Coated part, coating and method of coating

The article in accordance with the invention is a corrosion and erosion resistant article having good release characteristics which includes a metal body having a first surface thereon and a base coat adhering to the first surface. The base coat comprises at least one layer of inorganic particulate material bonded to the first surface. A second coat adheres to the base coat. That second coat comprising a cured coating of solid particulate lubricant in a phosphate/chromate metal ion solution. The invention also includes a corrosion and erosion resistant coating having good release characteristics which includes a base coat, the base coat comprising at least one layer of inorganic particulate material bonded to the first surface; and a second coat adhering to the base coat. The second coat comprises a cured coating of solid particulate lubricant in a phosphate/chromate metal ion solution. The invention also include the method of applying a corrosion and erosion resistant coating having good release characteristics which includes providing a metal body having a first surface thereon and applying a base coat to the first surface where the base coat comprises at least one layer of inorganic particulate material bonded to the first surface. The next step comprises partially curing the base coat, and applying a second coat that adheres to the base coat, the second coat comprises a cured coating of solid particulate lubricant in a phosphate/chromate metal ion solution. In some cases a third coat is applied.

BACKGROUND OF THE INVENTION 
The invention relates generally to erosion, corrosion, and abrasion 
resistant coatings, methods of coating, and coated articles. While the 
invention has particular application to coatings for use in glassware 
manufacturing processes it will be understood that it also has application 
to parts or substrates coated with such coatings and a process for making 
such coatings. 
The prior art includes U.S. Pat. No. 4,564,555 that discloses a coating for 
imparting corrosion, temperature and abrasion resistant properties to a 
part which has bonded thereto at least one layer of metal particles. The 
layer is bonded in a substantially water-insoluble manner to which is 
adhered a flame sprayed metal or metalloid oxide layer. The second layer 
that is always applied with a flame spray process. 
It is known to employ an electrolytic process to form a hard, corrosion 
resistant, glassy oxide film on metals as evidenced by the disclosures in 
U.S. Pat. Nos. 3,832,293 and 3,834,999 (both to Hradcovsky et al); U.S. 
Pat. No. 4,082,626 (Hradcovsky) and U.S. Pat. No. 4,184,926 (Kozak). These 
processes are commercially feasible for use in producing a film directly 
on metals which inherently possess electrolytic rectifiable properties, 
such as aluminum, magnesium, titanium and other light metals but such 
coatings have high permeability to gases and liquids. 
U.S. Pat. No. 3,248,251 ('251 Allen) issued to Charlotte Allen relates to 
coating compositions consisting essentially of a slurry of solid inorganic 
particulate material (especially aluminum) in an aqueous acidic solution 
containing substantial amounts of dissolved metal chromate, dichromate or 
molybdate, and phosphate. After application of a coating to the substrate, 
it is heated to a temperature upwards of about 500.degree. F. until the 
coating is water insoluble. 
U.S. Pat. No. 3,869,293 of Robert J. Brambaugh provides a coating 
composition similar to the composition of the '251 Allen patent which 
utilizes as the solid particulate material an alloy comprising aluminum 
and magnesium so as to further improve the corrosion resistance of the 
coating. 
Electrochemical methods for coating steel surfaces in an extremely short 
time in a dichromate solution containing phosphoric acid or in a chromic 
acid solution containing boric acid, borate or phosphoric acid are known. 
However, such procedures do not produce thick oxide coatings which are 
capable of withstanding abrasion, erosion and corrosion. U.S. Pat. No. 
3,400,058 of Edward C. Ross et al notes the problem of forming a 
successful coating on iron and steel by electrochemical coating. 
In U.S. Pat. No. 2,855,350 to Robert Ernst there is disclosed a procedure 
for producing an oxide coating on aluminum and aluminum alloys by 
electrolytic oxidation. The patent notes that the presence of copper and 
iron ions materially affects some electrolytic baths because the 
appearance of the ions requires an increase in current density which 
results in corrosion, that is, burning of the part being oxidized. 
In accordance with the conventional techniques employed in molding glass 
parts such as bottles, jars, and the like, the mold surface is frequently 
treated with a release material by a process known as swabbing. In 
accordance with swabbing technique or process, a swabbing composition, 
comprising a mineral oil carrier and a lubricant such as sulphur and/or 
graphite, is brushed into the glass forming equipment at intervals of 
between five and forty-five minutes. The swabbing composition is brushed 
into the mold to allow the molded glass part to be released from the mold 
without any marks on it and also to preserve the mold against 
deterioration during the molding process. 
