bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma Sprayed Self Lubricant Coatings
Authors: Tului M. , Valente T. , Becker D. , Wagner S. 
Published: August 2022

Abstract
The present work aimed at demonstrating the effectiveness of graphite containing plasma sprayed coatings to reduce friction coefficient in dry or starving lubrication conditions. Operative, environmental and economic considerations were important driving factors. Graphite particles were mechanical mixed with a cermet powder containing a fine dispersion of chromium carbide particles in a nickel-chrome metallic matrix. The coatings material was deposited by Atmospheric Plasma Spray onto steel substrates. The microstructure of the obtained coating was characterised by XRD and SEM/EDS. A strip draw apparatus, simulating the stamping process of steel sheets, was used to test the coatings. Several operative conditions were reproduced, by modifying the load and the amount of lubricant used. For comparison, uncoated samples were tested in the same conditions. The comparison of the results of strip draw tests carried out on coated and uncoated samples, shown that the use of graphite based self-lubricant coatings, deposited by plasma spray, allowed to decrease drastically the amount of lubricant.
Visualization of Impact of Plasma-Sprayed Molybdenum Particles on Hot and Cold Glass Substrates
Authors: McDonald A.G. , Lamontagne M. , Moreau C. , Chandra S. 
Published: August 2022

Abstract
Plasma-sprayed, molten molybdenum particles (~50 µm diameter) were photographed during impact (with velocity ~135 m/s) on a glass surface that was maintained at either room temperature or 400°C. A droplet approaching the surface was sensed using a photodetector and after a known delay, a laser was triggered to illuminate the spreading splat and photograph it with a CCD camera. A rapid two-color pyrometer was used to collect the thermal radiation from the impacting particles to follow the evolution of their temperature and size after impact. Molten molybdenum particles impacting on a surface at room temperature splashed and broke up after impact leaving only a small portion adhering to the substrate. On a surface held at 400°C, there was no splashing and a circular splat remained on the surface. Splats on a glass surface held at room temperature had a large maximum spread diameter, approximately 2.7 times that on a hot surface. The cooling rate on a cold surface was an order-of-magnitude lower than that on a hot surface, suggesting that thermal contact resistance was much greater.
Stellite 6 Coatings Obtained by HVOF using Different Fuel Gases
Authors: Guilemany J.M. , Nin J. , Miguel J.R. 
Published: August 2022

Abstract
Bulk, welded or laser cladded Stellite based materials are widely used in chemical industry due to their excellent combined properties against corrosion and wear processes and as a superalloy they have a high melting point and are designed to withstand high temperature for long periods of time. Problems related with poor inter-splat bonding arise when this kind of materials are sprayed with HVOF because it is characterized by having relatively low flame temperatures and high particle speed, and so dwell time may not be long enough to melt or soften Stellite particles completely. For these reasons, typical structured composed by a superposition of non-melted particles are obtained when spraying with propylene fuel gas. The aim of this work is to study the effect of using Hydrogen as a fuel gas and also to study the effect of the variation of the propylene flame characteristics. The coatings are characterized by SEM-EDS, XRD, and ASTM G99-90 sliding wear test has been done to compare the coatings. SWLI has been used to measure the volume lost after the wear test. Splat morphology studies have been also done in order to compare the melting behavior of the impinging particles.
Kinetic Spraying Deposition Behavior of Bulk Amorphous NiTiZrSiSn Feedstock
Authors: Yoon S. , Lee C. , Kim H.J. , Choi H. 
Published: August 2022

