Proceedings of the 42nd Porcelain Enamel Institute Technical Forum: Ceramic Engineering and Science Proceedings, Volume 2, Issue 3/4

202 Pages·1981·14.229 MB·English

Proceedings of the
42nd Porcelain Enamel Institute
Technical Forum
George B. Hughes
Conference Director
A Collection of Papers Presented at the
42nd Porcelain Enamel Institute
Technical Forum
October 29, 30, and 31, 1980
University of Illinois
Urbana, Illinois
ISSN 0196-6219
Published by
The American Ceramic Society, Inc
65 Ceramic Drive
Columbus. Ohio 43214
@ The American Ceramic Society
and the Porcelain Enamel Institute, 1981
Executiue Dlrector & Publisher Associate Editor
Arthur Friedberg Susan Stock Means
1.
Director Pub/lcatlons Graphlc hoduction
of
Donald C. Snyder Carl M. Turner
Editor CfrculatfonM anager
William J. Smothers Gary W. Panek
I
Commlttee on Publlcatlons: J. Lambert Bates, Chairman; Robert J. Beak;
H. Kent Bowen; William C. Mohr; Richard M. Spriggs; Louis J. Trostel, Jr.,
ex ofpclo;W illiam J. Smothers, ex ofpcfo;A rthur L. Friedberg, ex oflclo.
EdftorfalAduisoryBoard: L. J. Trostel, Jr., Chairman; R. Berger; W. G.
1.
Coulter; R. T. Dirstine; R. A. Eppler; E. J. Friebele; F. A. Hummel; W. J.
Lackey; T. D. McGee; G. W. Phelps; D. W. Readey; and W. R. Wale.
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of
CESPDK VOI. pp.
2, NO.3 -4, 143-336,1981
Foreword
A Message from the Technical Forum Chairman
It has been a real pleasure to serve as chairman of the 1980 PEI Forum Com-
mittee. The many individuals who contributed so much to make the meeting
another highly successful one have made my task especially easy and plea-
sant.
While it is impossible to acknowledge everyone, I do want to express my
appreciation and that of the officers and staff of the Porcelain Enamel In-
stitute to everyone connected with the University of Illinois for being such
fine hosts. Again this year, as they have been doing in alternate years since
the first PEI Forum in 1937, they amply provided for our every need. Coor-
dinator of the university arrangements was Dr. Clifton Bergeron, the new
head of the Ceramic Engineering Department at Illinois. We all owe him a
special thanks for his efforts.
This year’s Technical Forum program proved to be another successful
one in our long series of outstanding technical meetings. With a banner atten-
dance, we were pleased to have James D. Sullivan open the Forum with his
excellent A. I. Andrews Memorial Lecture. Directing his lecture to the sub-
ject of “Glass-Metal Reactions and Physical Properties of Enamels,” he
presented a substantive paper in which he discussed some fundamental
metallurgical and chemical factors involved in glass-metal reactions. Follow-
ing his lecture, the Forum audience heard two informative papers on the role
of porcelain enamel in microcircuitry applications. Next was a report on
research in specialized ceramic coatings and a summary of several industry
programs involved with government research efforts. The first afternoon ses-
sion concluded with an informal panel presentation on the status of govern-
ment environmental actions that threaten the porcelain enamel industry.
Thursday’s session led off with five papers touching on various aspects
of base metals and metal preparation techniques. The rest of the morning ses-
sion was devoted to a series of papers and panels on the subject of furnace
improvements and modifications. Thursday afternoon saw a variety of topics
receiving attention-several papers on the latest processing advances, others
on the subject of no-nickeVno-pickle systems, and a final group dealing with
low-cobaltho-cobalt ground coats. On Friday the session began with a series
of papers related to energy conservation. These were followed by individual
papers and two separate panels devoted to material utilization and waste
disposal.
