Spring 2000

ME/IE 8773-8774

THERMAL SPRAYING WHERE IS IT, WHERE DOES IT GO?

by

Prof. P. Fauchais
University of Limoges - France
Laboratory of Science of Ceramic and Surface Treatment Processes
UMR 6638 - CNRS

Wednesday, April 12, 2000
3:35 - 4:25 p.m.
Room 108 ME
Broadcast on UNITE Channel A
Coffee will be available in 152 ME following the seminar

Thermal spraying has drastically evolved from an art to a science. At the moment it is possible to achieve coatings tailored to specific service conditions and thermal spraying is now an integral part of the process of making industrial commodities. This has been achieved thanks to:

A better understanding, through modeling and measurements, of the flames, detonations or plasma jets, the flame or plasma-particle heat, momentum and mass transfer, the particle impact and flattening, the coating generation
A better design and control of the heat sources: flames, high velocity oxyfuel flames, D-guns, d.c. and r.f. plasma torches
Computerized control panels acting on the macroscopic parameters such as arc current, gas mass flow rate and composition and sophisticated robots allowing to achieve almost constant pass thicknesses especially when spraying parts of complex shapes.

However many problems are still to be solved to achieve a better reproducibility and reliability of substrate surface preparation, spraying and post treatment of coatings. Thus efforts are made to:

Develop new surface preparation devices avoiding the grit residue problem
Develop new plasma torches with less fluctuations and higher velocity, flames, wire arcs, HVOF devices, D-guns , new shrouding systems
Develop on-line control with reliable cheap sensors
Achieve a standardization of coating characterizations promote education at all levels and expert systems to help operators and designers.

Prof. Pierre Fauchias received a Diploma in Physics (1961) from the University of Poitiers, a Diploma in Aeronautical Engineering from the National School of Mechanics and Aeronautics, Poitiers, a Ph.D. degree in Mechanics and Aeronautics in Physics (1963), and the State Thesis in 1968, both from the University of Poitiers. From 1961-68 he was a Researcher at the National Research Center (Poitiers). He has been on the faculty of the University of Limoges since 1962. Prof. Fauchais' technical background includes research in the area of arc technology including plasma torches and transferred arc development, plasma heat transfer, and electrode effects. In the area of plasma diagnostics, he has conducted research on characterization of several plasma processes: plasma spraying and evaluation of the resulting coatings, plasma transferred arc reclamation, plasma CVD, extractive metallurgy, ultra fine particle production, and waste treatment. Prof. Fauchais is a member of the French Physical Society, French Society of Thermal Science, ASM, TSM; he has been a member of the IUPAC Subcommitte on Plasma Chemistry 1975-99; Chairman, 1979-81. He has been a member of the TSS of ASM since 1995 and has served as president of the Club EDF Hautes Temperatures since 1975. He was president of the University of Limoges from 1974-79, organizer of 27 international conferences, and he is the editor of J. of High Temperature Material Processes. He was inducted into the Thermal Spray Hall of Fame of the TSS - ASM, and received 7 best paper awards. Prof. Fauchais has over 240 publications in international refereed Journals and 250 papers in conference proceedings, and has been issued 4 patents.

Faculty Host: Prof. J.V.R. Heberlein