INDUSTRIAL AND ENGINEERING CHEMISTRY
2102
LITERATURE CITED
MacPhcaoii, D. I:., L-. S.Patent 2,435,594 (l'eb. 10,194s). (39) Merril, R.C., IND.ESG.CHEY.,41, KO. 2, 337-45 (1949). (40) Morgan, J. D., Smith, C. E., and Wicking, It. 11'. H., Brit. Patent 596,361 (Jan. 2 , 1948). (41) Slulcahp, E. IT., J . Electrodepositors' Tech. Soc., 22, 227-42 (:3b)
(1) (2) (3) (4)
Anon., Chem. Eng., 55, KO.7, 127-34 (1948). Anon., Ibid., X o . 11,99-128 (1948). Anon.. Chem. Eng. S e w s . 26, 746 (1948). Anon., I n d . Finishing, 24, 286-90 (December 1948). ( 5 ) Anon., M o d e r n Plastics, 25, 30. 5, 166 (1948). (6) Anon., Ibid.. 26, KO.5, 70 (1949). (7) Atwell, James, ISD.EXG.CHEM.,41, 1318-24 (1949). (8) Beiler, Gertrude, Verre siZicates ind., 12, 37-8 (1947). (9) Burr, Warren, Oficiel Digest Federation P a i n t R. T'nruish Production Clubs, No. 277, 198-207 (1948). (10) Callnhau, J . R., C'i~cm. Eng., 56, No. 2, 137-9 (1949). (11) Camp, E. J., Corrosion, 4, 317-98 (1948). (12) Charles, Saint Jlleux, U. S.Patent 2,430,481 (Kov. 11, 1947). (13) Cunningham, E. Y . , Rubber A g e , 62, 187-90 (1947). (14) Curk T. A., Plating, 35, No. 10, 1008-11 (1948). /15) Delong. W. B., and Peterson, E. V., Chem. Eng., o 6, 123-5 (1949). (16) Duecker, 11'. W., Estap, J. W.,Mayberry, M. G., ..n,l J. W., J . Am. Waterworks Assoc., 40, No. 7,715-28 1 I (17) Fitspatrick, J. J., thesis for master of science degrec, 1.chigh University (June 1949). (18) Foley, J. E., Corrosion a,nd Materiel Protect., 4, Xo. 5, (j-7 (1947). (19) Fox, K. XI., I n d i a Rubber W o r l d , 117, 487-91 (1948). (20) Frederick, L. R., and Starkey, 1%.L., J . Am. Watertcorks Assor., 40, No. 7, 729-36 (1948). (21) Gaylord, IV.AI., Chem. Eng., 55, No. 3, 225 (1948). (22) Glenn, J. D., Plastics ( L o n d o n ) , 11, 336 (1947). (23) Hancock, E. G., J . SOC.Chem. I n d . ( L o n d o n ) , 66,337-40 (1947). (24) Hersh, H. I. (to Owens-Illinois Glass Co.), U. S. Patent 2,432,890 (Dec. 16 1947). (25) Hershberger, Albert (to E. I. du Pont de R'emours & Co.). E. S.Patent 2,430,053 (Nov. 4, 1947). (26) Hill, F. B., Jr. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2,436,213 (Feb. 17, 1948). (27) Hodge, W. W., Chem. E n g . Progress, 45, No. 6,358 (19493. (28) Ilopkins, E. S.,C h e m . Eng., 55, No. 3, 102-3 (1948). (29) Imperial Chemical Industries, Ltd., Brit. Patent 586,767 (March 31. 1947). --(30) Ibid., 590,390 (July 16, 1947). (31) Jicwood, Ltd., Ibid.,389,906 (July 3, 1947). (32) Kauth, H. J. (to General Cable Corp.), U. S. Patent 2,432,623 (Dec. 16, 1947). (33) Kominek, E. G., Chem. E n g . Progress, 45, No. 7, 417-20 (1949). (34) Lasneret. J.. Bull. Assoc. Tech. I n d . Papetiere, 2, 1-5 (1948:. 1013
...
