US3741747A - Highly alkaline titanated cleaner - Google Patents

Abstract

ALKALINE CLEANING, ACTIVATING AND GRAIN-REFINING OF FERROUS AND ZINC SURFACES IN PREPARATION FOR ZINC PHOSPHATE COATING IS PERFORMED SIMULTANEOUSLY WITH A SINGLE STABILIZED TREATING SOLUTION HAVING A PH ABOVE 10 CONTAINING A COLLOIDAL TITANIUM SALT.

Description

3,741,747 HIGHLY ALKALINE THTANATED CLEANER Andrew Joseph Hamilton, Philadelphia, and George Schneider, Trevose, Pa, assignors to Amchem Products, Inc., Ambler, Pa. No Drawing. Filed Sept. 30, 1971, Ser. No. 185,409 Int. Cl. C23f 7/10 U.$. Cl. 1486.15 Z 7 Claims ABSTRACT OF THE DISCLOSURE Alkaline cleaning, activating and grain-refining of ferrous and zinc surfaces in preparation for zinc phosphate coating is performed simultaneously with a single stabilized treating solution having a pH above 10 containing a colloidal titanium salt.

This invention relates to methods and compositions for treating ferrous and zinc surfaces to improve their corrosion resistance and paint adhesion properties. It is particularly concerned with improvements in the formation of crystalline phosphate coatings on steel and galvanized steel. .Such coatings are here termed zinc phosphate coatings, although it should be understood that manganese and calcium are included in some zinc phosphating systems and that the coatings formed from these systems include manganese phosphate or calcium phosphate along with zinc phosphate.

It should be understood that the term ferrous metal surface used herein includes a wide variety of steels, iron, and iron alloys, including alloys of iron with chromium and/or nickel, and the term zinc surface used herein includes zinc and zinc alloys in which zinc is the principal constitiTent, as well as galvanized surfaces, including both hot-dipped and electrogalvanized surfaces.

The treatment of a ferrous or zinc surface to produce a zinc phosphate coating thereon most commonly involves the following sequence of steps:

(1 alkaline cleaning (2) water rinse (3) activating and grain-refining (4) Water rinse (5) zinc phosphating (6) water rinse, and

(7) final passivating rinse.

In some instances the rinse of step 4 is omitted.

Each step in the foregoing sequence requires its own equipment, and requires its own control and attention during operation to insure that it performs its function properly, and performs it in coordination with the other steps in the treatment sequence. From an operational standpoint, it can be appreciated that the elimination of any step in the sequence, without adverse effects, produces a simplification of the operation.

From an equipment standpoint, the safe elimination of any step reduces the amount of equipment needed. Such a reduction is important in any installation, but it is of particular importance in a number of existing plants which were designed to use other metal treating processes involving five stages rather than the six or seven stages of the zinc phosphating process. As a practical matter, such plants have been unable to exploit the considerable advantages of the zinc phosphating process because they do not have enough equipment stages.

The present invention is most directly concerned with improvements in the cleaning stage and in the activating and grain refining stage of the zinc phosphating process. In accordance with the invention, these two stages can be successfully combined, and the two functions performed .anited States Patt O 3,741,747 Patented June 26, 1973 "ice simultaneously under highly alkaline conditions. The combining of these two stages permits the elimination of one set of treating equipment and one set of rinsing equipment, thus reducing the process to a five stage treating sequence capable of performance in plants having only five stage equipment.

The alkaline cleaning stage of a zinc phosphating process has been shown by experience to be important to the overall success of the treatment because good quality, uniform, corrosion resistant, paint adherent, zinc phosphate coatings are not satisfactorily obtained unless the metal being treated is cleaned. The kinds of soils commonly encountered include dust, grease, and oil. Alkaline cleaners, that is, cleaners with a pH in the range above 10, have been found to be effective and economical in removing the kinds of soil which interfere with the formation of a good zinc phosphate coating.