Numerous disadvantages have been encountered in using such swabbing 
techniques. In the conventional swabbing method, the mold must be polished 
before the swabbing compound is applied. Such a polishing operation 
inherently involves the removal of metal from the mold, the useful life of 
the mold is necessarily reduced as the metal is gradually worn away. 
The swabbing procedure results in the production of significant amounts of 
smoke due to the heat at which the glass molds are operated. As a result, 
conventional oil swabbing techniques pose significant compliance problems 
under air pollution control regulations 
In addition, the swabbing technique exposes the worker performing the 
technique to the risk of personal injury. The glass making machinery opens 
for seconds at a time in the course of the operating cycle. If the 
operator does not complete the swabbing within those few second he will be 
maimed by the machinery. The worker is also exposed to health hazards 
because of the clouds of oily smoke produced in the ambient. 
Most of the prior art coatings have utilized one of more coatings of the 
same homogeneous mixture. Thus, coatings that include a lubricant, such as 
graphite in the mixture, have the graphite substantially uniformly 
distributed throughout the mixture. This distribution of the typical 
lubricant, such as graphite, throughout the entire mixture seriously 
compromises the strength, erosion resistance and durability of many prior 
art coatings. 
The patents described above disclose various coatings that have been 
proposed including some that have particular application to a glassware 
manufacturing process. These coatings have not been wholly satisfactory 
and the almost universal approach to the problem of release of the 
glassware in the glassware manufacturing industry is the swabbing 
technique. 
Accordingly, it is a primary object of the present invention to provide a 
new method for treating glass manufacturing molds. 
A related object is to provide compositions for use in accordance with such 
process. 
A further object is to provide a method for treating molds used in 
manufacturing glass parts which avoids the disadvantages of the prior art 
swabbing techniques. 
The general object of the present invention is to provide a coating to 
eliminate swabbing of blanks, molds, neck rings, bottom plates, plungers, 
and other parts utilized in the glassware formation process. 
Another object of the invention is to increase the production from any 
given production machinery by (1) permitting faster operation (more 
bottles per minute) and (2) reducing non-productive down time. 
It is a further object of the present invention to provide a coating that 
when applied to molds and blanks provides a more even temperature 
distribution and thus eliminates hot spots within the blank that result in 
defects in the glassware. 
It is another object of the invention to provide a coating that is applied 
to blanks which will eliminate the need to polish the substrate to 
facilitate release in the manner required in the prior art swabbing 
technique. 
It is a further object of this invention to provide a coating that will 
comply with air pollution control standards by eliminating the use of oily 
swabbing materials that produce significant amounts of scrap when applied 
to hot glass molds. 
Another object of the present invention is to provide an erosion resistant 
coating that will lessen the wear of the blanks and thus extend the 
useable life of the blank. 
Another object of the invention is to improve the quality of the glassware 
produced from a given blank by limiting erosion that causes substrate wear 
and thus results in unsatisfactory glass distribution which results in 
variations in wall thickness of the glassware. 
A still further object of this invention is to provide a durable 
lubricating coating which will facilitate the quick release of glassware 
during the forming processes. 
Still another object of the invention is to provide a coating that will 
allow the article on which the coating is applied to be repaired by 
welding procedures without the need to remove the coating or the need to 
reapply the coating after the welding procedure is complete. 
Still another object of the invention is to provide a coating and a method 
for applying the coating to an article in a manner that allows the user to 
control the thickness of the coating on respective parts of the article so 
that, for example, the distribution of the glass in a glassware 
manufacturing process will be controlled better. 
Yet another object of the invention is to eliminate the personal injuries 
risks associated with the prior art swabbing techniques. 
A further object of the invention is to provide a coating having discrete 
layers in which the lubritic materials are disposed in a top coat and 
substantially none of the lubritic materials are disposed in the base coat 
so that the overall coating has a higher durability, strength, and erosion 
resistance than would be the case if the lubiritic material were uniformly 
distributed throughout the entire coating. 
An additional object of the invention is to provide a coating that can be 
polished to meet the finish specifications of particularly exacting 
applications. 
SUMMARY OF THE INVENTION 
It will now be seen that these and other objects of the invention may be 
attained in an article, a coating and a method of applying the coating. 
