Note: Descriptions are shown in the official language in which they were submitted.
This inveDtion relates to methods snd matesials u0ed for reducing
gassing in electrochemical cells as vell as the amount of mercury required
in anode amalgamations for such cells.
Uetals such a8 2inc have beer, com~onl~ utilized as anodes in
electrochemical cells, particularly in cells with aqueous alkaline
electrolytes. In such cells the zinc is amalgamsted with mercury iD order
to prevent or reduce the e~tent of reaction of the zinc ~ith the aqueous
electrolyte with the detri~ental evolution of hydrogen gss. In the past it
has been necessary to utilize about 6-7% by ~eight of Qercury amalgamstion
in the anode to reduce the amount of "gassing" to acceptible levcla.
~owever, becau~e of environ~ental considerationa it has become desirable
to eliminate or, at the very least, reduce the amount of mercury utilized
in such cells but without concomitant increase in cell gassing, Various
ezpedienta have been utilized, to achieve such mercurg reduction, such as
special treatment of the zinc, the use of additives and e~otic
amslgamatioD methods. ~owever, such methods have either had economic
draYbacks or limited success.
It is sn object of the present invention to provide an econo~ic means
for reduction of gas~ing in electrocbemical cells.
It is a further object of the present invention to provide a
relatively economic means for permitting the reduction of a~ounts of
mercury used in amalgamation of aqueous electrochemical anode ~etals
without significant CoDCOmitant increase in cell gassing or reduction of
cell performaDce.
These and other objects, fe~tures and advantages of the present
invention ~ill become more evident from the following discussion as well
as the "drawingsn in which:
Figure 1 is a photomicrograph of cross aectioned polycry~talline zinc
particles; and
Figure 2 is 8 comparative photomicrograph of cross sectioued
polycr~stalline zinc as treated in accordance with the pre~ert iDveDtion.
~L~7~Z~7
Generally the present inv2n~ion co~prises a method for malcing an
electrochemical cell, with rednced gassing. The invention fnrther
comprises the cell containing the treated anode materisl. The method of
the present invention generally comprises reducing the number of grains in
the polycrystalline anode metal to one third or less of the ori~inal
number of grains. There~fter, the reduced grsin anode metsl is formed into
an anode auch as by colDpression of powder particles either on a substrate
or within a cavity. Alternatively, the aDode metal may be in the form of a
sheet witb the anode being convolutely wound in a "jelly roll"
configuration together with the cell separator and cathode. The sheet
metal may alDo be u~ed, ~ithout ~inding, in a prismatic cell, If desired,
the anode metal (particulsrly rinc) iB amalgamated ~ith mercury after the
grain reduction and prior to placement of the anode metal in the cell. In
all the aforementioned embodiments, with such ectent of grain reduction
there is a concomitant reduction in the e~tent of grain boundaries and a
reduction of gassing at such sites.
To further reduce the e~ctent of gaAsing 8 small amount of a surface
acti~e heteropolar substance (#urfactant) of a type that lill sct aD a
hydrogen evolution inhibitor is added to the cell. Because of the
heteropolar nature of the surfsctant it is generally at lesst slightly
soluble in the cell electrolyte and hAs a polar affinit~ eo the surface of
the anode metal particles vith a coating being formed thereby. Such
nffinity is psrticularly marlced ~rith respect to zinc particles commonly
utilized in snodes of alkaline electrolyte cells. The surfactant sllsy be
effectively incorporated in the cell in various ways. For e~arple, it may
be added to the anode, incorporated in the electrolyte, or in the
qeparator by pre-wetting or impregnating the separator with the additive.
The surfactsnt may eYen be added to the catbode. In all such instances the
surfactant migrstes to the surface of the snode meeal particles to form
the requisite hydrogen gas inhibiting coating. Adding the surfdctant to
the anodic materisl is by direct addition to the powdered ~etsl
tamalgamsted or unallalgam~ted) to form a surface costing for the anode
~.~7~1L2~
metal. Alternatively, the surfactant i~ added to the electrolyte whicb is
then admi~ed with the anode metal particles vith resultant migratlon of
the ~urfactant to the surface of the anode metal particles. Migration of
the ~urfsctnnt to the anode metnl pArticles may also be effected by the
addition of the surfactant to the separator or the csthode.