.
.
I
...
0.45 4.8 2.16 17.5 > 1013
,.. ,..
... ...
13.0 1.R 7.0
... ...
80,06b x loa
70,000 x 106
25,000
Cordierite
10:oo 11.25 0-1 .o 2.4
, . .
20,000
>io13
Titanium compounds have been extensively used in a wide variety of ceramic products. Titanium dioxide, as a glaze component provides opacity, improves acid resistance, and may promote attractive crystalline effects in artware glazes. Acidresistant and superopaque enamels having outstanding reflectance values owe these properties to titania (38). Some of these may be successfullv employeJ as single coat enamels on titanium enameling iron. Titania (rutile) and certain titanates have been employed for a number of years as fluxes for coated welding rods. Titania, or rutile, serves as the major constituent in special ceramic bodies of high dielectric constant. When fired under rigorously controlled oxidizing conditions, these bodies serve as capacitors, having a high dielectric constant combined with a negative temperature coefficient and lo^ loss factor. Minute trares of the reduced oxide and/or certain impurities cause these bodies to be photosensitive. Strongly reduced titania bodies
... ...
3500
280
TITANIA CERAMICS
feidiiar 1.25
10,000
250
tion of the lead ion, particularly a t the surface, must be considered. Several other approaches in developing nonwetting ceramic bodies have met with success-that is, self-glazing bodies and use of phosphate type glasses. Cordierite compositions provide excellent self-glazing structures. Glasses, which largely consist of phosphorus pentoxide provide effective surfaces for nonadhesion of water. The best results have been obtained by using a combination of a self-glazing body and a phosphate glass as the migrating flus ( 5 , 34).
flint.
Alumina
30,000
350 1300 0.17 5.8 0.99
> in:a
Lorn-Vol tage Insulation Clay-
9000
...
a.9 5.31 25ii
Vol. 41, No. 10
,..
6000
...
... ... jsi3600 ... ... ...
...
7000
...
3000
3o,060
...
2.6
...
2.7
0 . 00 15
1256 0.45
... ... 0
5 1
2 3G
.
...
17.5 >in)* SI30
...
...
100
> iw
780
become suff ciently good conductors that they find application thread guides allowing the removal of static electricity created by friction. Alkali-earth titanates used alone or in conjunction with tit,anium dioxide form a series of ceramic dielectrics having dielectric constants ranging from 13 to 10,000 with temperature coefficients from strongly positive through zero to strongly negative (3,21,97-39). Some values a t room temperature are: 35
Material Magnesium titanate Heavy grade Ti02 Calcium titanate Strontium titanate Barium titanate Barium-strontium titanate
R Value of Ceramic 13-17 95-105 150-175 2 2 5 -2 , i 0 1290-1n00 10,000
Barium titanate, when subjected to an orienting electric field while cooling after firing, provides a ceramic body having the unusual proper@ of being piezoelectric n-ithin the temperature range -20' to 120" C. ( 4 , 13). This material is gaining wide acceptance for use in phonograph pickups. Both barium and barium-strontium titanates display extreme variation in dielectric constant with change in temperature; the maximum values for barium titanate are ohtained a t 127" and 20' C., respectively. Ceramic bodies having high dielectric constants are extremely sensitive t o the presence of certain impurities and to the method of preparation and firing. Due to the wide choice of available properties, titania and titanate ceramics are employed in resistors, condensers of high capacity and small size, trimmers, temperature cornpensatins components, wave guides, and photoelectric cells. CHElIICAI. STONEWARE
The production of chemical stonn-are and its applications TABLE11. REPRESEKTATITE RIECHASICAL . ~ S D PHYSICAL have been reviewed (15, 22, 28). This ceramic is a vitrified PROPERTIES OF ZIRCOU PORCELAIKS COMPARED WITH OTHER CERAUICS
Specific gravity Absorqtion % F1exu;al stiength, Ib./sq. In. Tensile strength, lb./sq. in.