The article in accordance with the invention is a corrosion and erosion 
resistant article having good release characteristics which includes a 
metal body having a first surface thereon and a base coat adhering to the 
first surface. The base coat comprises at least one layer of inorganic 
particulate material bonded to the first surface. A second coat adheres to 
the base coat. That second coat comprising a cured coating of solid 
particulate lubricant in a phosphate/chromate metal ion solution. 
The second coat may further includes a non-metallic particulate material. 
The metal of the metal body may be selected from the group consisting of 
iron, nickel, chromium, cobalt, aluminum and their alloys and may be 
steel. The solid particulate lubricant may include one or more materials 
selected from the group consisting of aluminum powder particulates, 
graphite, molybdenum sulfite, molybdenum disulphide, tungsten disuphite, 
iron oxide, boron nitride, magnesium oxide, chromium oxide, polyphenylene 
sulfide (PPS), perflouralkoxy (PFA) and a fluoropolymer. 
In some forms of the invention the phosphate/chromate metal ion solution 
may include CrO.sub.3 and H.sub.3 PO.sub.4 and the solid particulate 
lubricant material may include magnesium oxide, aluminum powder, and 
graphite. In other forms of the invention the solid particulate lubricant 
material may further include molybdenum disulphide. The article may 
include a fluoropolymer in said solid particulate lubricant material. The 
article may also include a third coating that is disposed on top of the 
second coating and includes polyphenylene sulfide (PPS) or perflouralkoxy 
(PFA). 
The invention also includes a corrosion and erosion resistant coating 
having good release characteristics which includes a base coat, the base 
coat comprising at least one layer of inorganic particulate material 
bonded to the first surface; and a second coat adhering to the base coat. 
The second coat comprises a cured coating of solid particulate lubricant 
in a phosphate/chromate metal ion solution. The second coat may further 
includes a non-metallic particulate material and the the metal of the 
metal body may be selected from the group consisting of iron, nickel, 
chromium, cobalt, aluminum and their alloys. The solid particulate 
lubricant may include one or more materials selected from the group 
consisting of aluminum powder particulates, graphite, molybdenum sulfite, 
molybdenum disulphide, tungsten disuphite, iron oxide, boron nitride, 
magnesium oxide and chromium oxide and the phosphate/chromate metal ion 
solution may include CrO.sub.3 and H.sub.3 PO.sub.4. 
In some forms of the invention the invention the solid particulate 
lubricant material includes magnesium oxide, aluminum powder, graphite and 
molybdenum disulphide. In addition the solid particulate lubricant 
material may further includes a fluoropolymer. The coating may further 
include a third coat that is disposed on top of the second coat and 
including polyphenylene sulfide (PPS) or perflouralkoxy (PFA). 
The invention also include the method of applying a corrosion and erosion 
resistant coating having good release characteristics which includes 
providing a metal body having a first surface thereon and applying a base 
coat to the first surface where the base coat comprises at least one layer 
of inorganic particulate material bonded to the first surface. The next 
step comprises partially curing the base coat, and applying a second coat 
that adheres to the base coat, the second coat comprises a cured coating 
of solid particulate lubricant in a phosphate/chromate metal ion solution. 
In some form of the method the step of applying the second coat further 
includes applying a non-metallic particulate material. The providing step 
may include providing a metal body having a composition that is selected 
from the group consisting of iron, nickel, chromium, cobalt, aluminum and 
their alloys. The providing step may include providing a metal body having 
a composition that is steel. The step of applying a second coat may 
include applying a solid particulate lubricant that includes one or more 
materials selected from the group consisting of aluminum powder 
particulates, graphites, molybdenum sulfites, molybdenum disulphide, 
tungsten disuphite, iron oxide, boron nitride, magnesium oxide and 
chromium oxide. 
In some forms of the invention the step of applying a second coat may 
include applying a phosphate/chromate metal ion solution that includes 
CrO.sub.3 and H.sub.3 PO.sub.4. and the step of applying a second coat 
includes applying a solid particulate lubricant material that includes 
magnesium oxide, aluminum powder, and graphite as well as molybdenum 
disulphide. The step of applying a second coat may further include 
applying a fluoropolymer. 
