Note: Descriptions are shown in the official language in which they were submitted.
~a~3
TITLE
AQUEOUS E`LUX FOR llOT nIP ~ETALI ZING PROCESS
Bacl~ground of t:he ïnvention
Fi~ld of the nvention
The present invention relates to a zinc
chloride ~ase~ flux and its u~e in treating ferrous
ac~icles prior t:O being coat:ed witn an ~luminum-zinc
alloy ~
Pr i o r Ar t
~_____
L() U.S. 9 .,998 di scloses an aqueous galv~nizing
~lux containing ammorl`um chloricle, zinc chloride, and
potassium shlor ide .
U.S. 1,914,~9 discloses a molten salt flux
bath colltainincJ zinc c~lloride, an~lonium chloride, and
]. 5 a ~ lu o r i ne compound.
U.~. 3,74Q,~75 disc:Loses an aqueous flux
contaln:ing zinc cnloride, ~orax or boric acid,
potassi~lm alurninum fluoride, sodi.um chloride, and
eithe~. barium chloride or cal.cium chloride.
U.S. 3,80h,356 discLoses an aqueous flux
containi.ng variolLs combinatic!ns o fluorosilicic
acid, hl~drochloric acid, h~dYofluoric acid, potassium
fluoride!, and Z~ C chloride.
U.S. 3 rl316/188 discloses an aqueous f:Lux
~5 containing z:inc chloride or 3illC bro;niae and a zinc
phosphat:e or ziTIc phosphite and optionally a foan.i.rl$
agent and a chloride or bromi.de of any of sodium,
potassium, lith:ium r;lagnesium andfor calci.um.
Summ~ of t:he l:nvention
Tne pre:,ent invention relates to a flu~c for
the treatment of ferrous artirles prior to dipping in
a mo].t~n bat:h of aluminum and zinc. The aqueous flux
cc~r.taills 3inc chloride, ammonium chloride, and one or
more of sodium f luoride, am-lrlcniunL fluoride, or
ammonium bifluoride in t:he hereinbelow set forth
CH-ll99 A cr itica3 amounts~
Det:ailecl Descri~tion
Ferrous articles to be coated generally are
c.Ltaned of grease and ~cale (iron oxides) prior to
tht! appl:ication of ~he metallic coatingO In a
con.ti1luo~1s operal:ion~ i.e., stri.p or wire, the
mat.erial is gene]~ally cleaned c~rd then maintained in
an oxide reduci.n.~ atmosphere until it ~s imme.rsed in
a molten metal COa~ing bathO When using the a~ueous
f:l.ux of t:he present in~-ention, i.t is unnecessary to
maintclin ~he ferIous article in a reducing atmosphere
between the fl.uxi.ng step and the coati.ng step. The
aqueouc flu~ of ~.he present in.vention .LS inte1~c~ed for
use in fluxlnt1 ferrous --lrticles s1.~ch as steeL strip
pri~r to bei.ng coated in a rnolt:en metal bath
L5 containin~ ~rt?m 5 to 70 weigh~ % aluminum, 95 t.o 30
~eight ~ zinc,`ar,,d if desired, u2 to about 3 weight
percent, based on ~he al.uminum present, silicc)n. It
is also useful for fluxing articles that are
?rocec;sed in a noncontirluous fashion, by di.ppi.ng
:in,~lviduai.ly or in groups. The flux may L~e llsed as
mo:Lt:en fiux or in aqueou's solution.
enerally the aqueous.flux of the present
ini7ention will ~o:ntain fr.om 00 to 750 g/l and
preferably from 400 to 6~10 g/l o~ dissolved solids.
rrhe disso:Lved solidi consist essel~t:ia1ly of zinc
o~n1.oride, sodium ~luoride, and aLrJno1-Lium chloride. If
desired, other fiuoride s~lts SUCh as ammonium
fluor.de, ammoniu]n '~ifluoride or potassium fl1loride
can. be subs' tuted .or sodium fluoride on an
equivalenl fluoride basis. Ge1lerally ~he flu~ sollds
(~het~ler ~Ised as a molten bath or an aqueous
so].uti~!-L) will cornprise ~rom 91 to 9~.5 percent by
weigslt zinc chloride, from 1.5 to 9 percen~ by weigh'
asnmonium c:hi~ride and, based on z:inc chloride and
ammoniu1n c:~lloride, from 0.6 tO 2 percent by weight
~ 5 ~t~
fluoride ion. For use when the molten meta]. is 5
weight ~ aluminum ancl 95 weight: ~ zinc the preferred
flux cont:ains as dissol~ed soli.ds 9l. to 97 pe:rcent by
~ei.ght zi.nc chloride from 3 ~o 9 percent by weicJht
ammoniu.m chloride and, bast.~d on zinc chloride and
amrtlonium chloride, from 1 to 3 percent by weight
:Eluoride lon.. For use when the molten met~l is 55
perce3l1 by weight aluminum, ~3.5 percent b~ weight
zinc and i.5 percent by wei~ht silicon the prt.~ferred
1() i--lux contains as dissolved solids from 95 to 98.5
percent by weiclht zinc chloride from 1.5 to 5 percent
by weic~ilt ammonium cnlo~id~G and, based on z:inc
chl~ride and ammonium chlori.de, from 0.6 to ~. percent
by weight ~luoride ion. Immersion times are
generally t.rom 3 to 30 seconds for a continuoi!s line
a,nd ~ary with ~he thickness of the .~etal to be!
