AMMRC TR 83-1

GUIDE TO THE CONSTRUCTION OF

A SIMPLE 1500°C TEST FUR·NA'CE

GEORGE D. QUINN CERAMICS RESEARCH DIVISION

January 1983

Approved for public release; distribution unlimited.

ARMY MATERIALS AND MECHANICS RESEARCH CENTER Watertown, Massachusetts 02172

The findings in this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.

Mention of any trade names or manufacturers in this report shall not be construed as advertising nor as an official indorsement or approval of such products or companies by the Ll..,ited States Government.

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REPORT DOCUMENTATION PAGE READ INSTRUCTIONS BEFORE Cot.tPLETING FORM

1. REPORT N U WBI':A ,2. GOIIT A CC ESSION NO. l . RECIPIENT ' S CATALOG NUMBEIII

AMMRC TR 83- l I

4 . TITLE ( and Subtitle) ~ - T V PE OF REPORT 6 PERIOD COVERED

GUIDE TO THE CONSTRUCTION OF A SIMPLE 1500°c Final Report TEST FURNACE

6 . PERFORMING ORG. REPORT N~BER

7. AUTHOR( o) a. CONTRACT O R GRANT NUMBER( • )

George D. Quinn

•• P£RF'O~MING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJ ECT, TASK AREA 6 WO RK UNIT NUMBERS

Army Materials and Mechanics Research Center D/A Project : 1Ll62105AH84 Watertown, Massachusett s 02172 AMCMS Code: 612105. H840011 DRXMR- MC ~enc~ Accession : DA 47 37

II. CONTROLLING OF FICE NAME AND A DDRESS 12 . REPORT DATE

u. s. Army Materiel Development and Readiness January 1983 Command, Al exandria, Virginia 22333 I). NUMBER OF PAGES

17 14. MONITORING AGENCY NANE & AO ORESS(If dl llor..,l f ro"' C ontr.>lllnl O lfi oo) ·~ · SE CU RI TY C LASS. (ol tllle report)

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17 . DI STRIBUTION STATEMENT (ol the e botrec t entered In B/~c ~ 20. II dlfloTon l from Report)

18. SUPPLEMENTARY N O TES

Thi s r e por t 1 S an upda t ed r ev1s 1on o f AMMRC TN 77-44' August 1977 .

19 KEY WO RDS ( Conrlnuo on r•v•r•~ .1 i de If ne c e.1.t•ry and ldentUy br !Ji oc• n umber)

Furnaces Creep t e s ts Firebrick Ceramic mate ria l s Mechanica l t es ts Heating e l ements High t emperature Heat trans fe r Fl exural strength

20 ABSTRA CT (CorU inu• on r•"'•'•• • ;d• U ne c •••ftry end ld~ntdy by b lo c lc number)

(SEE REVERSE SIDE)

DO F O RM I JAN H 1473 EDITION OF I NOV 6~ IS O BSOLETE

UNCLASSIFIED SE CU RI TY CLASSIFICATION OF THIS PAGE ( When Dete Enl ~r~d)

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Block No. 20

ABSTRACT

A small, simple furnace for heat trea ting or mechanical testing up to 1500°C in air has been designed , constructe d , and operated suc cessfu l l y. The unit is c onstructe d with r e fractory fire brick a nd s ilicon carbide heat ­ing elements and i s inexpensive, e asy t o construc t, and requi res little power to operate. The design process and construction tips are describe d in general terms to guide the future furnace builder who ma y have alternate opera ting r equirements.

This report is an updated r evision o f AMMRC TN 77-4, August 1977.

UNCLASSIFIED

CONTENTS

INTRODUCTION .. .. .. . ....... .

FURNACE REQU IREMENTS AND GENERAL FEATURES

GENERAL SHAPE AND SIZE . . . . . ... .

POWER AND HEATING ELEMENT REQUI REMENTS.

GENERAL ASSEMBLY .

OPERATION

SUMMARY .

APPENDI X A.

APPENDI X B.

APPENDIX C.

HEAT LOSS FROM THE FURNACE

BEND FIXTURES ...

LIST OF MATERIALS.

Page

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2

2

4

7

9

10

11

13

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INTRODUCTION

The potential application of ceramic materials to structural applications requires mechanical test programs for both material development purposes and for mechanical property evaluation for design purposes. In particular, testing is required not only at room temperature but, more importantly, at elevated temper­atures to accurately reflect properties at the working conditions of ceramic components. Typical tests to be performed at elevated temperatures include: modulus of rupture in four-point bending, stress rupture in bending, bend creep testing, and fracture mechanics tests such as double torsion.

To that end, a simple furnace design was developed at AMMRC that is capable of temperatures of 1500°C in air (Figure 1). To date, twelve units have been con­structed and these have been used for high temperature MOR tests, bend stress rupture testing, and for routine soak heating of ceramic specimens.

Because of the simplicity of design, duplicate furnaces can be made at little cost and with unskilled labor. The furnace is rather small with a modest chamber size. Power requirements are minimal; the unit can be operated from a standard wall outlet rated 15 or 20 amperes 110 VAC. In addition, the furnace is portable and weighs only 100 pounds.

a. b.

Figure 1. a. Mechanical test furnace 1n a Universal test machine,

b. Heat treating and stress rupture versions.

As a r esult of r epeated in'{ui ri es concerning the f urnace const r uc ti on and operation, this report has be en written t o serve as a gui de to assis t investiga­tors in constructing their own models. Furnaces of thi s s tyle are not new and this report does not purpose to present new technology. Rather than mer e ly specify the dimensions and components necessary , it i s probably more he lpful to outline the derivation of the des i gn s o that t he new f urnace builder can consider alterations to the bas ic unit.

FURNACE REQUIREMENTS AND GENERAL FEATURES

The derivation of the design proceeded in a series of logical steps.

The requirements di ct a t ed that the furnace would be :

1. capable of 1500°C operation in air; 2. capable of en c losing mechanical test fixtures and fit

into a tes t machine rig ; 3 . inexpens ive (les s than $500) ; 4 . made from simple off-th e - she lf i tems; 5. easy to cons truct ; 6 . easy to r epai r or rep lace components ; and 7 . durabl e f or l ong time t es t s .

To wi thstand 1500°C the insul ati ng mat erial lining the furnace had to be very re f r act ory and have a l ow conduct ivity . Refractory firebrick met these requirements and i s economi cal, r eadily available , and easily replaced. It became apparent that to s atis fy r equirements 1 , 3 , and 4 , s ili con carbide heating rods would be r equired.

GENERAL SHAPE AND SIZE

Given that insulat ing firebri ck and si licon carbi de heating e lements were to be used, the next f ac t or t o be cons idered i s the s i ze of the fur nace chamber. It is apparent that the smaller the chamber vo lume, the smaller the over a ll furnace size and the less the amount of power necessar y t o heat it. Many commer­cial furn aces have l ar ge chambers , but r equire mass i ve power inputs. In addition, large furnace chambers ar e s uscept i bl e to undesirabl e t emperature gr adients. Realizing the chamber need be roughly cubi c with only a few inches per side, and keeping in mind a s implicity of cons truct i on, it was decided to make the chamber dimens i on a s imple multipl e of t he t ypi ca l r e fract or y bri ck s i ze. The ar r angement of br i cks in Figure 2 suff i ces t o gi ve G chamber 4-1/2 inches to a side and 3-3/ 4 inches high.

