Aqueous gel compositions and use thereof

The disclosure relates to aqueous-based gels and, in some cases, usage of such gels to impart corrosion resistance to steel and/or zinc containing surfaces, e.g., galvanized steel. The gel comprises water, at least one thickener, at least one silica containing material and an optional surfactant.

FIELD OF THE INVENTION 
The instant invention relates to aqueous-based gels and, in some cases, 
usage of such gels to impart corrosion resistance, for example, to steel 
or zinc containing surfaces, e.g., galvanized steel. The gel comprises 
water, at least one thickener, at least one inorganic material and an 
optional surfactant. 
BACKGROUND OF THE INVENTION 
The corrosion of steel and other metal containing products continues to be 
a serious technical problem which has profound effects on the economy. 
Corrosion causes loss of natural resources, and deteriorates key 
infrastructure such as roads and buildings. It also causes premature 
replacement of equipment and parts in industrial facilities, boats and 
other marine vehicles, automobiles, aircraft, among a wide range of 
metallic components. 
Current industry standards for corrosion prevention center around the use 
of barrier coatings, sacrificial coatings, alloys containing heavy metals 
such as chromium, nickel, lead, cadmium, copper, mercury, barium, among 
other heavy metals. The introduction of these materials into the 
environment, however, can lead to serious health consequences as well as 
substantial costs to contain or separate the materials or clean up 
environmental contamination. Damage associated with corrosion, 
accordingly, is a continuing problem and better systems for preventing 
corrosion are still needed. 
SUMMARY OF THE INVENTION 
The instant invention solves problems associated with conventional 
technologies by providing an aqueous based gel which can protect metals 
from corrosion in a manner that is compatible with the environment, 
non-flammable and cost-effective. 
The aqueous gel comprises or consists essentially primarily of water. The 
gel comprises water, at least one thickener, at least one silicate 
containing material and an optional surfactant. In some cases, the 
thickener may interact with one or more of the gel components and/or the 
metal surface, e.g., to form a metal substrate-thickener bond such as a 
zinc-organo product. e.g. zinc organo carboxylate. The gel can also 
include other components so long as these components do not adversely 
impact the viscosity or corrosion protection capabilities of the gel. 
The gel can be prepared by using conventional methods and technologies. The 
gel can be applied or coated upon a metal containing surface by using any 
expedient method such as aerosol spray, dipping, painting, among other 
suitable conventional methods. In one aspect of the invention, the coating 
method can be enhanced by applying an electrical current or other suitable 
source of energy. Depending upon the thickness of the coating and 
surrounding environment, the inventive gel can protect a metal surface 
from corrosion, e.g., salt water spray. If desired, the inventive gel can 
be employed as relatively temporary coating upon a metal surface. 
CROSS-REFERENCE TO RELATED PATENTS AND PATENT APPLICATIONS 
The subject matter of the instant invention is related to copending and 
commonly assigned Non-Provisional U.S. patent application Ser. Nos. 
09/016,853, 08/850,586; 08/850,323 (Attorney Docket Nos. EL001RH-8, 
EL001RH-7 and EL001RH-6), filed respectively on even date herewith and 
08/791,337 and 08/791,336 (Attorney Docket Nos. EL001RH-5 and EL001RH-4), 
filed on Jan. 31, 1997 in the names of Robert L. Heimann et al., as a 
continuation in part of Ser. No. 08/634,215 (Attorney Docket No. EL001RH-3 
filed on Apr. 18, 1996) in the names of Robert L. Heimann et al., and 
entitled "Corrosion Resistant Buffer System for Metal Products", which is 
a continuation in part of Non-Provisional U.S patent application Ser. No. 
08/476,271 (Attorney Docket No. EL001RH-2 filed on Jun. 7, 1995) in the 
names of Heimann et al., and corresponding to WIPO Patent Application 
Publication No. WO 96/12770, which in turn is a continuation in part of 
Non-Provisional U.S. patent application Ser. No. 08/327,438, now U.S. Pat. 