Activation and grain-refining have been found to be important operations in the process of producing a good zinc phosphate coating. The term activation refers to the conditioning of the metal surface so that a zinc phosphate coating will form on it readily and quickly. The need for surface activation varies somewhat with the particular type of zinc phosphating system employed. Some systems, such as the chlorate-nitrite accelerated systems disclosed in US. Patent 3,333,988, produce zinc phosphate coatings with a highly desirable set of properties, but require a highly activated surface to do so. Other zinc phosphating systems can be operated on less activated surfaces, but substantially all of them produce better coatings when the surface is highly activated. Grain-refining is a term employed to describe the conditioning of the surface to be treated so that the crystalline zinc phosphate coating when formed is made up of very fine closely packed crystals, as distinguished from relatively large, coarse, elongated and loosely arranged crystals. A fine grained zinc phosphate coating has been found by experience to be superior, both in its corrosion resistant and paint adherent properties, to a coarse grained surface. While the present invention is not intended to be limited by any theoretical explanation of this phenomenon, or any other phenomenon related to the invention, it can be pointed out that it is thought that large coarse crystals which are loosely packed leave significant areas of bare metal exposed in the interstices between crystals and that these exposed areas are very susceptible to rusting and corrosion. In addition, it is thought that large crystals are more susceptible to fracture upon being stressed, thus detracting from their paint adhesion properties. Coarse crystals tend to absorb more paint, thus decreasing the gloss of the finish, or making it necessary to apply extra coats of paint to obtain the same quality finish. Finally, coatings with coarse crystal structure are oftenloose or nonadherent.

The most widely used method for obtaining activation and grain-refining is to apply certain colloidal titanium salts to the surface prior to zinc phosphating. The salts are termed Jernstedt salts, as disclosed in US. Pats. 2,310,239 and 2,322,349, among others. It is thought that the Jernstedt salts act as activators and grain refiners by adhering to the surface, upon being contacted with it, in a multitude of closely spaced sites, thus providing a large number of crystallization nuclei on the surface. The large number of crystallization nuclei both activate the surface and grain refine it, because they make it possible for many zinc phosphate crystals to start to grow simultaneously. In this way, the coating is formed quickly, and the individual crystals remain desirably small because they grow into one another before any can become very large. In a sense, the Jernstedt salts undo the damage caused by efiicient cleaning. A good cleaner, in the course of removing soils, also removes the naturally occurring crystallization nuclei, thus deactivating the surface. The Jernstedt salts replace the crystallization nuclei.

Attempts have been made in the past to combine the alkaline cleaning stage with the activating and grain-refining stage in the zinc phosphate process. Pretreatments of surfaces with aqueous cleaning and activating baths are disclosed, for example, in Us. Pat. No. 2,490,- 062. However, problems have been encountered of the kind which often occur when attempts are made to perform two separate functions at once. In particular, it has been found that the Jernstedt salt colloid is not stable at the high pHs where cleaning solutions are most effective. The Jernstedt colloid tends to break at such pHs with the effect that it no longer activates or grain-refines the surface.

Attempts have been made to include certain stabilizing additives in combined activating and cleaning compositions. Such additives have included water soluble organic acids, examples of which are disclosed in US. Pat. No. 2,516,008. Even when by special manipulation a Jernstedt colloid can be maintained in operative condition in a high pH solution, such maintenance is so diflicult to perform that it has not proved practical or reliable. The accumulation of soils in the cleaner during use further aggravates the problem of maintaining the Jernstedt colloid in the solution in operative condition.

The conventional compromise which has been made to make it possible to clean and activate and grain refine simultaneously has been to use cleaner systems with relatively low pHs. This has been a less than satisfactory compromise because the mildly alkaline cleaners which are compatible with Jernstedt salts are not efficient and do not adequately clean heavily soiled metal.

It is an object of this invention to provide an improved method for applying zinc phosphate coatings to ferrous and zinc surfaces, which method employs a combined highly alkaline cleaning and activating and grain-refining stage, and produces fine grained zinc phosphate coatings.

Another object of this invention is to provide a method for stabilizing Jernstedt salts in a high pH environment, thus rendering them capable of use in eflicient alkaline cleaners.

A further object of the invention is the provision of improved metal treating compositions containing Jernstedt salts, which compositions are highly effective cleaners, activators, and grain-refiners, and are characterized by their high alkalinity.

A concomitant object of the invention is to provide a zinc phosphate coating process for ferrous and zinc metals which is a five-stage process, rather than six or seven stages, and which can be satisfactorily performed in plants having five-stage equipment.