Re fract or y fir tbr ick ar e sold in common basi c "s tra ight" br i ck (9 x 4 - I/ :~ x 2-1 /2"). soap, and split conf i gurations . Thes e latt er in half and are almos t one -half as l ar ge (t he into account). Manufc.cturers or dis t r:ihutor s

s i zes tha t are deriv at i v es of the Figure 3 depicts the s traight, t wo ar e made by cutting s traights s aw b lade thicknes s has to be taken will charge extra f or these cuts ,

1---~~--i -+ H /2' '

__ _L Straight

Soap

S;)lit

Figure 2. Chamber layout. Figure 3. Common brick shapes.

but it i s desirable t o have this done by the manufacturer (rathe r than cut them yourse lf) in order t o maintain good tolerances and save time. The charge is minimal.

The size of the working chamber depends upon the application. Taking i nt o account the size of our intended fixture s , and the insert ion of heat ing elements into the furnace chamber, a chamber height of 1-1/2 times the thickness of a r efractory brick was desired. This corresponds t o the height of a straight and a sp lit brick together. This resulted in a furnace chamber of size 4-1/2 x 4-1/2 x 3- 3/ 4". The wall thickness is 4-1 /2" thick. To seal the top and bottom, two extra layers of s traight bricks were added. The successive l ayers are illus ­trated in Figure 4 and assembled in Figure 5.

Severa l features merit explanation. First, the bricks in the layer above the chamber are a combination of s traights, soaps , and soaps cut in half by the builder. Thi s was done so that the two straights immediately above t he chamber would rest evenly on the chamber laye r bricks. The soaps were placed around the edges. The door placement was made t o allow front access to t he furnace. (In practice, the furnace can be disassembl ed in minutes, allowing top l oading as well.) Bricks should be placed to overlap joints between bricks i n l ower l ayer s.

In general, the building b l ock arrangement of standard bricks permits simpl e and inexpensive cons truction . It is apparent t hat alternate arrangements can readily be devised .

3

I 1 Top Layer 2 112" Th ick dncl *6 Layer

8 *2Layer 2 · liZ'' Tt11ck dl1d f) Layer

~ B Ct1arnber LtJj 2 -l;?' Ti ick

~ ~~~ Cr<dillDe r u u 1-1/4" Thick

Figure 4. Brick levels. Figure 5. Brick layout.

POWER AND HEATING ELEMENT REQUIREMENTS

Given the approximat e furnace dimensions, it was necessary t o conduct a heat transfer analysis to determine t he heat input necess ar y to balance heat l osses th rough conduction out the furnace wa ll s . The furnace is sea led to pr ohibit r adiation or convection losses from the interior. The detai l s of the simple analysis are given in Appendix A, and the equations also app l y to alternate sized furnaces . The results of the analysis showed that it would be necessary to pump approximately 1100 watts i nto the furnace to maintain an int ernal t emperature of 1500°C.

The next matter was to de cide whether this energy would be provided by one, two, or more heating e l ements. Referring to available catalog literature for si licon carbide heating e l ement s (see f or example, References 1-3) , it i s apparent the rods come in a variety of diameters, heat ing lengt hs, and overall lengths. The e lements are long, so l i d rods with a heat zone in t he middle and with nonheat ing ends that protrude through the furnace wal ls. Recommended oper­ational and des ign information is r eadily availab l e from t he manufactur ers. 1 , 2

I. llot Rod XJ. lleating 1:'/cments. Norton Company. Industrial Ccramil" Division , Wor~cstcr, Mass. 0 1606, 1973. 2. (:/ohar l.ij(· J.ine Tvpe l.L Silicon Carhide 1-:/ectric llt!atin~ h'h·n1ct1IS. Carborundum Com pan y, G lobar Plan t, P.O. Box 339,

Niag.ra Falls, New York 14302. O.:tohcr 197 3. 3. 7)•ru: RR Heating H!emenls. The I SquarC'd R Element Co mpany. 203 Saint Mary's Street, Lancaster, New York 14086.

4

For this furnace, a heat zone length of 511 and an overall l ength of 16" was chosen. 1he wattage output of these e lements is proportional to the radiating surface and it was decided the larges t diameter rod, 1/2", was appropriate. Each such element is recommended for no more than 38 watts per square inch radiating surface for an operational temperature of 1500° C. l-3 Thus, the 1/2"-diameter rods with a 511 heat zone can generate 299 watts each at maximum recommended loading [38 x S x ~(0.5)]. Therefore, to generate 1100 watts total, four such elements are necessary.

The spacing and location of these elements is important. They must not be placed too close to each other l est they self-radiate and overheat. Similarly, they cannot be placed too close to the furnace. walls or to the work. The manu­facturers' recommendations are very helpful in this matter.l-3

It was decided that for thi s furnace the four elements would best be p laced together in the upper portion of the chamber and run out the sides of the furnace. The two middle elements were spaced s lightly further apart than the others to permit clearance for a load train rod. This arrangement allows easy access from the front door opening and minimizes interaction with the fixtures on the furnace floor. The configuration chosen is depicted in Figure 6, A potential problem with such an arrangement is thermal gradients in the furnace chamber; however, the chamber is so small that radiation minimizes these gradi ents.

A typical temperature profile of the furnace chamber is shown in Figure 7. This data was obtained by using a special door brick with holes to permit the insertion (to various depths into the furnace) of a platinum thermocouple at various heights and spacings. The chamber exhibits good uniformity with a slight gradient from level one to the lower layers. Level one was only 5/8" below the

Element Portals

Figure 6. Chamber layout.

s

3-3/4"

Heat ing Elements

......

......

......

......

...... ....

LEVE L 1 . , ~91 • 1201 •1 202 •1184

• 1202 •1 211 • 1212 •1 201

•1 204 •1 209 •1 208 •1201

•1201 •1206 •1 205 •1201

• 1201 •1205 •1 203 • 1201

•1 201 •1205 • 1204 • 1201

• 1198 • 1205 •1 205 •1 199

• 1197 •1 205 •1 206 •11 98

•1 188 •120 1 •11 98 •11 87

•1 155 •11 78 •11 74 • 1155

FRONT

LEVEL 3 • 1165 •1177 •11 80 •1 161 • 1173 • 1183 • 1186 •1 173

• 1180 • 1187 • 1190 • 1180

• 1182 •11 90 •11 93 •11 84

• 1183 •11 90 •1 193 • 1184

•1 183 •1190 •11 92 •1183

e 1180 e1188 e11 91 e11 82

e 1177 e 1186 .~1 88 e11 76

• 1168 • 1180 e 1180 e 11 67

• 1137 • 1151 • i 155 e1 136

FRONT

.......

....... ......

....... ....... ......

...... ...... ......

......

/ / ...... .;' .... .;' :> ;

...... 4-1 /2"

LEVE L 2 e1 177 e 1186 • 1190 •1 173

•11 83 • 1190 • 1193 • 1182

•1 !87 e 1H2 •11 96 •1 187

•1188 •1 192 •1196 •1188

•1190 •1192 •11 9Ei •1188

• 1190 •11 92 • 1196 • 1188

•1 187 . , i£2 •1 196 • 1188

• 1184 • 1190 • 1195 • 1183

•1 176 • 1187 •11 9 1 •1 176

•1 148 • 1172 •11 76 •1155

FRONT

Figure 7. Temperature profile as determined by p latinum

thermocouple. Nominal t emperature: 1200°C.

