina.
Durability of the Zirconia based Coatings in Contact with Manganese Oxide at 1273 K
Authors: Gao Y. , Shun C.Q.
Published: July 2022

The phase transformation and reaction of ZrO2-CaO- ZrSiO4 and ZrO2-Y2O3-ZrSiO4 coatings with manganese oxide at 1273 K were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). SiO2 phase formed in the coatings, which was from the ZrSiO4 decomposed and easy react with manganese oxide or CaO. SiO2 has precedence over react with CaO than manganese oxides for ZrO2-CaO-ZrSiO4 coatings, and which result in to promote t-m phase transformation. On the contrary, the reaction between SiO2 and MnO is primary for the ZrO2-Y2O3-ZrSiO4 coatings and result in the damage or exfoliation on the surface of the coatings.
Plasma Reaction Synthesis of Agglomerated Oxide Powders by Axial Injection Torch
Authors: Mager J. , Cannon W.R. , Kear B.H.
Published: July 2022

Several compositions of agglomerated ZrO2(Y2O3), Al2O3 and MgAl2O4 powders were plasma sprayed through an axial injection torch into a water quenching chamber in order to obtain a fully melted and homogenized, metastable particle nanostructure. This metastable extended solid solution morphology allows the powder to be subsequently heat treated and superplastically formed into ceramic parts with potentially excellent optical and mechanical properties. Light microscopy, SEM and XRD analyses were used to evaluate the melt-quenched powder properties, and some comparison was made to previous work performed with traditional radial injection plasma torches. Thick build-ups were also sprayed from the melt-quenched powders to test their ability to superplastically flow. Results showed that during a single processing through the torch the axial injection equipment produced powders with a significantly higher fraction of fully homogenized powders than previously attainable. Homogenization of powders comprised of a larger particle size range was also achieved.
Deposition Rate Increase in APS Processes by Means of Multiple Injection Ports
Authors: Choquet I. , Nylén P. , Wigren J.
Published: July 2022

This paper presents a method to increase deposition rate of thermal plasma spray operations through the use of multiple injection ports. Numerical simulations indeed revealed a major energy loss in the process when using only one port. The influence of the carrier gas and the particle stream on the heat flow coming from the plasma torch was found very local and small compared to the total amount of energy. To take as much as possible advantage of the energy available in the plume, we thus propose to use a multiple number of injectors around the flame. Computational simulations are carried out to estimate the feasibility. They are based on the 3D Navier-Stokes equations coupled with a turbulence model. The gases (plasma gas, surrounding air and carrier gas) are supposed to be in local thermal and chemical equilibrium and loading effects are accounted for. The numerical results are supplemented by experimental results showing that multiple injectors can significantly increase deposition rate while preserving or even slightly improving the deposition efficiency. Characterisation of the microstructure, evaluated for all tests, is similar and no obvious differences can be detected apart from the porosity. This method thus results in a substantial reduction of the production cost.
Measurements of Elastic-Plastic Anisotropic Properties of Thermally Sprayed Coatings Using Nano-Indenters and Inverse Analysis Technique
Authors: Nakamura Toshio , Gu Yu
Published: July 2022

Thermally sprayed coatings are often anisotropic due to their manufacturing processes. However, identification of anisotropic properties is very difficult not only because of such material systems but also their small scales. The present work present a new procedure based on nano-indentation technique and inverse analysis to characterize transversely isotropic elastic-plastic coatings. In particular, it uses Kalman filter, which processes the indentation measurements to extract unknown material parameters. This procedure employs load-penetration records of two indenters, spherical and Berkovich. An advantage of this method is that it requires minimum specimen preparations and the measurement procedure is straightforward. APS NiAl coating is indented and their records are used to estimate its anisotropic factors. The results support the effectiveness of the new procedure.
Modeling of Inductively Coupled Plasma Flows in a Reactor: Comparison with Experimental Results
Authors: Guénadou D. , Meillot E.
Published: July 2022