The manner in which the foregoing objects, together with other objects, are attained will be understood by a consideration of the detailed description which follows.

It has been found that an aqueous alkaline solution comprising a colloidal titanium salt and a stabilizing composition consisting of silicate and a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate can be maintained in a stable state as it is utilized to clean and activate a plurality of metallic surfaces prior to the application of a zinc phosphate coating thereon.

In accordance with the invention the cleaning and activating solutions are highly alkaline, having a pH above about and contain the Jernstedt salt as a stable colloid. The amount of Jernstedt salt in the solution can be varied within wide limits in accordance with the general teachings of the above referred to Jernstedt patents. The concentration of the Jernstedt salt, expressed as titanium ion at the use dilution, may be varied between 0.005% by weight and 0.05% by weight. In accordance with the invention the Jernstedt salt is maintained as a stable colloid in the highly alkaline cleaning solution by a stabilizing composition, which is itself a combination of materials contributing to the cleaning action of the solution.

The stabilizing composition suitable for use in accordance with the present invention are those which are themselves stable in the alkaline cleaning bath having a pH above 10, under the temperature conditions normally obtained in a cleaning stage, that is, between about F. and about F. The concentration of the stabilizing composition, can be from about .03% weight/volume to about 1.5% weight/volume. The preferred use concentration for the stabilizing composition is between about .2% weight/volume and 1.0% weight/volume. Since the stabilizing composition also contributes to the cleaning action of the working solution as well as promoting the stability of the Jernstedt colloid, the amount required to be present is somewhat flexible, since one level of performance may be satisfactory for some operations, while a higher level is desired for others.

It should be understood that by aqueous cleaning, activating grain-refining solution, We mean the aqueous bath containing the Jernstedt salt and stabilizing composition, wherein said bath contains finely divided and colloidally dispersed particles which possess a certain stability resulting in no settling or precipitation and no loss in cleaning and activating effect. The term cleaning and activating concentrate or cleaning and activating composition means the combination of stabilizing composition, Jernstedt salt, other alkaline ingredients, and surface activators, said composition or concentrate employed to prepare the aqueous cleaning, activating, and grain-refining solution.

Among the materials which have been found to act as stabilizing compositions for the Jernstedt salt are a combination of silicate and condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate. Preferably, the silicate should be present as a combination of orthosilicate and metasilicate in certain proportions. The silicate and tripolyphosphate or pyrophosphate cooperate with each other to produce stabilizing results better than each of the materials produces alone.

In accordance with the invention, not all blends or mixtures of silicate and tripolyphosphate or pyrophosphate yield the desirable results described herein. The beneficial effects are dependent upon the proportions of silicate and condensed phosphate which are present. Such proportions can be conveniently expressed as weight ratios. The weight ratio of silicate to tripolyphosphate should be within the range of between about .4 and about 6 to 1. In the preferred embodiment of the invention the silicate portion of the stabilizing composition is comprised of orthosilicate and metasilicate and the proportions of each present should be such that for each part by weight of orthosilicate there is from about 1 part to about 5 parts by weight of metasilicate. Pyrophosphate can be substituted for tripolyphosphate thereby producing a substantially equivalent stabilizing composition, in which case the ratios of silicate and pyrophosphate should correspond to those specified hereinabove when tripolyphosphate is employed. The foregoing weight ratios are calculated on the basis of the sodium form of each material. In the preferred embodiment of this invention the sodium salts are selected for use, but the other alkali salts, such as potassium salts can be substituted.

It should be noted that the silicate and tripolyphosphate or pyrophosphate stabilizing composition contributes to the cleaning action of the alkaline cleaner in addition to protecting the Jernstedt salt. These materials, in various combinations, have been employed in the past to clean metals, although it has not been regarded as good practice to use silicates as cleaners for steel because of the difliculty in removing the silicate if it dries on the surface.

The aqueous cleaning and activating solution of the present invention can also contain ingredients such as soda ash, trisodium phosphate, and caustic soda, and any other high alkaline ingredients contributing to the alkalinity of the cleaning bath and to its cleaning action.

