The aim of this study is to characterize the mechanical behavior of wire-arc sprayed Zn-Al coatings and correlate the results with microstructure via computational techniques. High-resolution microstructural images obtained by SEM were imported into NIST-developed FEA software, which calculates macroscale properties based on user-selected features such as voids, pores, cracks, and splat boundaries. To assess the validity of the approach, elastic modulus was measured various ways and the results compared to the simulated value. Resonant frequency analysis provided the most accurate measurement, which was found to be closest to the simulated value.

This study aims to better understand stress fields in composite coatings produced by plasma spraying. To that end, Al 2 O 3 -TiO 2 coatings are deposited under conditions that result in architectures differing in pore content, crack density, and crack orientation. SEM images of the coatings are divided into discrete stress domains that are analyzed by finite elements. FEA simulations show that network architecture has a significant influence on stress fields and that secondary phases have a particularly negative effect. The paper also proposes a generic method for stress analysis based on representative volume elements and points out its advantages and limitations.

The aim of this work is to analyze the morphology and composition of iron-aluminide (FeAl) powders produced by liquid metal atomization using a de Laval nozzle. The variables studied are atomization gas pressure and melt nozzle diameter. Different sized powders were characterized via SEM, XRD, and EDS analysis and were found to be similar in composition and shape (spherical) regardless of their size. The paper provides a detailed description of how the powders were produced, classified, and tested, and presents and interprets the results.

The effect of process conditions on flame spraying of titania (TiO 2 ) and magnetite (Fe 3 O 4 ) was investigated. Designed experiments were conducted to determine spraying conditions, specifically total combustible gas flow, stand off distance, and oxygen/acetylene ratio that produce high deposition efficiency (DE) and dense coatings. Along with DE, particle temperature and velocity were determined and correlated with process conditions. Results indicate that for both titania and magnetite, hot and high velocity molten particles result in higher DE and lower porosity coatings. Micrographs of coating cross-sections and surfaces were taken with both field emission scanning electron microscope (FESEM) and optical microscope. X-ray diffraction analysis shows that the titania coating retained its rutile structure while the magnetite coating had small amounts of magnetite (γ-Fe 2 O 3 ) in addition to magnetite.

It is known that particles injected in a plasma stream follow differing trajectories which in turn leads to different thermal and kinetic history dependent on the location of particle in the plume. The variation in particle characteristics (temperature and velocity) across the plume has been the focus of research over the years. The corresponding variation in impacting particles, particularly in terms of their splat characteristics have not been explored as systematically. This is important for a complete understanding of the coating build-up phenomena and the variations in coating properties. This paper presents the results of a study in which the spatial variation in particle properties is mapped to the spatial variation in splat properties. This has been accomplished using a procedure to collect splats using a shutter mechanism that allows us to expose the substrate for approximately 50 milliseconds. Splats of Alumina and a Ni- Cr-B-Si-Mo have been collected on polished substrates maintained at 250ºC and studied. Micrographs reveal differing splat morphologies across the spray plume – from missing-cores in one part to complete disc-shaped splats in the other. Extent of flattening and fragmentation have been quantified and found to vary within the ‘splat map’. Correlation between the location of particle in the plume and the resulting splat has been constructed using this data. Abstract only; no full-text paper available.

This paper reports morphological study of coatings microstructure performed on two selected reference abradable materials: AlSi-hBN and NiCrAl-Bentonite. Scanning Electron Microscopy (SEM) was used to obtain adequate micrographs for analysis. The porosity and non-metal particles morphology was assimilated to elliptical inclusions within the metallic matrix. Accordingly, they were described by means of three different geometrical parameters related to the shape, size and orientation distribution, allowing additional statistical analysis on the coatings.

An analysis of physical and mechanical properties of coatings produced by kinetic and cold spray processes is presented. Adhesion, hardnesses, porosities, critical velocities and other properties of aluminum and copper coatings from both spray methods will be analyzed and discussed, including SEM and optical micrographs. Similarities and differences between each of the coating methods and their effects on the resulting coatings are presented. A brief history and discussion of the bonding mechanisms for larger particle coatings produced by the kinetic spray method is provided.