Inductive plasma torches are used in a wide range of applications such as spraying, waste destruction, powder treatment... In this kind of torch, the gas is heated to plasma state by ohmic heating due to the inductive current created by an electromagnetic field. Modeling this phenomenon has been studied by S. Xue and implemented in the commercial code FLUENT. This model is improved by introducing a turbulence model. To validate the model, experimental investigations are carried on. The gas temperature is measured using an enthalpy probe inside a tubular reactor at different positions. The measurements are compared with computational results and the accuracy is rather good.
Molecular Dynamics Simulation on Flattening Process of a High-Temperature and High-Speed Droplet
Authors: Shimizu J. , Ohmura E. , Kobayashi Y. , Kiyoshima S. , Eda H.
Published: July 2022

In order to clarify the flattening process of the high-temperature and high-speed droplet due to its impact on the substrate in an atomic level, several three-dimensional molecular dynamics simulations were conducted. The droplet and the substrate were assumed to consist of pure aluminum, and Morse potential was postulated between a pair of aluminum atoms. By visualizing the analytical result, the processes of melting and solidification, temperature distribution, deformation velocity and shape of the droplet were clarified. As a result, following conclusions were obtained: (1) The transfer of the droplet atoms to the horizontal direction in flattening process increases in proportion to the horizontal distance from the central axis of the droplet. (2) The solidification of the droplet starts from the outside edge of the droplet, and finishes as the flattening ratio increases. Such solidification behavior is different from the results analyzed with a continuum model on the assumption that the flattening finishes when the half volume of the droplet solidifies.
Study of the Porosity in Plasma-Sprayed Alumina Through an Innovative 3-Dimensional Simulation of the Coating Build-Up
Authors: Beauvais S. , Guipont V. , N'Guyen F. , Jeandin M. , Jeulin D. , Robisson A. , Saenger R.
Published: July 2022

Porosity is a key feature of thermally-sprayed coating microstructure. Porosity is made of pores and cracks of various orientations. Both pores and cracks can be intralamellar or interlamellar due to coating build-up which leads to lamellae from impinging of droplets. Pores are interconnected with cracks, which results in a 3-dimensional porosity network. Direct observation of this network is intricate and remains somewhat limited. A 3-dimensional simulation of this network was therefore developed in this work based on the building-up of objects which simulated the lamellae in the sprayed microstructure. These objects were constructed from morphological measurements using confocal microscopy of actual lamellae, i.e. “splats”, obtained from “linescan”-typed plasma-sprayed experiments. This simulation, in the lamella building-up, involves randomly cracks and pores the characteristics of which (i.e. content, orientation, size, …) were determined from thorough quantitative image analysis of cross-section plasma-sprayed alumina microstructures. Using 3-dimensional images resulting from the simulation, finite element calculations were performed to study dielectric properties of plasma-sprayed alumina as a function of porosity. The influence of anisotropy is discussed in particular and calculated values compared to experimental values.
The Formation Behavior of Thermal Sprayed TiO2 Coatings Using Agglomerated Nano-Powders
Authors: Yasuoka Junichi , Nakade Katsuyuki , Ohmori Akira
Published: July 2022

TiO2 coatings were prepared by High Velocity Oxy-Fuel (HVOF) spraying using agglomerated nano-TiO2 powders (200nm, 30nm and 7nm). The effects of spraying conditions on microstructure, anatase phase ratio, coating thickness have been investigated and then photo-catalytic properties were also evaluated. Although the anatase phase ratio decreased drastically with increasing fuel gas pressure in the case of agglomerated 7nm-powders (P7 powders), while higher anatase ratio could be obtained in the case of agglomerated 200nm and 30nm powders (P200 and P30 powders). Especially, anatase ratio more than 70% and thickness greater than 30µm could be achieved when 30nm-agglomerated powders (P30 powders) were sprayed. This means that 30nm agglomerated powders have lower susceptibility to heat. It was assumed that approximately 30nm particle was the limit size and optimum size for HVOF spraying. These coatings showed photo-catalytic degradation of gaseous acetaldehyde (CH3CHO). As a result of experiments, TiO2 coating formed by HVOF spraying using 30nm powder showed higher decomposition rate because of higher anatase ratio.
Mechanical Properties of Plasma Sprayed Nanostructured Titania Coatings with Al Addition
Authors: Chwa S.O. , Klein D. , Coddet C. , Bertrand G. , Liao H. , Toma F.L. , Ohmori A.
Published: July 2022

