CA1122888A - Metal phosphatizing employing chlorate and aromatic nitro compound accelerator - Google Patents
Metal phosphatizing employing chlorate and aromatic nitro compound acceleratorInfo
- Publication number
- CA1122888A CA1122888A CA294,399A CA294399A CA1122888A CA 1122888 A CA1122888 A CA 1122888A CA 294399 A CA294399 A CA 294399A CA 1122888 A CA1122888 A CA 1122888A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- chlorate
- aromatic nitro
- nitro compound
- coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
- C23C22/08—Orthophosphates
- C23C22/12—Orthophosphates containing zinc cations
- C23C22/17—Orthophosphates containing zinc cations containing also organic acids
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
- C23C22/362—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also zinc cations
Abstract
P-10719 AEK/dlr METAL PHOSPHATIZING EMPLOYING CHLORATE
AND AROMATIC NITRO COMPOUND ACCELERATOR
ABSTRACT OF THE DISCLOSURE
An aqueous composition for treating a metal surface to produce a phosphate coating containing zinc, phosphate, chlorate and an aromatic nitro compound.
AND AROMATIC NITRO COMPOUND ACCELERATOR
ABSTRACT OF THE DISCLOSURE
An aqueous composition for treating a metal surface to produce a phosphate coating containing zinc, phosphate, chlorate and an aromatic nitro compound.
Description
1 0 7 ] 9 131\CKt7R()UMD ()l? TlïF I~ NTI()I`I -It is well ]cnown to ,form coatings on me~al surfaces by chemical reaction between the surface and inc3reclients in a coating solution, the resultclnt coatincJS servill~, for example, to improve corrosion resistance and to provide a suitable base for s~hsequently appliec,t paint coatin~s.
Various chemical coating processes are known, probahly the most common usin~ coaling solutions such as æinc phosphate coating solutions, alkal.i metal phosphate coatin~ solutions and oxalate coatin~ solutions. It i5 well known that in order to accelerate the speed of formation of the coating and/or to modify the properties of the resul~ant coating it is usually des,irable to include an oxidizing agent in the solution to serve as an accelerator.
Over the years a ~ery large nul~ber OL accelerators have been proposed as have various speci~ic combinations oi.
them. In genera] d.ifferent types o.f coating processes re(~uire, for o~timum performance, different accelerators.
Thus, :Eor instance, as a general rule an accelerator that ~0 ~as ound to be optirnum for some particu]ar oxalat:e process would not be expected to be optimum ~or some entirely different process, such as a phosphate coating process.
Instead it i.s necessary to choose the oxid.i~.ing a~en-t accele~ator having re,qard to the speciflc component-s of the coati.n~ composition.
Pmonqst the materl.als that h-:lv~ been pro~osc~.l as .
acc~.leratoxs for Y~inc phospllate coati.nc~ so'l.llti.orls a$e~
chlorates, nitrates, orcJan,i.c nitro compoull(ls, hyclro~en pero~ide, n.itrites, hroma-tes alld io~a1-esA Illc]u~le(~ nonqst- :
30 QJ~~anic nitrc~ coml.~o~ cls that have beell pro~c.se(l c~re so~l:ium !
P-ln7 1.~
m-nitrohen%elle sul3?honclte and cl:initrobenzeIle ,sulpllorlate.
Such o~id:i~in~3 a~ents are listed in, for ins-tance, Bx~l_ish Patent Speeiication No. 828,9]6, whi.ch relates to a rather partieular type o:E zinc phosphate coatin~ solution, namely one eontaining ealcium.
A ~ine phosphate COatinCJ solwtion that has found particularly wide aeceptance is one aceelerated by ehlorate~
Mo~ever it has ~een well aceepted for a long time that ehlorate by itself is not al~A~ays adequate and when it has been desi.red to have a second oxidisin~ agent to serve also as an aceelerator it has become normal to use nitrate with the chlorate. Thus zinc phosphate solutions aecelerated by-a mi~ture of nitrate and chlorate have beeome very well established eonunercially. Such solutions are described in, for instanee, British Patent Speeifieations Nos. 551,261 1,296,S83, 1,2~7,715~ 1,374,963, and 1,376,309 and zinc calcium phosphate solutions aceelerated by nitrate and optionally also chlo~ate are deseri.bed~in British Patent Speeifieat,ion No. 828,906.