6

heating elements. A small gradient exists toward the front of the furnace since the special portal brick had so many holes in it and also because the crushed asbestos door was left off (see Figure 1).

An additional electrical characteristic of the element is its resis tivity. The resistivity will vary with temperature, from 80% to 160% of the rated resis­tance measured at 1093°C (2000°F). The nominal resistance and its variation are reported by the manufacturer ' s literature and is 1.00 ohm per element chosen for this furnace. The resistance will have a value of approximately 1. 6 ohms at 1650°C (3000°F) element temperature. It is desirable to use low currents in the electrical connections and thi s will influence the choice of electrical hookup of the elements; i.e., parallel, series, or combination. Since

v = IR

where v is the voltage in volts I is the current in amperes R is the resistance in ohms

and

p = r 2R

where p is power in watts

it becomes apparent that i s each element i s called upon to generate 275 watts (=1100/4 for 1500°C operation), then 13.1 amperes per etement will be necessary with only a 21.0-volt drop (for R of 1.6 ohms). Four elements in paralle l woul d require 52.4 A at 21.0 volts. On the other hand, four elements in series will require 13.1 A at 84 volts. These latter values are readily available from standard wall outlets rated 15 A at 110 VAC, and therefore the series arrangement was chosen.

A drawback to the series arrangement is that an element instability can result. As elements age their res i stance increas es . If the elements age differ­ently, the highest resistance e l ement will bear an increasing voltage drop, and thus greater wattage . The effect is self-propagating and the element may wear out rapidly. Thi s problem does not occur in parallel arrangements, but can be overcome in series connections by having the maunfacturer match the resistivities to within 5%. This service is readily offered and recommended by the manufac­turers. To date, with several thousand hours of operation on one furnace , we have not experienced an element imbalance. (1'-luch of the operation was well below 1500°C, however .) Electri cal fittings special l y made for the elements are avail­able from the manufacturers.

GENERAL ASSEMBLY

Holes were cut into the brick to accommodate the heating elements. Standard masonry drills wer e easily used since the refractory brick is porous and not very hard. The sizing of the holes should foll o\v manufacturer recommendations 1 - 3 to

7

e liminate any binding or constric tion on the elements as they and the furnace expand during heating. The entire assembly wa s encased in 3/8"- or 1/2"-thick ceramic fiber i n sulat ion panel s which gave the furnace added insulation and structural integrity. A sheet of aluminum was plac ed on the bottom as well. In the original design, dense a sbestos board was used as the outer shell , but we now advocate the use of the alternative material. Slotted steel angle was used on all edges to hold the assembly together. Al l e l ectrical connect i ons and meters should be spaced away from the furnac e walls to preclude exc ess ive heat­ing. An ammeter and vo ltmeter were insta lled . Insulating ceramic wool was padded into the openings such as the e l ement portal s .

The door was hand cut from a straight brick, and a special portal brick was made to accommodate the door (Figure 6) . The door brick had beveled edges t o per mit easy insertion. A hole was drill ed into the door bri ck t o allow insert ion of a ceramic tube. When th e door i s in place the tube extends 1'' beyond the front face of th e furnace and an insulating board with a matching hole is inserted over the tube. Alternat e door designs can be made but this method al l ows visual inspection into the furnace chamber. This can be val uable f or thermocouple i nserti on or direct observation with an opti cal pyrometer. A hol e was also drilled through the t op of th e furnace to allow a l oad train t o be inserted.

The general layout from the t op i s dep ict ed in Figure 8. The t op of the furnace and the upper layer bricks can be r emoved i n less t han one minute to reveal thi s view. Damaged or contaminated bri ck s can be r eadily r eplaced.

3

Figure 8. Top of furnace showing brick removed to expose hot chamber.

r I

Army Matcr1als and Mechanics Research Center, Watertown, Massachusetts 0?172 GUIDE TO THE CONSTRUCTION OF A SIMPLE 15000( TEST rURNAC[ -George D. Quinn

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Key Words

Technical Report AMMRC TR 83-1, January 1983, 17 pp- Furnaces 1l lus, D/ A ProJeCt 1LI62105AH84, Cerd1!1iC materials AMU1S Code 61?105.H8400l1 High temperature

A small, ~imple furnace for heat treating or mechanical testing up to 1500°( in air lia s been designed, constructed, and operated successfully. The unit is con~ strutted w1th refractory t1rebrick and s1l1 con carb1de heat1ng e lements and 1S lnex­pensive, e.1sy to construct, and requires little power to operate. The design pro­cess and constn;cti on tips are described in general terms to guide the future furnace builder who may have alternate operating reqllirements. This report is an updated rev1s1on 0 f AMMRC TN 7/ -4, August 1977.

>irmy Mater·ials and Mechanics Research Center, Wat er t own, Massachusetts 0?17? GUIDE TO THE CONSTRUCTION Of A SIMPLE lSOOO( TEST FURNACE -

AD

UNCLASSIFIED UNLIMITED DISTRIBUTION

George D. Quinn Key Words

Technical Report AMMRC TR 83-1, January 1983, 17 pp - Furnaces 1llus, 0/A Project 1Ll62105AH84, Ceramic materials AMCMS Code 6l2105.H840011 High temperature

A small, simple furnace for heat tn'ating or mechanical testing up to !500°C in air has been designed, constructed, and operated successfully. The unit is con~ slrucled w1th refractory firebrick and silicon carbide heating elements and 1s lnex­P"nsive, easy to construct, and requires little power to operate. The design pro· ces s and construction tips are described in general terms to guide the future furnace builder woo may nave alternate operating requirements. This report is an updated revision of AMMRC TN 77-4, August 1977.

--,

Army Materials and Mechanics Research Center, Watertown, Massachusetts 02172

AD

UNClASSIFIED UNLIMITED DJSTRIBUTION GUIDE TO THE CONSTRUCTION OF A SIMPLE

15000( TEST FURNACE -George D. Quinn Key Words

Techn1cal Report AMMRC TR 83-1 , January 19B3, 17 pp - Furnaces i llus, D/A Project 1Ll62105AH84, Ceramic materials AMCMS Code 612105.H840011 High temperature

A small, simple furnace for heat treating or mecnan1cal testing up to 1500°C in air has been designed, constructed, and operated successfully. The unit is con~ structed w1th refractory firebrick and silicon carbide heat1ng elements and 1s 1nex­pensive, easy to construct, and requires little power to operate. The design pro­cess and construction tips are described in general terms to guide the future furnace builder who may have alternate operating requirements. This report is an updated revis1on of AMMRC TN 77-4 , August 1977.

+ I

Army Mater1als and Mechanics Research Center, Watertown, Massachusetts 0217?

AD

UN CLASS IF I ED UNLIMITED DISTRIBUTION GUIDE TO THE CONSTRUCTION OF A SIMPLE

lSOO<lC TEST FURNACE -George D. Qu1nn Key Words

Technical Report AMMR( TR 83-1, January 1983, 17 pp - furnaces 1llus, 0/A Pr-oject 1Ll62105AH84, Ceramic materials AMCMS Code 612105.H8400ll High temperature

A small, simple furnace for heat treating or mechanical testing up to 1500°C in air has been designed, constructed, and operated successfully. The un1t 1s con~ structed with refractory firEbrick and silicon carbide heat1ng elements and 1s lnex­pensive, easy to construct, and requires little power to operate. The design pro­cess and construction tips are described in general terms to guide the future furnace builder who may have alternate operating requirements. This report is an updated revision of AMMRC TN 77-4, ~ugust 1977.