The method may further include the additional step of applying a third coat 
that includes polyphenylene sulfide (PPS) or perflouralkoxy (PFA) followed 
by the additional step of curing the second coat at a temperature 
substantially above room temperature. Ordinarily, the additional step of 
applying a third coat occurs after curing the second coat at a temperature 
substantially above room temperature. Usually the method includes the step 
of curing the third coat at a temperature substantially above room 
temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention includes a new technique for treating molds employed 
in manufacturing glass parts as well as other articles. In the glassware 
manufacturing field the coating permits a molded glass part to be quickly 
released and provides virtually complete protection for the mold surface 
while avoiding the disadvantages of the prior art. The part, coating and 
method of coating may employ either two or three discrete coatings. FIG. 1 
illustrates a part having the two coating embodiment of the invention and 
FIG. 2 illustrates a part having the three coat embodiment of the 
invention. 
FIG. 1 illustrates schematically the cross-section of a coated part 10 
comprising a substrate 12. The substrate 12 typically is a metal body 
having a composition selected from the group consisting of iron, nickel, 
chromium, cobalt, aluminum and their alloys. The substrate 12 has depoited 
thereon a base coat 14 and a second coat 16 in accordance with a preferred 
form of the invention are deposited. A "layer" 18 is formed intermediate 
the base coat 14 and the second coat 16. It is this layer 18 into which 
the base coat 14 and the second coat 16 flow if the base coat 14 is not 
fully cured at the time of application of the second coat 16. Ordinarily 
the second coat will have a particle size distribution in which more small 
particles are spaced apart from the substrate 12 than are near the 
substrate. This achieves a higher density of lubritic materials at the 
interface with glassware that is being produced. Stated another way, in 
any given volume, a greater amount of material can be placed in the volume 
if the particles occupying that volume are small. If the particles are 
large the irregular faces thereof will not mesh easily and there will be 
part of the volume that cannot be filled. Ordinarily, the particle size 
distribution is achieved due to the effects of gravity. Typically, but not 
always, the base coat 14 is applied, allowed to partially cure at room 
temperature, the second coat 16 is applied and then both coatings are 
cured by heating. This coated article has the coating that is satisfactory 
for many applications. 
FIG. 2 is identical to FIG. 1 with the exception that a third layer 20 is 
the top layer. This coating and the method of application is desirable for 
some rigorous applications. The layer 20 comprises a polyphenylene sulfide 
(PPS) or perflouralkoxy (PFA) powder either alone or in a binder. 
Ordinarily the powder will have a thickness of between 0.00015 and 0.001 
inch. Typically, the base coat 14 and the second coat are cured in the 
manner described above and then the third coat 20 is applied and cured. A 
more detailed description of the composition and manner of application of 
the respective layers follows. 
First or Base Layer 
In the preferred embodiment of the present invention the part to be coated 
is provided with a first layer formed with a chromate/phosphate 
composition that has air dried at ambient conditions. This drying step is 
not a complete cure such as would be accomplished by heating the coating 
at an elevated temperature as in the prior art methods. Thereafter, a 
second layer is deposited on top of the first layer by a spraying process. 
The second layer is a chromate/phosphate composition containing finely 
divided particles of graphite, molybdenum disulfide or other lubricating 
material. Other particulates may also be included to improve abrasion 
resistance. After the second layer is applied the first and second 
coatings are heated to render the entire coating water insoluble. 
The first layer may be referred to herein as a base or bond layer. This 
base layer is provided in the preferred embodiment to provide a strong 
bond to the part and to prevent erosion of the part. The 
chromate/phosphate constituent(s) in the bond layer also adds as a thermal 
barrier so that the blanks have an even heat distribution. In other words, 
the blanks will have smaller temperature gradients and less hot spots that 
compromise the quality of the glassware produced. 
Although the compositions of the coatings or layers and methods of this 
invention have as their prime utility the treatment of the surfaces of 
molds employed in molding glass parts, they can advantageously be employed 
to treat all metal surfaces of glass forming equipment auxiliary devices. 
These include, but are not limited to blanks, baffles, funnels, bottom 
plates, neck rings, delivery equipment, dead plates, stacker bars, wear 
transfer plates, metal conveyor belts, lehr plates as well as the finished 
molds themselves may be treated. Thus, as used herein, "mold surfaces" 
should be understood to refer to and encompass all such glass 
manufacturing and other equipment. Although the invention has particular 
application to glass manufacturing it will be readily apparent that there 
are many other applications for the present invention. 
Glass mold surfaces treated in accordance with the present method do not 
need treatment as frequently as in the prior art method. For example, in a 
typical application the treatment need only be accomplished once every 88 
hours (in contrast to a swabbing treatment every five to forty-five 
minutes in the prior art technique), thereby greatly increasing glass 
molding productivity. Although some applications may not have such a 
dramatic advantage there will still be a substantial advantage associated 
with the present invention. 