TiO2 and TiO2-Al composites coatings were prepared by plasma spraying using a reconstituted nanosized feedstock via a spray drying method. Effects of various spray conditions on the microstructure, porosity, microhardness and wear resistance related to the mechanical performance of coatings were evaluated. The coatings sprayed at relatively low plasma power were composed of two distinct microstructures of well defined lamellar structure, similar to microstructure of conventional plasma sprayed coatings typically observed from fully melted particles, and embedded nano or sub-micron particles originated from partial/non-molten particles of feedstock materials. The fraction of partial/non-molten particles in coating layers was increased by Al additive. Such a characteristic of blended microstructure of coatings was clearly confirmed from a bimodal distribution of microhardness described by Weibull plots. The optimized addition of Al into TiO2 improved mechanical properties such as microhardness and wear resistance.
Microstructure and Properties of Al2O3/YAG Nano Composite Coating Prepared by Plasma Spray
Authors: Suzuki M. , Sodeoka S. , Inoue T. , Murakami T. , Sasaki S.
Published: July 2022

Nano-dispersed α-Al2O3/YAG composite coatings were successfully obtained by plasma spraying of the granulated Al2O3/Y2O3 powder, and the post heat treatment. The as-sprayed coating was composed of an amorphous phase, metastable Y-Al-O solid solution. After the heat treatment around 1473K, two crystalline phases, α-Al2O3 and YAG, precipitated, so that the fine dispersed Al2O3/YAG composite coatings were formed. The sizes of the precipitates could be widely controlled by time and temperature of the heat treatment. Hardness and wear property were evaluated in this nano-structured CMC coating.
Wear Characteristics of Plasma Sprayed Nanostructured Yttria Partially Stabilized Zirconia Coatings
Authors: Tao Shunyan , Liang Bo , Ding Chuanxian , Liao Hanlin , Coddet Christian
Published: July 2022

Reconstituted nanostructured and conventional yttria partially stabilized zirconia (YPSZ) coatings were deposited by atmospheric plasma spray. The tribological properties of the coatings against 100C6 steel were evaluated with a ball-on-disc configuration under dry friction conditions at room temperature. Microstructure and the phase composition of the powders and the coatings were examined using SEM, optical microscope (OM) and X-ray diffraction (XRD). Microhardness, Young’s modulus and fracture toughness of coatings were measured by indentation test. Results showed that the wear resistance of the coatings produced using the nanostructured powder is improved compared with the coating produced using the conventional powder. The wear rates of nanostructured zirconia coatings are about four-fifths of those of conventional counterparts under a load of 5 N. The wear mechanism is also discussed.
Fatigue and Mechanical Properties of Nanostructured WC-Co Coatings
Authors: Ibrahim A. , Berndt C.C.
Published: July 2022

Nanostructured materials and nanocomposites have the potential to have a dramatic impact on technological progress in the 21st century. Of great interest, is the outstanding deformation behavior of nanostructured materials and nanocomposites. In this study, the fatigue and mechanical properties of HVOF sprayed nanostructured and conventional WC-Co coatings were investigated. High velocity oxy-fuel process was used to spray the WC-12Co from a feedstock in which the WC phase was mainly in the micron size range (conventional) or contains a significant fraction of nanosized grains (multimodal).The fatigue strength of coatings deposited onto Aluminum alloy showed that the nanostructured WC-Co coated specimens exhibited higher fatigue strength compared to the conventional WC-Co coatings. Microhardness test was performed. Relationships between the microstructures and mechanical properties were discussed.
Titanium Oxide - New Opportunities for an Established Coating Material
Authors: Berger L.-M.
Published: July 2022