The cleaning and activating composition or concentrate of the present invention is prepared by adding a Jernstedt salt to an alkaline cleaner concentrate comprising the stabilizing composition and desirable alkaline cleaning ingredients, said Jernstedt salt added in an amount from about 1% to about 20% by weight. The concentration of the stabilizing composition in the cleaning and activating concentrate can be from about 50% by weight to about 80% by weight, depending upon the amounts of the additional alkaline cleaning ingredients present.

Alternatively, the cleaners and activators of this invention can be added to an aqueous bath as two separate component concentrates the cleaner concentrate as one component and the Jernstedt salt added as a separate component to form the stable aqueous cleaning, activating, and grain-refining solution at concentrations for use.

Surfactants and foaming agents are desirably included in the cleaning and activating composition or concentrate. Such materials enhance the cleaner performance but are not of the essence of the invention since they are used to perform functions substantially similar to the function they perform in prior art solutions. It can be observed, however, that nonionic surfactants and foam control agents operate best in cleaning baths of the invention.

In accordance with the invention a suitable solid concentrate, when added to water that is capable of both cleaning, activating and grain-refining ferrous and zinc Following are further examples of solid concentrates for simultaneously cleaning, activating, and grain-refining surfaces, utilizing the stabilizing compositions of this invention and formulated in accordance with the present invention:

FORMULA 2 Percent by weight Sodium tripolyphosphate (anhydrous) 20 Sodium metasilicate (anhydrous) 40 Sodium orthosilicate (anhydrous) Soda ash l0 Jernstedt salt 13 Nonionic surfactants 7 FORMULA 3 Percent by weight Sodium tripolyphosphate (anhydrous) 10 Sodium metasilicate (anhydrous) 50 Sodium orthosilicate (anhydrous) 10 Soda ash 1O Jernstedt salt 13 Nonionic surfactants 7 FORMULA 4 Percent by weight Sodium tripolyphosphate (anhydrous) 50 Sodium metasilicate (anhydrous) 10 Sodium orthosilicate (anhydrous) 10 Soda ash 10 Jernstedt salt 13 Nonionic surfactants 7 6 FORMULA 5 Percent by weight Sodium tripolyphosphate (anhydrous) 40 Sodium metasilicate (anhydrous) 20 Sodium orthosilicate (anhydrous) 10 Soda ash 10 Jernstedt salt 13 Nonionic surfactants 7 FORMULA 6 Percent by weight Tetrasodium pyrophosphate 30 Sodium metasilicate (anhydrous) 30 Sodium orthosilicate (anhydrous) l0 Soda ash l0 Jernstedt salt l3 Nonionic surfactants 7 FORMULA 7 Percent by weight Tetrasodium pyrophosphate 40 Sodium metasilicate (anhydrous) 20 Sodium orthosilicate (anhydrous) 10 Soda ash 10 Jernstedt salt l3 Nonionic surfactants 7 FORMULA 8 Percent by weight Tetrasodium pyrophosphate 20 Sodium metasilicate (anhydrous) 40 Sodium orthosilicate (anhydrous) 10 Soda ash l0 Jernstedt salt 13 Nonionic surfactants 7 FORMULA 9 Percent by weight Sodium tripolyphosphate (anhydrous) 30 Sodium metasilicate (anhydrous) 3O Jernstedt salt 13 Sodium sulfate 10 Soda ash l0 Nonionic surfactants 7 FORMULA 10 Percent by weight Tetrasodium pyrophosphate (anhydrous) 23 Sodium orthosilicate (anhydrous) 44 Jernstedt salt 8 Soda ash 17 Nonionic surfactants 8 In all of the formulations, the component referred to as Jernstedt salt was prepared by slurrying parts of disodium phosphate with 5 parts of potassium fluotitanate in water. The slurry Was then evaporated to dryness at 70 C. to produce the Jernstedt salt. Other forms of Jernstedt salt can be prepared in accordance with the teachings of the references mentioned above, and utilized in accordance with this invention.

The treating solutions of this invention when employed in the cleaning and activating process can be applied to the substrate utilizing any of the contacting techniques known to the art. Preferably, application will be effected by conventional spray or immersion methods. The time of treatment of a metal surface with the cleaning and activating solution need only be long enough to ensure complete Wetting of the surface and can be as long as 5 minutes. Preferably, the surface should be treated for a time from about 15 seconds to about 1 minute.