No. 5,714,093 (Attorney Docket No. EL001RH-1 filed on Oct. 21, 1994). 
The subject matter of the instant invention is also related to 
Non-Provisional patent application Ser. No. 09/016,250 (EL001DP-1), filed 
on even date herewith and entitled "An Electrolytic Process For Forming A 
Mineral" The disclosure of the previously identified patent applications 
and publication is hereby incorporated by reference.

DETAILED DESCRIPTION 
The inventive aqueous gel comprises or consists essentially of water, at 
least one thickener, at least one inorganic material and an optional 
surfactant. The gel can contain from about 80 to about 99.9 weight percent 
water, and normally about 95 wt. % water. 
One or more thickeners can be employed as a component of the gel in order 
to increase the viscosity of the water. In some cases, the thickener may 
interact with one or more of the gel components and/or the metal surface, 
e.g., to form a metal substrate-thickener bond such as a zinc-organo 
product. While any suitable thickener can be employed, for best results 
the thickener is stable at a pH from about 9 to about 12 and has a 
relatively high ionic strength. Examples of suitable thickeners comprise 
one or more members from the group consisting of an aliphatic polymer with 
carboxylic acid groups, e.g., CARBOPOL supplied by B. F. Goodrich, xantham 
gum, silica, synthetic minerals, e.g., LAPONITE supplied by Southern Clay 
Products, mixtures thereof, among others. The specific amount of thickener 
is dependent upon the composition of the thickener(s); but, normally the 
total amount will range from about 0.05 weight percent to about 20 weight 
percent. When the previously identified aliphatic polymer is employed, the 
thickener corresponds to about 0.5 to about 2.0 wt. % and normally about 
1.0 wt. % of the gel. 
The inventive gel can also include one or more organic compounds for 
modifying or tailoring the characteristics of the gel. In one aspect, the 
protection of the aqueous gel is enhanced by the presence of other 
functional groups, e.g., thiolacetic and maleic anhydride functional 
polymers. Other variations in the functional polymer include the frequency 
of the repeating acetate groups and the use of maleic anhydride to 
increase the effective number of zinc-oxygen bonds as well as adding 
grafted compounds. In another method of improving protection, a polymer 
grafted onto a polyacrylic acid is introduced to the gel. Without wishing 
to be bound by any theory or explanation, it is believed that the 
aforementioned organic compounds; especially the grafted compounds, would 
be hydrophobic thereby repelling water and imparting enhanced protection 
to the underlying compounds, materials and substrates. 
The aqueous gel can also include at least one inorganic material. Normally, 
the inorganic material comprises at least one silica containing material 
such an alkali silicate such as sodium or potassium silicate. While the 
cost and handling characteristics of sodium silicate are desirable, at 
least one member selected from the group of water soluble salts and oxides 
of tungsten, molybdenum, chromium, titanium, zircon, vanadium, phosphorus, 
aluminum, iron, boron, bismuth, gallium, tellurium, germanium, antimony, 
niobium (also known as columbium), magnesium and manganese, mixtures 
thereof, among others can also be employed. Particularly desirable results 
have been achieved by using salts and oxides of aluminum and iron, which 
can be employed along with a silicate. All of the claims require a silica 
containing material. When sodium silicate is employed, desirable results 
can be achieved by using G or N grade sodium silicate supplied by 
Philadelphia Quartz (PQ) Corporation. While either G or N grade materials 
can be employed, in some cases, increased corrosion resistance is obtained 
by using N grade silicate, e.g, N grade is a dissolved version of G grade. 
The amount of inorganic material will vary depending upon the thickener; 
but, normally about 3 to about 5% by weight of silicate is effective, 
e.g., the gel can contain about 5 wt. % of G grade sodium silicate which 
is a mixture containing about 37% by weight sodium silicate. 