Extensive research activities were conducted over the last few years on coatings made of titanium oxide, an established material for thermally sprayed coating solutions. Multiple existing and potential applications are closely connected with the existence of different titanium dioxide modifications and the formation of suboxides. This provides a basis for discussions on the Ti-O phase diagram as well as the properties and conditions of formation of relevant phases. Coating microstructures, phase compositions and mechanical properties are discussed as a result of interactions of different spray powders in different spray conditions of atmospheric and vacuum plasma spraying (APS and VPS), as well as of high-velocity oxyfuel (HVOF) spraying. The discussion on applications is focused on electrically conductive coatings, coatings with photocatalytic properties and coatings for wear applications.
Computer Tomography of Plasma Jets - Applied on a TRIPLEX II torch
Authors: Landes K.D. , Forster G. , Zierhut J. , Dzulko M. , Hawley D.
Published: July 2022

For the effective development and optimization of plasma torches and plasma processes a knowledge of the spatial distribution of plasma properties within the generated plasma jets is useful. Information about some of these properties also in case of arbitrary distribution can be achieved by computer tomography (CT) using radiation emitted by the plasma jet. The stationarity of the plasma jet is a necessary condition for the CT technique described in this paper. By CT in principle the radiation from a small cross-sectional disk of the plasma jet is recorded successively under different directions perpendicular to the torch axis. From the recorded data the spatial distribution of radiation emissivity within the jet is calculated using an algebraic recursive algorithm. The CT was applied for the investigation of a TRIPLEX II plasma jet giving the following results: The jet is characterized by a very high degree of stationarity and exhibits a definite triple symmetry, which can be described by three partial plasma jets. Measuring their positions the influence of the arc current on the TRIPLEX plasma jet rotation was determined.
On a Prospective On-Line APS Process Control Based on Artificial Neural Networks
Authors: Guessasma S. , Montavon G. , Coddet C.
Published: July 2022

On-line process control appears today as a potential way to improve thermal spray coating quality and reliability. In order to reach that goal, several requirements are needed. Firstly, reliable sensors have to be developed to accurately diagnose in-flight particle characteristics but also some other parameters, such as coating surface temperature during spraying. Secondly, a robust command, linked to a model, is required to insure the stability of the control system. Finally, an extensive and representative database is required as reference. Several methodologies can be implemented to define such a structure. Artificial Neural Networks (ANNs) and neuromimetic models, based for example on fuzzy logic, appear as an interesting way with a large potential of improvement to control non-linear systems, such as the thermal spray processes.
Experimental Investigation of the Splashing Processes at Impact in Plasma Sprayed Coating Formation
Authors: Cedelle J. , Vardelle M. , Pateyron B. , Fauchais P.
Published: July 2022

This paper is devoted to an experimental investigation of the different splashing phenomena (impact and flattening) when a plasma sprayed single particle impacts on a flat smooth substrate. This research is carried out using an imaging technique with a fast CCD camera aimed either parallel to the substrate for impact splashing or almost orthogonal to it for flattening splashing. The correlation of the image with the results of a set up allowing to determine particle in flight parameters just prior to their impact allows a better understanding of the splashing processes.
Surface Changes in Thermally Sprayed Hard Coatings by Wear of Different Abrasives
Authors: Vuoristo P. , Laurila J. , Mäntylä T. , Niemi K. , Rekola S. , Ahmaniemi S.
Published: July 2022