Typieally aeeelerated zinc phosphate solutions need to be eontaeted with the metal sl1rfaee for, say r at least 1 millute in or~ler to form the eoating. For instanee if a solution such as is deserihed in Rritish Patent 9peeifieations Nos. 1!296,883, 1,297,7].5, or 1,37~,963 is being ayplied to a metal surfaee by spraying them a spraying period of at least . 60 seeonds, and preferably 90 seeonds is needed to aehieve opti~um eoatin~ condition.q. IIowever in some i.nstanees it ~ould be desirable to be able to obtaill optimum eoat:iny .in a shorter period and so there i.s a nePd for a æi.ne pllosphate eoatin~ solution that will form ~1 satlsfaetory eoatin~ qllieker ~ ~ 2 ~.......... .
.
P-1071~
than ~ e conventiona], an;l widely uscd zinc phosphate coating solutions that are accelerated with c~hlorate or chlorate and n.itrate. Of course the speed of coating can be increased by increasing the temperature but this is inconvenient in many in.stances.
The four most commonly used accelexat,ors are chlorates, nitrates, hydrogen peroxlde and ni.l:rites.
Peroxldes do not help solve the particula,r problem since they tend to cause even slower coating formation than chlorates with or without nitrates. Nitrites will give ~uicker coating formation, either by themselves or with chlora.te, but unfortunately suffer from the disadvantage that their ; use generates toxic sases, this being a particularly serious problem in a spxay process. Accordingly they are not desirable either. ' , A combination of chlora~e and aromatic nitro compolmd is disclosed as an accelerator in an oxalate solution in British Patent Specification No. 823,373 but the requirements for such accelerators are entirely different from those ~or zinc phosphate solutions and, as disclosed therein, the purpose of adding the aromatic nitro compound is to overcome the'd.isadvantage that chlorate alone, ln an oxalate solutiont ~id not ~ive a ~ood coating with a freshly prepared solution, ',:
.
and there was no su~gestion in that specificat.ion that the combination of chlorate and nitrate would have any desirable ' : or other effect either on coating weigh,t or on the rate oE
coating formation in oxalate coatings. : :
.
- : ~
-~: ~3~
: :
.
.
. -, - . - . , . . . ' , , : .
SUMMAR~ OF THE INVENTION
We have now found the coating formation using a zinc phosphate coating solution accelerated with chlorate can be accelerated still further by including in it a water soluble aromatic nitro compound as additional accelerator. It is par-ticularly surprising that the combination of chlorate and water soluble aromatic nitro compound results in increased coating formation since the aromatic nitro compounds themselves are by themselves less effective accelerators than both chlorate and nitrate and so would not be expected to increase -the rate of coating formation above that when chlorate alone or chlorate and nitrate are used. Thus the combination of chlorate and aromatic nitro compound is, in a zinc phosphate solution, syner-gistic as regards rate of coating formation. It also has the advantage that it tends to give a lower coating weight than when either chlorate or aromatic nitro compound is used alone, and this is desired in many instances.
The aqueous treating solution according to the inven-tion consists essentially o~: an a~ueous treating composition consisting essentially o~:
Zinc 0.15 - 0.4 wt%
Phosphate 0.4 - 1.6 wt%
Chlorate 0.3 - 0O5 wt%
Aromatic Nitro Compound ~,O~ - o.l~ W t ~
wherein the weight ratio of chlorate to aromatic nitro compound is 3 - 5 : 1.
A phosphate coating is formed on a metal surface by contacting the surface with the aqueous treating solution accord-ing to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The aromatic nitro compounds pre~erably contain not ~ 4 .
more than two nitro groups. The preferred compound for use inthe invention is sodium meta~nitro-benzenesulphonate, but other compounds including dinitro aromatic compounds such as those disclosed in sritish Patent Specification No. 970,366 and nitro phenols may be used.
The composition of the invention may also advantage-ously contain nitrate. We also find that the maximum coating speed is achieved where zinc is present in an amount greater - 4a -P~1071 than tha~ stoiclli.ometrically required to form ~inc dihyclrogen phospllate. The excess zinc i~ preferabl~ aclded in zinc nitrate.
