A Universal Method for Representation of In-Flight Particle Characteristics in Thermal Spray Processes
- PDF / 1,469,697 Bytes
- 12 Pages / 593.972 x 792 pts Page_size
- 16 Downloads / 170 Views
W. Zhang and S. Sampath (Submitted April 6, 2008; in revised form June 5, 2008) The advent of user-friendly in-flight process diagnostic tools has significantly improved our understanding of thermal spray processes. This paper examines the critical attributes of these diagnostic measurements and the applicability of the nondimensional group parameters as a mapping strategy for data visualization. Specifically, first-order process maps (process-particle interactions) have been addressed by converting the temperature (T)-velocity (V) of particles obtained via diagnostics into nondimensional group parameters [Melting Index (MI)-Reynolds number (Re)]. This approach provides an improved description of the thermal and kinetic energy of particles and allows for cross comparison of diagnostic data within a given process for different materials, comparison of a single material across different thermal spray processes, and detailed assessment of the melting behavior through recourse to analysis of the distributions. An additional group parameter, Oxidation Index (OI), has been applied to relatively track the oxidation extent of metallic particles under different operating conditions.
Keywords
diagnostics and control, particle states, melting index, kinetic energy, Reynolds number
1. Introduction In recent years, the advent of user-friendly process and particle diagnostic tools has percolated the thermal spray industry. These devices have played a pivotal role in enhancing not only our ability to comprehend the complexities in thermal spray processes, but also allows for minimizing variability and enhancing reliability. A variety of diagnostic strategies are available to measure particle parameters in the thermal spray processes. They range from sophisticated to rudimentary based on the measurement method, interpretation, and analysis. Many of these sensors have now been successfully utilized within the harsh confines of the spray booth. The principle objectives of these diagnostic devices are to measure the spray plume characteristics namely, the particle velocities, temperatures, trajectories, and size distributions. The basis of this interest relies on a widespread appreciation that the in-flight particle velocity, temperature, and size, to a first approximation, determine the nature of the microstructure and properties of sprayed coatings (Ref 1-5). Different strategies are employed to meet these requirements. They include measurement of
W. Zhang and S. Sampath, Center for Thermal Spray Research, Department of Materials Science and Engineering, State University of New York, Stony Brook, NY 11794-2275. Contact e-mail: [email protected].
Journal of Thermal Spray Technology
individual particle parameters within the spray stream (e.g., Tecnar DPV 2000 and Inflight integrated particle sensor) as well as ensemble particle sensors for group measurements of particle velocities and temperatures (e.g., Tecnar Accuraspray, Oseir Spraywatch, Inflight Particle Pyrometer, Stratonics Thermaviz, etc.) (Ref 2, 6-10). Many
Data Loading...