Abstract
Kinetic spraying process that is basically a solid-state deposition process was used for the formation of a fully amorphous coating. As the application of pre-heating system for the powder carrier gas and using Helium for the process gas, it was possible to form of amorphous coating. Main process parameters evaluated in this study were gas species[N2 and He]and pre-heating temperature[RT(below Tg) and 550 (liquid metallic region)] for carrier gas. Aside from empirical approach, in-flight particle velocity within kinetic spraying process was measured with spray-watch- 2i. The deposition behaviors of a NiTiZrSiSn bulk amorphous powder were observed when it was sprayed using kinetic spraying process. When the bulk amorphous feedstock material was coated, both kinetic energy and thermal energy of the in-flight particle are important. The former did affect on the deposition of the bulk amorphous coating, while the later did more affect on mechanical properties of coating. Particle deposition behaviors were considered from the viewpoint of the environmental effect such as particle energy combination on the deposition behaviors. The bonding of the impacting NiTiZrSiSn bulk amorphous particle was primarily dependent on the temperature dependent deformation and fracture(local liquid drop formation) behavior.
Diagnosis of In-Flight Particles During Arc Spraying of Carbon Steel and Relationships with Microstructures of the Deposited Layers
Authors: Seong B.-G. , Kim J.-H. , Hwang S.-Y. , Baik K.-H. 
Published: August 2022

Abstract
An experimental study was conducted to study the effects of properties of in-flight particles on microstructures of coating layers using a wire arc spraying system. In this study, 0.8% carbon steel wires were used for arc spraying and nitrogen gas was used as atomizing gas. Temperature, velocity and distributions of the in-flight particles were measured by DPV2000 for different working conditions. Specimens of spray-footprint were made and microstructures of them were evaluated. As a result, amount of oxide in a coating layer was proved to be related with the temperature of the in-flight particles. Because oxidation of the molten steel particles is an exothermic reaction, higher temperature of the particles during arc spraying means higher area fraction of oxide in the coating layers. For this reason, oxide level is lowest at the central area of spray footprint and it becomes higher as the distance from the center increases. Hardness, porosity and phase are changed according to the distance from the center. Abstract only; no full-text paper available.
Computational Modelling of a Thermo-Aabrasive Blasting Gun
Authors: Gorlach I.A. , Markgraaff J. 
Published: August 2022

Abstract
In the last few years, a new method for surface preparation has evolved, namely thermo-abrasive blasting. This technique utilises a high enthalpy thermal jet to propel abrasive particles. The thermo-abrasive blasting gun, also called a thermal gun, is based on the principles of High Velocity Air Fuel (HVAF) processes. Some empirical data is available on thermo-abrasive blasting method and systems. To effectively improve on nozzle design and productivity, modelling of the thermo-abrasive blasting process was required. This paper describes the computational modelling of the thermal gun with computational fluid dynamic software, namely STAR-CD. The developed computational model can be applied to HVAF systems used for thermo-abrasive blasting and thermal spraying.
Modeling of the Heating of Cast Iron Particles during Plasma Spraying
Authors: Kharlamov Y.A. , Shevchenko A.V. , Budagyunts N.A. , Chattha J.A. 
Published: August 2022

Abstract
The mathematical model intended for modeling of the acceleration, heating, and melting of alloyed cast iron particles into plasma jet is presented. Comparison of mathematical modelling and experimental measurement results showed fairly good agreement.
Effect of Substrate Surface Change by Heating on Flattening Behavior of Thermal Sprayed Particles
Authors: Fukumoto M. , Ohgitani I. , Nagai H. , Yasui T. 
Published: August 2022

Abstract
It has been confirmed in the flattening behavior of the thermal sprayed particles that the splat shape on the flat substrate surface changes to a disk type from a splash type at relatively narrow temperature range with increasing the substrate temperature. The temperature increasing actually causes a certain non-reversible change on the substrate surface, because the changing effect is maintained till the substrate is cooled down to the room temperature. We have pointed out that this non-reversible change on substrate surface due to the heating might be the possible domination for the transition phenomenon of the thermal sprayed particles, that is, the essence of the substrate surface change due to the heating is surface roughness in nano-meter range. In this study, several kinds of substrates once heated to some elevated temperature were analyzed precisely by atomic force microscope (AFM) to characterize the change in their surface roughness character. The fundamental static wetting behavior of the substrate surface by a water droplet was investigated for the reference in the present study. The results obtained revealed that the change of the substrate surface topography in nano-meter range affect most effectively the wetting behavior of the droplet or splat on the surface. Hence, the substrate heating may bring about the change in the physical way on the substrate surface and this change induces the transition phenomenon.
Interaction between a Thin Non Continuous D.C. Plasma Sprayed Alumina Layer and Preoxidized Low Carbon Substrate
Authors: Valette S. , Denoirjean A. , Danoix R. , Hannoyer B. , Lefez B. , Lopitaux J. , Lefort P. , Fauchais P. 
Published: August 2022