Alternatively, or in addition, the anode material p~rticles, auch 88
~inc, sre prealloyed with a smsll amount of one or more of indium,
cadmium, gallium, thallium, biamuth, tin, and lead and then changed into
particles with reduced number of graiD~ or ioto individual discrete single
crystal psrticles which are thereafter amalgsmated with mercury.
In order to effect reduction in the number of grains, polycr~stalline
anode materials such as zinc are heat treated at a temperstur2 belo~ the
melting point thereof for D &ufficient time ~hereby the number of grsins
in the polycry~talline material is rednced to one third or le~s of the
original material.
Though the anode maeerial remains polycrystalline sfter thi6 heat
treatment, the amount of grain boundsries are reduced with the reduction
in number of grains. ~8 a result, the amount of 8as~ing in the cell, with
the treated particles, is markedly reduced ~ince it is the area of the
grain boundaries vhich iB most conducive to high chemicsl activity snd gas
formation. In addition, mercury infiltrates into grain boundaries reAdily.
With the reduction of grain boundsries there is a reduction in the amount
of mercury required for amalgamation ~ith the anode material. ~ith the
reduced Brain anode m&terials the amount of ~ercury required for
amalga~sation can be effectively reduced from &bout 6-7Z to up to about 4Z.
~ eat treatment of the anode material is dependendent upon the factors
of purity of the polycrystalline atarting materisl, the temperature at
which the heat treatment ia effected, and the duration of such heat
treatment. It is understood that heat treatment of powder particles of
different bulk quantity may differ in length of ~ime requiret since the
interior of the aggregate is somewhst insulated by e~terior ~aterial and
does not "soe" the sa~e amount of heat as e~ternal material in direct
receipt of the heat. In practice, a contiDuou~ tumbling calcined furnsce
~7~
~ill provide mo3t effective heating snd ns a result, with properly desigDed
cslciner, less thnn teo minutes at temperstures sbove 370~C i8 ~ufficient to
effect sufficient grain reduction. ~ecry~tsllization and grain coarsening
depeDds UpOD maDy factors such as temperature, time, strDin energy ~ithin tbe
materisl, snd the purity. As a result, e~sct heat treatment psrA~eters are
determined iD accordnnce with the specific heat treatment equipmeDt being
utilized. For clarity, the effect;ve heat nnd temperature, hereinsfter
referred to, relste to a direct applicntion of heat to the material. In all
ewents, a reduction of the number of grains in the material to one third or
less of the original material is the desired result.
The heJt treatment of the polycrystalline snode Tnaterinl i8 effective
with both powdered materisl generally used in the construction of compressed
anodes in cells hsving a bobbin type structure, nnd such treatment is alao
effective ~rith respect to the treatment of metal strips or aheets utilized in
prismatic or con~oiutely wound cell structures.
The purity of the initial polycrystalline anode mnterial determines, in
part, the length of time required to provide the requisite reduction of
grain~ or conversely the temperature st ~hich the material should be heated
for n given period of time; the lo~er the purity, the higher the temperature
or the longer the time period required. The ~ost co~on snode materisl for
electrochemicnl cells is zinc with the ~o~t common impurity contsined thereio
being lesd. Other, le~s co~mon, snode materiala include cadmium, nickel,
magnesium, Yluminum, manganese, calcium, copper, ironj lend, tin and mixtures
thereof including ~i~tures with rinc.