Compressive strength, l h . / s q . in. Linpar coefficient of thcrmal expanpion X 108 (20' t o 600" C.)
Zircon Porcelain (Low-Loss) 3.7 0 26,000
Electrical Steatite Porcelain Fused Porcelain (High Tension) Silica 2.6 2.4 2.2 0 0 0 20,000 10,000 ...
13,000
8,000
5,000
90,000
75,000
45,000
.. ...
4
9
6 , .i
0. 5
product n-hich more generally has heen prepared from rnixhres of the following range of composition: 30 t o 70y0clay, 5 to 25Y0 feldspar, and 30 to 60% silica. Specinl compositions have been employed for certain applications--for example, where greater thermal endurance is needed or for certain specific operations ( 9 , 11, 16). Physical properties of typical stoneware and chemical porcelain are given in Table V. Stonen-are, like glass, resists all acids except hydrofluoric. Strong, hot caustic alkalies have R slight surface action on this ware. This universal chemical resistance, with above-mentioned
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
2105
TABLE I. PROPERTIES OF WHITEWARE BODIES(Continued) Chernicai Ware
Clayflintfeldspar
_-_ Zircon
6 0 510 7.0 13 0 0 2 8 5.0
Tiler mal Ware (Porous) Cordierite
4.0
1.7
10.0 14.0
5:i
1100
0-o.np 3 ,
8.0
7.4 12.0 2 .0 7.0
...
9000 ,,
.
... 15
x ‘1’6
Sanitars Ware: ClayFlintFeldspar
Floor Tile, ClayFiintFeldspar
3.0 130 8.0 11.0 0-0.03
0 90 10.0 10.0 0-0.01 2.25 8.0
2.4
...
... ...
...
5000
3500
90,000 24 x 106
40,000
...
... ... ... ...
...
2.5
..
2.8
6 ,5
12,7011
1.4
...
...
4.0 0.004
4.9 0.006
...
...
...
1000
...
n om ,
1200 1400
,.. , . .
... ...
..
Wall Tile, Talc 0
100 1.0 1.0 17.0
2.0
Vitrified Hotel Ware ClayFiintFeldspar
...
. .
3500
9600 12,300
8.300
2i.nin
, . .
..
.. .. .. .. ... ...
,.. , . .
..
... .. ...
... ...
.. ..
...
..
..
, . .
m o 7000
..
...
...
0.92
...
... .. ... ...
... ... ...
GLASS-BONDED MICA
Glass-bonded mica, produced under various trade names, is essentially an aggregation of fine mica particles embedded in a glass matrix. -4commonly used ratio consists of 60% mica to
TARLE 111. PROPERTIES OF CARTERET ZIRCON (Carteret Zircon So. 1.50) Fiexural Strength, Ih./sq. in. 8500 Absorption, % 8 Density Apparent 2 .6-3 .02 True 3.68 Linear thermal expansion, a t C. 20 to 100 0.020 200 0,050
, .
. .
. .
..,
... .. ..
...
6.i , . . , . .
1200
...
9000
8000
... ... ...
...
. . i
...
...
840
... I
0
...
..
.
16
2.2 7
770
...
, . .
... ... ... ...
.
,..
...
...
...
.. .. .. ...
... ,.. ...
...
... ...
, . .
...
...
40% glass, the latter generally lead borate or lead borosilicate. It is formed by compression molding, pressing a preformed blank to the desired shape, by transfer molding, or injection molding. This ceramic is available in sheet and rod form which can be machined readily (ordinary machine shop equipment for cutting, drilling, and tapping). Fabricated parts may also be obtained from the suppliers. The material has found many applications, as panels, shields, supports, spacers, and numerous insulating parts. Properties of some commercial glass-bonded mica products are given in Table VI. PERLITE-A
NEW BUILDING MATERIAL
Perlite, a siliceous volcanic glass, which on quick heating yields an expanded product, is receiving increasing ceramic application. Because of its lightness, durability, and superior heat- and moisture-resistance properties, expanded perlite is being used for lightweight aggregates, thermal and sound insulation, refractory brick, and ceramics. Data on the properties and heating of perlite have been summarized and references t o the ceramic uses have been reported (23). These include: sub-
PHYSICAL PROPERTIES OF TYPICAL CHEMICAL STONEWARE AND CHEMICAL PORCELAIX
TABLE V.