As noted, the composition in accordance with this invention is applied in 
aqueous solution form. An important advantage of this process resides in 
the fact that mineral and other oils and other smoke producing materials 
are not utilized. Thus, the noxious smoke given off by the prior art 
swabbing compounds is not produced in the process of this invention even 
when the molds are heated to their 600-1000.degree. F. operating 
temperatures. 
Since the breakdown and sacrificial deterioration of the protective layers 
provided by this invention is predictable, molds may be periodically 
coated on a scheduled basis so that the glass manufacturing process will 
be more systematic than in the irregular nature of the application of 
swabbing techniques of the prior art. Moreover, use of the coatings and 
processes of this invention not only permits molded glass parts to be 
released from the molding equipment in the desired manner, but also 
provides the desired level of protection of the molding equipment. The 
mold surfaces need only be cleaned before the coating is applied. The 
polishing step of the prior art swabbing method, which actually wears away 
the mold surface, is not required. Thus, mold life is greatly enhanced. 
Since the coatings of the invention are of uniform thickness, the molded 
glass parts can be produced to tight specifications more easily and fewer 
glass parts are rejected. 
The coatings of this invention protect the mold surface. Intimate contact 
between the hot glass and bare metal does not occur. Thus, the galling and 
scaling produced by the contact of hot glass and bare metal which is 
routine in the prior art is avoided in the present invention. This results 
in a still further useful life for the molding equipment. 
It should be pointed out that in the preparation of the composition for 
forming the chromate/phosphate layer, the +2 and +3 valence metals are 
preferably used to introduce metal ions into the chromate/phosphate 
solution. Magnesium has been found to be outstanding for this purpose; 
however, zinc ion also is desirable. To achieve optimum bonding of the 
second or oxide layer to the first layer and optimum errosion resistance 
of the entire coating, it is preferable that the metal ion concentration 
be at least about 1.5 moles per liter. Further, where the metal cation is 
all valence +2 or +3, and especially for magnesium as is preferred, it has 
been found desirable that the molar concentration of the metal ion not 
substantially exceed about one-half the total of the molar concentration 
of the phosphate and chromate (and/or molybdate) ions. At the same time, 
however, it is desirable that the metal ion concentration be at or 
approach this ratio of one mole per every two moles of phosphate plus 
chromate (and/or molybdate). For example, in the most preferred 
compositions where all the metal cation is valence +2, specifically 
magnesium, the molar concentration of metal to phosphate to chromate is 
about 2 to 3 to 1. 
In accordance with the preferred methods of this invention, the coating is 
established, or formed, in a two or three stage operation. First, a 
chromate/phosphate binder and a quantity of metal particles (e.g. aluminum 
powder) are applied to the part to be coated, such as by spraying, dipping 
or other suitable technique. The liquid binder in which the metal 
particles are dispersed is an aqueous solution of a combination of 
inorganic compounds from the group consisting of phosphoric acid, chromic 
acid, molybdic acid and the metal salts of these acids. The combination of 
compounds in the solution will have at least 0.1 mole per liter of 
dissolved phosphate (preferably 0.5 mole per liter), at least 60 0.2 mole 
per liter from the group consisting of chromate and molybdate, and 
optionally, at least 0.5 mole per liter of dissolved metal. Preferably, 
the metal particles dispersed in the binder have a grain size of less than 
325 mesh (referred to herein as -325 in accordance with the custom in the 
art), and in the most preferred embodiment of this invention are aluminum 
powder (spherical, 4-10 microns) present in the amount of about 10 to 2000 
grams per liter of the solution. The chromate/phosphate layer may be of 
any size desired, however, it has been found that a layer size of about 1 
to about 1.5 mils provides desirable results. The thicker the coating the 
greater the thermal insulation. Most preferably, the concentration of 
aluminum powder is from about 600 to 800 grams per liter of solution. 
It is noteworthy that, in accordance with the invention, a greater latitude 
is provided in the type of phosphate compositions which can be used. For 
instance, with respect to the above-mentioned Allen patent (U.S. Pat. No. 
