PREPARATION AND INVESTIGATION OF RADDELEYITE - CORUNDUM ELECTROFUSED REFRACTORIES

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A008000360002-2
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 7
• Document Creation Date: December 22, 2016
• Document Release Date: July 21, 2009
• Sequence Number: 2
• Publication Date: October 19, 1959
• Content Type: REPORT

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ti nd N. M. Gelding
Prof. pl. V. :yolomin, 1x'c. Tech. 8C4?,
(All-Union Glass Research Institute)
I'REi AFv+ y; N , ~ ' r 1 ( - l' ICiN
;v PPELEY rTE - CORD l "JM E ?E:' `.i')FU:;FI; RF;I'~.i'.','ro ir: `
lass tank fklrnaces and tiR h1 k,"
ut of g
ps s rec?;ilt of the incrcasf?d ~'atP 3f the Vroduct,
of
m%>l.t ing t in .~1 iez to improve the 9'~
rosion-resistance are reyuire~ li for ir r,tos: 101---
rig?s of t hi eratgheurerscorused
''~'fract3 ec' to attack.
-.:tit are most ., eubj
,. t,e n,c i on-mull i tt, re-
the ni&nufect;are of eiectL'o. lead z1r
T^ves ir:t1~'i')L1" L' t in t;& q'.i'i U t bL: In an. incre SE in
n ref.)c-
1,..,~rf l,rav:: '"; .lte;' in an improvement iemPllrrli'='_9, i'sct this
;?:')nt trace ',~ c~rr7ei~a:. o t.Lir,t 16 if ss resi:,tant to
a sabst,a-~G- trier i rjve1W nt of
opt; more 2 and AL20 - 1 imtt? he fur 1'
melts than Zr _~
i ne act i n o~ "
-P stubil:'Y >
,-` 1
faa~i rf fractory cone ainln , of `+4Z
, mix~rt
::: f,f,a put IDsuufe':?.ure
rr', more t`? " ` of tut has rf cee: tfra~ly L tory Is ::irhly rf`91y!ti Lt to ,IBBe,
e t . z `'c being as a result of mark,-' die ant iruit.ies in
has t:.f iiwsuvantage that, ted up r':l,i: ui
-urLi err vision, the g-a S'ur lace m'4tt not be Fs
has
, of
oj. years the Re!'ra~torit.s Lst~vrs orrationhra:Galr=-on t;-f~1,L.te
airylat, -.it i.t.6ect.f t .on, on r,~ prepo
w ntlteriai `
t:eeii to 4a 8 fr?:)m native rca
refract. ~;?i~-'F of hit;i: resistance ~ r, : JZr~;->
os.tLons of the refractories in the system A~i'3"em shown in
The i omp a are intli sated on the terwrf dt=
which we studied in 1951-5^ ram that in these re''rectDrier- the
Fig. 1. It vi'~l be seen from the dreg
nents varied over the followB+retter (xPeri'
concentrations of the components 2 - 5 1+?5 SiO2 p.4- 13.
ALZC;a 5 u Zr( 8
l~fusicns the SiO2 content sometimes strained 15$?
nenta tPchnicnl
T .e miF.tilre' taken for fusion were generally compounded fr=
a1t:niina and z1rconic conce1141rate of low iron content. tJeor the pr.et$d tion The
p,:;:+>rlm~ntel melts in the laborst,ly,
~ap rite crucibles in an electric resistance
1Irna iJ, doF-i :rie rit t1g?tace temperstures of up t
~., f de. ~-it~-reed by y the authors. ~ In tnic echedul.es could be
court be attained, and '.L'e t.e~+tirg and coo.
'Oc;~(X ~?
accurately controller.
r'!'ractaire ;1 +;he ;AT~oratory investigations;.
R. I'atec: loo, '~erre et , No. 1, in t
;,~ t,veeva can, M. F.C,u iabcyvl~ '.ooK Pert 1
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Experiment showed that the optimum fusion temperature was generally in
the range 2100-2250?. Such temperatures are readily attained in large-
scale industrial electric furnaces.
In all, more than seventy fusions were carried out in the laboratory.
After each fusion the melt was cooled down slowly in the furnace, the rate
of cooling being controlled (with the aid of a brush autotransformer) so
that the conditions under which the crystallization of the melt occurred
would be similar to manufacturing conditions.
The crystallization products were investigated and tested in vari:;as
ways. The t'ollowing were determined: chemical composition (by a methoi
developed under the direction of 0. V. Krasnovsky in the chemical labora-
tory of the Institute), microstructure, phase composition, bulk density,
true density, apparent porosity, true porosity, coefficient of expansion,
deformation under load at high temperatures, resistance to corrosion by
glass of the usual composition, stability to caustic alkali., and stability
to sodium carbonate.
Petrogruuphic investigations showed that, in fused refractories in the
type, Pthcorundum
field of compositions studied, the Rmain efractories crystalline
ofethis phases
erefore,
(o-A120o) and baddeleyite (Zr02).
may be termed baddeleyite-corundum refractories - or "bacor", for short.
