Powder morphology in thermal spraying

Abstract

Thermal spraying (TS) is a suitable method to protect a substrate or to improve its surface properties and achieve the specific surface requirements for a prescribed service environment. In this method the feedstock material is heated up to a melted or semi‐melted state, accelerated to high speed by an energetic flow and sprayed onto a prepared substrate. Powders are the most commonly used feedstock materials in the TS process. Their composition, size distribution, morphology, physical and mechanical properties determine the coating microstructure and related thermo‐mechanical performance. Among other variables, powder morphology plays a fundamental role to ensure the consistency and reproducibility of the feeding mechanism, to control the interaction between feedstock particles and TS heat source, and to influence the microstructure of the coating. This review highlights the crucial function of powder morphology in TS and proposes introductory information on the importance of powder morphology in cold spraying.

Influence of Atmospheric Plasma Spray Parameters (APS) on the Mechanical Properties of Ni-Al Coatings on Aluminum Alloy Substrate

“…Typical parameters influencing the APS process include the plasma gas composition, the geometry of the electrodes, the spraying distance, the atmosphere used, the transverse speed of the torch, the substrate temperature and the powder size and quality [22][23][24]. Generally, the plasma gas is composed of Ar or mixtures of Ar + H 2 , Ar + He and Ar + N 2 , sometimes N 2 and a mixture of N 2 + H 2 .…”

Review of Functionally Graded Thermal Sprayed Coatings

“…The physico-chemical properties of powders, including e.g., melting point, crystallinity, heat conductivity, coefficient of thermal expansion or specific result from their chemical composition. However, the production route significantly influences the powder characteristic such as particle morphology, size distribution, and apparent density [164]. The most important powder manufacturing processes are [1,165]: (i) atomization (gas or water); (ii) fusion or sintering followed by crushing; (iii) agglomeration by spray-drying; (iv) cladding; and (v) mechanical alloying.…”

“…Furthermore, the feedstock should be appropriate for the specific thermal spray technology. The smallest size of powder particle sizes is generally and for all spray techniques about 10 to 15 µm [164]. The greatest size depends a lot on the coating application.…”

“…The value of 90 µm is a typical one used for APS and the value of 30 µm-for LPCS. The powders used in other spray techniques have the greatest sizes between these two values [164].…”

Welcome to the second year of the Journal of Advanced Manufacturing and Processing

“…In particular, we would like to encourage reviews of topics in advanced manufacturing and we are pleased that we have already published three of these. [5][6][7] In our first year, we published a wide variety of articles on advanced manufacturing that sought to link research work with important measures of manufacturing systems-particularly in the area of life cycle assessment. Shah and Bakshi [8] considered how to integrate the capacity of nature to absorb our industrial wastes with the operation of a chemical process.…”