The e~sential ingredien-cs of the coatin~ solution are zinc, phospllate r chloratc and the aromatic ni~.ro compound.
Preferred amounts fox the various ingredlents are Zn 0.15 O . 4 0 % w/~r; P 0 4 0 ~ 4 0 - 1 0 6; C 10 3 0~3 ~ Q.5; NO3 0 - 1.2;
aromatic nitro compound 0~05 - 0O15; and most preferably Zn 0.3 - 0 35, P0~1 O.A5 - 1~2; Cl03 0.33 - 0.4; .N03 0.3 -0.7; arol~atic nit.ro compound 0.06 - 0.09. In these formulations the aromatic nitro compound is preferably sodium nitro benzene sulphonate (SNBS). The ration by wei.ght of chlorate to aroma~ic nitro compouncl is preferably 3 : l 5 : l.
Although the advantages are less marked, if desired calcium can be included in the coating solution, for instance in the proportions based on zinc phosphate suygested in British Patent Specification No. 828,916.
The coatin~ solutions may be used ~or orming coating on iron, steel, zinc and alumi.nium surfaces, but i the solution is to be used for coating aluminium surfaces then fluoride should be included in the solution. Fluoride containinc..~ ~.inc phosphate so].utlons preferably contain from 0.03 - 0.1~- F. . ~ :
The total acid content of the soluti.ons is preferably from 7 to 2A point:s and the :Eree acid content is ~5 preferabl~ from 0.2 to 22 points.
: ~he 7.inc~, phosphate, ch].orate and, ie present, fluoride can~all }~e introduced in conventi.onal form. ~.
~ It i~ a cO~i~Oll practice to ma]-~c a liquid conc~entrate and to dilute this to orm a work:lnq soluti.on. If ~ hic~hl.y concent.xated composition is l:o be Inacle ancl stored :Eox use , ' i :' ~ .'j - .
~-10719 without forminy a precip.i.tate dur.ing storaye, it mu-;t con~air too much free acicl i.n proportion to thetotal acid, ancl ~hcn it is diluted some neutralising substance must thel-e~ore bc added to reduce the free aeidity~ Suitable sub.st~lnces for this purpose include zinc carbonate, zinc ox.ide, c~ustic soda and sodium carbonate, but care must he taken not to ~Idd anything which might be deleterious to the phosphate coatinc3.
Solutions according to the invention ma~ contain other ingredients such as metal accelerators and coating refining additives. Specifically, the solution may also contain from 0-001 to 0.025% w/w niekel, eobalt or copper as a metal aecelerator, and preferably the metal is niclcel in an amount from 0.005 to 0.02% w~w. Examples of coat refining additives are tartarie and eitric acids, an~ calcium in the form of any suitable compound as described in British Specifications Nos. 828,916 and 866,377.
The solutions of the invention can be applied i.n any eonvenLent manner, for example by immersion or spray, but are preferably applied by spray or combinecl spray and
Various chemical coating processes are known, probahly the most common usin~ coaling solutions such as æinc phosphate coating solutions, alkal.i metal phosphate coatin~ solutions and oxalate coatin~ solutions. It i5 well known that in order to accelerate the speed of formation of the coating and/or to modify the properties of the resul~ant coating it is usually des,irable to include an oxidizing agent in the solution to serve as an accelerator.
Over the years a ~ery large nul~ber OL accelerators have been proposed as have various speci~ic combinations oi.
them. In genera] d.ifferent types o.f coating processes re(~uire, for o~timum performance, different accelerators.
Thus, :Eor instance, as a general rule an accelerator that ~0 ~as ound to be optirnum for some particu]ar oxalat:e process would not be expected to be optimum ~or some entirely different process, such as a phosphate coating process.
Instead it i.s necessary to choose the oxid.i~.ing a~en-t accele~ator having re,qard to the speciflc component-s of the coati.n~ composition.