c:oated, '.he amount of preheat and the thickness of
c:oating desired. For large st.ructural pieces much
l.vnger times may be required.
Wt-~tt:ing agents may be added to the flux
sollltion i desi-ed.
~ptionally, ~H car.lbe control.led to get high
coneentrati.ons of salts in solu-tion. I'hus, ~he pF~
may be a~usted downward below the natural pH, for
example down to pH2. Hydrochlc)ric acid is preFerred
i.or this purpose. Generally, t:he flux bath will be
used at temperaturts r^rom ambient to 6CC.
E~amples
i:n each of ';he Examples the zinc chloride
reported i.s a. commefcial gracle ot zinc chloride
cont:aininc; 95 wt. ~ zinc chlc)ri.cle, 1.7 wt. ~ ammonilm
c:hlc,ride, l..i5 ~t~ ~ zinc oxide- ana the remainder
minor impurities.
.'5
E:xample_l
_ __ _
',teel parlelr measuring 2 inches (0.05 m) by
4 inches ~0.1 m) are hung on steel wires and pickled
in 15% hyclrochlclric acid for one minuie at room
telllperature. The panels are rinsed with water and
ther rinsed ~lth methyl alcohol to remove all the
water. The panels are immersed in the aqueous flux
at L80F (82C) for 30 seconds and then hung
T~ertically in an oven at 220E (104C) ~or a minimum
of 5 minutes~ l'he flux is an aqueous solutiorl
containing 2 1~ per ~allon ~240 Kg/m3) of a solid
compositiorl conC;istinq of 95.5 w~ ~ zinc cllloride,
2.5 wt. % sodium ]uoride, and 2.0 wt. % al~nonium
chloride. The pH of ~he flux bath is adjusted to pH2
by addition of n~droch:Loric ~cid to fully dissolve
the fluoride components. Each panel is hun~ on a
rack whlch automatically immerses the panel in a ~ath
of a moltell alloy ~f 5 wt. ~ aluminum, 0.04 wt. %
cerium, O.t)2 wt % lan'ha~urn and the remainder zinc
mai3ltairled at ~50C for a preset ~ime and then
removes it. Just before the panel is immersed, the
molten allc,y bat:~ is skimmed to remove c~urface
oxides. Skimming is done again before removal of the
panel to rem~ve flux residues as well as surface
o~ides.
Example 2
Example 1 is repeated except the solids used
to prepare the aqueous flux are 91 w~. ~ zinc
chloride, 3 wt. ~ sodium fluori.de and 6 wt. %
3(3 ammonium chloride.
Exa~!ple 3 ~CcJntroll
~ x~mple 1 is repeated except the solids used
to prepare the a~Iueous flux are! ~0 wt. % zinc
chïoride, 1~ wt. ~ sodium fluoride and 10 wt. %
ammonium biEluGrlde~
Ex~m~ 4 (Control)
Example 1 is ~epeated except the solids used
~o prepare ihe aqueous flux are commercial flux
products whose important components are 55.5 wto ~
~inc chloricle 42,.7 wt. ~ ammonium chloride and 0.1
wt,. ~ of a ]iquid nonionic ethylene oxide condensate
wet:ting agent and the pH OL the flux ba~h is not
ad~usted.
~ (Control)
Example 1 is repeated except the solids used
to prepare tne aqueous flux are 95 ~t % zlnc cnloride
an~ 5 wt~ ~ ammonillm chlo~ide.
Exa~pl* 6
___
Example 1 is re?eated except the flux is an
a~ueous soluti4n containirlg 2 lb. per galloll
(240 Ks~m3~ of a solid composition containing 94
wt. ~j zinc chloride, 4 wt. ~ sodium rluoride, and 2
w~. P6 ammonium chloride.
E~p~e 7
Example 1 is repeated except the flu~ is an
aqueous solution containing 2 lb. per gallon
(240 Kg/m3) of a solid composition containing 94
wt. % zinc chloride, 2 wt. ~ sol~ium fluoride, and 4
wt. % a~nonium chloride.
