Arc Plasma Technology in Materials Science

215 Pages·1972·11.3 MB·English

by  Dennis A. Gerdeman B.M.E.

Applied Mineralogy
Technische Mineralogie
Edited by
Herausgegeben von
V. D . Frechette, Alfred, N.Y.
H. Kirsch, Essen
L. B. Sand, Worcester, Mass.
F. Trojer, Leoben
3
Springer-Verlag
Wien New York 1972
D. A. Gerdeman, N. L. Hecht
Arc Plasma Technology
in Materials Science
Springer -Verlag
Wien New York 1972
DE~S A. GERDEMAN, B.M.E., M.S., Research Scientist,
University of Dayton Research Institute, Dayton, Ohio, U.S.A.
NORMAN L. HECHT, B.S., M.S., Ph. D., Research Ceramist,
University of Dayton Research Institute, Dayton, Ohio, U.S.A.
This work is subject to copyright.
All rights are reserved,
whether the whole or part of the material is concerned,
specifically those of translation, reprinting, re-use of illustrations,
broadcasting, reproduction by photocopying machine
or similar means, and storage in data banks.
© 1972 by Springer-VerlagfWien
Softcover reprint of the hardcover 1st edition 1972
Library of Congress Catalog Card Number 75-186877
With 73 Figures
ISBN-13:978-3-7091-8295-6 e-ISBN-13:978-3-7091-8293-2
DOl: 10.1007/978-3-7091-8293-2
This book is dedicated to our parents,
Mr. and Mrs. 1iymatt Hecht and Mr. and Mrs. Felix Gerdeman
Preface
Although a considerable amount of information concerning the applications
for arc plasmas in the materials sciences is available, it is contained in literally
thousands of separate manuals, technical notes, textbooks, and government and
industrial reports. Each source generally deals with only one specific application
or, at best, a narrow range of utilization. This book was developed to provide a
comprehensive and up-to-date compilation of information in the technology of arc
plasma utilization. The book is divided into two general categories: flame spraying
and materials evaluation.
In the flame spraying section a comprehensive review of the plasma spraying
process is presented. The design and operation of plasma spraying equipment are
described. Included are a description of the nature of a plasma, and the design and
operation of plasma generators, powder feed systems and accessory control equip
ment. The general process procedures, and associated process variables are de
scribed. Particular emphasis is given to the particle heating process and the
mechanisms for adherence and cohesion of coatings. Competitive flame spraying
equipment is also detailed (combustion process, detonation and electric arc) and
compared with the plasma spray process. A discussion and compilation of flame
sprayed ceramic and metal materials, their properties and applications are also
included.
In the chapters dealing with arc plasma testing, the various types of test facil
ities which utilize the arc plasma as an energy source are reviewed. The general
areas of testing discussed include reentry simulation, thermal stress, thermal shock,
ablation, dynamic oxidation, rocket ex:haust simulation and rocket nozzle evalua
tions. The advantages and limitations of arc plasma testing are compared with
competitive evaluation techniques. Diagnostic instrumentation, including heat
flux meters, enthalpy probes, pitot tubes, ablation gauges, and devices for deter
mining ionization level, etc., are described and discussed at length. A major portion
of the tex:t is concerned with the difficulties involved in defining the ex:tremely
high temperature, nonequilibrium test environment, measuring model response,
and interpreting test results. The final section of this tex:t contains a comprehen
sive bibliography of literature dealing with flame spraying and plasma arc testing.
The authors wish to acknowledge the efforts of the many individuals who have
contributed in one way or another to the successful completion of this manuscript.
In particular we wish to thank our editor, Dr. V. D. FRECHETTE for his many con
structive comments. We also wish to thank Dr. W. G. LAWRENCE, of the State
University of New York College of Ceramics, Alfred University, and Dr. L. I.
BOERMAN of the University of Dayton Research Institute for critiquing these
VIn Preface
works. The assistance provided by Mrs. JUDITH HECHT in reading the manuscript
and compiling the bibliography is also gratefully acknowledged. The efforts of Mr.
FRED KRAMER in preparing many of the illustrations, Mrs. CARMA MERKERT in
checking the references, Mrs. MARy ROSENBERG in checking the index, and Mrs.
GAIL ST. FELIX MOORE in typing and retyping the manuscript are likewise ack
nowledged.
Finally the encouragement, understanding, and phenomenal patience of our
families, and especially our wives, JUDITH HECHT and JANE GERDEMAN, are
appreciated.
Dayton, Ohio, Summer 1972 DENNIS GERDEMAN
NORMAN HECHT
Table of Contents
1. Introduction 1
2. The Plasma Arc 4
2.1. The Plasma State 4
2.2. Plasma Generators . 6
3. Plasma Spraying. 10
3.1. Plasma Spraying Equipment 10
3.2. The Plasma Spray Process (Powder Spraying) 15
3.3. Testing of Sprayed Coatings 34
3.4. Other Flame Spray Process 42
3.4.1. Combustion Spray Process 42
3.4.2. Detonation Process. 44
3.4.3. Liquid Fuel Gun . 45
3.4.4. The Electric Arc Process 48
3.4.5. Comparison of Flame Spray Processes 48
4. Materials and Applications for Plasma Spraying 49
5. Material Evaluations Utilizing the Plasma Jet 74
5.1. Plasma Test Facilities 74
5.2. Screening of Ablation Materials 77
5.3. Thermal-Shock Evaluations. 80
5.4. Thermal-Stress Tests . 82
5.5. Dynamic Oxidation 83
5.6. Reentry Simulation 85
5.7. Rocket-E:x:haust Simulation. 88
6. Characterization of Plasma Effluent '93
6.1. Energy Balance Technique 93
6.2. Sonic-Flow Method 99
X Table of Contents
7. Diagnostic Techniques 104
7.1. Enthalpy Probes 104
7.2. Calorimeters 119
7.3. Pressure Probes 129
7.4. Velocity Measurement 129
7.5. Density Determinations 131
7.6. Gas Temperature 133
7.7. Chemical Composition 134
7.8. Catalytic Effects 136
7.9. Material Response 140
References. . . . . . . 144
Appendix:: Bibliography of Plasma Arc Technology 151
Subject Index: . . . . . . . . . . . . . . . . 202
1. Introduction
The arc plasma has achieved significant importance in a diversity of research
and industrial applications within the past twenty years. Of major interest is the
use of the arc plasma for flame spraying and as a heat source for material testing.
The range of plasma arc applications is illustrated in Fig. 1.
1riC;-,
~,.ce,~~ -~
Tnerlllo-CIIellllCill li'e3ctlollS I'arlicle i'3jJoriz3tioll
LP==d.!:t~~
L
Crucible Crgs!;;1 J'ul'/ace
lIelllRg Crowillg (i/3ZIRg Cullillg
Fig. 1. Industrial Applications for the Plasma Arc
(after Thermal Dynamics Corp.)
The flame spray process is one of the major methods employed in the fabrica
tion of coatings and thin-walled components. In this process materials are intro
duced into a hot gas stream (effluent) and propelled onto the surface of a substrate
or mandrel. The heated particles are generally in a molten or plastic state and are
rapidly cooled upon impact on the cooler surface. The impacting particles flatten,
interlock and overlap one another, securely bonding together and forming a co
herent layer of material. When the substrate is properly prepared, an adherent
bond is formed between the coating layer and the substrate.
There are three principal flame spray processes:
(1) Plasma Spraying,
(2) Combustion,
(3) Arc Spraying.
Applied Mineralogy 3