The ~lkaline electrolyte solution in uhich the anode maeeridl i~ placed
and ~Ihich generallv iB a factor in tbe gss generstion (usuallY the anode
rescts with the electrolyte with resultant ga;i formation) is usually sn
squeou3 solution of a hydro~ide of slknli or alkaline earth metAls ~uch as
RaOH snd ~01~. Common cAthodes for the alksline cells include manganese
dioxide, cadmium oxide and hydroYide, mercnric o~ide, lesd oxide, nickel
oxide snd hydroxide, silver oxide and oir, The reduced grain number anodes of
the present invention ho~ever are Also of utilit~ in cells haYing other
electrolytes in ~/hich gAssing of the anode is problemstical ~uch as in acid
t~7pe electrolyte3.
--4--
~ ~7~
Co~oa al~aline t~p~ c~ contai~ compre~l~2d pol~cr~tallin~ lC
particl~ ha~ ag ~er~e particlo ~ o about 100 ~icron~. ~elb o
oueh pasticle~ h9~ ~'DoUt 16 or 2~0r~ ~5rl~iD~a aDd isl aceorda~co ~Oieh t~
pre~2nt in~ontioll t~e nu~ r of gr-in~ e~ch of the p~rticl¢~ i~ red3ced
by h~tin~ tho ~i~c psreicl~ ~t ~5l offect;vo teDlpes~tur~ bet~eD ~out 50
to 419.5~C (th~ lstter bei~ th~ ~ltiD~ poin~ o Zi'tlG~ for
perio~l of ti~ ra38ia~ fro~ ~bot~t t~o hour~ At 50C to IdbO~lt fiv~ ute~
at 419.S~C to reduco th~ Ot o~ ~rai~l to a~l BV-3r~,B of abo~t 3 to 5
gr~ per p~r~ciel~. Zi~c p~rticl~ll h-~iD~ lesd i~puriei~o reqllir~ A
te~p~r~tur~t of ~bo~t lO0-C fo~ tha Y~ini~ tllO hou!~ p~riiod to schi~
~i~ilar r~d~etio~ r of ~rs~.
ul ~urf~ct~ntl~, ~ich G~gl bs sdd~ to t~ eelllD is ccords~c~ vit~
thq pre~e~ u~ion i~ order to furth~ se~l~cls t~ de~reat of
il~clude ~h~len~ 03ido co~t~in~ poly~r~ 3tlC}1 a~ t~O~d~ h~ g pho~phst~
group~, DlatU~:lAtea or u~aaturated ~noc~r~os~lic acit ~ie~ a~ le~t tvo
e~sol~id- l~ro~ 3; tritae~los~po1~(ethyl~o~) et~ol; an~ t
pr2f~r~bl~ org~i¢ pbo0p~t~ ~tes~. ~hoe pr~ferz~d or~ ic pl~oJph~t~
e3s~r~ gen~r~lly llr~ ~1119a~ SIII or ~ic3a~r~ tl~a follo~ fOn~31B:
~0(3tO)~ C ~ P - ~9
(I~S)~
~h~r~ ~ 4 ~ ~ 3
X ~ Il, a~Dnisg ~i~o, or ~ ali or alE:ali~ ~s1rth ~tsl
h~ r ~ 1 or ~ yl of 6-~8 el~rboll ~to~
Sp~eif~G u-~l o~ga~ic po87~a~ t~ sur~lets~ts iDelu~a s~~ ri~ls
vhich cæ~ bo ill~nt}fi~ Dy th~i~ e~rcial a~.~ip~t10~ 600 (U~
~nio~ic o~ c pl~o0pb~ t~r up ~ r
b~ d o~ sr ~ris~r~ slco~ol, ~ a u~str~ sl p~sgf~l
o~t3r o~ p~o~pho~e aeid3; 1~ ~610 ~ 10llic c~pl~ org~e
p~o-p~e~ ~t~r ~u~ll~ by GU Cosp. ~ th~ ~re~ aci~ g 8~ ~r~tic
h~d~o~o~, aaa 1~ u~a~ersl~d par8i~ r o~ ~hosy~hosic acid);
TM
aD~ A3lPAC ~--040 tul soio~io ~llo ~titt3te~ o~ebo pl~8~ C~i3 oBt~s
i~ bg ~ 1~ d~ Cor~
1;~7~
It h~ been found eh~t the iDcorporation of a ~urfJctD~ sdditi~e
of tho typ~ referre~ ts her~i~ in ~ c~11 iD ~ n-o~nt of fro~ O-OOlS to
5~ preferaSly O.OOS to 1~ snd 20Dt prefer~bly 0.01 to 0.3S by Yeight of
the ~CtiY~ ~DOd~ oo~pon~t of the cell, precludea or ~t lc~at
~i3Dific~6a~1~ iD~i~ie- tk~ o~olutio~ o hydrog~n ~ithi~ th~ coll, s~d
thercb~ Lncre~e ito ahelf life ~d its u~ful vor~ lif~.