Exa~ple 8
~ xample 1 is repeated except tne flux is an
aqueous solution sontaining 2 lb~ per gallon
(''40 Kg~m ) of a solid composition containing 91
wt. ~ zinc c~lloride, 5 ~t. % sodium fluoride, and 4
wt. ~ ammonium chloride.
Exam~
Example 1 lâ repea',ed exce~t the flux is an
aqueous solution containing 2 lb~ per gallon
~240 ~Cg/m3) of a solid composition containing 92.5
: 5
~Lt~
wt. ~ zinc chloride, 3.4 wt. % ammonium bifluoride,
and 4.1 wt. ~ ammonium chloride.
Evaluation of Examples 1-9
A11 of the fluxes were tested using 5 an(l 15
second periods in the molten allGy ba~h. All of the
fluxes of E~amples 1 9 produced complete coating of
the panel. The fluxes of Examples 1, 2, and 6-
~produced significantly better coatings than the
fluxes of Examples 3, 4, and 5. The coatings
produced using the fluxes of Examples 1, 2, and 6-8
were quite smooth and had well defined spangles. The
flux of Example 3 ga~7e somewhat poorer results than
the fluxes c,f Examples 1, 2, and S-8. Next in order
was the flux of Example 5 and then the flux of
Example 4, borh of wnich gave considerably poorer
resul~s. The ~lux of Example 8 gave the hest results
with the flux of Example 7 a close seconcl.
ExamLoles 10-19
In Examples 10-19 steel panels measurina 3
inches by 5 inches by 0.0145 inch (,.6~ cm by 12.7 cm
b~r 0~037 cm~ are cleaned bv pickling in warm aqueous
10% hydrochloric acid for two min;ltes. Following an
immersion in the aqueous flux, whicn is heated up to
25 177~ (77C), the panels a-e dried in a verrical
position in an oven at 200C. A~.er drying, the
paneis are immersed in a 3O5 inch (0.089 m) inside
diameter by 6 inch (0.015 m) deep bath of 55 wt
aluminum, 43.5 wt ~ ~inc and 1.5 wt ~ silicon
30 maintained at 1110 to 1130E (5'39 - 610CC) for up
to 30 se~onds. ~he surface oxides of the molten bath
are removed by skimming both before immersion and
before removal of the panel. After remova~ fro~ the
molten batht ~he panels are air cooledO The ~anels
are evaiuated by a three judge panel as to percen age
t~
of area covered and as ~o surface smoothness. As to
smoothness, the three judge panel independently
examined the strips and rated them on a scale of 1 to
4 where 1 is roughest, 2 is fairly rough, 3 is light
5 or scattered roughness, and 4 is smoothest.
One series of coated articles was prepared
using the flux solutions reported ln Table I with the
results shown.
Table I
1 0
Solids NaF NH4Cl ZnCi2 Coverage Smoothness
Exa~ple ~J0. g,/l~ % % % Ratir,g
l~ 240 lO0 94 3
ll 24~ 5 95 96 3.7
12 240 5 95 94 3
13 240 7 8 85 94 1.7
14 480 2.8 9G ~39 4
~5 48~ 0 5 ~5 99 3~7
Exam~12 16
_
Example iO is repeated except the flux is an
aqueous solution containing 4 lb./gallon
(480 Kg/m ) of a solid composi~ion containing 97
wt. % zinc chloride, l.S wt. % ammonium chloride and
1.5 wt. % sodium fluoride to which has been added 0.4
wt. % Merpol* SH, a liquid fatty a:Lcohoi e~hylene
oxide condensation product sur~ace active agent.
Example 17
Example 10 is repeated except the flux is an
aqueous solution contain~ng 4 lb./gallon
(4~0 Kg/m3) of a solid composition containing 94.75
wt. % zinc chloride, 3.75 wt. % ammonium chloride and
1.5 wt. ~ sodi~m fluoride, to which has been added
0.4 wt. % Merpol* SH.
*denotes trade mark .
Example 18
-
Example 10 is repeated except the flux is an
aqueous solution containing 4 lb./gallon of a solid
composition containing 97.5 wt. ~ zinc chloride, 1.0
wt. ~ ammonium b.fluoride~ and 1.5 wt. % ammonium
chloride.
~:xample 19
Example 10 is repeated except that the flux
is an aqueous sollltion containing 4 1~.~gallon of a
solid composition Gontainlny 96~'35 wt~ ~ zinc
chloride, ~.55 wt. ~ ammonium bifluoride, and 1.5 wt.
ammoniu~ chloride
The fluxes of Examples 16 19 all produced
complete coating of the panel and a good quality
coating. Example 18 was the best of Exampies lG-l9.