Thermally sprayed hard coatings, including tungsten carbide and chromium carbide cermets and other hard metallic materials, were studied in two types of wear tests. Surfaces of the coatings were worn by coarse and hard quartz sand in a rubber-wheel dry abrasion wear test, and by fine and soft kaolin abrasive in a wet slurry abrasion wear test. The aim of the work was to study how the surfaces retain their high polished finish and gloss, and the type of wearing of different coatings and materials. The results showed that coatings with hard tungsten carbides were worn preferentially by removal of the the binder material. Cermet coatings with softer chromium carbides, and with another types of uniform microstructures showed more uniform wear and better retained their glossy finish.
Thermomechanical Behaviour of Bimodal Structured Thermal Barrier Coatings
Authors: Soltani R. , Coyle T.W. , Mostaghimi J.
Published: July 2022

During the past few years thermally sprayed ceramic coatings deposited from nanostructured feedstock powder have often demonstrated improved properties relative to coatings produced from convention powder. Nanostructured or bimodal structured ceramic coatings have been reported to exhibit better wear resistance and adhesion strength. For thermal barrier coatings, key properties include thermal conductivity and thermal stability. In this study thermomechanical properties of plasma sprayed, bimodal structured, yttria stabilized zirconia coatings were investigated. The thermal stability was examined by measuring the hardness and elastic modulus of free standing coating layers before and after heat treatments in air at 600-800 °C. The creep behaviour was investigated using free standing coating layers loaded in the four point bending configuration at temperatures of 1000 °C in air. The results for bimodal structured coatings have been compared with the behaviour of conventional plasma spray coatings under the same test conditions.
Effect of Interface Roughness on Internal Stress of Ceramic Thermal Barrier Coating
Authors: Kawamura M. , Okado H. , Suzuki K.
Published: July 2022

An investigation was carried out into the effect of the interface roughness between the metallic bond coat and the ceramic topcoat on internal stresses in a thermal sprayed ceramic thermal barrier coating (TBC). To evaluate the effect of the interface roughness on the residual stress in the top coat, the specimens with two kinds of bondcoat roughness (rough type and smooth type) were prepared. The in-plane stresses of the specimens were measured with laboratory X-rays. The in-plane stresses for the both of the rough and smooth specimens were about 60MPa and independent of the roughness of the bond coat. Using high energy X-ray, the stress of the rough specimen was compressive and the stress of smooth specimen was tensile. This tendency is different from the result measured by laboratory X-ray. This difference in the stress value is coursed by the out-of-plane stress. Theses stresses in the topcoat were estimated by the hybrid method, that is to estimate out-of-plane stress using laboratory X-rays and high-energy synchrotron X-rays. As a result, the larger the roughness of the bond coat became the larger out-of-plane-stress become.
Diagnosis of a Faulty I/O Circuit Using PICA (Picosecond Imaging Circuit Analysis)
Authors: Song Peilin , McManus Moyra , Motika Franco , Steen Steven , Knebel Dan , Lee Julie
Published: July 2022

Picosecond imaging circuit analysis (PICA) is an advanced diagnostic technique that measures device switching activity on CMOS ICs through the backside of the die. Due to its relatively large field of view, it can quickly locate defects among large numbers of candidates. In this case study, the authors explain how they used PICA to identify a particular I/O circuit defect on the IBM System/390 G5 microprocessor. They also explain how they verified the diagnostic result using circuit simulations.
pn Junction Location Using an EBIC Technique in a Scanning Transmission Electron Microscope
Authors: Bunker Kristin Lee , Stark Terry J. , Batchelor Dale , Gonzalez Juan Carlos , Russell Phillip E.
Published: July 2022

STEM-EBIC imaging, a nano-characterization technique, has been used in the study of electrically active defects, minority carrier diffusion length, surface recombination velocity, and inhomogeneities in Si pn junctions. In this article, the authors explain how they developed and built a STEM-EBIC system, which they then used to determine the junction location of an InGaN quantum well LED. They also developed a novel FIB-based sample preparation method and a custom sample holder, facilitating the simultaneous collection of Z-contrast, EBIC, and energy dispersive spectroscopy images. The relative position of the pn junction with respect to the quantum well was found to be 19 ± 3 nm from the center of well.
ABCs of Photon Emission Microscopy
Authors: Bruce Michael R. , Bruce Victoria J.
Published: July 2022