In one aspect of the invention, the aqueous gel further comprises one or 
more surfactants. While any suitable surfactant can be employed, for best 
results the surfactant is non-ionic. An example of a suitable surfactant 
comprises SURFYNOL supplied by Air Products Corporation. The surfactant(s) 
can comprise about 0.01 to about 10 weight percent of the gel. 
In another aspect of the invention, the gel comprises relatively small 
amounts of additives such as colorants, curing agents, antifungal or 
antimicrobial agents, metal ions, e.g., zinc, among other substances that 
have no adverse impact on the viscosity or corrosion protection properties 
of the gel. 
The gel can be prepared by using any expedient method. Typically, the 
thickener is dispersed into deionized water and agitated for about 5 to 10 
minutes. Agitation is not a key aspect of the invention and can be 
performed by using a suitable method. The inorganic material, e.g., sodium 
silicate, is added to the dispersion thereby causing an increase in pH. 
The high pH dispersion is again agitated in order to ensure thorough 
mixing of the gel's components thereby forming the inventive aqueous gel. 
If desired, the pH of the gel can be increased further by adding an 
alkaline material such as at least one member selected from the group 
consisting of sodium hydroxide, potassium hydroxide, triethanolamine, 
ammonium hydroxide mixtures thereof, among others. The pH of the prepared 
gel typically ranges from about 10 to about 11. 
The gel can be applied to a virtually unlimited array of substrates such as 
galvanized steel, stainless steel, aluminum, lead, iron, copper, brass, 
alloys thereof, among others. Particularly desirable results have been 
achieved by using a sodium silicate containing gel for protecting a zinc 
containing surface or alloy from the corrosive affects of salt spray. If 
desired, the gel can be removed from the substrate, e.g, by rinsing or 
spraying with water. 
While any suitable method can be employed for contacting a substrate with a 
gel, an example of a suitable method includes passing an electrical 
current through the gel and substrate during application. That is, a gel 
applicator apparatus is in contact with a source of electricity and when 
the gel within the applicator contacts a substrate an electrical circuit 
is complete. The gel applicator can be of any suitable design that 
dispenses the gel in a controlled manner, e.g., comprising a porous 
dispensing terminal member such as a sponge that is in fluid contact with 
a gel reservoir. The electrical energy to the gel applicator can be 
supplied via a connection to the applicator itself or the substrate to be 
coated with the gel. 
The gel must be sufficiently conductive to permit current can flow between 
the electrode and the working piece. Normally, the voltage applied through 
the gel is about 6 to at least about 18 V and a current density of about 
0.1 to at least about 0.5 amps/in2; but, the voltage can be tailored to 
satisfy a wide range of end-uses. While a gel having any suitable 
viscosity can be employed, normally the gel must be viscous enough to 
remain upon the substrate to be treated. 
Moreover, the substrate can be contacted with the gel in accordance with 
the electroylic methods disclosed in copending and commonly assigned U.S. 
Non-provisional patent application Ser. No. 09/016,250 (Attorney Docket No 
EL008-1), filed on even date herewith and entitled "Electrolytic Process 
for Making a Mineral". That is, a substrate is immersed in the inventive 
gel and a current is applied to the gel. As dicussed above, the current 
can enhance the formation rate of a corrosion resistant mineral layer upon 
the substrate. 
The aforementioned gel application method can be employed for the general 
purpose of applying a corrosion resistant material as well as for 
particular end-uses. Examples of such end-uses include a pretreatment for 
a metallic surface prior to painting, E-coating, plating, repair damage to 
a metallic surface, among other uses. 
The incubation time of the gel, that is, the time the gel is allowed to be 
in contact with the substrate can affect the corrosion resistance. For 
example, increasing the incubation time has a tendency to cause an 
increase in corrosion resistance. While the incubation time can vary 
depending upon other operating parameters, normally the incubation time 
will range from about 1 sec to about 24 hours. The temperature during 
incubation as well as the temperature when the gel-treated substrate is 
exposed to a corrosive environment can also affect the corrosion 
resistance. Normally, the incubation temperature ranges from about 20 to 
about 100.degree. C. 