Th~ ~tditio~ of th~ sur~ct~at ~4 c~ eo~t~i~iD& rsd~ced u~ber of
DOdO ~ dl g~iD~ or ~iD~l~ o~t~l~ of uc~ ~od~ ~tal~ pro~id~s -
~Ger~i~eie fur~h~r red~e~ioa ~f c~ll g~ei~S.
~ ho~6~ eh- U~2 of ci~ cr~atal anod~ ~stsri~1 ~n~ t~ u~ of or~a~ic
phospb~ta ~t~r ~ur~-c~s~t~ (~8 P~t~e ~o-. 4,4~7,6Sl ~nd ~,195,120 o~ned
by th~ 8aa~ ig~o~ ~ th~ pr~3~ne iD~tioa) b~v~ ~ep~ratolg bQ~ ~DDND
~o ef~cti~ red~e~ cffll g~s~io~ or to p~r~it ~GUY r~uction o ~rcur7
cont~Dt i~ t~ ~n~a- ~ith4~ ~str~ent~ ere~o i~ 8~ 9 t~ effoce
4f th~ coD~i~a~io~ has unexp~et~dl~ 5e~n di~co~6r~a ~o be co~oider~bl~
r- th~n ~ddit~Y~. Tb~, in esll~ n8 ~s~ m~t~d ai~6lo cr~Jt~l ~iDs
~ode~, tha ~sou~t of ~-reur~ i~ th~ 6~ c~ b~ ~ff~cti ~l~ r~dnc#~
ros abo~g 6-7~ to ~bo~ 4~ or ~t~t~ di~f~re~ be r~t~ of ~00in~ o~
~ol~cr~t~ aa~l~ CoRt~ 1.52 ~Qrc~r~ C2~ bo red~c~
~bo~t 2-fol~ ~t~ t~ u~ o~ aiD~l~ cr~ot~ c. SL~ rl~ th~
TM
u~ilisatioa o ~ or~oic ~ho~ha~3 o~tær ~s~eta3t ~eh ~ GU~a ~600
i~h pol~er~t~ ioe ~13~a ~o~a r~sl~ bo~ ~ 4 fol~
TM
r~t~ct~ o~ ~sa-iD~ ~it~ for ~$a~ ol~ G U ~C ~600o ~o~ r~ ~a
~ccord~c~ h tb~ ps~ g i~ eio~ a co~b~Datio~ of t~ t~o~ . 8
~iD~le cr~e~l si~e us~l~a~ ~ith ~ ~rfsc~a~t u~p~et~ p-r~igs ~b~
~f~cti~o ~d~ct10D o th~ ~e~corg to ~bo~e 1.5S ~igh 4bo~t ~ 20 ~old
~o~ ra~ iahibi~io~ or ~bo~e ~bl~ ~h~t ~l~bt ~o b~ poet~ o
8 ~tt~r 0~ co~r8~, Co8~iD~io~ 0~ ch~2ic~1 gao rsd~ctio~ di~t~ doe~
~ot u~ually 3~ p;o~ D ~dit~Y~ Ct ~0~ do~ c~o~ ti~ tiD~
o ~dd~ . Yh~ u~- o~ tb~ ~r~c~sa~ ~se~rial ~itb ~ red~e~d ~rs~
~b~r ~ ao~ tor~1 p~9~ c~c~i~8~ r~ e ~ e~io~ ~
e~ ~b~ thB~ o~ ith 8~ ry~e~ ~t~ l b~lt
lo~ th~C o~in2~ ~ie~ tho hi~ ~ra~ ~u~ al~cry~ co
'7
The ~iDgl2 cryst~lc of zinc ~re preÇer~17 prep~red ~a d~3cribed i~
~id ~S PaCent No, 4~487,651~ Such procedur~ olve~ tho fo~atio~ o ~
thi~ ~kin crucibl~ o~ e~c~ o~ t~ siac particle~ by o-idl~tion in ~ir ~It u
te~per~tur~ juae belo~ t~ ltisu pcis~ (419C) o t~Q ~i~c, he~tiD~ o