Pmonqst the materl.als that h-:lv~ been pro~osc~.l as .
acc~.leratoxs for Y~inc phospllate coati.nc~ so'l.llti.orls a$e~
chlorates, nitrates, orcJan,i.c nitro compoull(ls, hyclro~en pero~ide, n.itrites, hroma-tes alld io~a1-esA Illc]u~le(~ nonqst- :
30 QJ~~anic nitrc~ coml.~o~ cls that have beell pro~c.se(l c~re so~l:ium !
P-ln7 1.~
m-nitrohen%elle sul3?honclte and cl:initrobenzeIle ,sulpllorlate.
Such o~id:i~in~3 a~ents are listed in, for ins-tance, Bx~l_ish Patent Speeiication No. 828,9]6, whi.ch relates to a rather partieular type o:E zinc phosphate coatin~ solution, namely one eontaining ealcium.
A ~ine phosphate COatinCJ solwtion that has found particularly wide aeceptance is one aceelerated by ehlorate~
Mo~ever it has ~een well aceepted for a long time that ehlorate by itself is not al~A~ays adequate and when it has been desi.red to have a second oxidisin~ agent to serve also as an aceelerator it has become normal to use nitrate with the chlorate. Thus zinc phosphate solutions aecelerated by-a mi~ture of nitrate and chlorate have beeome very well established eonunercially. Such solutions are described in, for instanee, British Patent Speeifieations Nos. 551,261 1,296,S83, 1,2~7,715~ 1,374,963, and 1,376,309 and zinc calcium phosphate solutions aceelerated by nitrate and optionally also chlo~ate are deseri.bed~in British Patent Speeifieat,ion No. 828,906.
Typieally aeeelerated zinc phosphate solutions need to be eontaeted with the metal sl1rfaee for, say r at least 1 millute in or~ler to form the eoating. For instanee if a solution such as is deserihed in Rritish Patent 9peeifieations Nos. 1!296,883, 1,297,7].5, or 1,37~,963 is being ayplied to a metal surfaee by spraying them a spraying period of at least . 60 seeonds, and preferably 90 seeonds is needed to aehieve opti~um eoatin~ condition.q. IIowever in some i.nstanees it ~ould be desirable to be able to obtaill optimum eoat:iny .in a shorter period and so there i.s a nePd for a æi.ne pllosphate eoatin~ solution that will form ~1 satlsfaetory eoatin~ qllieker ~ ~ 2 ~.......... .
.
P-1071~
than ~ e conventiona], an;l widely uscd zinc phosphate coating solutions that are accelerated with c~hlorate or chlorate and n.itrate. Of course the speed of coating can be increased by increasing the temperature but this is inconvenient in many in.stances.
The four most commonly used accelexat,ors are chlorates, nitrates, hydrogen peroxlde and ni.l:rites.
Peroxldes do not help solve the particula,r problem since they tend to cause even slower coating formation than chlorates with or without nitrates. Nitrites will give ~uicker coating formation, either by themselves or with chlora.te, but unfortunately suffer from the disadvantage that their ; use generates toxic sases, this being a particularly serious problem in a spxay process. Accordingly they are not desirable either. ' , A combination of chlora~e and aromatic nitro compolmd is disclosed as an accelerator in an oxalate solution in British Patent Specification No. 823,373 but the requirements for such accelerators are entirely different from those ~or zinc phosphate solutions and, as disclosed therein, the purpose of adding the aromatic nitro compound is to overcome the'd.isadvantage that chlorate alone, ln an oxalate solutiont ~id not ~ive a ~ood coating with a freshly prepared solution, ',:
.
and there was no su~gestion in that specificat.ion that the combination of chlorate and nitrate would have any desirable ' : or other effect either on coating weigh,t or on the rate oE
coating formation in oxalate coatings. : :
.
- : ~
-~: ~3~
: :
.
.
. -, - . - . , . . . ' , , : .
SUMMAR~ OF THE INVENTION
We have now found the coating formation using a zinc phosphate coating solution accelerated with chlorate can be accelerated still further by including in it a water soluble aromatic nitro compound as additional accelerator. It is par-ticularly surprising that the combination of chlorate and water soluble aromatic nitro compound results in increased coating formation since the aromatic nitro compounds themselves are by themselves less effective accelerators than both chlorate and nitrate and so would not be expected to increase -the rate of coating formation above that when chlorate alone or chlorate and nitrate are used. Thus the combination of chlorate and aromatic nitro compound is, in a zinc phosphate solution, syner-gistic as regards rate of coating formation. It also has the advantage that it tends to give a lower coating weight than when either chlorate or aromatic nitro compound is used alone, and this is desired in many instances.