Time and temperature can also control the removal rate of water and in turn 
the aforementioned reaction. For example, when the gel is dried upon the 
substrate, then the increased concentration of a zinc silicate, higher 
temperature and longer contact time will drive the reaction forward. 
Consequently, it is believed that water serves a dual role in this 
process. The first role of water is as a product and by LeChatelier's 
Principle, removal of the water will drive the reaction forward. The 
second role of water is as a reaction medium in that the gel is aqueous 
based. 
The corrosion resistance of the gel can be affected by heat and the length 
of time undried gel is permitted to remain on the surface of the substrate 
(incubation time). That is, the effectiveness of the gel can be varied 
depending upon whether or not the gel is dried when exposed to a corrosive 
environment, the length of time the gel remained upon the substrate prior 
to removal or being dried, and the temperature of corrosive environment. 
For example, a relative increase in gel contact time can permit the 
aforementioned reaction to proceed further, and heat will increase the 
kinetic energy of the reactants thereby increasing the reaction rate. 
In connection with a zinc containing surface or alloy and without wishing 
to be bound by any theory or explanation, it is believe that the following 
reaction can occur between a silicate containing gel and the zinc surface 
thereby forming a mineral surface: 
EQU A.sub.x B.sub.a O.sub.b -nH.sub.2 O 
The value of x can vary widely as a function of the amount of reactants 
present and processing environment, e.g., at a sufficiently high 
temperature a condensation reaction can occur which yields water as a 
product. The values of a and b can also vary, but the empirical ratio of 
b:a is always 4:1 or lower and a and b cannot be 0. In this case, the 
mineral comprises a zinc silicate containing reaction product, e.g. a 
layer comprising an amorphous matrix surrounding crystalline zinc-silicate 
compounds, can form a film or layer upon the surface of the substrate 
thereby imparting improved corrosion resistance among other properties, 
e.g., at room temperature a zinc silicate containing monolayer can form in 
less than about 2 hours. It is also believed that in some cases, the 
aforementioned reaction includes an organic component such as an organic 
thickener thereby forming a zinc organo silicate product. If desired, 
water within the gel as well as reaction product water can be removed by 
heating, e.g, at temperature from about 50 to about 100.degree. C. thereby 
increasing the relative concentration of zinc silicate product and 
improving corrosion resistance, e.g., the gel is dried while in contact 
with the substrate. 
In a further aspect of the invention, at least a portion of the crystalline 
component of the mineral layer that is surrounded or incorporated within 
the amorphous phase comprises: 
EQU M.sub.x M'.sub.y M".sub.z (Si2O7).sub.A (SiO3).sub.B (Si.sub.4 O11).sub.C 
(Si4O10).sub.D (OH)s(A).sub.w (A').sub.v -nH.sub.2 O 
where M, M', and M" are ions of Group I, II and/or III metals, and A and A' 
are the previously defined anions and where v, w, x, y, and z each can be 
any number including zero but x, y and z cannot all concurrently be zero. 
Analogously, A, B, C and D can each be any number including zero but 
cannot all concurrently be zero. "n" is the water of hydration and 
normally ranges from about 0 to about 10; and typically, ranges from about 
0 to 6. "S" is an interger that ranges from about 0 to about 4. At least 
one of M, M' and M" is a metal supplied from the substrate in contact with 
the mineralized layer, and normally up to two of M, M' or M" corresponds 
to an alkali or alkaline earth metal, e.g, calcium, potassium, sodium and 
mixtures thereof. Without wishing to be bound by any theory or 
explanation, it is believed that the presence of alkali cations, e.g, M", 
can influence the presence of other metal ions, e.g., M' supplied from the 
metal substrate, by an exchange or a replacement mechanism. For example, 
when the metal substrate comprises zinc and a precursor comprises sodium 
silicate the crystalline component, which is embedded within the amorphous 
matrix to form the mineralized layer, comprises 
EQU Zn.sub.x Na.sub.y Mz(Si2O7).sub.A (OH).sub.S *nH.sub.2 O. 