Specific gravity Flexural strength. lb./sq. in. Tensile strength, lb./sq. in. Compressive strength Ib./sq. in. Modulus of eiasticity 106, Ib.(sq. in. Coefficient of thermal expansion x 10-6 (200 to 6000 c.)
COXDUCT~V~TIES OF MATERIALS TABLE IV. THERMAL
TABLE
VI.
1.0
0.004
, . .
..
2.4 7
...
,.. ,..
... ...
850
n
, . .
0.33
... ...
850 15136
... ... ... ..
...
6.0
1. Dental Ware Body Enamel
325 3.5 8.5 12.0
...
...
k
0,007 0.006
... , . .
n ow
0.50 0.38 0.26 0.16 0.11
$100
...
Texture
cu A1 B e 0 porcelain Brass Fe Steel Porcelain MgO type .iizOa, type 3lullite type
..
..
, . .
Thermal Conductivity (Room Temperature), Cal./Cm./Sec./’ C.
Artware ClayFlintFeldspar 5.0
8.4 14.7 0-0, I
...
exception, explains its many uses in the chemical and process industries. I t s many applications include tanks and storage vessels in various shapes and with capacities ranging from 10 to 700 gallons, piping and cooling coils, towers, pumps, ducts, and Cans. The materials and processes involved in the manufacture of these items provide for a relatively inexpensive ceramic. Chemical porcelain is preferred to chemical stoneware in certain applications where a white, hard body is desired. Typical properties of the latter ceramic are given in Table V. Except for the large shapes, equipment may be made of either ceramic.
snn
6.3 400
4.6 340 i.4 12.0 ‘3-0.02 2.4
5.0 7.0
..
Ovenware Clay FlintFeldspar
Specific zravitv Absorpt Flexural .~ ~
Tensile stren Compressive Hardness, BI Maximum sa
Chemical Stoneware 2.2 6,500 2,500 80,000 10
5
Chemical Porcelain 2.5 14,000 6,000
100,000 15 4
PROPERTIES O F COMhfERCIAL GLASS-BONDED hfICA PRODUCTS (20) Compression Molded 3.0
Injection Molded 3.8
2106
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 2.
RIul tiple-Bank Cascade Cooler for Hydrochloric Acid
P) rex heat-exchanger tubes, 2 inches inside diameter
stitute for feldspar in ceramic bodies nhere color is of minor importance in the finished product; lightweight brick; building block; and sewer pipe. A ceramic composition, suitable for building block and similar products, i.i comprised of perlite, clay, and cellulose ( I d ) . One of the potentially largest uses of expanded perlite is for concrete aggregate ( 2 3 ) . Perlite has promise for many thermal insulation applications. Perlite is a ne\?- material which will compete with a number of mineral products like exfoliated vermiculite, diatomite, pumice, and mineral wool, for various specific uses. All-ceramic building construetion has received increasing attention. A type of home, which has been constructed (18), employs cavity walls to ensure dry interior walls and to reduce heat losses. Combination tile and concrete ribbed floors, in which a hot-water radianbheating system is installed, are used for first and second floors. The interior wall finish in the living room, dining room, and bedrooms is plaster applied direct to the backup tile forming the interior of the cavity wall, Glazed and unglazed facing tile provide the finished wall surface for kitchen, bathroom, and all closets. Glazed tile provides the interior wall finish for all basement rooms, which include the recreation, laundry, storage, and utility rooms. The radiantrheating system located in the basement, first and second floors, is so designed that flow of heat can be controlled t o each individual room. Other types of all-ceramic home construction are also reported (18). h E W LOW TEMPERATURE PORCELAIN ENAMEL FINISHES
(14)
Vol. 41, No. 10