tb~ enclo~ inc p~rticl~!a in ~ inerg at~o~pher~ ~07~ the ~eltiDg
poln~ of the si~c a~d slolv cooli~8 th~r~-~t~r ~7i h r~oval oiE the oxite
aO ZiDe particl~ o~ ge~rall~ r~8- b~t~ 80 ~d 600 ~icroola ~or
utilit~ i~ electrae~ic21 cclls ~l~d ~uch ~etho~ provit~s D~a eff~ctiv~
o~a~6 for ~ iDSl~ cr~l~t~l p~rticlG~o ~f l~ueh ~11 di~ io~.
T~ DOU~ of s~rcur~ iD tl~- A~ R u~lg~ ~ r~ fros~ 0 - 4
depe~d~Ds upo~ t~ e~ll utill~tios sud t~ d-~re~ o~ oin~ to b~
tolor~lt2d .
~lgs~t~d s~duc~ ~r~ ~iber or sin~lq er~l~t~ t~l p~rticlo~
TM
~rith ~urf-ee~l~t ad~i~*~ æeh ~c ~C 8~600 3re fOQIl~d into ~ e~ for
~loetroeh~nie~l e-llD p-rtieul~rl~ Allcali~ etroeh3~ieal c~
ti~ h~ as~ ~o~d ~Fro~ eh~ r~d~c~ ~r~i~ 3ugib~r or
cr~sC~ Q~ partielco ~ t~ ~rfsletult ~i~r~ th~r2to r~
oth6~r c-ll eo~on~e~ uch ao t~ ~l-c~Pol~e~, s~r~eor or cathod~ to
vhieh th- ~r~aet~ta ~ itially d~lo Ot~r 3D0
c~p2bl- o b~ fon~ O r~dues~ ~,r~ a~b~r o~ ÇliD~llll Cr~8~
po~r~ Dd Qhish ~rc u~ ctro~sis~l c~ iucl-ada ~1, Cd, Ca,
Cs, l~b, 19~ D ~Ut ~3D -
~ ~urth~r l~ itiOl18l or al~cr~dt~ 8a~ 8~ for r~otlol3 o ~i~ th~ llo~i~ o pol~e~ e~lS~ O~ t-l p~rticl~ ~sith ~ or
oth~r ~iLti~- prior to ~aod~ ~-t~ ,r~a~ r~d~cti0~ or t~ lEor~t~0l3 of
th~ ,lo er~t~ t~l par~ eal~rally iD D~U~t~ ~Do~i~ b~t~s
2S-5000 p~s ~$~ ~r~bly l~tq~ 10~1000 p~ ~o~t o~ ~rGtlLr~ i~
~ asod~ r~ f~9 0 - 4g d$~ u~o~ t~ c~ll
u~ eios ~a th- ~3rs~ oE ~ S ~O ~- eol~ra~
~L2~ 7
The amalgamated single cryatal ~etal particles uith prealloyed
inclusions of materisls auch as indium are then formed into nnodes for
electrochemical cella particularly alkaline electrochemicsl cells. Other
anode metals capable of being formed into single crystnl powders and which
are u~eful in electrochemical cells include Al, Cd, Ca, Cu, Pb, Hg, Ni,
and Sn. It is understood that with anodes of these ~etsls the prealloy
material is not the sa~e as the anode active material but iB less
electrochemically Dctive.
