Search results for "Spraying"

Surface modifications induced by nanosecond pulsed Nd:YAG laser irradiation of metallic substrates

2006

International audience; Substrate surface preparation is a key step in coating deposition process. In recent years, pulsed laser cleaning has emerged as a possible technique to challenge the traditional preparation methods (based on degreasing and eventually grit-blasting). The laser operated at short-pulse mode offers high cleaning efficiency and therefore has been largely used. In a specific process named PROTAL®, a nanosecond pulsed laser is introduced to prepare the surface simultaneously to thermal spraying, with the purpose of eliminating the contaminants and generating favorite surface conditions for coating deposition. This study aims at clarifying some fundamental aspects of nanose…

Thermal increment due to ErCr: YSGG and CO2 laser irradiation of different implant surfaces. A pilot study

2010

Podeu consultar la versió en castellà http://hdl.handle.net/2445/118903

2019

Abstract The fatigue life of thermally sprayed Al2O3- and Cr2O3-based coatings has been studied under low-energy (0.7–5 mJ) impact conditions. A threshold impact energy and amount of repetitions the coatings can endure with said energy before catastrophic failure was obtained. The catastrophic failure was determined to occur when the fracture mode of the coating switched from brittle cone cracking to quasi-plastic radial cracking. The results are examined relative to the microstructural features along with other properties of the coatings - hardness and cavitation resistance. The experiment provided a new approach for a straightforward comparison of the micro-scale impact fatigue life of th…

Adhesion Strength Test Comparison for HVOF Nickel-Based Superalloy Powders on Steel Substrates and Layer Characterization

2018

Thermal sprayed nickel chrome powders are known as the best materials for combined wear and corrosion applications and represent a good alternative to hard chrome plating. The coating from these materials are resistant to wear abrasion, contact with hard surfaces, particle erosion, fretting and have excellent submerged saltwater corrosion resistance. The work in this paper is focused on determining the adhesion strength for nickel powders and structural characterization of the deposited layers using metallographic analysis. The adhesion strength testing was carried out in accordance with ASTM C633 procedure. During the experimental program, an investigation was also carried out for studying…

Prediction and analysis of high velocity oxy fuel (HVOF) sprayed coating using artificial neural network

2019

Abstract Thermal spray comprises a group of coating processes for coating manufacturing in which metallic or nonmetallic materials are deposited in a molten or semi-molten condition. Most often, the coating properties are significantly influenced by the operating parameters. However, obtaining a comprehensive modeling or analytical analysis of the thermal spray process is too difficult to be practical due to the complex chemical and thermodynamic reactions. Accordingly, the present study aims at applying an artificial neural network (ANN) model to predict the HVOF sprayed Cr3C2−25NiCr coatings and analyze the influence of operating parameters regardless of the intermediate process. The proce…

Microstructure and mechanical properties of plasma spraying coatings from YSZ feedstocks comprising nano-and submicron-sized particles

2015

Atmospheric plasma spraying (APS) is an attractive technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanoparticles cannot be fed into the plasma using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, nanostructured and submicron/nanostiuctured powders of yttria-stabilised zirconia (YSZ) were deposited using APS, with a view to obtaining high-performance thermal bather coatings (IBC). All powders were reconstituted by spray-drying from different solid loading suspensions, followed by a thermal treatment of the spra…

Synthesis of bulk FeAl nanostructured materials by HVOF spray forming and Spark Plasma Sintering

2006

Abstract This paper examines the efficiency of two consolidation processing techniques: High Velocity Oxy-Fuel (HVOF) spray forming and Spark Plasma Sintering (SPS) to obtain bulk nanostructured materials from an Y 2 O 3 reinforced Fe–40Al (at.%) milled powder. The microstructures of the sintered end-products were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in order to gain new insights in their microstructure formation mechanisms. HVOF spray forming is more effective to retain fine nanograins, in particular within retained unmelted powder particles. The drawbacks of this technique are that it inevitably leads to a high fraction of porosity…

Laser Ultrasonic Testing for Estimation of Adhesion of Al2O3Plasma Sprayed Coatings

2001

Abstract The aim of the present study was to investigate the possibility of using a laser ultrasonic technique for the estimation of the adhesion of ceramic coatings, deposited onto metallic substrates by thermal spraying techniques. For this purpose, a pulsed Nd : YAG laser (λ = 1064 nm, 14 ns) was used to irradiate Al2O3 coatings, of different thickness (30–350 µm), deposited onto stainless steel substrates by atmospheric plasma spraying. The laser generated ultrasonic waves were in situ recorded at the epicentre using a laser heterodyne interferometer. The acoustic waveforms were correlated with the interaction between the pulsed laser radiation and the coated metal, taking into account …

Influence of laminated architectures of heterostructured CeO2-ZnO and Fe2O3-ZnO films on photodegradation performances

2020

Abstract The development of photocatalytically active films has gained a great attention in recent years. Herein, new heterostructured films associating ZnO and CeO2 or Fe2O3 and exhibiting various architectures were prepared by the solution precursor thermal spray (SPPS) process. The paper examines the effect of the films laminated architectures on the photodegradation performance. For CeO2-ZnO and Fe2O3-ZnO films, the photodegradation efficiency of the Orange II dye is 100% and 95% after 240 min UV light irradiation and after 360 min visible light irradiation, respectively. The photocatalytic activity of the laminated structures was found to depend on the materials used to construct the h…

Bulk FeAl nanostructured materials obtained by spray forming and spark plasma sintering

2007

Abstract This paper examines the efficiency of two consolidation processing techniques high velocity oxy-fuel (HVOF) spray forming and spark plasma sintering (SPS) which allow to obtain bulk dense nanostructured materials. An oxide dispersion strengthened (ODS) Fe–40Al (at.%) based milled powder (with a nanostructure