As I conclude my remarks, I want to thank each of our speakers and the
individual session chairmen. Of course, I don’t want to forget the work of
the Technical Forum Committee that planned the program and contributed
in so many other ways. Looking ahead, we hope to see you at the 1981 PEI
Technical Forum at The Ohio State University in Columbus. The dates are
October 6 and 7, and we urge you to begin now to make plans to attend.
George B. Hughes, Chairman
Technical Forum Committee
...
111
Table of Contents
A. I. ANDREWS MEMORIAL LECTURE
.......
Glass-Metal Reactions and Physical Properties of Enamels 143
James D. Sullivan
PORCELAIN ENAMEL IN MICROCIRCUITRY
Industry Experience with Porcelain-Enameled Steel Substrates
................................
for Electronic Applications 160
Robert B. Schabacker
Developments with Porcelain Enamel Steel Substrates
................................
for Electronic Applications 166
Lubomyr Onyshkevych
GOVERNMENT INVESTIGATIONS AND PROGRAMS
Some Thermal Stress Problems in Porcelain
....................................
Enamel-Coated Rods 178
Glenn McDonald and Robert C. Hendricks
Some Current Government Activities Relating to the Porcelain
........................................
Enamel Industry 188
Howard F. Smalley and Richard I. Moss
Current Environmental Programs Impacting the Porcelain
.............................
Enamel and Related Industries 192
(A Panel Presentation)
BASE METAL AND METAL PREPARATION
Properties and Enameling Characteristics of Sheet Steels for
Porcelain Enameling ..................................... 193
Donald A. Toland
....................................
Identifying Steel Soils 199
Patrick J. Crilley
Practices in Porcelain Enamel Plants That Cause Production
..........................
Difficulties and Enameling Defects 205
Fred Allenbaugh
..................
Low-Temperature Cleaning- A Case History 210
Alfred H. Pope
Mechanism of Nickel-Flash Coating in Porcelain
.................................
Enamel-to-Steel Bonding 214
Yong-Wu Kim
FURNACE INNOVATIONS
Energy-Efficient Furnace Systems .......................... 228
Louis C. Kolar
.......
Energy Savings in Furnaces Using Ceramic Fiber Modules 232
Ronald L. Allen and Lester N. Smith
V
Plant Experiences with Ceramic Fiber Modules as a
.................................
Veneer Lining in Furnaces 238
Thomas E. Penisten
Industry Experiences with Furnace Modifications:
......................................
APanel Discussion 244
Oscar A. Jeude, James Marcotte, Edward L. Macoicz, and
W. Charles Bennight
ADVANCES IN ENAMEL APPLICATION
...........................
Two-Coat/One-Fire Alternatives 249
Werner Joseph
......
Analysis of Two-Coat/One-Fire Powder System Adherence 256
William D. Faust, Holger F. Evele, and James W. Smith
Study of Bond Development and Cobalt Replacement in Frit
........................................
Powder Systems 270
Gary F. Howorth and R. Stephen Barr
......................
The P/E Plant of 1990-A Look Ahead 281
Jeffrey F. Wright
.........
A Decision to Move to P/E Powder-A Progress Report 290
Donald R. Sauder
........
Experiences with Porcelain Enamel Powder in Production 295
Hans W. Hoffman and Jorn Drake
Quick Color Change Capabilities with Porcelain
.........................................
Enamelpowder 301
Gunter J. Lissy
NO-NICKEL/ NO-PICKLE SYSTEMS
.....
Production Experience with a Pickle-Free Enameling System 304
Alfred G. Carter and M. George Sinkovec
LOW-COBALT/NO-COBALT GROUND COATS
Observations on Industry Experiences with Low-Cobalt/
......................................
No-Cobalt Systems 310
Archie E. Farr
Industry Experiences with No-CobaltlLow-Cobalt Systems:
.....................................
A Panel Presentation 313
Daniel R. Yearick, Lester N. Smith, and Narayan M. Sedalia
ENERGY CONSERVATION
Industry Looks at Energy Conservation: A Panel Presentation ..... 316
Bobbie G. Stewart, G. Thomas Cavanaugh, and Gordon Shippy
MATERIALS UTILIZATION AND WASTE DISPOSAL
.............