The treating bath can be operated at temperatures as high as 180 F. It is preferred that the cleaning and activating process be operated at temperatures from about F. to about F.

In accordance with broader aspects of the invention, there is considerable flexibility available to those practicing it with respect to portions of the overall zinc phosphating process. In particular, substantially all of the various zinc phosphating formulations known to the art can be used to good effect. The operating conditions of the zinc phosphating stage can similarly be varied in accordance with good art practice, so far as treating time, temperature, method of application, and the like are concerned. In the examples which folow, particular zinc phosphating solutions are employed for illustrative purposes, but other zinc phosphating solutions may be used.

Similarly, the final passivating rinse may be any one of the variety of solutions which are known to perform this function well, operated under the conditions regarded by the art as good practice. For example, a dilute chromate solution can be utilized as the final passivating rinse following application of the zinc phosphate coatmg.

The following examples are illustrative of this invention and are not considered as limiting for other materials and operating conditions falling within the scope of this invention that might be substituted.

EXAMPLE 1 A series of tests were performed utilizing Formulas 1 through 5, at a concentration of 5.6 grams/liter, in order to illustrate the cooperation of orthosilicate, metasilicate, and tripolyphosphate for protceting the Jernstedt salt under highly alkaline conditions while cleaning is effected concurrently.

The aqueous cleaning, activating, and grain-refining solutions prepared by adding 5.6 grams of concentrate per liter of water were evaluated by treating cold rolled steel panels. The panels were sprayed with the baths for one minute at about 160 F. The solutions, as made up, had a pH as listed in Table 1 which remained substantially constant throughout.

The panels were subsequently sprayed with a zinc phosphate coating solution of the chlorate-nitrite type. This phosphate coating bath was formed from a concentrate having the following composition:

This concentrate was diluted with water to about 1% by volume for use. Sodium nitrite was added as a separate accelerating component in amounts sufficient to maintain a concentration of about .006% by weight. The bath temperature was maintained at about 130 F. and the treating time was about 1 minute.

The coating weights obtained when the pretreated panels were subjected to the phosphate coating bath are noted in Table 1. The zinc phosphated panels were visually evaluated to determine whether the solutions adequately grainrefined and activated the surfaces. A thin non-uniform and powdery phosphate coating indicated a lack of activation, and coarse crystals visible to the naked eye or under a low power microscope indicated a lack of refinement. The results are reported in Table 1.

TABLE 1 Coating weight Solution Coating appearance Uniform, fine grained. Uniigrm, slightly enlarged grain.

The significance of the foregoing coating weight data is that it provides a measure of the degree to which grain refinement is obtained. A high coating weight is an indication of the presence of coarse crystals, while a lower coating weight indicates that the crystals are refined and that the coating is more dense. Coating weight determinations are not an absolute measure of grain refinement and coating quality, since the optimum coating weight is strongly dependent on the particular kind of zinc phosphating solution employed. For the chlorate-nitrite accelerated solutions used in the present example, a good coating weight for the steel panels is in the neighborhood of to about 225 mg./ft. with a coating weight from about mg./ft. to about 180 mg./ft. being preferred.

It can be seen from Table 1 that the aqueous baths prepared with Formulas 1 through 5, simultaneously cleaned, activated and grain-refined and produced satisfactory coatings.

EXAMPLE 2 A series of tests were performed utilizing Formula 1 and formulas based on Formula 1 in which the tripolyphosphate or silicates were deleted and replaced by inert fillers. The treating solutions were prepared by adding the compositions to water at a concentration of 4/ 10% weight per volume. The various solutions were evaluated by spraying cold-rolled steel panels with each of the aqueous baths for one minute at about F- Test panels were sprayed in each test bath at each two hour interval. In order to determine the activating and cleaning qualities as well as the colloidal suspension qualities of the treating solutions in this test, the baths resistance to degradation caused by shear stresses within pumping systems and spray nozzles was observed. The solutions were not only employed at each two hour interval to spray test panels, but were continuously being circulated through a pumping system and sprayed at 160 F. and 10 p.s.i.g. pressure upon 3" x 4" stainless steel panels suspended between dual spray nozzles mounted approximately 2 inches apart. At each two hour interval, the stainless steel panels were replaced by the cold rolled steel test panels. After treatment, the panels were rinsed in cold water and immersed in a zinc phosphate coating solution of the chlorate-nitrite type. This phosphate coating bath was formed from a concentrate having the following composition:

Percent by weight Zinc oxide 12.2 75% phosphoric acid 58 Nickel oxide 1.4 Sodium chlorate 3.8 Water 24.6

This concentrate was diluted with water to about 1% by volume for use. Sodium nitrite was added as a separate accelerating component in amounts sufiicient to maintain a concentration of about .006% by weight. The bath temperature was maintained at about 130 F. and the treating time was about 1 minute.