Photon emission microscopy (PEM) has proven to be a powerful tool for fault isolation and has adapted well to ongoing changes in technology and emerging needs. In this tutorial, the authors describe the fundamentals of photon emission, the essential elements of a typical PEM system, and the procedures involved in diagnosing various types of failures. They also classify a wide range of photon-emitting defects and explain how PEM is used for backside analysis of flip-chip packaged devices and for timing diagnostics.
Package Technology Challenges and the Role of the Sematech Assembly Analytical Forum
Authors: Samuelson Gay
Published: July 2022

The Assembly Analytical Forum (AAF) is an organization under the auspices of the Sematech Quality Council. The AAF charter is to develop Packaging Analytical Roadmaps five to ten years into the future that are consistent with the International Technology Roadmap for semiconductors (ITRS). At ISTFA 2003, the AAF will convene with interested conference attendees to review, edit, and validate a white paper that will quantify critical gaps in the current suite of test, measurement, and characterization tools used in the semiconductor industry and provide recommendations on how to address them. The intent is to update the document biannually and review it in numerous industry venues to ensure its relevancy and utility. This article is somewhat of a preview to the Rev 0 AAF white paper.
Optoelectronic Device Failure Analysis
Authors: Barton Daniel L.
Published: July 2022

This article discusses the types of defects that occur in vertical cavity surface-emitting lasers (VCSELs) and the tools typically used to detect them and identify the cause. It describes the basic design and operation of VCSELs and explains that most failures are due to dislocations in the crystal structure of the materials from which the devices are made. Of the various methods used to analyze such defects, electroluminescence (EL) is by far the most powerful as demonstrated in several EL images included in the article. The article also discusses the use of EBIC analysis, FIB cross-sectioning, and thermally induced voltage alteration (TIVA).
Ethnographic Notes of N. V. Nikolsky on the Chuvash People of the Village of Apanasovo-Temyashi
Authors: Egorova Olga Nikolaevna
Published: July 2022

The work is devoted to the analysis of ethnographic records of the doctor of historical sciences, professor N. V. Nikolsky about the Chuvashs of the village of Apanasovo-Temyashi, Yalchik district of the Chuvash Republic, stored in the scientific archive of the Chuvash State Institute of the Humanities. The materials of the scientist are valuable historical sources that describe the general picture of the everyday life of the Chuvash village at the turn of the 19th-20th centuries. The collection of ethnographic material was carried out by the researcher through participant observation as part of his expedition. A special layer in the fund of N. V. Nikolsky is represented by Chuvash folk songs, which reveal links with modern vocal culture. The work is based on the analysis of archival documents in their relationship with historical events in general and the biography of N. V. Nikolsky in particular. The study aims to introduce newly discovered documents into scientific circulation, as well as song material, which is important from the point of view of folklore. The ethnographic materials of N.V. Nikolsky are important not only for the descendants of the inhabitants of Apanasovo-Temyashi: his work in the study of the history, ethnography, folklore and language of the Chuvash is of national importance.
Library Management in Chuvashia in the 1920s
Authors: Ivanova Ekaterina Konstantinovna
Published: July 2022

The article is devoted to the peculiarities of the formation and development of library management of the Chuvash Autonomous Region. The purpose of the article is to consider the state of library management in Chuvashia in the 20s of the twentieth century and the main activities of reading huts and libraries in raising the educational and cultural level of the population in the period under review. The article is written on the basis of a thorough analysis of a wide range of literature on the topic, statistical collections, the study and selection of materials from central and local state archives, most of which are introduced into scientific circulation for the first time. It was revealed that in the years under study, many methods of mass work were developed and tested in practice, which, being improved at subsequent stages in connection with new tasks, have been used and used by libraries to this day: thematic book exhibitions, review evenings, literary evenings, evenings for discussion of new works of fiction, long-term mass campaigns to promote relevant books and libraries among the population, etc. It is concluded that libraries and reading rooms during the period under study gradually gained experience in cultural and educational work: from the mechanical issuance of books, passive service of readers to the search for methods of active work among the masses. By the mid-1920s, libraries and reading rooms began to switch to more organized and planned work.
Mídia local, rádio, audiência ativa e jornalismo precário
Authors: Quiroga Sergio Ricardo
Published: July 2022