Responding to the Hazardous Waste Requirements 321
James J. Carleton
.............
Role of Eight Selected Metals in Porcelain Enamel 322
Thomas L. Stalter
vi
Concepts and Experiences in Using Reclaimed Enamels:
.....................................
A Panel Presentation 325
Frank Vondracek. Thomas L . Stalter. and Bernard Borowski
Plant Programs for Materials Reclamation:
.....................................
A Panel Presentation 329
Daniel R . Yearick. Rush S . Dale. and W . Roland Verchota
......................................
A'lTENDANCE 333
LIST
vii
Cerurnic Engineering and Sciences Proceedings
William J. Smothers
Copyright The American Ceramic Society and the Porcelain Enamel Institute, 1981
THE A. I. ANDREWS MEMORIAL LECTURE
Glass-Metal Reactions and
Physical Properties of Enamels
JAMESD . SULLIVAN
A. 0. Smith Corp.
P.O. Box 584, Milwaukee, Wis. 53201
Some fundamental metallurgical and chemical factors involved in glass-metal
reactions are reviewed in light of their eflect on physical properties of glass-coated
steel. Steel compositions, steel-treating procedures, and some electrochemical and
thermodynamic data for oxides in enamel compositions are discussed in relation to
enamel defects and adherence.
The major variables involved in the glass-metal reactions in firing enamels are
as follows:
Base metal composition
Metal surface preparation
Mill additions
Furnace atmosphere
Heating rate
Cooling rate
Each of these variables must be carefully controlled. Modification of
each variable is required to accommodate changes in the conditions of the
others. The present discussion focuses on the first three variables.
Base-Metal Compositions
Iron base-metal compositions include decarburized enameling-grade
sheet steel, low-carbon enameling iron, cold-rolled sheet steel, hot-rolled
sheet steel, low-alloy/high-strength steel, stainless steels, and cast iron. Each
of these alloys has significantly different steel cleaning requirements, dif-
ferent reactions with the enamel compositions, different thermal expansion
or contraction during firing, and varying tolerance for water content in frit,
mill additives, and furnace atmospheres. The problems and technology re-
James D. Sullivan, a graduate of the University of Missouri-Rolla, has been involved in
ceramic research for more than 30 years. Since 1971 he has headed the Ceramic Research
Lab at A. 0. Smith, and prior to that he was manager of technical development for the
Glascote Div.. Pfaudler Corp. He has published more than a dozen technical papers and has
been awarded 11 patents.
143
quirements of the enameler working with thin-gage, cold-rolled, low-carbon
steels for kitchen or laundry appliances are considerably different from those
in the water heater, chemical process equipment, or crop storage equipment
areas, where one encounters higher carbon steels, higher strength steel, low-
alloy/high-strength steels, and stainless steels in thicker gages. Because most
of my own experiences have involved the higher strength, thicker gage steels,
this presentation is related more to that area of enameling.
The iron-carbon phase diagram for steel offers insight into fundamental
problems in coating higher carbon and low-alloy steel compared with low-
carbon enameling iron. The entire iron-carbon equilibrium diagram is shown
in Fig. 1, which provides a perspective of the relation of enameling steels (up
to 0.2% carbon) to the other steel grades and cast iron. The area of concern
for enamelers is shown in Fig. 2. Enameling iron contains about 0.02% car-
bon, and decarburized steel for enameling about 0.002-0.004% carbon. It
can be seen from the iron-carbon diagram that when steels in these carbon
ranges are heated to fire enamel at about 815 "C, the steel stays at alpha iron.
However, when, e.g., steels used in water heaters, which are about 10 times
higher carbon (0.1-0.2% C) are enameled, a partial transformation occurs in
the crystal structure from the body-centered cubic, alpha iron, to face-
centered cubic gamma iron as the steel is heated above about 705 "C.