Additional information regarding the mineral layer can be found in the 
aforementioned commonly assigned patents and patent applications; already 
incorporated by reference. To enhance mineral layer formation on at least 
a portion of the surface of a metal substrate, the metal surface may need 
to be prepared or pretreated. Metal surfaces normally tend to be covered 
with a heterogeneous layer of oxides and other impurities. This covering 
can hinder the effectiveness of the buffering and/or mineral layer 
formation. Thus, it becomes useful to convert the substrate surface to a 
homogenous state thereby permitting more complete and uniform mineral 
layer formation. Surface preparation can be accomplished using an acid 
bath to dissolve the oxide layers as well as wash away certain impurities. 
The use of organic solvents and detergents or surfactants can also aid in 
this surface preparation process. Phosphoric acid based cleaners, such as 
Metal Prep 79 (Parker Amchem), fall into a category as an example commonly 
used in industry. Other combinations of acids and cleaners are useful as 
well and are selected depending upon the metal surface and composition of 
the desired mineral layer. Once the surface is pretreated, the surface can 
then be subjected to further activation, if necessary, to enhance the 
buffering capability, including but not limited to oxidation by any 
suitable method. Examples of suitable methods comprise immersion in 
hydrogen peroxide, sodium peroxide, potassium permanganate, mixtures 
thereof, among other oxidizers. 
The corrosion resistance can also be affected by pretreating the substrate, 
e.g., steel or zinc, using a process comprising the following procedure: 
1. immerse panel in solution comprising 25% Metalprep 79 (Parker-Amchem) 
for 2 minutes, 
2. remove Panel and rinse with deionized water, 
3. immerse panel in 0.1 M NaOH solution for at least about 10 seconds, 
4. wipe off excess NaOH solution, 
5. immerse panel in 50% H2O2 solution for at least about 5 min., and; 
6. wipe off excess hydrogen peroxide. While particularly desirable results 
have been achieved by using so-called Metalprep, any suitable cleaner such 
as phosphoric acid can be employed. Normally, the acid cleaner is 
neutralized by subsequently exposing the acid cleaned substrate to any 
suitable basic substance. After neutralizing the acid, the 
cleaned/neutralized surface is oxidized by being exposed to any suitable 
oxidizer such as hydrogen peroxide, KMnO4, mixtures thereof, among other 
conventional metal oxidizing compositions. 
In another aspect of the invention, the inventive composition comprises a 
gel which is employed for providing temporary corrosion protection of a 
finished metal surface, e.g., as a processing step just prior to storage 
or shipment of a material. Upon reaching its destination or removal from 
storage, the coating could be removed from the metal article by rinsing 
with water. The gel could also contain an acrylic, which would allow for 
either a physical removal, such as peeling, or an immersion in a solution, 
which would permit the breakup of the coalesced acrylic. One specific 
example of employing the gel for such a usage comprises applying the gel 
when producing zinc galvanized coiled steel. After the galvanization 
process and just prior to the coiling process, this gel can be applied. 
The gel imparts enhanced corrosion protection to galvanized steel so that 
the coil can be delivered to its final destination, wherein the 
gel-coating may be removed by any of the aforementioned methods. 
While the above description places particular emphasis upon using the gel 
for corrosion protection, a skilled person in this art would understand 
that the gel can be employed in a wide range of end-uses. Examples of such 
end-uses include as a coolant when extruding metals wherein the corrosion 
and heat resistant properties of the gel are desirable, a temporary 
coating for storing or transporting metallic articles such as coiled metal 
sheets, among other end-uses. Further, prior to completely curing or 
drying the gel, the gel can be readily removed by rinsing thereby 
permitting usage of the gel as a temporary protectant. The gel can be 
applied or reapplied as appropriate for the particular end-use. The 
properties of the gel can also be tailored to satisfy a virtually 
unlimited range of end-uses, e.g, tailoring the silicate concentration in 
the gel and drying the gel. 