In order to more clearly illustrate the effectiveness of the present
invention in reducing cell gsssing, the following comperative e~amples are
presented. It is understood that such e~amples are for illustrative
pnrposes only and that details contained therein are not to be construed
as limitationA on the present invention. Unless otherwise indicated herein
and throughout the present specification all parts are parts by veight.
EXAMPLE
Three batches of polycryDtalline rinc of average particle aize of
about 100 microna are heat treated for varying periods of time and
temperatures and are then amalgns~ted with sbout 4~ mercury by veight. A
fourth batch of 41 mercury amalgamated polycrystalline zinc is not heat
treated and is used as a control. Ivo grams of each batch are placed in
37I ~O~ solutions tsimilar to the electrolyte of al~aline cella) at 90C
vith heating parameters and gsssing rates given in Table 1:
TABL~ 1
Zinc Tre~tment Dl gaB (24 hours) ~1 ga~ (93 hours)
Control, not hested 0.62 3.77
114 hours at 400C 0.25 2.07
235 hours at 400-C 0.28 2.78
70 hours at 419-C 0.28 2.18
It is evident froD the above that the heat treat~ent of the present
invention serve~ to more than halve the gDssing rate of a~algamDted zinc. It
is further evident that continued long term heating does not ~ignificantly
affect 8assing rates and ia generally economically unde~irable.
EXANPLE 2
Polycry~talline zinc powder (a~erage particle size of 100 microna) from
the Ne~ Jerse7 Zinc Co. (~JZ) is heat treated at 370'C by tumbliDg for one
hour in a rotating calcine furn~ce. The powder, as received from NeY Jersey
Zinc, has the crystalline structure sho~n in Figure 1. After the heat
treatment the po~der has the crystalline structure shown in Yigure 2 ~herein
grain size is markedly increased, the number of grains is rednced und the
smount of grain boundnries is concomitantly reduced. The polycrystnlliDe
rinc, as received and after heat treat~ent i~ amalgamated Yith 4~ mercury and
t~o gram snmples of each are tcsted for gassing as in Erample 1. ~n
additional tvo gram sample of 7Z mercury amalgamated zinc from ~oyce Zinc
Co., Yith similar polycrystalline grain structure and average particle size,
is also tested for gassing a8 sn additional control (representiDg prior art
amalgamated rinc) with gausing results given in Table 2:
TABLE 2
Zinc Type Gassing (ml) after 24 hour- at 90C
AB receiYed from NJZ 4Z ~g 0.ô5
heated ~t 370~C for 1 hour 4~ ~g 0.4
7Z ~g Royce 0.25
Eent treatment, as described, provides an anode m~terial having markedlv
superior gssning properties ~hen compsred to untrested polycryutslline zinc
and slightly worse than prior art amAlgs~ated ~inc having considerably more
mercury in the amalgam.
E3AMPLE 3
T~o grams of each of the amslga~sted zinc materials of RYample 2 are
similarly tested for gassing at 71-C after periods of 7 and 14 days ~ith the
results given in Tables 3 and 4:
TABLB 3
Zinc Type 7 Duys (~1 gas) 14 dags (ml gas)
As received from NJZ 4~ Pg 0,9ô 1,95
'dested st 370-C for 1 hour 4% Bg 0,50 1,19
7~ 'dg ~oyce 0.46 0.95
TA U ~ 4
Zinc Type Gassing Rate (ul/gm-day)
0-7 Dsya 7-14 dnys 0-14 days
A8 recei~ed from NJZ 4Z Lg 70 69 70
~eated dt 370'C for 1 hour 4~ ~g 36 49 43
7~ Ng RoYce 33 35 34
_g_
Both ~he toe~l U~ t of e~olve~ ga~ ~nt the 8s~ing rate of he~t
treate~ ~inc po~t~r~, after e~:teu~ period~ of ti~ re comp~ o
tho~e of sinc pov~r3 e~lga~at~ l~ith igDifics~tly ~oro ~ercur7.