Enameling iron remains as alpha iron during the firing process. The iron
crystals remain body-centered cubic lattice structure, as shown in Fig. 3.
as
For the higher carbon steel types referred to herein as hot-rolled, cold-rolled,
and low-alloy steels, the transformation to gamma iron, face-centered cubic
crystals occurs (Fig. 4). The phase transformation produces a significant ef-
fect on enameling properties. The steel structure makes a volume change, and
the lattice distances of crystal structure are reported to change from 0.29 nm
for body-centered cubic to nm for face-centered cubic iron crystal.' The
0.35
capacity to absorb hydrogen into the crystals increases with gamma iron
crystals; however, the diffusion rate of hydrogen through the gamma crystals
is reported to be lower. The absorption and diffusion of hydrogen are
especially important in the enameling of higher carbon steels.
Hydrogen Absorption
Figure 5 shows the increased solubility of hydrogen in iron at increased
temperatures.2 Also shown is the jump in solubility for hydrogen that occurs
in the alpha-gamma transformation. The curves show that nickel alloyed in
the steel composition increases the capacity of the steel to hold hydrogen in
the metal crystal structure. In addition, the lower transformation
temperature effect of nickel additions in iron is shown by the hydrogen
solubility curves. Hydrogen absorption in the steel during enameling is
related to the amount of water in the bisque and furnace atmosphere during
firing of the glass. Figure 6 shows the large volume of water vapor that was
recovered from dried bisque as reported by Swe0.l
Figure shows hydrogen recovered from glass fired with increasing
7
water vapor in the furnace atm~sphere.N~o te that more hydrogen was
recovered from steel with both sides coated. More hydrogen was also
recovered from the steel coated with cobalt-free frit. Glass ax is the same frit
composition without cobalt. A significant result of the study of furnace at-
mospheres was that although there is much water in the glass bisque, very lit-
tle hydrogen enters the steel unless there is a significant amount of water
144
vapor in the furnace atmosphere. Hydrogen defects in enamels are very sen-
sitive to water vapor in the furnace atmosphere, especially when the dew
point exceeds - 1.1 "C, or about 1% water vapor by volume. On the other
hand, a small amount of water, about 0.5% by volume, in the furnace at-
mosphere may be helpful to increase fluidity of some enamel compositions.
A direct-fired furnace atmosphere may contain large amounts of water vapor
in the range of 8-12'7'0 by volume. This presents a very difficult problem.
Gamma iron crystals have a higher capacity to hold hydrogen; thus
problems are encountered not only in hydrogen absorption but also in in-
creased thermal expansion in the steel when the higher carbon grades are
enameled. As the steel transforms back to alpha iron and shrinks on cooling,
some of that absorbed hydrogen is squeezed out of the crystals and collects at
the interface of metal and enamel. When the hydrogen ions reach the glass-
metal interface, they diffuse into the bubbles or voids at the interface. There
they recombine to form molecular hydrogen with a very large increase in
volume. This increasing gas pressure at the glass-metal interface results in
spalling or fish scaling of the coating. Reboiling will occur if a second coat is
applied. Increasing the volume of voids in the steel or bubbles in the glass can
relieve some of the hydrogen pressure and prevent pressure buildup to the ex-
tent that the glass may not spa11 or reboil. The diffusion of the hydrogen out
of the steel structure can be a slow process that may take weeks, causing
delayed spalling defects.
As was mentioned above, voids in the steel can help relieve the problem
of hydrogen diffusion to the metal-enamel interface. Cold work or cold roll-
ing the steel creates crystal dislocations and voids in the steel. This condition
is indicated by decreases in density measurement of the cold-worked steel in
the range of 0.002-0.004 g/cm3. The voids in the steel are not detectable
microscopically but are readily shown ultrasonically. This seems to be a
minor change, but it can help the fish scaling problem significantly.
However, cold rolling is not a practical solution for thicker gages of sheet
steel.