The aqueous treating solution according to the inven-tion consists essentially o~: an a~ueous treating composition consisting essentially o~:
Zinc 0.15 - 0.4 wt%
Phosphate 0.4 - 1.6 wt%
Chlorate 0.3 - 0O5 wt%
Aromatic Nitro Compound ~,O~ - o.l~ W t ~
wherein the weight ratio of chlorate to aromatic nitro compound is 3 - 5 : 1.
A phosphate coating is formed on a metal surface by contacting the surface with the aqueous treating solution accord-ing to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The aromatic nitro compounds pre~erably contain not ~ 4 .
more than two nitro groups. The preferred compound for use inthe invention is sodium meta~nitro-benzenesulphonate, but other compounds including dinitro aromatic compounds such as those disclosed in sritish Patent Specification No. 970,366 and nitro phenols may be used.
The composition of the invention may also advantage-ously contain nitrate. We also find that the maximum coating speed is achieved where zinc is present in an amount greater - 4a -P~1071 than tha~ stoiclli.ometrically required to form ~inc dihyclrogen phospllate. The excess zinc i~ preferabl~ aclded in zinc nitrate.
The e~sential ingredien-cs of the coatin~ solution are zinc, phospllate r chloratc and the aromatic ni~.ro compound.
Preferred amounts fox the various ingredlents are Zn 0.15 O . 4 0 % w/~r; P 0 4 0 ~ 4 0 - 1 0 6; C 10 3 0~3 ~ Q.5; NO3 0 - 1.2;
aromatic nitro compound 0~05 - 0O15; and most preferably Zn 0.3 - 0 35, P0~1 O.A5 - 1~2; Cl03 0.33 - 0.4; .N03 0.3 -0.7; arol~atic nit.ro compound 0.06 - 0.09. In these formulations the aromatic nitro compound is preferably sodium nitro benzene sulphonate (SNBS). The ration by wei.ght of chlorate to aroma~ic nitro compouncl is preferably 3 : l 5 : l.
Although the advantages are less marked, if desired calcium can be included in the coating solution, for instance in the proportions based on zinc phosphate suygested in British Patent Specification No. 828,916.
The coatin~ solutions may be used ~or orming coating on iron, steel, zinc and alumi.nium surfaces, but i the solution is to be used for coating aluminium surfaces then fluoride should be included in the solution. Fluoride containinc..~ ~.inc phosphate so].utlons preferably contain from 0.03 - 0.1~- F. . ~ :
The total acid content of the soluti.ons is preferably from 7 to 2A point:s and the :Eree acid content is ~5 preferabl~ from 0.2 to 22 points.
: ~he 7.inc~, phosphate, ch].orate and, ie present, fluoride can~all }~e introduced in conventi.onal form. ~.
~ It i~ a cO~i~Oll practice to ma]-~c a liquid conc~entrate and to dilute this to orm a work:lnq soluti.on. If ~ hic~hl.y concent.xated composition is l:o be Inacle ancl stored :Eox use , ' i :' ~ .'j - .
~-10719 without forminy a precip.i.tate dur.ing storaye, it mu-;t con~air too much free acicl i.n proportion to thetotal acid, ancl ~hcn it is diluted some neutralising substance must thel-e~ore bc added to reduce the free aeidity~ Suitable sub.st~lnces for this purpose include zinc carbonate, zinc ox.ide, c~ustic soda and sodium carbonate, but care must he taken not to ~Idd anything which might be deleterious to the phosphate coatinc3.
Solutions according to the invention ma~ contain other ingredients such as metal accelerators and coating refining additives. Specifically, the solution may also contain from 0-001 to 0.025% w/w niekel, eobalt or copper as a metal aecelerator, and preferably the metal is niclcel in an amount from 0.005 to 0.02% w~w. Examples of coat refining additives are tartarie and eitric acids, an~ calcium in the form of any suitable compound as described in British Specifications Nos. 828,916 and 866,377.