In a porcelain enameled object, glass is only one of the cornponents, and the metal is the other component. These are conibined into a single unit. Thus, the engineering properties of a porcelain enameled object might be described as follows: chemical durability of glass; mechanical strength of metal; decorative or optical properties of glass; and electrical properties of a glasrmetal combination. There are two general classes of porcelain enamel-namely, wet process and dry process. The former usually is associated with light-gage metal parts and the latter with heavy-gage or thick cross-section parts made from cast iron. In the Lustron porcelain enamel house, only light-gage metal is used, thereby limiting its enameling operations to the wet process method of application. Wet process enameling in simplest terms may be described as the application of powdered glass in a water suspension to previously prepared fabricated sheet steel. After water removal by drying, the coating is brought to a continuous layer by heating the coated metal a t a relatively high temperature. Since metal tends to distort and lose strength a t these high temperatures, some means must be provided to support the part to prevent distortion during the fusing of the glass, or some temperature must be used a t which the metal does not undergo deformation from heat. Steel has been especially developed for porcelairi enamel objects to prevent this distortion a t the relatively high temperatures, and is marketed as a special-purpose metal, commonly referred to as enameling iron. This premium steel i b produced by relatively few mills and does not represent a large tonnage item in their over-all production. The Lustron house program, with its high-volume usage of sheet metal, could not be established on the basis of using tailor-made steel due to the short supply of this special metal. The most available sheet metal continuously produced for consumer goods is used in the automotive field. This sheet metal is of the open-hearth, low-carbon class. Availability of this material predetermined the type metal to be used in the Lustron porcelain enameled houses and thereby established the enameling program since automobile stock is conducive to distortion a t high temperatures. At a relatively lower temperature (1300' F.! than the 1520 F. usually employed in enameling-firing operations, automobile stock has comparable stability with enameling iron. Hence, low temperature enamel adaptable to this lowcarbon, open-hearth steel, can ensure as much success as if enameling iron were used. Some of the most recent postwar developments in porcelain enamel have been directed a t this new market or outlet for enamel-the Lustron house. Although these developments are directed primarily toward satisfying this one particular demand, their use in other products can enable porcelain enamelers to explore and realize on other products. The requirements for low temperature enameling of the Lustron house components may be defined under two general classes of service: 1. EXTERIOR.Parts subjected to severe weathering action require an acid-resisting class of porcelain enamel since acid resistance is the accepted criterion for evaluating weather resistance. 2. INTERIOR. Sheltered portions on the house do not requirc as great a corrosion resistance, and therefore a lesser degree 01 acid resistance can be tolerated.
To satisfy these two conditions, specific enamels developed for Lustron are as follows: 1. 1300" F.-firing base coat 2. 1300 F.-firing, mat texture, acid-resisting, hlgh opaque cover coat for white and light pastel colors 3. 1300 O F.-firing, mat texture, acid-resisting, low opaque cover coat for dark colors 4. 1300" F.-firing, high opaque, one coat for light pastel and white interior parts O
Porcelain enamel is unique in the ceramic field since in the completed article a combination of a nonceramic material, steel, is combined with a ceramic material, glass. In practically all other ceramic products, the finished piece is entirely ceramic material. To qualify as a ceramic material in the broadest sense, mineral substances composed of silicates are bonded by a glass phase.