The following Examples are provided to illustrate certain aspects of the 
invention and do not limit the scope of the invention as defined in the 
appended claims. The water employed was deionized water. Unless noted 
otherwise, all materials referenced in the following Examples were 
commercially available. The XPS data in the following Examples 
demonstrates the presence of a unique organozinc species, e.g., XPS 
measures the binding energies of the atoms and compares the measured 
energy to standardized values in order to determine bonding properties. 
EXAMPLE 1 
In the following Example, panels comprising electro zinc galvanized steel 
(supplied by ACT Laboratories), and measuring about 3" by about 5" inches 
were tested in accordance with ASTM B-117. 
All panels were prepared by rinsing twice with reagent alcohol. Panels were 
taken from ACT lot# 30718614. The matrix with the salt spray results can 
be seen below in Table A-1. 
A 10% solution of Carbopol polymer was prepared (10 g in 80 g water). After 
the polymer was hydrated in the water, the appropriate amount of sodium 
silicate solution was added (3-10% or 3 to 10 g into the solution) while 
stirring. The pH was then adjusted as needed to 11 using a 10% wt solution 
of NaOH and topped off with water to reach a total weight of 100 g thereby 
forming the gel. 
The gel was applied to the test panels by the so-called gate method for 
applying a wet film of 1/16 in. The apparatus for these methods includes a 
"stick", or piece of plastic with a groove cut into it. Gel is applied 
onto a panel (by hand) and the the stick is slid over the panel thereby 
removing any excess gel so that only a 1/16 inch layer of gel remains on 
the panel. 
Once the gel was coated upon the panels, the coated panels were heated. 
Heating was carried out in a "Crock" Pot containing deionized water. Four 
panels were placed into the pot upon an upright rack and temperature was 
recorded at 90.degree. C. Relatively long incubation times were carried 
out in a covered pan to avoid drying the gel. 
The gel was dried upon the surface of certain test panels. Drying was done 
in a vacuum oven with no heat. Pressure was dropped 25 in Hg. Drying took 
approximately 1.5 hrs. 
Testing time in the salt spray chamber was determined by measuring the time 
until 5% coverage of Fe2O3 appeared on the test panels. The presence of 
red rust was determined visually. The longer the period in the salt 
chamber prior to the appearance of red rust corresponds to improved 
corrosion resistance. 
TABLE A-1 
______________________________________ 
GEL SILICATE INCUB CHAMBER TIME 
DRY TEMP (WT. %) TIME (SALT SPRAY) 
______________________________________ 
No RT 1% 1 day 120 
Yes RT 1% 1 day 
168 
No 90 1% 1 day 
144 
Yes 90 1% 1 day 
120 
No RT 10% 1 day 
144 
Yes RT 10% 1 day 
240 
No 90 10% 1 day 
168 
Yes 90 10% 1 day 
240 
No RT 1% 1 hr 
96 
Yes RT 1% 1 hr 
120 
No 90 1% 1 hr 
120 
Yes 90 1% 1 hr 
168 
No RT 10% 1 hr 
144 
Yes RT 10% 1 hr 
240 
No 90 10% 1 hr 
144 
Yes 90 10% 1 hr 
240 
______________________________________ 
Table A-1 also shows the length of time within the salt spray chamber until 
the appearance of 5% red rust. The results shown in Table A-1 are also 
shown by the cube plot of FIG. 1. Referring now to FIG. 1, the cube on the 
left is a plot for undried gels whereas the cube on the right is for dried 
gels. The vertical axis ("y" axis) on both cubes is silicate loading or 
percent silicate in the gel, i.e., from about 1% to about 10% by weight 
sodium silicate solution that corresponds to about 0.3 to about 3 wt % 
sodium silicate in the gel. The horizontal axis ("x" axis) refers to the 
length of time the gel was permitted to remain on the surface of the 
panels prior to being exposed to the salt spray, i.e., that ranges from 1 
hour to 1 day. The axis into the plane of the paper ("z" axis) plots the 
temperature of the salt spray, which ranges from room temperature (RT) to 
about 90.degree. C. The comers of the cubes document the length of time in 
hours that the test panel remained in the salt spray chamber until the 
appearance of red rust. A dried gel having about 10 wt. % sodium silicate, 
e.g obtained the greatest resistance to corrosion, the upper corners of 
the right-hand cube of FIG. 1. 