3,248,251) it is not necessary that the phosphate binder be confined to 
the various concentrations and other molar relationships disclosed by that 
patent. (For example, the base coat may be similar to that described in 
the Collins, Jr. et al U.S. Pat. No. 4,319,924) The present invention, 
therefore, allows for the use of a large number of and a great variety of 
acid binder solutions for molding the coating composition in accordance 
with the invention. 
In accordance with the invention, the composition of the first layer or 
coating of the invention comprises the acid binder which comprises 
phosphate ions and ions of the group of chromate or molybdate ions and 
metal particles dispersed therein. Most preferably the metal is aluminum 
and its alloys. However, any combination of metals may be utilized 
depending upon the particular requirements. 
Therefore, in accordance with the invention, there is provided the liquid 
acid solution (which contains the phosphate ions) and the particulate 
metallic material, which preferably is aluminum, for use in forming a 
first layer on a substrate. 
A preferred manner of forming the first layer of the coatings of the 
invention is to admix the particulate metal material under vigorous mixing 
conditions into the chromate/phosphate and/or molybdate-containing binder. 
The sequence of addition of the components of the phosphate solution is not 
critical either, as is disclosed in the prior art, such as the Allen U.S. 
Pat. No. 3,248,251. 
After the chromate/phosphate coating has been applied to the part or 
substrate, it is dried or cured at ambient conditions before the second 
lubricant layer is applied. 
Thereafter both the base and second coat are cured at a temperature 
sufficient to form a substantially water-insoluble material with the metal 
particles firmly bonded therein. 
The application of the chromate/phosphate coating and ambient curing may be 
performed one or more times depending on the thickness of the layer 
desired. Ordinarily, only one layer will be necessary or desirable 
although some articles may require more than one application to form the 
base coat. 
It will be understood that other particulate materials may be added to the 
binder for the second coat, prior to mixing, in amounts depending on the 
specific characteristics desired for the layer such as graphite, 
refractory metal oxides, refractory carbides, nitrides, silicides and 
borides, and metal carbides, nitrides, silicides, and borides. 
The following are representative compositions of chromate/phosphate first 
layer coatings usable in the invention. The invention is not limited in 
any way by these examples, which are provided only by way of illustration. 
EXAMPLE 1 
A composition for use in preparing the first layer of the coating of the 
invention of the type disclosed by Allen (U.S. Pat. No. 3,248,251) is 
prepared by mixing the following components: 
______________________________________ 
MgCr.sub.4.7H.sub.2 O 266 grams 
H.sub.3 PO.sub.4 98 grams 
Mg(H.sub.3 PO.sub.4).sub.2.3H.sub.2 O 
272 grams 
Aluminum powder (spherical, 5-10 mu) 
600 grams 
______________________________________ 
H.sub.2 O quantity sufficient to bring the total volume of composition to 
1000 cc 
This composition may be coated on ordinary steel stock (SAE 1010 steel) 
although any other suitable substrate may be used in place of the steel, 
i.e., nickel, chromium, copper, glass, ceramic, etc. The composition is 
ordinarily sprayed on the stock and then dried approximately normal room 
temperature for between 5 and 30 minutes (although at very high humidity 
conditions it will be difficult to achieve any drying). Typically, 
sufficient drying will have occurred when the composition turns gray. The 
preferred form of the invention does not cure the composition at a high 
temperature for an extended period of time. 
Variations of this example may replace the magnesium chromate with any one 
of the following chromate containing compounds: 
______________________________________ 
Chromic acid H.sub.2 CrO.sub.4 or CrO.sub.3 
Magnesium dichromate 
MgCr.sub.2 O.sub.7 
Zinc chromate ZnCrO.sub.4 
Zinc dichromate ZnCr.sub.2 O.sub.7 
Calcium dichromate CaCr.sub.2 O.sub.7 
Lithium dichromate Li.sub.2 Cr.sub.2 O.sub.7 
Magnesium dichromate 
MgCr.sub.2 O.sub.7 and Na.sub.2 Cr.sub.2 O.sub.7 
plus sodium dichromate 
______________________________________ 
EXAMPLE 2 
Following the procedure of Example 1, the binder for the first layer of the 
coating of the invention is a mixture of the following: 
______________________________________ 
MgO 7.25 grams 
Chromic acid 9.20 grams 
Phosphoric acid (85%) 
22 ml 
Water 80 ml 
______________________________________ 
80 g of aluminum powder (-325 mesh) is added to the binder with mixing 
under high shear so as to form the composition for the first coating. 
