Plazwire technology and the use of laser-aided diagnostics for its future evolution

This article first describes plazwire technology, a novel method of plasma spraying of molten metals. It has shown to be an effective and efficient means of preparing anti-corrosive coatings on metal surfaces exposed to outside air/water for extended periods of many decades. For its further development, there exist certain behavior of droplets in a plasma flame which must be elucidated, and these data needs are then enumerated. Against this background, the potential of laser-aided diagnostics for droplets are assessed, in particular laser-shadowgraphy, laser in-line holography, and laser-Doppler velocimetry/phase Doppler particle analysis. In addition to these diagnostics design studies, two proof-of-principle (POP) experiments were conducted on laser in-line holography for droplet size determination and on laser-Doppler velocimetry for the droplet velocity relaxation with background gas flows, with the results clearly demonstrating the validity of these methods for the above-mentioned purpose.