Abstract
As already shown 3 years ago, the preoxidation of smooth (Ra &lt; 0.05 µm) low carbon steel substrates in a furnace under a CO2 rich atmosphere at atmospheric pressure allows the formation of a wustite (Fe1-xO) layer which improves significantly the adhesion (&gt; 55 MPa) of alumina coatings in spite of the rather low roughness (0.10 µm &lt; Ra &lt; 1.00 µm) of the oxidized surface. This contribution is devoted to a more precise study of the wustite layer and its interface with the alumina layer by X-ray diffraction (XRD), Mossbauer spectroscopy and scanning electron microscopy (SEM). Firstly the substrate was oxidized under different temperatures and durations in order to control the oxide layer thickness and structure. Secondly the substrate samples were preoxidized during 15 minutes at 1273 K under CO2 atmosphere and, afterwards, preheated by the plasma jet in air just before coating. In this case the analysis was focused both on the alumina splat formation and the interface between splat and the oxide layer. Only a non-continuous alumina layer (a few splats) was sprayed: this allowed surface analysis down to the substrate through the alumina layer and the interface. This method avoids any modification of the searched information by a complex specimen preparation as required in the case of transmission electron microscopy (TEM) for example. For the steel surface preheated in CO2 atmosphere, before spraying, SEM observations and XRD patterns showed the presence of a continuous oxide layer formed by wüstite crystals with an average size of 1-5 µm. After deposition, splats consisted of transitional alumina (γ phase) but the underlayer was no longer pure wüstite. XRD and Mossbauer identified magnetite at the surface of the oxide scale in contact with alumina. This can probably be considered as the result of a partial topotactic transformation of wustite into magnetite, since no morphological change of the oxide layer has been observed. It has been established that this transformation is a consequence of the pre-heating treatment, and not due to any reaction with alumina. It is worth noting that, under these conditions, γ alumina has a spinel structure analogous to that of the magnetite phase with which it was in contact: the alumina structure was possibly induced by that of the magnetite underlayer.
Thermal Behavior of Y-PSZ TBCs in situ Remelted During Their Deposition
Authors: Antou G. , Hlawka F. , Montavon G. , Coddet C. , Cornet A. , Machi F. 
Published: August 2022

Abstract
In previous works, laser irradiation was associated to thermal spraying in the so-called MELTPRO process to improve the performance and the durability of TBCs. This study aims at presenting results concerning the thermal behavior of TBC's manufactured according to this process. Two types of severized thermal cycling were implemented: (i) “oxidizing” test: isothermal shocks were performed at different temperatures, ranging from 900°C to 1050°C down to 0°C; (ii) “quite non-oxidizing” test: thermal shocks were implemented from a temperature of 1100°C down to 50°C. Moreover, thermal annealing at 1100°C were performed to compare sintering phenomenon. TBC microstructure and its evolution during heat treating were characterized using image analysis, Knoop micro-indentation and XRD analysis. MELTPRO process was shown to increase twofold the lifetime of TBCs during isothermal shock tests. This is attributed to the fact that the columnar structure and the pore-crack architecture of remelted coatings improve the compliance property and decrease the permeability of TBCs. XRD analyses show that, in the Y-PSZ TBCs, the main phase is the metastable tetragonal (t’) phase both for as-sprayed and MELTPRO processed coatings. Moreover, remelted TBCs show a higher phase stability than as-sprayed TBCs during thermal shock tests: it seems that the remelted coatings have higher phase stability thanks to their pore architecture, which lead to a better compliance in relation to the thermo mechanical stresses, and so to a decrease in the stress variations undergone by the structure during the thermal cycles. During thermal annealing, it seems that MELTPRO processed coatings are less affected by sintering than as-sprayed coatings. Sintering phenomenon primarily concerns inter-lamellar cracks of non remelted areas. Besides, whatever the coating manufacturing process, the main remaining phase is the metastable tetragonal phase whatever the heat treating duration.
Pore Network Architecture and Thermal Conductivity of Y-PSZ TBCs in situ Remelted During their Deposition
Authors: Antou G. , Hlawka F. , Bolot R. , Montavon G. , Coddet C. , Cornet A. 
Published: August 2022