It ia e~id~t fro~ eh~ p~oto~icro~r~phl~ of i!'igUrQ 1 and 2 t~ the
nu~ero~ polycryst~lline gr~i~ bound~rie~ h~ becn reduced i~ nw~lh~r ~ith
~ concositult r~d~ct~oa i~ th~ er o pol~cryst~ o 8rsin~ per
particle ithout gener~l ch~n~ tbe ~h4p~ o th~ iadi~id~al p~rticles~
rb~ nu~ber of gr~ io t~ he~t t~e~t~t p~ticlo~ i8 a thir~ 09: le~ OP
t~t o ehe origizul p~rti~lca.
!SS~Llt 4
Zi~e ~oe~r 81~ D cont~iniD~ 1.5S ~re~ry a~ it)l llt~d~râ
gr~i~ pol~cry-tAllin~ e ~lo~, ot~d~lrd gr~ olyer~l~tslli~ e ~i~h
O.lS ~600 ~- an ~dltiY~ e~t, ai~gl~ er~eal ~ e, nd 5ia~ r~Qt
~ine ~it~ O.lS ~600 ~ 3~ ~ti~v~ ~ls~s~t. ~qual u90u~e~ of t~e uaal~a~a
po~s~ ~r~ e~ 8Coe~l io equ~ ou~t~ of 37% ~:011 al1~1iD~ oolu~ion
(t~pieal ~l~et~ol~t~ ~olueio~l o~ 211taliD~ coll~) ~ te~lte~ or ga-~iRg ~t
tesllper~t~rs~ of 71~C. ~h~ O.lX ~C R~600 i~ dd~ ~o th- ~lk~
~olutioY~ tirriDg o t~ e lsl hueh ~olu~oo r~ule~ t~
depooi~ioo o~ ~h~ a6t~t o~ ~h~ siae. Th~ ~u~ o ~ is8, ~-s~r~ed
in ~icrollt~r~/~r~ p-r dl~ L/~ay) ~d th~ raeu r~d~ctio~ ae~or~
(~ith t~ ol~cr~ liEw s~i~c co~atrol b~ r~ 8i~: forth ~ T~l~ S:
~I~ 5
~OD~ 1; QUl~ C~IO~ CTO~
Polycry~tsll~ 3in~, 1.5S ~ 29S
Pol~crgatall~ si~c, loS~ ao 3~7
~600
Si~l~ c~t~ iDC,, l .S~g ~ 14~
~iD~ls cr~s~al ~i~c, l.SS ~ lS 19.7
0.~ 01
~ r~e~ ~tact~o~ s~t~ 8~ Jt ~ ~alt~ b~ ~l t~
b~ b~g 708 (307 8 2.1) go~ ~ c~ ue~ seio~3 o~ cr~otal ~i~o
8n~ ~600 ~ rato ~ lo~ eo n~ 3~ ~L/g-d~7O Th~
co~ stioa ~0~ 7~r ~ r~ ic~lly ~8~0C@B ~C)IIII ~5111~alill~ to ~bo~ doublo
the e~p~ete~ s~c~tio~.