EXAMPLE 2 
The method of Example 1 was repeated with the exception that the test 
panels comprised steel panel which was electrozinc galvanized (also known 
as E-GALV-gal and corresponds the steel panels employed in the automotive 
industry). The panels were coated with an inventive aqueous gel comprising 
3% sodium silicate, 1% Carbopol polymer solution at a thickness of 1/16 
inch. The coated panel was heated in an oven at a temperature of 
175.degree. C. for 30 min. The panel was removed from the oven and place 
into a salt spray chamber the next day, and tested in accordance with ASTM 
B117. The panel was exposed to the salt spray for a period of 648 hours 
before 5% red rust. 
EXAMPLE 3 
The method of Example 2 was repeated with the exception that the coated 
panel was allowed to incubate for 1 week at ambient temperature and 
conditions. The panel is placed into the salt spray chamber and was 
exposed for a period of 600 hours before the appearance of 5% red rust. 
EXAMPLE 4 
Two electrozinc galvanized steel panels (ACT Laboratories) were coated with 
the following formulation: 3 wt % N-grade Sodium Silicate Solution (PQ 
Corp), 0.5 wt % Carbopol EZ-2 (BF Goodrich) in DI water. This gel was 
applied at a 1/16 inch wet film thickness using an adjustable drawdown 
blade. The coated panels were heated at 125.degree. C. for 1 hour. The 
panels were allowed to set overnight and the excess residue was washed off 
the panel with deionized water. Panel 2 was exposed to 24 hours salt spray 
exposure according to ASTM B117 methods whereas Panel 1 not processed 
further and employed as standard for comparison to the salt exposed Panel 
2. 
X-ray Photoelectron Spectroscopy (XPS or ESCA) analysis in accordance with 
standard procedures was performed on these two panels. Panel #1 shows the 
presence of silica indicated by the Si(2p) photoelectron binding energy of 
103.2 eV. The small intensity of the Zn (2p3/2) photoelectron indicates a 
presence of a relatively small amount of zinc. The sampling depth of this 
type of analysis is 50 angstroms thereby indicating that these data 
indicate an accumulation of the silica on top of the zinc surface. 
Panel 2 was used to characterize the zinc surface. The salt spray exposure 
washed away the excess build up of silica and silicate to expose a deeper 
profile. ESCA analysis reveals the presence of a build up of an organic 
carbon substance. The C (1s) photoelectron binding energies of 289 and 291 
eV representing a multi-faceted carbon, organo-anion. The Zn(2p3/2) 
photoelectron binding energy at 1023.45 eV indicated the presence of a 
zinc acetate species. 
The above ESCA data gives two conclusions. The first is the formation of an 
organo zinc species, comprised of zinc and the aforementioned Carbopol 
thickener. 
The Carbopol comprises a polyacrylic acid thickener, which contains 
repeating carboxylic acid functional groups. Without wishing to be bound 
by any theory or explanation it is believed that the presence of basic 
material, e.g., sodium silicate, deprotonates the acid groups thereby 
leaving an acetate functionality (R--COO--). It is also believed that this 
functional group can react with the zinc surface and form the previously 
identified zinc acetate species found on the surface. The second 
conclusion is the continued deposition of silica once the organo-zinc 
species was formed. In contrast, Panel #1 shows no zinc or organic carbon 
signatures; the only species present was a silica or silicate. 