With this range of compositions, a wide variety of colors oi porcelain enamel with severe and less severe corrosion resistance
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
can be obtained on diverse piece part shapes fabricated from relatively light-gage, low carbon sheet steel. GLASS FOR THE CHEMICAL INDUSTRY ( 2 5 )
In reviewing the development of glass over the past year as applied to the chemical industry, it is found that the more important advances have been in the improvement of existing products or the expansion of their use. Perhaps the most significant developments of this kind are those carried out recently on Pyrex brand piping which have resulted in greater strength and in greater facility for installation. The improvements include the tempering of fittings, such as T's and L's, and also of the flanged ends of straight lengths. In addition closer dimensional tolerances are being maintained, as in the case of the length of straight pieces, the leg lengths of fittings, and angular tolerances of the faces of the flanges. Because of their shapes, fittings naturally have lower strengths than the straight lengths, and the clamping forces a t the joints exert additional stresses in the conical glass flanges. Tests made on the improved piping show that the tempering operation a t the critical spots raises their strength levels to that of the piping itself. This additional strength becomes of added importance with the increased use of interface gaskets of very hard materials such as Teflon which require heavy clamping forces a t the joints. The adoption of closer dimensional tolerances has been found to simplify the installation of the piping in many instances. The line of Pyrex piping has also been expanded by the inclusion of a &inch size, with essential fittings. Although this larger size cannot be recommended for working pressures as high as the smaller sizes, it is finding important applications for the transfer of gases and liquids a t low head pressures and also for columns and other special equipment.
TABLEVII. RECOMMENDED WORI~IKG PRESSURES FOR PYREX PIPING Size (I.D.), Inches
Working Pressure (Max.), Lb./Sq. Inch
1 1.5
50 50
2 3 4
6
50 50 35 15
The working pressures ordinarily recommended for the various sizes of Pyrex piping are given in Table VII. For other types of plant equipment, it may be remarked that there is now a definite tendency toward the increased use of glass columns and other special equipment in pilot plants in the chemical industry. Not only are there advantages in the use of glass for its high corrosion resistance, but also for its transparency, which permits the internal conditions to be observed, and thus provides important information for utilization in the planning of a full size plant. A number of interesting applications of glass have recently been made in the electrochemical industries. Glass heat exchangers have recently proved effective for the heating or cooling of plating solutions. Because glass is not subject t o electrolysis, it not only gives long service, but also eliminates any contamination of the plating operation from this cause. For many plating tanks a number of glass bayonet type heaters, ~5 hich can be used alternately for both steam for heating and water for cooling, have proved a simpler and effective means for temperature control. In the case of engraving tanks, Pyrex pipe lines have been used for drainage with the expectancy of greatly extended life over other materials. A recently announced new glass composition has several properties which are unique in a single glass: high resistance to alkali
2107
(SO); the property of remaining clear rather than fogging under
alkali attack; and a low coefficient of thermal expansion. This glass is available for sight glasses which may be subjected to strong alkali solutions. It is also used for the regular line of flat gage glasses for liquid-level gages. In the case of steam boilers this glass has been f o m d to have from two to three times greater resistance to corrosion than the glass composition previously used. The advent of high steam pressures in power boilers has raised n e v problems in the application of glass to direct reading liquid-level gages. At the temperatures of high pressure steam, the effects of tempering, which is essential for high strength, become vitiated with time for any of the glasses normally used for this purpose. For steam pressures of 1500 pounds per square inch and above, there is available a new glass which will retain its tempering for greatly prolonged periods.
TABLE VIII.
FOAMGLAS
PROPERTIES O F
Specific weight lh./cu. ft. Compression strength, lb./sq. it. Modulus of rupture, lb./sq. in. Capillarity
10 140
log v
K.Thermal Conduetivicl B.T.U./Hr./Sq. Ft./' F.
- 103
+loo f400
0.31 0.44 0.62
For the thermal insulation of equipment and pipe lines in chemical plants, there has been an expanded use of Foamglas, n cellular glass block, which will withstand temperatures up to 800" F. and the corrosive effects of a wide range of chemical reagents. It is also particularly effective in operations involving refrigeration because it is impervious to condensed moisture. It is available in the form of blocks which are shaped so that they may be fitted and cemented in place to form a complete covering for the part to be insulated. Table VI11 includes a few of the properties of this material. REFRACTORY BODIES AND COATING
Much development work has been continued in the field of refractory bodies and linings t o provide the structural requirements of component parts of the ram jet, gas turbine, and various high temperature engines ( 2 , IO, 41). Refractory linings of combustion chambers and flame conduits may be expected t o be exposed to temperatures of a t least 2000 O F. under oxidizing conditions. A large number of refractory materials have been and are being studied in various industrial and university laboratories. Cermet bodies, composed of metals and oxides, are also being developed for high temperature service (1). Fundamental information is being acquired concerning the mechanics of development of bond between metals and such crystalline oxides as alumina and magnesia. ACKNOWLEDGMENT
The section on New Low Temperature Porcelain Enamel Finishes mas prepared by E. E. Howe of the Lustron Company. The section on Glass for the Chemical Industry was prepared by E. B. Shand, Corning Glass Works, Corning, N. Y . LITERATURE CITED (1)
Blackburn, A. R., Shevlin, T. S., and Lowers, H. R., J. Am.