Abstract
Yttria partially stabilized Zirconia (Y-PSZ) thermal barrier coatings (TBCs) have numerous applications as insulation layers onto gas turbine components. The main function of TBC is to enhance efficiency by increasing working temperature. These coatings are commonly manufactured using air plasma spraying. The characteristics of TBCs strongly depends on their pore and crack network architecture. Engineering the coating architecture by an adapted process is a prerequisite to modify TBC characteristics. Therefore, air plasma spray and in situ laser irradiation by diode laser processes were combined in this study to modify structural characteristics of TBCs. The coatings were remelted layer by layer during their deposition or alternately (i.e., an as-sprayed layer followed by an in situ remelted layer). This process was named MELTPRO. TBC apparent thermal conductivity was quantified implementing numerical computations based on 2-D real discrete structures. Coating thermal properties were correlated to their pore network architecture characteristics quantified by image analysis (i.e., nature, orientation, percentage, etc.). Moreover, thermal annealing at 1100°C were performed to compare sintering phenomenon of manufactured TBCs. Results show that the MELTPRO process permits: (i) to modify of the pore network architecture of as-sprayed TBCs. The porosity level increases by the in situ remelting process due to the formation of large horizontal cracks (as shown by image analysis). These horizontal cracks behave as thermal resistances and are responsible for the decrease of the coating thermal conductivity of about 30 % compared to the as-sprayed ones; (ii) to architecture differently the pore network for a constant thermal conductivity, because thermal conductivity and porosity level are not explicitly correlated; (iii) to improve the thermal insulation which remains unchanged after thermal annealing treatments: this seems to be due to the fact that the large cracks of remelted TBCs are less sensitive to sintering than inter and intra lamellar cracks of as-sprayed TBCs.
Collection of Nano-Powders Generated by Radio Frequency (RF) Plasma Spray Synthesis (PSS) Processing, using a Sampling Probe
Authors: Jia L. , Gitzhofer F. 
Published: August 2022

Abstract
A particle-sampling probe has been designed and constructed for the continuous collection of nano-powders produced by the plasma spray synthesis (PSS) process. The probe comprises a powder sampling line (inner tube), a quench gas line (outer tube) and a water-cooling jacket surrounding the outer tube. A sample holder is disposed at the exit of the inner tube to hold a standard 3.08 mm diameter TEM copper grid which is used to collect the powders by means of the pumping pressure differential. Quenching gas is introduced to the probe, via the outer tube to quench and entrain the as-synthesized clusters. After each sample collection event, the inner tube can be cleaned in-situ by means of a water injection, and then dried using a compressed gas flow. The results obtained to date indicate that the sampling probe location in the plasma reactor and the quenching gas flow rate employed are the most important parameters involved in the satisfactory operation of the sampling probe.
Study of Lamellar Microstructure of Plasma-Sprayed ZrO2-8wt.%Y2O3 Coatings
Authors: Wang W.-Z. , Li C.-J. , Sonoya K. 
Published: August 2022