The first coat is dried at approximately normal room temperature for 
between 5 and 30 minutes. Typically, sufficient drying will have occurred 
when the composition turns gray. The preferred form of the invention does 
not cure the composition at a high temperature for an extended period of 
time. 
If desired, in place of the aluminum, at least one of the following metals 
in powder form may be used: Mg, Fe, Ti, Nb, Ca, Zr, Hf, La, Mn, Rn, V or 
their alloys. 
EXAMPLE 3 
Following the procedure of Example 1, a composition especially useful for 
forming the first layer of a coating of the invention on low carbon steel 
parts or stainless steel parts is prepared as follows: 
______________________________________ 
CrO.sub.3 92 grams 
H.sub.3 PO.sub.4 323 grams 
MgO 72 grams 
Aluminum powder 800 grams 
______________________________________ 
(spherical, 5-10 mu) 
H.sub.2 O having a quantity sufficient to bring the total quantity of the 
composition to 1000 cc 
The ingredients are mixed, coated onto the part and dried at normal room 
temperature for about 5-30 minutes. Typically, sufficient drying will have 
occurred when the composition turns gray. The preferred form of the 
invention does not cure the composition at a high temperature for an 
extended period of time. If desired, other particulate materials may be 
added to the composition prior to mixing, i.e., graphite (5-10 microns), 
refractory metal oxides, refractory carbides, nitrides, silicides and 
borides. 
If desired, the part may be repeatedly coated with the composition and 
cured so as to obtain a layer of desired thickness onto which the second 
coating is then placed as will be hereinafter described. 
EXAMPLE 4 
Another composition was prepared following the procedure of Example 1 with 
the following ingredients: 
______________________________________ 
Chromic acid 35.97 grams 
Magnesium oxide 6.26 grams 
Phosphoric acid (85%) 
64 ml 
Water to 1000 ml 
Aluminum powder 600 grams 
______________________________________ 
(-325 mesh, 4-6 mu average particle size) 
EXAMPLE 5 
A first layer for a stainless substrate steel is prepared utilizing a 
composition of the type disclosed by Wydra (U.S. Pat. No. 3,857,717). No 
cations are added, but phosphorous acid is used to react with some of the 
chromic acid producing trivalent chromium and phosphoric acid in situ. 
______________________________________ 
H.sub.2 O (deionized) 
295 grams 
H.sub.3 PO.sub.4 (85%) 
87 grams 
H.sub.3 PO.sub.3 42 grams 
CrO.sub.3 62 grams 
Aluminum powder 400 grams 
______________________________________ 
(spherical, particle size 4-6 mu) 
The composition may be applied to the substrate by a spray gun according to 
the procedure of Wydra to obtain a layer thickness of 0.1 mm. The first 
coat is dried at approximately normal room temperature for between 5 and 
30 minutes. Typically, sufficient drying will have occurred when the 
composition turns gray. The preferred form of the invention does not cure 
the composition at a high temperature for an extended period of time. The 
steel substrate which can be utilized is any one of the AISI standard 
alloy steel compositions, including the Mn steels, Ni steels, Ni--Cr 
steels, Mo steels, Cr--Mo steels, Ni--Mo steels. Cr steels and Cr--V 
steels. 
EXAMPLE 6 
A binder is prepared by mixing the following components: 
______________________________________ 
MgCr.sub.2 O.sub.7.6H.sub.2 O 
174 grams 
Na.sub.2 Cr.sub.2 O.sub..7.2H.sub.2 O 
75 grams 
MgO 40 grams 
H.sub.3 PO.sub.4 
196 grams 
H.sub.2 O in a quantity to bring the total quantity of the composition to 
1000 cc 
Silica (-325 mesh size) 
800 grams 
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The prepared composition may be coated on the articles of this invention by 
spraying, drying at 80 degrees Fahrenheit and then curing at normal room 
temperature as described in the previous examples. 
Second Coat 
After the base coat has partially cured or dried at ambient conditions a 
second coating is applied consisting of a chromate/phosphate solution in 
which metal particles (preferably aluminum) are dispersed with a solid 
lubricant such as graphite. For some applications a further lubricant 
coating may be added to the coating. The further lubricant may be a 
fluoropolymer, polyphenylene sulfide (PPS), or perflouralkoxy (PFA). 
Ordinarily, fluoropolymers will not be used in applications involving 
elevated temperatures such as those encountered in a glass making process 
although they will be satisfactory for many other applications. 