Without wishing to be bound by any theory or explanation, it is also 
believed that Example 4 illustrates the formation of a zinc acetate bond 
and Example 5 illustrates the formation of an iron acetate bond. The 
presence of a steel or zinc acetate type of bond has been confirmed by XPS 
analysis. The bond formation is believed to be due at least in part to the 
polymeric nature of the thickener. Because the polymer contains repeating 
carboxylate groups, it is believed that there are many "anchor" sites for 
the polymer to lay on the surface. If one of the zinc acetate bonds should 
break, the polymer may possess at least two functionalities in close 
proximity, facilitating the reforming of the bond. Such indicates that 
maleic anhydride and/or any suitable polyacrylic acid, or functional 
equivalent can be employed as a thickener in accordance with the instant 
invention. 
It is also believed that the multi-point anchoring nature of an polyacrylic 
acid provides enhanced desirable corrosion protection (among other 
valuable properties) by using a relatively large number of bonds with the 
underlying substrate in comparison to other organic thickeners. It is also 
believed that incorporating a water-born urethane would permit two types 
of surface reactions. Establishing conditions sufficient to cause two 
competing reactions within one inventive composition may produce two types 
of zinc formations on the surface, namely, a zinc disilicate and a zinc 
acetate. This formula would incorporate the robust bonding of the silicate 
while retaining the multipoint anchoring of the acetate polymer. 
EXAMPLE 7 
The following formulation is applied as a coating that provides improved 
corrosion protection to a metal containing surface. The coating can form a 
self-supporting layer upon the metal surface. If desired, the 
self-supporting coating is removed from the metal surface by being peeled 
or stripped from the surface. 
______________________________________ 
AMOUNT COMPONENT SUPPLIER 
______________________________________ 
90 wt. % PL-958 acrylic B.F. Goodrich 
10 wt. % N-grade sodium silicate 
PQ Corp. 
0.5 wt. % sodium nitrite 
Fisher Scientific 
______________________________________ 
EXAMPLE 8 
This Example illustrates using an electrical current for applying the 
inventive gel onto a substrate. The coated substrate was analyzed by using 
ESCA to confirm formation of a mineral layer, e.g, a reaction product 
formed between the substrate and the gel. 
An aqueous gel was made by admixing by hand 5% sodium silicate and 10% 
fumed silica. The gel was used to coat cold rolled steel panels (supplied 
from ACT). One panel was washed with reagent alcohol, while the other 
panel was washed in a phosphoric acid based metal prep, followed by a 
sodium hydroxide wash and a hydrogen peroxide bath. 
The apparatus was set up using a DC power supply connecting the positive 
lead to the steel panel and the negative lead to a platinum wire wrapped 
with glass wool. This setup was designed to simulate a brush plating 
operation. The "brush" was immersed in the gel solution to allow for 
complete saturation. The potential was set for 12 V and the gel was 
applied in a painted motion onto the panel with the brush. As the brush 
passed over the surface of the panel, hydrogen gas evolution could be 
seen. The gel was brushed on for five minutes and the panel was then 
washed with DI water to remove any excess gel and unreacted silicates. 
An ESCA analysis performed in accordance with conventional techniques was 
used to determine the surface characteristics of each steel panel. ESCA 
permits examination of any reaction products between the metal substrate 
and the environment set up from the electrolytic process. Every sample 
measured showed a mixture of silica and metal silicate. The metal silicate 
is a result of the reaction between the metal cations of the surface and 
the alkali silicates of the coating. The silica is a result of either 
excess silicates from the reaction or precipitated silica from the coating 
removal process. The metal silicate is indicated by a Si (2p) binding 
energy (BE) in the low 102 eV range, typically between 102.1 to 102.3. The 
silica can be seen by Si(2p) BE between 103.3 to 103.6 eV. The resulting 
spectra show overlapping peaks, upon deconvolution reveal binding energies 
in the ranges representative of metal silicate and silica.