Abstract
The lamellar microstructure of plasma-sprayed ZrO2-8wt.%Y2O3 (8YSZ) coatings was quantitatively characterized by a novel approach. The porous structure of the coating was visualized through infiltrating the tracer into voids in the coating combining with the energy dispersed X-ray line analysis of the tracer in the coating. The quantitative characterization parameters included the mean lamellar interface bonding ratio, mean lamellar thickness and width distribution of lamellar interface gaps. 8YSZ coatings were deposited by plasma spraying under different spray distances to reveal the effect of spray distance on the lamellar microstructure of plasma-sprayed 8YSZ coatings. The results showed that the maximum mean bonding ratio was 32% when the coating was deposited at spray distance from 65 to 80 mm. As spray distance was increased to 100-120 mm, the mean bonding ratio was reduced. The mean lamellar thickness was not significantly influenced by spray distance although it was found that the mean lamellar thickness tended to increase with the increase of spray distance from 80 mm. It was observed that lamellar interface gaps in the coating were mainly in submicrometer order. With the increase of spray distance, the mean width of interface gaps and fraction of wide interface gaps tended to increase.
QUALIDADE DE CAFÉ, EM DIFERENTES ESTÁDIOS DE MATURAÇÃO, EM FUNÇÃO DA APLICAÇÃO DE Cladosporium cladosporioides
Authors: Manoel Rezende de Melo Bruno , Cristina Pereira Francisco Karoline , Ferreira Sindynara , Miranda dos Santos Telma , Marinello Souza Vítor , Lima Salomão Leme Raissa 
Published: August 2022

O objetivo foi avaliar a qualidade química e sensorial do café variando-se o estádio de maturação do café para aplicação do fungo Cladosporium cladosporioides. O trabalho foi desenvolvido entre maio e agosto de 2019. O delineamento experimental foi em blocos casualizados, composto por cinco tratamentos, determinados em função do estádio de maturação para aplicação do Cladosporium: (testemunha (sem aplicação com 12% frutos verdes)), 70%, 50% e 30% de frutos verdes e aplicação do Cladosporium no pátio de secagem com 12% frutos verdes) e cinco repetições. A colheita e secagem de todas as parcelas de cafés seguiram o mesmo protocolo. Foram avaliadas as seguintes variáveis: análise sensorial, ocorrência de microrganismos e análises físicos químicas. Os dados foram submetidos à análise de variância e rede de correlações. Não houve diferenças significativas para os atributos avaliados devido às condições edafoclimáticas da lavoura que não foram favoráveis a ocorrência dos fungos deletérios a qualidade do café. Portanto, o uso do fungo Cladosporium cladosporioides para bioproteção da qualidade do café não se justifica em lavouras onde as condições não são favoráveis à ocorrência de fungos deletérios à qualidade do café, como baixa umidade e temperatura amena.
Palavras-chave: Controle biológico; Coffea arábica L.; bioproteção; cafés especiais.

Coffee quality at different maturation stages, due to the application of Cladosporium cladosporioides

ABSTRACT: The objective was to evaluate the chemical and sensorial quality of coffee by varying the coffee maturation stage for application of the fungus Cladosporium cladosporioides. The work was carried out between may and august 2019. The experimental design was in randomized blocks, consisting of five treatments, determined according to the stage of maturation for application of Cladosporium: (control (without application with 12% green fruits)), 70 %, 50% and 30% of green fruits and application of Cladosporium in the drying yard with 12% green fruits) and five replications. Harvesting and drying of all coffee plots followed the same protocol. The following variables were evaluated: sensory analysis, occurrence of microorganisms and physical-chemical analyses. Data were submitted to analysis of variance and correlation network. There were no significant differences for the attributes evaluated due to the soil and climate conditions of the crop, which were not favorable for the occurrence of fungi deleterious to coffee quality. Therefore, the use of the fungus Cladosporium cladosporioides for bioprotection of coffee quality is not justified in crops where conditions are not favorable for the occurrence of fungi deleterious to coffee quality, such as low humidity and mild temperature.
Keywords: Biological control; Coffea arabica L.; bioprotection; specialty coffees.