I

1 I

L _ _j_ _ _j

I r

Army Mater ials and Mechanics Research Center, Wat ertown, Massachuse tts 07172 GUI DE TO THE CONSTRUCT ION OF A SIMPlE 15QOOC TEST FURNACE -

AD

UNClASS IF I EO UNLIMITED DISTRIBUTION

George 0. Quinn Key WOrds

Technical Report AMMRC TR 83-1, January 1983, 17 pp - Furnaces i !Ius, 0/A Project 1Ll62105AH84, Ceramic materia 1 s AMCMS Code 612105.H8400ll High temperature

A small, s imple furnace for heat treating or mechanical testing up to 150ooc in air has been designed , constructed, and operated successfully . The unit is con­s tructed with refractory firebrick and silicon carbide heating e lements and is ine~­pens ive , easy to construct. and requires li t t le power to opera te. The design pro­cess and construction tips are descr i bed in genera l terms to guide t he future furnace builder who may have a lternate operat ing requirements . Thi s report is an up~.•ted revision of AMMRC TN 77 -4, Aug us t 1977.

T Army Material s and Mechanics Research Cen ter ,

Watertown, Massachusetts 02172 GUIOE TO THE CONSTRUCTION OF A SIMPLE 15QOOC TEST fURNACE -George D. Quinn

Technica l Report AMMRC TR 83-1, January 1983, 17 pp -illus . 0/A Project 1L162105AH84, AMCMS Code 612 105 . H840011

AO

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Key WOrds Furnace s Cerami c mater ials High temperature

A small , simple furnace for heat treating or mechani ca l tes ting up to 1500°C in ai r has been desi gned, constructed, and operated successf ul ly. The uni t is con­s tructed with refractory f irebrick and sil icon carbide hea ting e lements and i s inex­pensive, easy to construct, and requires l i ttle power to oper ate. The desi gn pro­cess and construct ion tip~ are descr ibed in general terms to guide t he future furnace builder who may have al ternate operating requi remen t s. This report is an updated rev is ion of AMMRC TN 77-4, Augus t 1977 .

J

+ I

-1 r"·my Mat eria ls and Mechanics Researc h Center,

Watertown. Massachusetts 0217? GU IDE TO TH£ CONSTRUC TION Of A SI MPLE 15000( TE ST FUR NACE -George 0. Qui nn

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Key W<J rds

Tec hni ca l Report AMMRC TR 83-1, Ja nuary 1983, 17 pp - Furnaces 11 Ius, D/A Project 1Ll62105AH84, Cerami c mat eri al s AMCMS Code 612105.H8400ll High temperature

A smal l , simp le fur nace for heat treat ing or mechanical testing up t o 1500°C in air has been designed, constr uc ted, and operated successful ly . The uni t i s con­structed with refractory firebrick and s ilicon carbide heating elements and is inex ­pens ive , easy to construct, and req uires l i ttle .power to opera te. The des ign pro­cess and construc t ion t i ps are described in general terms t o guide the future furnace bui lder who may have al ternate operati ng requirement s. This report is an updated revision of AMMRC TN 77-4, August 1977.

Army Materials and Mechanics Resedr ch Center·, Watertown, Massac huse t ts 02172 GUIDE TO THE CONSTRUCTI ON Of A SIMPLe ISOQOC TE ST FURNACE -

AD

UNC LASSlF!ED UNLIMITE D D!STRIBUT!ON

George D. Quinn Key ~ords

Tec hnical Report AMMRC TR 83-l, January 1983, 17 pp - Furnaces illus . D/A Project lll6210SAH84 , Ceramic mater ial s AMCMS Code 61210S.H8400ll High temper at ure

A sma l l, s imple furnace for heat treating or mechanica l tes ting up t o 15oooc in ai r has been des igned, const ructed, and operated success fully. The unit is con­structed wi t h r efractory f irebr ick and s il icon carbide heal ing e lemt!nts and is inex­pensi ve, easy to construct , and requ i res lit tle power to opera te. The des ign pro­cess and construct ion t ips ar e descri bed in general terms t o gu ide t he fu t ure f urnace builder who may have a lternate operat ing requi r ements. This report is an updated revision of AMMRC TN 77-4, August 1977.

L_

OPERATI ON

Twelve furnaces were constructed with t en currentl y serving as flexural s tress rupture units, one for high temperature modulus of rupture testing, and one for heat treating only . Figure 8 also shows a s ilicon carbide four -point bend fix ture in place. A front vie\v of the furnace in the stress rupture mode with these fix­ture s i s illus trated in Figure 9. A dead-we ight load scheme has been employed through a l ever l i nkage which connects through the top of the furnace onto the fixtures . A timer and microswitch l i nked to the lever arm detect time of failure .

The power actually required to heat the furnac e t o 1500°C is approximately 13-1 / 2 amperes a t 104 volts f or a t .otal of 1400 \va tts . These va lues will differ slightly for each furnace due to the differen ce in el ectrical characteri stics of each set of elements . Thi s power requirement is 27?o greater than the amount arrived at by ca lculation, 1100 wat ts . The difference is due to heat l oss through the portals of the furnace, through t he element ends, and t hrough th e abutments of the brickwork . In addition, t he appr oxi ma t ions used in the heat transfer analys is can account for a portion of t he error. Nevertheless , these power values are readi ly avail abl e from any s tand ard wall outlet. As the elements age, their r esistance increases (see maitufacturer' s data) . To generate the same amount of power P, incr eased voltage must be appLied (V = IPR) . This must be cons idered in power equipment design . Aging is a function of t emperat ure, time at temperature, and the number of heat -up and cool-down cycles . We have success ­full y operated t hese furnaces for many thousand s of hours at l 200°C with only a minimal increase in th~ voltage input . The response time of the furnace i s not long; only a few hours are necessary to heat t o I 200°C , but a slower r ate is advi sed to prolong e l ement l i f e.

Figure 9 . Furnace in stress ruptu re mode .

In addition, with relatively little material on hand i t is possible to con­struct a new furnace with a revised heat zone in less than one week , if necessary. Wnen material is bought in quantity, the cost per furnace i s very low (Appendix C). This flexibility can be a valuable asset in the laboratory.

SUMMARY

A small, simple furnace for heat treating or mechanical testing up to 1500 Coin air has been designed, constructed, and operated successfully . The unit is inexpensive, easy to construct, and requires little power to operate. The desired operating criteria were established and the process of designi ng the unit outlined in general terms. This was done to guide the future furnace builder who may have alternate operating requirements. Several usage modes and variations are briefly discussed.

Furnaces of this type are commonplace and are not new. This report is intended as a guide to the design of such units rather than as an assembly manual.

10

APPENDIX A. HEAT LOSS FROM THE FURNACE

There are a variety of t echniques that can be used to calculate the heat loss by conduction from the simple furnace. A simple "conduction shape factor" analysis described by Holman4 or alternately Schneider 5 was used. The equation for steady state conduction heat transfer through a wa ll is:

q = kA t:,T/d

where q is the heat loss per unit time k is the thermal conductivity A is the wall area

liT is the tempera ture difference d is the wall thickness.

A conduct ion shape factor S can be defined S = A/d such t hat

q = kS t.T.