The zinc phosphated test panels were then visually evaluated to determine whether the solutions adequately grain-refined and adequately activated the surfaces. The coatings were evaluated both visually and photomicrographically at 330x magnification for both crystal size and coating density. When crystal size enlarged noticeably and coarse, elongated crystals were present, this was an indication of a lack of grain refinement and failure was considered to have occurred. In addition, a thin, nonuniform coating indicated a lack of activation.

The results of the above test procedures are reported in Table 2 below.

TABLE 2 Coating results Solution Fresh bath After 2 hrs. After 4 hrs. After 6 hrs. After 8 hrs. After 16 hrs.

Formula 1 Excellent coating, Excellent coating, Excellent coating, Excellent coating, Excellent coating, Excellent coating,

grain refined. grain refined. grain refined. grain refined. grain refined. grain refined. Formula 1 w/o silicate.-. Good coating, Patterned coating Patterned coating, Thin uneven coating,

slightly enlarged slightly enlarged slightly enlarged coarse grained. grain size. grain size. grain size. Formula 1 w/o tripoly- .-...do Thin uneven coatphosphate. ing, coarse grained.

From the foregoing data, it can be seen that the com- From the foregoing data, it can be seen that the treatbination of silicate and tripolyphosphate produces a cleaning bath prepared with Formula 1 produced fine grained ing, activating, and grain-refining solution having procoatings for a prolonged period of time under the riglonged stability and giving results superior to a treating orous testing procedures utilized herein. bath wherein one or more of the essential constituents is We claim: removed. 1. A method for simultaneously cleaning, activating, EXAMPLE 3 and grain-refining ferrous and zinc surfaces to prepare A series of tests were performed utilizing Formulas 9 l? for the apPhcatmn of Zmc Phosphate cpatmg coinand 10, at a concentration of 4/ 10% weight per volume Fusing contactmg the slirfaces ,wlth a f f 501119011 in order to illustrate the effectiveness of these composi- P P 3 PH above l fi P P P a Colloldal tions for protecting the Jernstedt salt under highly alkatltamum Salt and a Ftablhzmg composltlon an amount line conditions. The solutions were evaluated by sprayfrom about Welght/Volume to about 15% Weight/ ing cold rolled steel panels employing the same method Volume, the Stabilizing composition consisting of a Siliand conditions as in Example 2 above. The test panels cate selected from the group consisting of orthosilicate were then zinc phosphated as in Example 2 above. The reand metasilicate and mixtures thereof, and a condensed sults are illustrated in Table 3. phosphate selected from the group consisting of tripoly- TABLE 3 Coating results pH at Solution make-up Fresh After 2 hrs. After 4 hrs. After 8 hrs. After 12 hrs. After 16 hrs.

Formula 9 ll. 3 Good coating, Good coating, Good coating, Good coating, Good coating, Good coating,

grain refined. grain refined. grain refined. grain refined. Slightly enslightly enlarged in larged in grain size. grain size. Formula 10 ll. 7 Excellent coating, Excellent coating, Excellent coating, Excellent coating, Excellent coating, Excellent coating,

grain refined. grain refined. grain refined. grain refined. grain refined. grain refined.

From the foregoing data it can be seen that treating phosphate and pyrophosphate.

baths employing Formulas 9 and 10 produce fine grained 2. The method of claim 1, wherein the silicate in the coatings and the treating solutions have prolonged stastabilizing composition is comprised of a mixture of bility under the rigorous testing procedures employed orthosilicate and metasilicate present in amounts such that herein. for each part by weight of orthosilicate there is from EXAMPLE 4 about 1 part to about 5 parts by weight of metasilicate,

. calculated as sodium salt.