Este artigo é uma descrição inicial do surgimento, desenvolvimento e papel da mídia local e rádio local na província de San Luis, Argentina. A categoria de “mídia local” pode ser inédita para caracterizar pequenas mídias alternativas que com grandes dificuldades tentam oferecer visões de realidade diferentes de suas práticas jornalísticas subordinadas. O espaço construído por essas mídias locais permite que as pessoas não apenas sejam ouvidas, mas também expressem sua visão da realidade, com clara influência nas normas sociais e culturais que sustentam o conhecimento e a exposição dos abusos de poder.
A interação no rádio pelo Facebook: uma análise das mensagens enviadas pelo ouvinte/internauta nas lives do programa Toque Esportivo
Authors: Balacó Bruno Anderson Ferreira , Patrício Edgard
Published: July 2022

O presente artigo tem como objetivo analisar os comentários postados pelos ouvintes/internautas nas transmissões ao vivo (as lives) do programa Toque Esportivo, da rádio O Povo CBN, de Fortaleza, pelo Facebook. A partir deste estudo, de caráter exploratório e qualitativo, pretende-se identificar os principais assuntos abordados e que são recorrentes nas mensagens enviadas pela audiência através dessa rede social, amparada nos conceitos de interação, interatividade, rádio expandido (KISCHINHEVSKY, 2016) e hipermidiático (LOPEZ, 2010. Com base em estudos anteriores sobre a interação radiofônica em plataformas digitais (QUADROS, 2013 e GUIMARÃES, 2020) definimos as nossas categorias de estudo, adaptando-as ao contexto e conteúdos das interações do programa analisado. No processo sistematização dos dados, recorremos à abordagem multimétodo (KISCHINHEVSKY et. al, 2015), utilizando como ferramentas a Análise de Conteúdo (BARDIN, 2004) e o Estudo de Caso (DUARTE, 2008).
Analisis Sistem Pendukung Keputusan Penentuan Lulusan Terbaik Menggunakan Lima Algoritma Pada Program Studi Sistem Informasi UIN Sumatera Utara Medan
Authors: Suendri Suendri , Harahap Aninda Mulyani , Nasution Adnan Buyung , Kartika Silvia
Published: July 2022

Program Studi Sistem Informasi adalah bagian dari Universitas Islam negeri Sumatera Utara yang salah satu perannya untuk mencetak lulusan sarjana komputer yang berkualitas. Pada setiap periode kelulusan mahasiswa, pihak program studi akan menentukan dan memilih mahasiswa lulusan terbaik diantara lulusan lainnya dan yang menjadi kriteria penentuan hanya dilihat dari nilai Indeks Prestasi Kumulatif (IPK) saja dan tidak melihat aspek kriteria lainnya, serta perhitungan dilakukan belum secara komputasi. Unguk itu, penelitian ini bertujuan untuk membantu dalam proses penentuan lulusan terbaik dengan memanfaatkan sistem pendukung keputusan dengan tertentu. Pada penelitian ini menggunakan perbandingan 5 metode sistem pendukung keputusan yaitu metode SAW, AHP, WP, SMART, dan MAUT dengan 4 (empat) kriteria penilain yaitu Indeks Prestasi Kumulatif (IPK), masa studi, aspek spiritual, dan nilai tugas akhir. Hasil dari penelitian ini adalah sebuah sistem pendukung keputusan berbasis web dan hasil yang ditampilkan berupa pperankingan nama lulusan terbaik.