For a three-dimensional wall such as the furnace, separate shape factors are used to calculate heat loss through the edge and corner sections. Referring to Figure A-1 for dimensions:

r==l L:J

Front Vi ~N

--l Top View

IT i 5"

'+ 3 llilo ·

-t D Side View

Figure A-1. Furnace dimensions for heat transfer calculations.

4_ HOLMAN, J.P. J/eat Transfer, 2d ed. , McGraw-Hill , 1968. 5. SCHNEIDER, P. J. Conduction Hear Transfer. Addison-Wesley, I 955 .

11

Swall = A/d

Sedge = 0.540

Scorner = 0 .1 5d

where A is the wall area D is the edge length on the inside d is the wall thicknes s .

The total shape factor for the furnace is the sum of the i ndiv idual pieces (all dimensions in inches).

For the four sides: Sside -wall = (3.69 X 4 .5)/4.5 = 3 .69

For the top and bot t om: Swall = (4 .5 X 4 .5)/5 = 4.05

For the f our vertical edges: Sedge 0 .54 X 3 .69 = 1. 99

For the eight horizontal edges: Sedge= 0.54 x 4 .5 = 2.43

For the eight corner s: Scorner = 0.15 x 4.5 = 0 . 68

St atal = 4(3.69) + 2(4. 05) + 4(1.99) + 8 (2 . 43) + 8(0 . 68) = 55 . 7 inches.

The refractory firebri ck chosen [rated 1650°C (3000° F)] had a thermal con­ductivity that varied continuously from 2 . 2 to 4 .0 as t emperature varied from 200°C to 1315°C. The units (as commonly used in t he r efractory industry) are: Btu·in ./ (hr ·ft2 ·°F). It i s apparent the thermal conductivity will vary with position through the wall since a temperature gradient exi s ts. This factor could be analytically accounted for; however, for estimating purposes an average is satisfactory . With a furnace interior of 1500°C (2732° F), an average value of 4.0 wi ll be used for thi s ca l culation .

The ext erior wall t emperature of the furnace is not known since the convection condi tions are comp l ex . Again for rudimentary ca l culat ions, it will be assumed to be 149°C (300°F) .

'Thus:

q = [4. 0 Btu ·in. /hr .ft 2: F] [55 .7 i n.] [ 2732 - 300° F] [1 ft2/144 in . 2] = 3763 Btu/hr = 1102 watts .

Note that had the external wa ll temperature been 204°C (400°F) , the heat loss would have been 3608 Btu/hr, only a four percent difference . A similar ana l ys is can be performed using the above formulas for a l ternate geometry furnaces . The actual power required may be different due to heat loss t hrough cracks in the bricks, element portal s , doors , etc. Furthermore , the insul ating value of t he outer shell has not been incorpor ated in the ana l ysis . Nevertheless, the above anal ysis wi ll give a valuabl e first estimate of the power required .

12

APPENDI X B. BEND FIXTURES

Figure B-1 shows an elevated temper ature s tress rupture fixture. The f ixture was 1nachined from a billet of hot-pressed silicon carbide. The specimen size is 0.080 x 0 .11 0 x 2.000" and the fixtures have an outer span of 1.5", an inner span of 0.75". It is desirous to use small specimens to minimize the load that must be brought into a furnace. This permits s impl er fixtures.

The lower portion of the fixture is an assembly of simple block-like pieces rather than one complex part. The pieces can be bonded together by f iring a t el evated temperatures . Silicon carbide is ve r y difficult to mach i ne, thus r equ iring this s t ep. This se t of fixtures costs more than three times the cost of the furnace itself. The upper fixture is one piece and is a llowed to s it on the specimen. The load rod, with a rounded tip, is then brought through the top of the furnace and seat s in a s l ight recess in the upper fixture block . This insures even load ing on the t 1vo upper l oad pins.

When the specimen is loaded onto the lower fix tures, a gage strip is used to push it back just far enough so that it will be directly below the l oading pi n. The upper fixture is then carefully inserted on top of the specimen so that it i s flush, but not contacting the rear guide block. This insures the upper fixture is directly centered over the specimen . The upper fixture is then shifted laterally if necessary to bring its edges parallel with the edges of the guide b l ock, insuring correct spacing of the inner load pins with respect to the outer load pins. Finally, the load train is inserted through the furnace top. It consis ts of a steel r od with a hol e machined to accept the silicon carbide rod. No mechanica l joining device or fastener is used since the pair wi ll be compressively l oaded in service. (A tiny amount of cement aids assembly . ) The si licon carbide rod is allowed to rest in the recess in the upper fixture and a half-pound preload put on to maintain alignment. Care i s taken to see that the upper fixture does not r ock when the rod is brought into place . The fixtur es must seat squarely.

Wi th a little practice , thi s can be qui ckly done and we are satisfied the alignment is excellent. Most failures occur within the gage length.

13

Figure B-1. Four-point bend fixtures made from hot-pressed silicon carbide. Upper fixture block sits atop a bend specimen.

APPENDIX C. LIST OF MATERIALS

Prices are approximate as of publication date and the cos t in the right-hand column reflects the cost per f urnace . Most of the items must be bought in minimum quantities, however, thus causing a higher initial investment.

1 . Refractory Firebrick [rated 1650°C (300ifF)] $40

a . ' Straights ', a minimum of 25 recommended b. ' Sp lits' , 5 are necessary c. ' Soaps ' , 10 are necessary

The straights usuall y come 25 to a box; the others SO t o a box . All are about $1.50 per brick.

2 . Ceramic Fiber Insulat ion Panel (3 /8 or 1/2" thick)

Approximately nine square feet are necessary, although more should be ordered.

3. Heating Elemen ts and Electrical Connect ions

1/2 x 19", 5" hot zone , 4 @ $35 .

4. Slotted Angle Steel, 16 feet necessary

Usually so ld in t en 10' sections (100 f eet altogether ) with nuts and bolts included ($40).

S. Electrical Meters

l ammeter, 1 voltmeter.

6. Variable Voltage Autotransformer for 20 amperes, 110 VAC

7. Insulating Cerami c Wool

Only a handful i s necessary . Unfortunate ly, it is generally sold in mi nimum quantities of 25 to 50 pounds.

$20

$140

$10

$60

$125

$1

Total $396

This cost excludes thermocoupl es , clock timer, labjack, and an auto­matic temperature controll er and power pack.

14

!IS TR IBUI ! C~ L : ST

No. of Co pi P.s To

Off ice nf t hp Jnder Scc r-etarv o t DP.fen se for Kest::an h dnd Engi r.e•!ri ng, The Penta gon , Wa sh inyton, CC .!03 l0 ATTN : Mr . J. Persh

Dr. G. Gamot a

12 C00111ander, Def ense Techn i ca i lnfor mat i on Center, Cameron Stat ion, Building 5 , 5010 Du ke S~reet , Alexandri a , VA 2?.314

National Tech" i cal I n f ormation Serv ice, 5?85 Por t Ruyol Road, Spr inqf ie ld , VA. 22 161

Director, De. f ense Advanced Research Pro.jects Agency , 1400 Wi lson Bou l evard, Arl ington , VA 2!?.09 ATTN: Dr . A. Bement

Or . Van Reuth MAJ Harry Wi nsor

Balif'l le Col umtlus Laboratories, Meta l s and Ceramics Informat ion Cente r· , 505 King Avenue, Co l umbus , OH 4 3201 ATTN: Mr. Wi nston Duckworth

Dr . D. Niesz Dr . R. Wills

Oepu·.y Chief of Sta ff, Research, Oeve l oj)lllent, and ll.cqu •sition , Headquarters, Departmen t of the Army, Washington, DC ?G310 ATTN: DAMA- ARZ

DAMA- CSS , llr. J . Br yant OAMA- PPP, Mr. R. Vawter

CO!llllander , U. S. Army Med i cal Rese arc h and Deve lopm~nt CoiTITIMrd For t. Detr i ck, Freder i ck, MD 21 701

l ATTN: SGRD-SI, Mr. Lawrence l. Ware, Jr .

Commander , Army Research Off i ce, P.O. Box l 22 ll, R~ search Triangle Park, NC 27709 ATTN: Infor mat i on Processing Offi ce

Dr . G. Mayer Or. ,]. Hurt

Corrrnand~r, U. S. Army Materiel Development .1nd Rcad ' "'''S Command, 5001 E i ~enhower Avenue, Ale xandr i a, VA ??1 33 ATTN: ORCOMO-ST

DRCLDC

COP.l!llander , U. S. Army c l ecrroni cs Research and Deve lopment Command, For t Monmout h, rJJ 0/703 ATTN : DEL SO-L

Corm• ctnder, U. S. Army Mater i el Systems Ana l ys i s Acth· it.y, Aberde~n Provi ng Ground, MD 21005 AT T~: DRXSY-MP, H. Cohen

CoiTITiander, U. S. Army Ni ght Vi s i on El ectro-Optic s I JbC> 'dt ory, For t Be lvoir, VA l 2060 A.TTN: DELNV - S, Mr . P. Tr avesky

0£LNV- 1 -0 , Or. R. Buser

Corm1ander , Har r y Di amond I aboratories , 2800 Powder Mi II Road, Adelph1, MD 207 83 ATTN : Mr. A. Benderl y

Techn ic a l Jnformation Off i ce OELHD- RA£

Commander, U. S. Army Mi ss i le Conmand , Rerl st onc Ar-,enal , AL 35809 1\TTN: Mr. P. Ormsby

Tec hn1ca l L i brar y DRSMJ- TB, Reds t one Sc ien tiiic l nfcr mct i on Cen t er

CorrrnJnder , IJ. S. Army Av iation Research and OC'vP lOplll('n l Comnand , '1300 Goodfel1ow Bou levar d , St. Lo~i > , MO 6312C ,nTN: DROfl'/ -t GX

DRDAIJ- QE Tec hn ical L i br ary

Corr>,lander, U. 5 . Army Natick Rese.1rc h ar:d Deve 1 opmc·• t Laboratori es , Nat ick, MA 01760 Afl N: Techn ica l Library

Or . J . H~nson

Conwnander, U. S. Army Sat e l l ite Conmunirations ,,genc.v, f or t Monmouth , NJ 07703 ATT~: Technrcdl Document Center

Nr. . oi t:op i e5 To

Commander, U. S. Army Tan k-Automotive Command , '..Jarr·en, ~1l 48090 ATTN : Dr . II. Br yz i k

Mr. E. Hamper i an o. Rose DRSTA-RKA ORSTA- UL , Techn i c al Libr ary DRS TA-R

Commander· , II. S. Army Armament Research and Devel opment CoiTITiand , Dover . NJ 071.\1.1 1 ATTN : Mr. J. Lannon

Or. G. Vezzo li Mr. A. Graf Mr. Har r y E. Pebly , Jr. , PLASTEC, Di rector Technica l Li brary

Commander , U. S. Army Armament Mater i e l Readi ness Command , Rock !s t and, I L 61299 ATTN: Techn i ca l L i brary

Conmander , Aberrteen Pr o v i n9 Ground, MD ? 1005 .~ TTN: OR OAR -CLB - PS , Mr. J . Verv i er

Commander, U.S. Army Mobll i t y Equipment Research and Development Commartd, fort Be lvoir, VA 22060 ATTN: ORDME- EM, Mr. W. McGover n

DRDME - V, Mr . E. York DRDME-X, Mr. H. J . Peters

Di rector , U. S. Army Ball i st i c Re search Laborat ory , Ab.erdeen Pro ving Grounc1 , MD 21005 ATTN: DRDAR- TSB-S (ST INFO}

Commander , Roci: I sl and Ar sena l , Roc k [ s tand, I L 61299 ATTN: SARRJ -EN

,_:ommanrler, U. S. Army Tes t and Ev aluati on Command, Aberdeen Prov ing Ground, MD 21005 ~.TTN: OR STE -ME

Co•tTnander, U. S. Army Fore i gn Sc i ence and Tec hno l ogy Center, 22C 7th Street , N.E. , Ch ar lo t tesv i l l e, VA 22901 ATTN: M ili t~ry Tech, Mr . W. Mar ley

Ch ief , Benet We apon s Laborator y, LCWSL, USA ARRADCOM, Wat enl iet, NY 12189 ATTN: DR DAR -1. CH- Tl

Con:lllomler , Waterv lie t Arsenal, Wat ervliet, NY 12189 AHN: 8r . T. Dav id son

ll i r ector, Eus ti s Di r ec tor ate , U. S. Army Mobili ty Research and :Jeve Topmen ~ Laboratory, f ort £us t is , VA 23604 A:TN: Mr . ,J. Rob i n son, DAVDL-E- MOS (AVRADCOM }

Mr . C. Wal ker

Commander , U. S. Army Engineer Waterways Exper iment Stati on, Vicksburg , MS 3~180 ATTN: Rese arch Cent er Li bra r y

U.S . Army Munitions Production Base Moder nization Agency, :lover , NJ 07801 A:TN: S1lRPM-PBM-P

lechn i ca l Direc t or, Humdn Eng i neer i ng Laboratorie s , Aberdeen Pro>· i ng Go·ound, MD 21005 Ai~~: Techn j c al Reports Off i ce

Chie f o f Nav~ l Re, earch, Ar l i ngton , VA 22217 ,; ~~N: ~ode· 4 71

Ur . A. Oi ness Dr. R. Poh anka

N,wo1 "('Search Laborat o ry, Wa>hington, DC 20375 .~T~N : Dr . ,J. M. Krafft - Code 5830

Mr . ~ . Ri ce Or . ,Ji m C. r. Chang

Hedd quar·t,rs, Nava 1 Ai r Sys t erns Corrrnand, \Ids h i ngton , DC 20360 A fTN : Code ~203

Cvde MAT -042~1

No. of Copies To

Headqua r ter s , Nav a I Se a Systems Commaod, 194\ J0Ue• s·Jr: Dav" liighway , Ar lingtou , VA <'2376 ATTN : Code 035

He adquart e rs , Naval Elec tron ics Systems Comm~ rrd, Wash rngton, DC 20360 ATTN: Code 504

Coowander , N~val Ordnance Station , Louis ville , KY 4C<: 4 ATTN: lode ~. 5

Conman~er, Naval Material l ndus trra l Resources Off ice , 5ui1 dinq 537 -2, Phi l ade l phi a Naval Base, Philadelphic, PA 11!: ? · ATTN: Tec hn ica l Di rector

Conmander, Nava l Weapons Cente r , Ch ina Lake, ,., \,.. ."', 93~1~1 1~

ATTN: Mr. F. t1ar k ar ian Mr. E. Teppo Mr. M. Ri tch ie

COl11llander , U. S. l;ir Force of Scientifi c Rl'search, Building 410, Bolling Ai r Force Base, Was hi nqto rr , DC ?033? ATTN: MAJ W. Simmons

Commander, U. S. Air Force Wright Aeronaut ical Labor .,t.ur·rr5 , Wr ight -Patte r son Air Force Base, OH 45433 ATTN: AFWAL/MLLM, Or. N. Tal l an

AFWAL/MLLM, Or. H. Graham AFWAL/MLLM, Dr . R. Ruh AF WAL/MLLM, Or. A. Katz Af WAL/I~LLM, Mr. K. S. Mazdi yasni Aer o Pr opul s i on Labs, Mr. R. Mar sh

Commander , Air ror ce Weapons Labnrdtory, Kir tland Air force Base, Al buqLJerqlte, N~1 R7 1 U> ATTN : Dr. R. Rudder

Command e r, Air Force f;rmament CP.nH=~-. Eg l in ,ll. i r :=un .. (~ 8dSC , FL 32542 AT TN : ~ec nnr ca l L1brar y

Nati onal Ae ronauti cs and Space Admini s t r otion, Washington , UC 20546 ATTN : Mr. G. C. Deutsch - Code RW

Mr. ,J. Gangler AF SS-AO, Office of Scrent i f ie and Techr ic d1 :·rf orma:. ior.

National A(~ronaut ics and Space Admi oist ratinn, Lewis Resear ch center, 21000 Brookpark Ro ad, Cleveland, OH 441 35 ATTN: J . Accur i o , USAMROL

Or. H. B. Probs t . MS 49 - 1 Or. R. Ashbrook Or . S. Outta Mr. S. Gr isaffe

Na t ional Aeron aut ic s and Space Admi nistration, Ldng 1e_v Rese arch Cente r , Center, Hampton , VA 23665 ATTN: Mr. ,J. Buck I ey , Ma i I Stop 387

Cofl'rnander. 11'ihite S3r,ds Missi l e f{anqe ~ E1ec tron'<: Wdrfdrt'

Labor a tory, OMEW , ERADCOM , Wh ile Sands , N~ HR002 ATT N: Mr . Thomas Reader , DRSF 1. -WLI4-Mf

Oepartme,,l ot f nc t·Q.Y. D i v ~ s~on of rransportati on, 20 Mass~c husetts Avenue, N.W . , Wash ingLun , DC (.0~4~ ATTN : ~r. George Thur (TE C)

Mr . qobert Sc hull (HC) Mr' . ,:o hn Nee. 1 W NRT ) Mr. St eve ~dnder [f o5Si l fuels)

t>epartmr.nt of lran~portat ion, ~eo Se"Venth Street, S . 1~ • •

Was hi ngton , DC 20590 ATT N: Mr . M. Lauri ente

Mech~nl c al ?r opcr:..ie s 0dtr. Center, Be lic ur Stul('n :"lr. , 13917 W. Bay Shun • Drive , lrave"e City. Ml ( 9684

Nati Crrdl Uurcau of Standords , Wdshi nytorr, DC coz.~r. ATTN: i)r . S. ~· i ederhorn

:Jr . ,J. B. NdCht rPar.

Nati onal Re~~arc h co,1ncil . Nat ~o~al Mate rial s Advi ~cr ·t Bud,·(: , 2101 ~ons ti~ lJ t ior : A.v e ~1 ue , '..J -3- ~h i n~,;tor , [)( 20a:p. .. ·HTr~ : 0. Grove $

:~ . r~ . ~.p ;~ir;gs

~l o . of Copies. To

~~Liond l Scrence Foundat ioo, Washi ngt on , OC 20550 ATTN : R. A. Wilcox

Admir alh Mat eri a h Technology [stahlrshment, Po lle, Dor set BH I6 6JIJ , UK -;. :n: Or . 0. Godfrey

a~-. r~. !.indley

ArRese<n·ch Manuf acturi ng Company , AiRe~earOr Cas t ing Company, ?s;~, Wr st ! 90th <,treet, Torrance, CA 90S05 .~TTN : Mr . K. St yl1 r

Dr . fJ . Kotc hi tk

AtMesc ar ch Man ufoctur rng Company, Mater i a l s Engi neer ing De pt . , ll l So~t h 34th Street, P.O. Box 5217 , Phoeni x, AZ 85010 Al l N: fir . 0. '" · Richerson, MS 93-393/,03 -44

o~ -. W. Cdrru t tler s

AVCO Corpo,·ation, Applied Technology llivi ~ i nn, Lowe ll [ndustrial Park, Lowen, ~~t\ 01887 ATTN: Dr . >. 'lasrlos

carborundum Company , Research and Deve lopment Divi s i on, P.O. Oox l GS4, Ni agar a Fa ll s , NY 14302 ATTN : Dr. J . A. Coppo l d

Cdse 'o/e sti'rn Reserve Uni versity , Depar tment of Metallurgy, Cl ~ .,.e l.dn.d , OH 44106 ATTN: Prof . A. H. Heu~r

!:€.-adyne , Inc ., P. O. Box 11030 . 3030 Snu t h Red Hil i Aven ue , ) Mrta ;\nJ , Cl\ Y?7C5 ATTN: Dr. ~icn M·d Pal ic kn

CanrDust 1Crr Eng rnce r i ng, Inc ., 911 West Mdi n Street , :~hattarrooqJ , TN 3740? A•"N: C. -H . Sump

Culll!ll <ns Fny ine Company , Columbus, HI 47201 ~.TTN: ~r . R. K,JmQ

De fHCC Research Es tab l i s hment Pac i fi c , FMO, Victoria, B.C . , VOS i ~0, Cdnac1 a ATTN· R. ll. Bare r

DPpc.srt s .1n.1 Com[los i tes , Inc . , 182 1 Mi chael Faraday Dri ve, Re s t on, VA 22090 ATT~ : Mr . A. [ . Engdahl

( !ec t ri c Power Research [nstrtute , P. \1. Box 104 1?. , ?~~~Hii lv iew ~\venue , Pal o Al to, CA 9a 304 , ... ,, llr . A. ~o hn

Eur ope .m Rese~rr h Off1ce, 223 0 \(J Mary leborne Road , London, ~ wl - ~t he , [ngland ~.TTN: iJr . R. Quattrone

LT COl. J ames Kenneoy

ford Motor ~orrr pany , Tur bine Researc h llep~rtment , 20000 r<ot Jnda Dr ive , Dearbor n , Ml 481?1 ATT N: Mr . ~~ - F. ~c le an

Jjr. [ . 1\ . r is he r Mr , u. A. Mangels f1r . R. Govi Ia

Gener~ ! Atomic [ompany, P.O. Box 81608, S~n Uiego, CA 92 138 AfHj Jrm H,J l zgra f

Gcner.1l I' icctri c Co111pany, Moil Drop H-99, Cinc innat i, OH 45215 /H .... N: Mr. Warren Ne I son

Ge~er rl l ll H. tr ; r Compdny, Resear c ~ dnd Deve l opmen t Center, eo, 2 , Schenec tndy , NY 123a5 A'I N: Or . ~ - J . Char les

Or . r. . J. Gres kov i ch nr . S. ?rochazk a

Gene•·• ! Motors Cor pnr-dt ion, 1\r. Spark Pl,Jg Oivi,ion, r I int , MJ ~8~ Sf,

ATT N: Dr . M. Berg

Georgi a : :;s l iL>te ()f Tec hnology, [£$ , t. tlant.1 , G,\ 30332 A.T"!'N: Mr . .. J. J. Well ton

No. of Copie ~ To

GH Labor <J t.,,r i es , Walth am Re;e.1r c h Center , 4() Sy I v ,m R" dU , Wal tham, MA 02154 ATTN : !Jr . C. Quac~enbush

Dr . W. H. Rhodes

l iT Re search In s titute, 10 West 35th 'treet, Ch icago , ! ! 60616 ATTN: Mr. S. Bor tz, 011·ector, Cerami cs Research

Or. 0. l .~rsen

Institut fur Wer kstoff-forschung, OfVLR, 505 Pcrz-W~~~. i i~<ler Hohe, Gerrnan.v ATTN: Dr . W. Bunk

l nst itut fur Werks toff- for schung, DFVLR, 5000 Koln 90(Po rz ) , Linder Hohe , Germany ATTN: Dr. lng Jur gen Hei nr i ch

International Harvester , So l ar Di vi s ion, 2200 Pacific H1ghway, P.O. Box 80966, San Di ego, CA 921 38 ATTN: Or . A. Me t ca l f e

Ms . M. E. Gulden

Je t Propu l s ion Labordtor y, C. I .T., 4o00 Oa k Grov•• Drive, Pasadena, CA 91103 ATTN: Dr . ~ichard Smoak

Kawec ki Beryl co Industr ies , Inc ., P. O. Box 1462 , RP.ad ing, PA 19603 ATTN: Mr. R. J . Longenecker

Mr . Edwar d Kr aft , Pr oduct Development Manager , Indus t•·i.i i S; lr s Divis ion, Kyocer a Inter national , Inc. , 8611 Balboa Avent"'• San Di ego, CA 92123

Marti n Mar ietta Laborator ies, 1450 Sout h Holl ing Road, Bal timore , MD 21227 ATTN: Dr. J . Venab les

Massachusett s Inst itute of Tec hnol ogy, De par t men t of i"P to 1 I.Jrgy and Mater i a ls Science , Cambri dge, MA 02139 ATTN : Prof . R. L. Cob l e

Prof. H. K. Bowen Prof . ~. D. Kingery Prof . R. Cannon

Mat eria 1 s Research Laborator ies, P. U. Box SQ , Ascot 'I • lr, VIC 3032 , Australi a ATTN: Dr. C. W. Weaver

Mi dwest Research Inst i tute, 425 Volker Boulevard, Kansas Ci ty, MO 64110 ATTN: Mr . Gordon W. Gros s , Head , Physics St at ion

Dr. Howard Mizuhara , GTE-Wesgo , 477 Harbor Boulevaru, B~lmont, CA 94002

National Techni ca l In formati on Servi ce, 5?85 Port Roya l Road, Spr ingfi eld, VA 22161

Norton Company, Worcester, MA 01606 ATTN: Or. N. Au l t

Or. M. L. Tor t i R. Torre

Pennsylvan i a State Un i•1ersity , Material s Resear ch Labo r a l orv, Mater ial s Sc ience . Oepartment, Un iver sity Par~, PA 16R02 · ATTN : Prof . R. Roy

Prof . R. £. Newnham Prof. R. E. Tress ler Prof. R. 8radt Prof. V. $ . Stubi can

Pra tt and Whi t ney Ai rcraft, P. O. Box 2n9l, West PJlm Beacn . ~L 33402 ATTN: Mr . Mel Mende l son

PSC , Box 1044, APO San Fran CISCO 96 328 ATTN: MA,I A. An t hony Borges

RIAS , Division of t he Mart in Company, Ba l ti mor e , MD ?12G3 ATTN: Dr . A. R. C. Westwood

Rockwe ll Internat iona l Sc i ence Center , 1049 Camino Dos ~ i o•. Thousand Oaks, CA 91360 ATTN : Dr . F. Lange

No . -::f (np' '-' 0:. To

Rc•ya l Airc raft Es tab l ishment, Mat er ial s Department , R 178 Bu ilding , Farnborough, Hants , Eng l and ATTN : Or . N. Corney

Shane Assoc iates , Inc ., 7821 Carrleigh Par kway, Spr ingf i e l d , VA 22152 ATTN : Dr. Ro bert S. Shane, Co nsultant

S1lug !nc ., F.O. Drawer fl, Old Buncombe at Popl a r Greer, sc ?9651 ATTN: Or . Bryaot C. Bechto ld

So l ar Turbi ne Internat ional , 2200 Pacific Coast Highway, San Di ego , CA 92138 .~I TN: Mr . Andrew Russel, Mail Zone R-1

Stanfo.-d R~ searc h Internat iona l , 333 Ravenswood Aven ue , Menlo PMk , CA 94025 PTT N: Or . P. Jorgensen

Or . 0 . Rowc liffe

State Univer sity of New York at Stony Brook, Department of Materi als Scieuce , Long Is land , NV 11 7g0 ATTN: Prof . Frank lin F. Y. Wang

TRW De fense an d Space Systems Group, Redondo Beach, CA 90278 ATTN: Franc i s E. Fende ll

UnitP.d Technologies Research Center, East Hartford, CT 06108 ATT N: Or. J . Br ennan

Dr. F. Galasso

u ... ivcr s ity of Ca l ifornia , Department of Material s Science and Engineering , Hearst Building, Berkeley, CA 947<:0 ATTN: Or . D. Clarke

Un i ver sity of Ca l iforn i a, Lawrence Li vermor e Labora tory, P.O. Box 808 , Li vermo re, CA 94550 ATTN: Mr. R. Landingham

Or. C. F. Cli ne

UnivPr s i ly of Fl orida , Depar tment of Mater ials Sc ience and Engineering , Ga inesvill~ . Fl. 12601 ATTN: Or . c. Hench

Uni ve r si ty of Massachu setts, Department of Mec hanical Engineeri ng , Amherst, MA 01003 ATTN: Prof . K. Jaku s

~rof. J . Ritter

Uni ver s i l.y of Newcas t le Upon Tyne , Depar tment of Met all urgy and ~ngineer in y Material s , Newcast le Upon Tyne, NEI 7 RU , England AITN: Pro f . K. H. Jack

University of Wash i ngton, Ceramic Eng ineeri ng Div i s ion , FS- 10, Seattle , ·~A 98195 I<'TN: Prof . J ames [. Muell er

Virgi nia Pol ytec hn ic Institute , Department of Materi al s Engineer·i ng , ijlac ksburg, VA 24061 Prof . U. P. H. ~asse lman

West i nqho~se Elect r i c Corpor at i on , Research Laborat or ies, P it t sb~ rg h, PA 15235 ATTN: !)r . R. J. Gratton

:lr . R. Ro"ing

~1r . . Joseph T. Bailey , 3M Company , Techn ical Cer ami c Product s :livi~10n , 3M Center, Bui l d ing 207- HI, St. Paul , MN 55101

lk. ,:acob Sti g l ich, Oart [ndus tries/San Fernando Labora tor ies, 102•,1) Norri s Avenue , P a co irna, CA 91331

Or . J . Petrovic - CMB- 5 , Mai l Stop 730 , Los Alamos Sc ientif i c Labor atories, Los Alamos, NM 87545

Mr . R. J . lentner, EAI Corporation, 198 Thomas Johnson Drive , Suite 16, Fred eri ck, MD 21701

Director· , Army Material s and Mechanics Research Center, watertown , f1A 02172 rrN: DR XMR- PL

Aut ho•·