It was found that by forcing atomic hydrogen into the steel structure
electrolytically and allowing it to recombine in the voids or dislocations of the
iron crystal lattice, the voids in the steel could be produced and significantly
increased in size. This result was indicated by steel density's being decreased
in the same degree as was achieved by cold rolling. The hydrogen was then
removed by heating the steel to about 93 "C in a hot water bath. This process
could produce voids in the steel and accomplish an effect similar to cold roll-
ing on hot-rolled steel sheets and decrease fish scaling. This procedure put
voids in the metal structure to achieve the reduced density of the base metal.
It was effective in preventing fish scaling of higher carbon hot-rolled steel.
Later, a less costly way to prevent the hydrogen from entering the steel
was discovered, but the hydrogen treating process was effective and was used
commercially for a time. The less costly method involved spraying an oxide
film on the steel prior to applying glass. A special nickel oxide and frit mix-
ture was developed to accomplish the desired result to prevent hydrogen
penetration into steel.
Transformation Range
Figure 8 shows thermal expansion curves of a rimmed steel containing
0.12% carbon and 0.5% manganese and a cover-coat glass. The hump in the
145
steel expansion curve occurred through the range of 700 "-825 "C in heating;
this hump identifies the alpha-gamma transformation range, The transfor-
mation range is lowered during cooling and is completed at about 650°C. The
curves were drawn from data developed by heating and cooling glass and
steel rods in a dial gage extensiometer apparatus. The heating and cooling
rate is programmed at 0.2 "C/min.
This slow heating and cooling rate is far less than an actual enameling
firing and cooling rate. Coated ware cools at a couple of hundred degrees per
minute. Faster cooling will have the effect of lowering the transformation
range on cooling. The decreased transformation range becomes of concern in
enameled low-alloy/high-strength steels or in the enameling of weld deposits
that contain alloying elements. Arc weld deposits have low carbon content,
but up to 2% manganese is common. The occurrence of the steel or weld
metal of the gamma-to-alpha transformation at temperatures low enough
where the enamel has cooled to a semiviscous or solidified state cannot be
tolerated during the cooling of enameled steel. Obviously, as the solidified
enamel is shrinking during cooling and the steel is expanding during cooling,
cracking or crazing of the glass coating will result. Since the phase diagram
shows equilibrium slow cooling conditions that do not exist in the cooling
rate of enameled ware, it must be recognized that this zone occurs at a lower
than equilibrium temperature in actual production enameling. In addition,
enameled parts do not cool evenly; thus, some areas transform and shrink at
different rates, resulting in warpage, uneven residual stress, and poor enamel
quality. Slower quality rates help relieve this problem.
Alloying elements such manganese, nickel, and chromium in the steel
as
tend to move the phase transformation temperature range downward and to
the left on the iron-carbon diagram. Manganese and nickel do not have as
much effect per percent as does chromium. For example, 1% manganese in
the steel will lower the transformation range about 83 "C. This may not be
enough to cause the enamel to crack, but it will reduce the residual com-
pressive stress in the enamel. The result is lower thermal shock resistance in
the enamel. About 1.2% maximum manganese in conjunction with 0.15%
maximum carbon are the maximums that can be tolerated in a high-strength
steel for enameling. In enameling iron, as little as manganese promotes
0.3010
sagging and fish scaling, probably a result of the tendency of manganese to
induce the gamma phase transformation range into enameling iron at the fir-
ing temperature of the enamel. The strengthening effect of manganese addi-
tion in steel can be tolerated in the enameling process easier than increased
carbon content for strengthening the steel.
Nickel has somewhat greater effect than manganese in lowering the
transformation range; thus less of it (only about 0.5%) can be tolerated in
low-alloy steel for enameling. These alloying elements must also be con-
sidered relative to the amount of carbon in the steel. Carbon intensifies the
effect of the alloying elements, so that carbon in low-alloy/high-strength
steel for enameling must be limited to 0.18%.
As the alloying elements are increased in the steel composition, it is
possible to suppress the gamma-to-alpha transformation so that it does not
occur on cooling to room temperature. This is the case for the 300-series
stainless steels. These alloys have a higher coefficient of expansion than car-
bon steel. However, the very low carbon types, 304L and 316L, can be coated
146