After the chromate/phosphate layer has been dried, the application of the 
lubritic second coat is applied. The water soluble base coat is again made 
wet when the second coat is deposited on the base coat. (The wetting is 
somewhat analogous to the effect on a primer coat of paint that has a 
second layer of paint added on top of the primer before the primer 
completely dries.) The rewetting of the base coat in combination with the 
solid lubricants of the second coat results in some flow between the 
respective coats and forms an intermediate layer between the base coat and 
the second coat. This interface or intermediate layer couples the base 
coat, that is tenaciously bonded to the article, to the second coat. The 
second coats is preferably formed with solid lubricant particulates which, 
at least in some cases, have a particulate size that is larger on the face 
of the second coat that is nearest the intermediate layer and that is 
smaller on the face of the second coat that is farthest from the 
intermediate layer. 
The multi-coat coating in accordance with the present invention is 
satisfactory for some applications if the base coat is fully cured. It is 
preferred, however, that the base coat not be fully cured before 
application of the second coat because this results in a more clearly 
defined intermediate layer into which both coats flow, mix and lock 
together. In other words there is much greater bond strength between the 
base coat and the second coat if the base coat is not fully cured at the 
time of application of the second coat. Ordinarily, the second coat is a 
phosphate/chromate metal ion solution with metallic and non-metallic 
materials in a ratio that will depend on the physical characteristics 
required for a particular application such as bond strength, thermal 
conductivity, abrasion resistance, and lubritic release properties. 
Typically, the solid particulate lubricant includes one or more materials 
selected from the group consisting of aluminum powder particulates, 
graphites, molybdenum sulfites, molybdenum disulphide, tungsten disuphite, 
iron oxide, boron nitride, magnesium oxide, chromium oxide, polyphenylene 
sulfide (PPS), perflouralkoxy (PFA) and a fluoropolymer. 
The following are examples of second coats that have been found to the 
satisfactory. 
EXAMPLE 1 
The composition is prepared by mixing the following components and then 
coating the mixture on the base coat followed by curing at about 600 
degrees Fahrenheit for 90 minutes. 
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CrO.sub.3 4.7 grams 
H.sub.3 PO.sub.4 
18.9 grams 
MgO 3.9 grams 
Aluminum powder 
19.8 grams 
Graphite 9.9 grams 
Molybdenum Disulfide 
9.9 grams 
H.sub.2 O quantity to bring total quantity up to 70 cc. 
______________________________________ 
EXAMPLE 2 
Another composition for the second coat was prepared that was identical to 
that of the preceding example except that the molybdenum disulfide was not 
included. After mixing of the ingredients and coating the ingredients on 
the base coat by spraying or other application technique the second coat 
was cured at 1000 degrees Fahrenheit for 90 minutes. 
EXAMPLE 3 
The composition described above in example 2 was mixed with a quantity of 
fluoropolymer powders and the mixture was sprayed on the base coat and 
cured at 750 degrees Fahrenheit for 10 minutes. 
Third Coat 
For many applications the two coatings or layers are all that is necessary 
to achieve the desired results. However, for some applications the process 
also includes a third step. The third step includes a further step of 
spraying a polyphenylene sulfide (PPS) or perflouralkoxy (PFA) powder on 
the outermost surface of the second layer. Ordinarily the powder will have 
a thickness of between 0.001 and 0.010 inch. For most applications, a 
thickness closer to 0.001 than to 0.010 will produce better results. The 
application may be accomplished by spraying the powder alone or with a 
binder. Alternatively, the application may be achieved with an 
electrostatic process with the powder in a binder. Usually, this third 
coating will not be used in those coatings that also have a fluoropolymer 
in them. 
It will be understood that the second coat will preferably be fully cured 
before application after application of that coat. This is the preferred 
approach if (1) a third coat is not to be applied or (2) a third coat is 
to be applied. After application of the third coat, the part is preferably 
cured at 750 degree Fahrenheit for 5 minutes. 
Testing the coating, produced by the process, and the article on which the 
coating is deposited on glassware manufacturing apparatus has confirmed 
that all of the noted objects of the invention are achieved. Those skilled 
in the art will recognize that the release properties of the coating will 
have many other applications. 
The invention has been described with reference to the preferred 
embodiments. Persons skilled in the art of such inventions may upon 
exposure to the teachings herein, conceive other variations. Such 
variations are deemed to be encompassed by the disclosure, the invention 
being delimited only by the following claims.