The solutions of the invention can be applied i.n any eonvenLent manner, for example by immersion or spray, but are preferably applied by spray or combinecl spray and
2() immersion. The temperature is pref~rably from 40 - 55C.
rrhe time of contact with immersion may be S - 10 minutes and with spray .it is preferably 45 - 90 seconds.
` During use the bath of coating solution will need to be replenished and preferably it is repleni.shecl usi.ny two repleni~hment solutions, as descri.bed in Brl tish Patent Speeifieation No. 1,376,30~. Thus one .';OlUtiOII eon-ta.i.ns : the zinc and phosphate and optionally ni.trat.e a~d ~luoride and the other contains a].kali, usually sod.ium hydroxicle, ehlorate, usually sodium chlorate, and the aromatic nitro ~O compouncl.
The following are Examples. - ~
6" x 4" panels were treated by 60 second spray at 45C. In all 445m2 of cleaned mild steel were processed.
Sample panels were taken every lOOm2 electropainteci in a grey electroprimer and salt spray tested accordlng to ASTM B117. After 240 hours all gave excellent~ corros.ion results. Adhesion results were also good.
Finely crystalline uniform phosphate coatings were obtained throughout wlth coating weights in the range 1.4 -- 1.8 g/~
I.M.U. Main Replenishment .
ZnO = 125 pts. wt~ ZnO = 125 pts. wt.
~3PO,l = 173 " " El3PO~ = 230 1!
HN03 = 128 " " ~IN03 = 80 " "
HF -~ 14 " " HF = 3 " "
Tartaric acid = 27 " " Tartaric acid = 27 " "
H20 to ma]ce 1000 H20 to make 1000 ACCI~I.ERATO_PLENISI-I~IENT
NaO~I ~ 101 pts. wt.
2~ Na~103 = 16 " "
SNBS -- 8 '' II20 to ma]ce 1000 3Q Litres of working solution ~Jere prepared from:
30 ~/1 I.M.U. ~ 5 g/l NaC103 -~ 1 cJ/l SNr,S -~ 2g/1 NaOH.
During use the zinc content was ]cept constant by freclLIent additions of the main replenishment and the re;3 acidity of -~ the solution ~r!aS recju1ated by additiorls of accelerator replenishment.
~7-
rrhe time of contact with immersion may be S - 10 minutes and with spray .it is preferably 45 - 90 seconds.
` During use the bath of coating solution will need to be replenished and preferably it is repleni.shecl usi.ny two repleni~hment solutions, as descri.bed in Brl tish Patent Speeifieation No. 1,376,30~. Thus one .';OlUtiOII eon-ta.i.ns : the zinc and phosphate and optionally ni.trat.e a~d ~luoride and the other contains a].kali, usually sod.ium hydroxicle, ehlorate, usually sodium chlorate, and the aromatic nitro ~O compouncl.
The following are Examples. - ~
6" x 4" panels were treated by 60 second spray at 45C. In all 445m2 of cleaned mild steel were processed.
Sample panels were taken every lOOm2 electropainteci in a grey electroprimer and salt spray tested accordlng to ASTM B117. After 240 hours all gave excellent~ corros.ion results. Adhesion results were also good.
Finely crystalline uniform phosphate coatings were obtained throughout wlth coating weights in the range 1.4 -- 1.8 g/~
I.M.U. Main Replenishment .
ZnO = 125 pts. wt~ ZnO = 125 pts. wt.
~3PO,l = 173 " " El3PO~ = 230 1!
HN03 = 128 " " ~IN03 = 80 " "
HF -~ 14 " " HF = 3 " "
Tartaric acid = 27 " " Tartaric acid = 27 " "
H20 to ma]ce 1000 H20 to make 1000 ACCI~I.ERATO_PLENISI-I~IENT
NaO~I ~ 101 pts. wt.
2~ Na~103 = 16 " "
SNBS -- 8 '' II20 to ma]ce 1000 3Q Litres of working solution ~Jere prepared from:
30 ~/1 I.M.U. ~ 5 g/l NaC103 -~ 1 cJ/l SNr,S -~ 2g/1 NaOH.
During use the zinc content was ]cept constant by freclLIent additions of the main replenishment and the re;3 acidity of -~ the solution ~r!aS recju1ated by additiorls of accelerator replenishment.