In some of the microscopic sections, mullite and glass were also detected,
though in smaller amount.
A pec'lliarity of fused refractories containing an appreciable amount
of' zirconia is the occurrence of anomalous points on the thermal expansion
curve, the presence of which leads to some reduction in the thermal dura-
bility of the refractory. Most of the dilatometric curves of the labora-
tory samples showed two anomalous points.
One of these was the usual anomaly in the range 1100-1200?, which
appears as a result of the rapid conversion of monoclinic Zr02 into the
tetragonal form during heating and the reverse change during cooling, the
change in volume being about 7%. The extent of this anomaly was found to
be directly proportional to the zirconia content, and it is small for pro-
ducts containing less that 20% of ZrO;>.
The second anomaly generally occurred in the range 560-700?. Prelimi-
nary experiments showed that r.his anomaly was associated with the presence
of an appreciable amount of reduction products in the laboratory samples.
For samples prepared under laboratory conditions the temperature at
which softening began under a load of 2 kg/sq.cm was in the range 1520-
1810?. In particular, bacor No. 15 began to soften at 1710?. The be-
ginning of softening; was followed closely by melting. The samples were
-)i hi ,,h mechanical strength, the compressive strength of bacor No.5, for
ex,. ,ple, being about 5000 kg/sq.cm.
It their resistance to glass melts, the e.~perimental samples were foun'l
to be butte:- than electrofused zircon-mulllte and thermite-corundum.
From the formulations that did not require the addition of artificia'.
bacor N,;.15 was selected for large-scale trials on account of its
r m the basis of this formulation, two experiments'
b?;l dues of bacor blocks were prepared in 1957 with the aid of workers of
Frevan M.Llite Works, including the chief engineer, M. B. Sulkhanov,
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?:g. 1. Ternary system A1203 - ZrO2 -
.ii02: compositions of refractories
Investigated.
the director of the laboratory, S.
F. Rustaabekov, and one of the fore-
men, V. M. Srmoyan. In one batch of
blocks, measuring 600 x 400 x 25o mm,
there were many failures due to crack-
ing (the diatomite was not technically
i
_ )
I
m
7
'V #
L? A
b 1q7 #
k? 900z
o 1JOp 7~
.
ro
ternr4twe .C
Fig. 2. Thermal expansion of
bacor (first trial batch)
satisfactory). A 100 % yield of satisfactory blocks measuring 600 X 500 X
X 250 mm was obtained from mixture No. 4.
Details of the chemical compositions, bulk densities, and apparent
porosities of the bacor blocks are given in Table 1. The thermal expansion
curve for the refractory is shown in Fig. 2, from which it can be seen that,
unlike the laboratory bacor, the bacor prepared on the large scale gives a
smooth curve. In the temperature range 20-11000, the mean coefficient of
linear expansion is 76.107, i.e.almost the same as that of electrofused
aullite and zircon-mullite.
Figures 3-6 show photomicrographs of samples taken from bacor blocks
(we carried out the petrographic investigations under the direction of V.
V. Lapin, Doc. Mineralogical and Geological Sci.). The samples taken for
petrographic investigation were taken from the working face and from the
center of the block. The photomicrographs show that bacor contains an
appreciable amount of dendrite formations composed of baddeleyite crystals
(Zr02). No natural minerals could be detected in the sections.
The following refractories were selected for submission to comparative
measurements of resistance to glass: the first large-scale trial batch of
bacor, prepared in 1953; improved zircon-mullite, block No. 2403, made on
the works in 1952; improved zircon-mullite, of low iron content, block No.
7076, made in 1953 under manufacturing conditions.
In tests on the resistance of the fused refractories to glass, test
samples were taken at a distance of 100 mm below the working face of the
block so as to obtain more reliable results.
The chemical compositions of the refractories tested are given together
with some of their properties in Table 1.
In the testa on resistance to glass, a glass melt of the following com-
position was used (%): SiO2-73.00; S03-0.55;A 1203.37; Fe203--0.06;
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Microstructure of bacor from
woi?kini; pirL of block. (Transmitted
li,;ht; magnification 901 parallel
nicols.)
;rlicrosLractare? o' bacor
rom n,,-?r of block. (Transmitted
li.;i, ; ma;,nif?ication 90; parallel
ni,_ols. )
Fig. 4. Microstructure of bacor
from vorking part of block.(Re-
flected light; magnification 86;
parallel nicols.)
Fib. o. .dicrus of bacor
from center of block. (Re;lected
light; magnification 1651 paza-
llel nicols.)
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 Bacor; first trial
batch, 1953
Becor; third trial
batch
Improved experimen-
tal zircon-sallite
of low iron content
block No. 7076
Improved zircon-
sullite; block No.
2403
High-allaim cers-
sic block
Ceramic corundum
refractory
nnXM1aloe CntR
Qy a m S m m C fD a
+ t +! m C+
?-+ A M
C+O C+ C+K a f~-'m 0
pr D cr a m r? n pr O
C+ C+
O e o' A CY ? M C G
tl