-1~
1~7~L'7
~P~B 5
ZiDc po~d~s ~lguu of polgcryat~ a~:d DiDgl~ cs~-t~l ~inc ~ith
TM
aut ~itho~t th~ 0.1% GU~C ~600 ~di~ ar~ te~t~d ao in B~ 3 ~ue
~ith 0.5~ ~reur~ aJul~u~ e ~ou~t of gaJ~iD~ 0~red i~
~icrolit~rllt~r~ p~r da~ (uL¦g-da~) ~d th~ r~t~ r~ac~ios f~etors (YiCb
th~ pol~cr~ae~llin~ c co~trol b~iD6 1) ~r~ ~t fore~ i~ T~l~ 6:
T~l.B 6
~IIOD~ ~T~ L GlU9I~G I~T~513~ ~D~CS~01l ~AC~O~
Pol~cr~st~ $islS, 0.5S ~g 720
Pol~cr~t~llias ~iae" 0O5S 8~ 130 S.S
o.~ 600
8~Dsl~ cr~ot21 ~c a O .SS ~ 26S
giI~gl~ cs~t~ c~ O~S~ ~26 2a
0 .1~ ~A600
~ r~t~ r~etio~ faetor (i ~a~ ~o~l~ 8e ~fit h~ be~n ~sp~cte~l to
b~ ~bo~ 14.9 (S.S ~ 2.7) for ~ eo~e~l otilis~ltio~ of ~iagl~ cr~tal
~i~o a~d 1~600 ~rith ~ooi~ rat~ r~d~c~io~ to ~bo~e 4~ t~L/g-d~g
COIagiDatio~ hol~70r ~r~ ieall~r r~d~c~l~ th~ a~ to ~e~ doubl~
th~ e:-p~stQ~ r~ et~o1~.
It i~ a~ t ~o~ tho ll~O~- ~Ysspl~ d tsbl~ tb-t th~ ~l~a~
c~yct~ c vith o~ or s~r~ f~die~ul~ af D~ pr~ t in~ o~ i~
~dly ~f~ct~v- i~ p~r~itti~g 18r8~ Y~re~s~ re~so~io~ itl~ ~er~so~
iu c~ll 8
l~L~ ~
Pol~crgal:sllin- ~iao iu p~slloy~a ~itb SSO ~p~ of ~alli~a ~d 100 ppa o
in~iuD. ~ fir~e ~ r~of iB ~h~s ~l~ loSS ~ rSOIr~o
~tCO~ I&~qp~ d8 into ind~i&o~ s~eal ~llo~ p~r~icl~9 ~
d~ocsib~ I~ o~r~9 psior to ~ ~tioa vitlb ~rc~r~G T~o ~r~ of ~ch of
~h~ B~~ are~ 8C~d ia a 37S 1~ eerol~:~ 801~0~ ~itl~ ga~oi~ ths
~d o~ 24 ~d 4~ ho~ta b~ B~ g?~ 11 b~ ei~ ~
oo~ro~io~. ~o co~trol ~ olger~lg~ e ~ith 7S
~re~ry ~ r to ~hae co~ly UB~ai illl al~ c~ . Beoult~ oS 1~1~6
tli~l~t5 dtlll 8i~@$ i~ S9~1dl 7 .
~7~
T~BLE 7
SA~PL~ - VOL~H~ OF GAS (mL), 90~C
24 Hours 48 ~our~
polycrystalline alloy 0.7 1.9
single crystal ~lloy0.3 l.O
control (7Z ~g) Q.2 0.5
2X~HPLB 7
A first portion of polycrystalline ~inc powter cont~ini~g 0.04~ lead is
amalgamated ~ith 2X Hg and 3 ~econd portion i8 convert~d to individual single
cry~tal particles prior to the a~Algamation. The amalgs~s are then tested for
corrosion rate iD 10M ~O~ containing 2X ZnO~ The gassing raees at 71C ~re
225 uL/gm per da~ and 80 ~L/g~ per day reapecti~ely.
It is evident thst the corrosion reduction of snode metals such a~ ~inc
by the prealloying with corrosion reducing additive ~aterials iB greatly
enhanced by the formstion of single cryst~ls from the anode metal-additive
alloy.
It iB understood th~t the above e~a~ples sre illuatratiYe in nature aad
that chsDge~ in materisl treatment, m~terial proportio~a, the specific
mAteriale, cell construction snd the like are ~ithin the scope of tbe pre~ent
invention as defined in the follo~ing cl~im8 .
1~ .