~7-
Claims (10)
1. An aqueous treating composition consisting essen-tially of:
Zinc 0.15 - 0.4 wt%
Phosphate 0.4 - 1.6 wt%
Chlorate 0.3 - 0.5 wt%
Aromatic Nitro Compound .05 - 0.15 wt%
wherein the weight ratio of chlorate to aromatic nitro com-pound is 3 - 5 : 1.
Zinc 0.15 - 0.4 wt%
Phosphate 0.4 - 1.6 wt%
Chlorate 0.3 - 0.5 wt%
Aromatic Nitro Compound .05 - 0.15 wt%
wherein the weight ratio of chlorate to aromatic nitro com-pound is 3 - 5 : 1.
2. The composition of Claim 1 additionally containing 0 - 1.2 wt% nitrate.
3. The composition of Claim 1 wherein the aromatic nitro compound is selected from the group consisting of di-nitro aromatic compounds and nitrophenols.
4. The composition of Claim 3 wherein the aromatic nitro compound is sodium metanitro-benzenesulphonate.
5. The composition of Claim 1 wherein the concentration of the aromatic nitro compound is 0.06 - 0.09 wt%.
6. The composition of Claim 1 exhibiting a total acid of 7 to 24 points and a free acid of 0.2 to 22 points.
7. The composition of Claim 1 additionally containing 0.03 to 0.1% fluoride.
8. The composition of Claim 1 additionally containing from 0.001 to 0.025 wt% of a metal ion selected from the group consisting of nickel, cobalt and copper.
9. A process for forming a phosphate coating on a metal surface comprising contacting the surface with the composition of Claim 1 for a time sufficient to form a coating.
10. The process of Claim 9 wherein the composition is maintained at a temperature of 40 - 55°C during the contact period.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB299/77 | 1977-01-06 | ||
| GB77299A GB1542222A (en) | 1977-01-06 | 1977-01-06 | Phosphate coating compositions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122888A true CA1122888A (en) | 1982-05-04 |
Family
ID=9701932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,399A Expired CA1122888A (en) | 1977-01-06 | 1978-01-05 | Metal phosphatizing employing chlorate and aromatic nitro compound accelerator |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU517973B2 (en) |
| CA (1) | CA1122888A (en) |
| GB (1) | GB1542222A (en) |
| ZA (1) | ZA777688B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4498935A (en) * | 1981-07-13 | 1985-02-12 | Parker Chemical Company | Zinc phosphate conversion coating composition |
| DE3311738A1 (en) * | 1983-03-31 | 1984-10-04 | Metallgesellschaft Ag, 6000 Frankfurt | METHOD FOR PHOSPHATING METAL SURFACES |
| DE3325974A1 (en) * | 1983-07-19 | 1985-01-31 | Gerhard Collardin GmbH, 5000 Köln | METHODS AND UNIVERSALLY APPLICABLE MEANS FOR THE ACCELERATED APPLICATION OF PHOSPHATE COATINGS ON METAL SURFACES |
| GB2148950B (en) * | 1983-10-26 | 1987-02-04 | Pyrene Chemical Services Ltd | Phosphating composition and processes |
| ES8606528A1 (en) * | 1985-02-22 | 1986-04-01 | Henkel Iberica | Process for the phosphating of metal surfaces. |
| DE3630246A1 (en) * | 1986-09-05 | 1988-03-10 | Metallgesellschaft Ag | METHOD FOR PRODUCING PHOSPHATE COVER AND ITS APPLICATION |
| DE3631759A1 (en) * | 1986-09-18 | 1988-03-31 | Metallgesellschaft Ag | METHOD FOR PRODUCING PHOSPHATE COATINGS ON METAL SURFACES |
-
1977
- 1977-01-06 GB GB77299A patent/GB1542222A/en not_active Expired
- 1977-12-28 ZA ZA00777688A patent/ZA777688B/en unknown
-
1978
- 1978-01-05 CA CA294,399A patent/CA1122888A/en not_active Expired
- 1978-01-05 AU AU32179/78A patent/AU517973B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU3217978A (en) | 1979-07-12 |
| AU517973B2 (en) | 1981-09-10 |
| GB1542222A (en) | 1979-03-14 |
| ZA777688B (en) | 1978-10-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |