Porous APS YSZ TBC Manufactured at High Powder Feed Rate (100 g/min) and Deposition Efficiency (70%): Microstructure, Bond Strength and Thermal Gradients

There is a strong driving force to improve the production efficiency of thermal barrier coatings (TBCs) manufactured via air plasma spray (APS). To address this need, the high-enthalpy APS torch Axial III Plus was employed to successfully manufacture TBCs by spraying a commercial YSZ feedstock at powder feed rate of 100 g/min using an optimized set of N2/H2 spray parameters; which yielded an impressive YSZ deposition efficiency (DE) value of 70%. This exact same set of optimized spray parameters was used to manufacture the same identical YSZ TBC (over ~160 µm-thick bond-coated substrates) but at two distinct YSZ thickness levels: (i) ~420 µm-thick and (ii) ~930 µm-thick. In spite of the high YSZ feed rate and DE levels, the YSZ TBC revealed a ~14% porous (conventional looking) microstructure, without segmented cracking or horizontal delamination at both thickness levels. The bond strength values measured via the ASTM C633 standard for the ~420 µm-thick and ~930 µm-thick YSZ TBCs were ~13.0 and ~11.6 MPa (respectively); which are among at the upper end values reported in the literature. After the first objective was attained, the second key objective of this work was to evaluate the thermal insulating effectiveness of these two as-sprayed YSZ TBCs. To achieve this objective, a thermal gradient laser-rig was employed to generate a temperature reduction (ΔT) along the TBC-coated coupons under different laser power levels. These distinct laser power levels generated YSZ TBC surface temperatures varying for 1100 to 1500 °C, for the ~420 µm-thick YSZ TBC, and from 1100 to 1680 °C YSZ TBC ~930 µm-thick YSZ TBC. The respective ΔT values for both TBCs are reported. The results of this engineering paper are promising regarding the possibility of improving considerably the manufacturing efficiency of industrial quality conventional-looking porous YSZ TBCs, by using a high-enthalpy N2-based APS torch. This is the first paper published in the open literature showing R&D results of coatings manufactured via the Axial III Plus APS torch.

Effect of Spray Distance and Powder Feed Rate on Particle Velocity in Cold Spray Processes

Cold spray technology using micron-sized particles to produce coatings is increasingly used for reparative tasks in various industries. In a cold spray setup, the gun is usually connected to a robotic arm to deposit coatings on components with complex geometries. For these components, the standoff distance used in the cold spray process has to be large enough for easy maneuverability of the gun around a small radial feature. However, a small standoff distance is commonly found in most studies, which is thought to prevent a velocity drop of the particles over a larger distance. Here, a study was carried out by measuring the Inconel 625 particle velocity at different spray distances, ranging from 3 to 40 cm. The highest average velocity of 781 m/s was found at a spray distance of 8 cm. Furthermore, a study with varying powder feed rates was also conducted. An increase in the powder feed rate was found to have a minimal effect on the particle velocity. Inconel 625 coatings deposited at the optimum standoff distance (8 cm) were found to have low porosity and high hardness. The results in this study demonstrate that a larger standoff distance can be applied without a significant drop in velocity for cold spray applications requiring high maneuverability.

Optimizing the Characteristics of the Laser Hardfacing Process Parameters to Maximize the Wear Resistance of Ni-Based Hard-Faced Deposits Using the RSM Technique

The nickel-based Colmonoy-5 hardfacing alloy is used to hard-face 316LN austenitic stainless steel components in fast reactors. The nominal composition (in wt%) was listed as follows: 0.01 C, 0.49 Si, 0.87 Mn, 17.09 Cr, 14.04 Ni, 2.56 Mo, 0.14 N, and balance Fe. Hardfacing is a technique of applying hard and wear-resistant materials to substrates that need abrasion resistance. The thickness of hardfacing deposit varies between 0.8 mm and 2 mm based on parameter combinations. In this study, laser hardfacing process parameters including laser power, powder feed rate, travel speed, and defocusing distance were optimized to reduce weight loss of laser hard-faced Ni-based deposit. The tribological characteristics of reactor-grade NiCr-B hard-faced deposits were investigated. The RSM technique was used to identify the most important control variables resulting in the least weight loss of the nickel-based alloy placed on AISI 316LN austenitic stainless steel. Statistical techniques like DoE and ANOVA are utilized. Changing the laser settings may efficiently track the weight loss of laser hard-faced nickel alloy surfaces. These are created using the response surface technique. The deposit produced with a laser power of 1314 W, powder feed rate of 9 g/min, travel speed of 366 mm/min, and defocusing distance of 32 mm had the lowest weight loss of 16.4 mg. Based on the F value, the powder feed rate is the major influencing factor to predict the hardness followed by power, travel speed, and defocusing distance.

Effets de la supplémentation de l’aliment en poudre des feuilles de goyavier (Psidium guajava) sur les performances de croissance des porcelets

Dans le but de contribuer à une meilleure connaissance des effets des feuilles de goyavier sur la croissance en élevage porcin, une étude a été menée sur les effets de la supplémentation de l’aliment en poudre des feuilles de goyavier (Psiduim guajava) sur la croissance des porcelets hybrides (Large White x Landrace). A cet effet, 24 porcelets de 65 jours d’âge et de poids moyen de 10,83±0,26 kg ont été répartis en quatre lots de 6 porcelets (03 mâles et 03 femelles) chacun. A chaque lot choisi au hasard a été attribué par jour et pendant 30 jours consécutifs une ration supplémentée avec 0 ; 0,5 ; 1 et 1,5% de poudre des feuilles de goyavier. Les performances de croissance ont été étudiées. La consommation alimentaire et le poids vif ont été comparables entre tous les traitements. Le gain de poids, le gain moyen quotidien et l’efficacité alimentaire ont été significativement (P<0,05) plus élevés avec la ration contenant 1,5% de poudre de feuilles de goyavier comparé à la ration contenant seulement 1% de cette poudre. L’indice de consommation et le coût de production ont été relativement plus faibles chez les porcelets ayant reçu 1,5% de poudre des feuilles de goyavier comparés à ceux des autres traitements. Il a été conclu que la supplémentation de l’aliment au taux de 1,5% de la poudre des feuilles de goyavier améliore les performances de croissance des porcelets.Mots clés : Psidium guajava, enrichissement, porcelet, croissance, coût de production. English Title: Effect of feed supplementation with dry powder of guava leaves (Psidium guajava) on growth performances of cross breed pigletsIn order to contribute to a better understanding of the effects of guava leaves on growth in pig farming, a study has been conducted on the effects of supplementation of guava leaves powder feed (Psiduim guajava) on the growth of hybrid piglets (Large White x Landrace). For this purpose, 24 piglets of 65 days of age and an average weight of 10.83±0.26 kg were distributed in four batches of 6 piglets each. To each group choosing randomly, diets supplemented with 0; 0,5; 1 and 1,5% of guava leaves powder was assigned daily for thirty consecutive days. Growth performances characteristics were studied. Feed intake and live weight were comparable between all treatments. The weight gain, daily average gain and feed efficiency were significantly higher with the diet containing 1,5% guava leaves powder as compared to the one with 1% of that powder. Feed efficiency and the cost of production were non-significantly lower in piglet haven received diet containing 1,5% of guava leaves powder compared to other treatments. It can there be concluded that food supplementation by 1,5% with guava leave powder improve growth performances of piglets.Keywords: Psidium guajava, supplementation, piglet, growth performances, production’s cost.

Novel Liquid Fuel HVOF Torches Fueled with Ethanol: Optimization and Erosion Wear Response of Cr3C2-NiCr Coatings

In this work; a novel liquid fuel HVOF process fueled with ethanol was used to prepare 75wt%Cr3C2–25wt%NiCr coatings on AISI304 stainless steel substrate. Taguchi method was employed to optimize the spray parameters (ethanol flow rate; oxygen flow rate; powder feed rate and standoff distance) to achieve better erosion resistance at 90° impact angle. The results indicated that ethanol flow rate and oxygen flow rate were identified as the highly contributing parameters on the erosion wear loss. The important sequence of the spray parameter is ethanol flow rate &gt; oxygen flow rate &gt; standoff distance &gt; powder feed rate. The optimal spray parameter (OSP) for minimum erosion wear loss was obtained under ethanol flow rate of 28slph; oxygen flow rate of 420slpm; powder feed rate of 76.7 g/min and standoff distance of 300mm. The phase composition; microstructure; hardness; porosities; and the erosion wear behaviors of the coatings have been studied in detail. Besides; erosion wear testing of the optimized coating was conducted at 30°; 60° and 90° impact angle using air jet erosion testing machine. The SEM images of the erodent samples were taken to analyze the erosion mechanism.

Hari metalikoetan eta arku elektrikoan oinarritutako fabrikazio-gehigarriko WAAM teknologiaren oinarriak eta aplikazioak

Fabrikazio-gehigarria geruzaz-geruza piezak eratzean oinarritzen den produkzio kontzeptu berria da. Fabrikazio-gehigarriaren barneko teknikek duten izaera dela eta, orain artean fabrikazio-teknika tradizionalek inposatutako diseinu mugak gainditzea ahalbidetzen dute. Material mota anitzetan lan egin dezaketen arren, lan honetan material metalikoetan oinarritutako fabrikazio-gehigarriko teknikak azalduko dira. Teknika hauek hiru multzo nagusitan sailka daitezke: Hauts-ohearen fusioa (Powder Bed Fusion, PBF), Hauts elikatzedun deposizioa (Powder Feed Systems, PFS) eta Hari elikatzedun deposizioa (Wire Feed Systems, WFS). Hauen artetik, WFS motaren barnean sailkatzen den arku eta hari bidezko fabrikazio gehigarrian (ingelesez, Wire Arc Additive Manufacturing (WAAM) bezala ezaguna) arreta berezia ezarriko da, erakusten dituen abantailak direla eta. Horien artean esanguratsuena, eskaintzen duen materialaren ezarpen-tasa altua da, tamaina handiko piezen fabrikazioa posible bihurtuz. Gainera, fabrikazio-teknika tradizionalekin alderatuz erabiltzen den material kantitatea murrizten du eta beraz, materialaren erabilera efizientzia altua lortzen da, amaierako piezatik gertu dauden aurreformak lortuz ondoren mekanizatu beharko direnak. Azkenik, WAAM teknologiaren bidez, soldagarria den edozein materialetan fabrika daitezke piezak, materiala hari metaliko formatuan sartzen delarik prozesuan. Hala, kilogramoko materialaren prezioa hari formatuan, zenbait fabrikazio-gehigarriko teknikak erabiltzen duten hauts formatuan baino askoz ere merkeagoa da. Gainera, lan honetan, zenbait aplikazio kasu ere azalduko dira aplikazio eremu bakoitzeko (fabrikazio zuzena, ez-zuzena eta konponketak) adibide bat azalduz.

Optimization of EI961 steel spheroidization process for subsequent use in additive manufacturing: Effect of plasma treatment on the properties of EI961 powder

For use in additive manufacturing (AM), powders that have a spherical shape, high fluidity, and packing density are required. One of the methods for producing spherical powders is spheroidization using inductively coupled plasma. In this work, the powder of steel grade EI961 was used. To obtain the powder for subsequent use in 3D printing, the selection of modes was carried out with the change in various parameters of the unit: different power, powder feed rate to the plasma as well as the height of feed rate. The optimal spheroidization mode is as follows: power of 15 kW, pressure of 1 atm, feed rate height of 0 mm, and powder feed rate of 28 g·min−1. The temperature distribution over the plasma torch cross section was calculated and the maximum plasma temperature was also determined. In addition, the effect of plasma treatment on the granulometric composition, phase composition, and chemical composition was studied.