Ceram. Soc., 32 (3), 81-98 (1949). (2) Bobrowsky, A. R., Am. Ceram. SOC.Bull. 28 ( 3 ) ,89-93 (1949). (3) Bunting, E. PIT., et al., J . Research h'atl. Bur. Standards, 38, 337-49 (1947). ( 4 ) DeBretteville, A., Jr., J . Am. Ceram. SOC., 29 ( l l ) ,303-7 (1946). (5) Gebler, K. +4., unpublished data. (6) Gebler, K. A,, and Wisely, H. R., J . Am. Ceram. Soc., 32 ( 5 ) . l6.?-.5- (191.9). (7) Geller, R. F., and Inslcy, H., J . Research XatZ. Bur. Standards, 9, 35-46 (1932).
___
\ - - - - I
2108
INDUSTRIAL AND ENGINEERING CHEMISTRY
(8) Geller, R. F., Yavorsky, P. J., Yteierman, B. L., and Creamer, A. S., Ibid., 36, 277-312 (1946). (9) General Ceramics and Steatite Corp., “Properties of Ceramic Bodies for Chemical Stoneware Equipment.” (10) Hartwig, F. J., Sheflin, B. W.,and Jones, R. J., N a t l . Advisor?/ C o m m . Aeronautics, Tech. Notes, 1399 (1947). (11) Herstein, F. E., Ciiem. Eng., 53, 214-16 (1940); 54, 216-20 (1947). (12) Hicks, W.H., U. S.Patent 2,388,060 (Oct. 30, 1946). (13) Howatt, G. N., et al., J . Am. Ceram. Soc., 30 (8), 237-42’(1947). (14) Howe, E. E., personal communication (July 8, 1949). (15) Kingshury, P. C., T r a n s . Am. I n s l . Chem. Engrs., 36 (3), 433-42 (1940). (16) Kingshury, P. C., T r a n s . Electrochem. Soc., 75, 131-9 (1939). (17) Koenin. J. H.. IND.ENG. CHEX..40. 1782-5 (1948). (18) hkKai1, S.H., Am. Ceram. SOC.Buil., 28 (4); 16&1 (1949). (19) hlohr, IT. C., el al., Zhid., 27 (7), 272-3 (1948). (20) Mycalex Corp. of America, data (1948). (21) Navias, L., J . Am. Ceram. Soc., 24, 148-55 (1941). (22) Olive, T. R., Chem. & Met. Eng., 40, 369-71 (1933); 46, 512-16 (1939). (23) Ralston, 0. C., U. S. B u r . M i n e s , I n f o r m . Circ. 7364 (August 1946).
(24) (25) (26) (27)
(28) (29) (30) (31)
(32) (33) (34) (35) (36) (37) (38) (39) (40) (41)
Vol. 41, No. 10
Russell, R., Jr., Electmnics, 17, 136-42 (1944). Rutledge, C., Jr., personal communication (July 11, 1949). Schleicher, H. N., personal communication (July 12, 1949). Scholes, W. A., presented at 5 l s t meeting of American Ceramic Society (1949). Singer, F., Ceram. Aye, 17,300-5 (1931). Skinner, K. G., J . Am. Ceram. s’oc.. to be published. Smith, R. D., and Corbin, P. E., Ibid., 32