A serlcs of tests were performed utillzing Formula 1. The method f claim 2 wherein the weight ratio f T aqueous cleaning ,activating, and grain'refining the silicate to the condensed phosphate in the stabilizing tion, prepared by adding 7.2 grams of concentrate p composition is between about .4 and about '6 to 1, calculiter of water, was evaluated by treating galvanized test lated as Sodiumsa1t panels. The solution, as made up, had a pll 0f 50 4. A method for applying a zinc phosphate coating to The test panels were sprayed for one minute at each ferrous and Zinc surfaces comprising the Steps f;

two hour interval at about 160 F. and 18 p.s.i.g. pres- (1) Simultaneously cleaning, activating and i sure. The solution was not only employed at each two fi i the rf by contacting them with a 1 hour interval to spray test panels, but was continuously tion having a pH above 10, h l i containing circulated through a p p System and p y at a colloidal titanium salt and a stabilizing composiand 18 P- P Stainless Steel Panels Suspended tion present in an amount from about .03% weight/ between dual spray nozzles. At each two hour interval, volume to about 15% i h l h bili the Stainless Steel Panels were replaced y galvanized ing composition consisting essentially of a silicate test panels. selected from the group consisting of orthosilicate After treatment, the panels were rinsed in cold water and t fli at and mixtures th r of and a and p y With a Zinc P p Coating Solution of densed phosphate selected from the group consisting the chlorate-nitrite type. The phosphate coating bath was f tripolyphosphate d pyrophosphate, formed as in Example 2 above and was sprayed on the (2) rinsing the surfaces, test panels for 1 minute at about 130 F. (3) contacting the rinsed surfaces with a zinc phos- The zinc phosphated test panels were visually evaluated phate ti l ti to determine whether the solutions adequately grain-re- (4) rinsing the surfaces, and fined and activated the surfaces. (5) passivating the surfaces by contacting them with The results are illustrated in Table 4. a dilute chromate solution.

TABLE 4 Coating results Solution Fresh After 2 hrs. After 4 hrs. After 8 hrs. After 16 hrs.

Formula 1 Excellent coating, Excellent coating, Excellent coating, Excellent coating, Excellent coating,

grain refined. grain refined. grain refined. grain refined. grain refined.

5. The method of claim 4 wherein the stabilizing composition consists of a silicate selected from the group consisting of orthosilicate and metasilicate and mixtures thereof, and a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate wherein the weight ratio of the silicate to the condensed phosphate is between about .4 and about 6 to 1, calculated as sodium salt.

6. A method for stabilizing a colloidal titanium salt in a cleaning, activating, and grain-refining solution having a pH above about 10, the titanium salt being present therein in an amount between about .005% to about .05% by weight calculated as titanium ion, comprising incorporating a stabilizing composition in the solution, in a concentration from about .03% weight/volume to about 1.5% weight/volume, the stabilizing composition consisting of a silicate selected from the group consisting of orthosilicate and metasilicate and mixtures thereof, and a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate, the ratio of silicate to condensed phosphate being between about .4 and about 6 to 1, calculated as sodium salt.

7. A composition for simultaneously cleaning, activating, and grain-refining ferrous and zinc surfaces in prep aration for the application of a zinc phosphate coating comprising basic cleaning material in an amount sufficient, upon mixing of the composition with water for use,

to produce a solution having a pH above 10, a colloidal titanium salt in an amount sufficient to provide, upon dilution of the composition for use, between about .005% and about .05% by weight of said colloidal titanium salt calculated as titanium ion, and a stabilizing composition in an amount sufficient to provide, upon dilution of the composition for use, a concentration of the stabilizing composition from about .03% weight/volume to about 1.5% weight/volume, the stabilizing composition consisting of orthosilicate, metasilicate, and a condensed phosphate selected from the group consisting of tripolyphosphate and pyrophosphate.

References Cited UNITED STATES PATENTS 2,310,239 2/1943 Jernstedt 148-6.l5 Z

3,523,043 8/1970 Newell 1486.15 Z

FOREIGN PATENTS 1,191,202 4/ 1965 Germany.

RALPH S. KENDALL, Primary Examiner US. Cl. X.R. 148-6.l5 R