Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1998-01-30
2001-02-20
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Composite
Of metal
C428S450000, C252S389300, C252S389500, C252S389510, C252S389520, C252S389530, C423S326000, C423S331000, C423S332000, C106S014140, C106S600000
Reexamination Certificate
active
06190779
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to the forming coatings on metal containing surfaces and to methods of forming such coatings on a suitable substrate. The coating can include a wide range of compounds and normally at least a portion of the coating corresponds to an amorphous phase. The inventive coating and method are particularly useful in providing a corrosion resistant coating or film upon a metallic surface. This aspect of the invention involves the formation of a corrosion resistant “mineralized” layer of tailored composition upon a metal containing surfaces.
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.
A more detailed discussion of mineral containing materials can be found in Manual of Mineralogy, by Dana, 21
st
edition, American Society of Metals, vol. 13, Corrosion in Structures, “Reaction Sequence in Atmospheric Corrosion of Zinc ASTM STP 1239”, by W. W. Kirk et al., and Physics and Chemistry of Mineral Surfaces, by Bradly (1996); the disclosure of each of the aforementioned references is hereby incorporated by reference.
Conventional practices for improving protecting metal containing surfaces and imparting improved surface characteristics to metals rely upon compositions and methods which are undesirable as being costly or environmentally unsound.
SUMMARY OF THE INVENTION
The instant invention solves problems associated with conventional practices by providing an improved method and a composition for improving the surface characteristics of a metal containing surface. While the inventive composition is normally compatible with conventional compositions and methods, the inventive composition can obviate the need to employ heavy metals such as chrome and environmentally undesirable solvents.
The present invention in a broad aspect relates to compositions and methods for improving or modifying the surface characteristics of a metal containing surface. In one aspect, the invention involves methods for forming a “mineralized” layer upon the surface of a substrate. One method of forming the mineralized layer comprises delivering precursors of the mineralized layer to the surface of the metal surface via a carrier. The carrier can be a wide range of known compositions such as a film forming composition, lubricants, gel, sealant, adhesive, paint, solvent and water-borne resins, among other conventional compositions for forming coatings or films upon metals. If desired, the carrier can function as a reservoir of precursor materials thereby permitting additional formation of the mineralized layer, e.g., when in the presence of a reservoir a breach in the mineralized layer can be overcome by secondary mineral formation from mineral precursors in the reservoir—a so-called self healing effect. If desired, the carrier can also function as a reservoir of buffer materials, e.g., materials that passivate the pH of the metal surface, which can protect the metal surface by providing an environment in which the metal is resistant to chemical attack. Depending upon the utility of the carrier, the carrier can be removed or remain permanently in contact with the mineralized surface (and at least a portion of the metal surface).
The instant invention provides an improved surface on articles by tailoring the surface chemistry and effecting a new mineralized surface through chemical reaction and interaction. The mineralized surface is formed when precursors are delivered to the surface of a metal or metal coated articles or substrates. In some cases, the carrier includes materials which can function to buffer the surface, as a precursor of the mineralized layer, alter pH, activate the surface by changing the surface chemical species, or all of these functions. In some cases, the surface mineralization is enhanced by a pretreatment step prior to application of the precursor-containing carrier. After providing a proper environment, precursors can interact thereby in situ forming the mineralized layer upon at least a portion of the metal surface. Depending upon the surface environment, the metal or metal coated substrate can contribute donor ions to react and/or interact with delivered precursors thereby forming a relatively thin mineralized layer that is effective in altering and preferably enhance the characteristics of the entire article, e.g., by altering and preferably enhancing the surface characteristics of the article. Consequently, the instant invention permits tailoring a metal containing surface to possess improved corrosion, coating adhesion, chemical resistance, thermal resistance, mechanical abrasion, acid rain resistance, UV resistance, resistance to effects from atomic oxygen and vacuum UV, engineered electrical resistance, among other improved properties. As will be described below in greater detail, at least a portion of the mineralized coating or layer normally corresponds to a novel amorphous phase.
DETAILED DESCRIPTION
The instant invention relates to compositions and methods for forming a mineralized coating or film upon at least a portion of a metal containing surface. By “mineralized” it is meant a composition containing at least one member selected from the group of oxygenated cations and anions wherein at least a portion of the mineral corresponds to an amorphous phase or matrix that embeds or surrounds an inorganic complex oxide crystal. Normally, the amorphous phase is the predominate phase component of the mineralized layer and, in some cases, substantially transparent to visible light. This type of predominately amorphous structure is characterized by continuous random network (CRN). In general, the mineral layer has a network structure in which metal atoms are bound to oxygen atoms by predominantly covalent bonds. The CRN or network can be modified by the introduction of metal oxides which are, in many embodiments of the invention, contributed by the substrate. By “metal containing surface”, “substrate”, or “surface” it is meant to refer to a metallic article and any metal containing surface as well as any substrate at least partially coated with a metal layer, film or foil including a non-metallic article having a metal layer. A wide variety of substances can be employed as precursors of the mineralized layer, such as one or more cations of the metals of Groups I, II and III, and the transition metals, of the Periodic Chart of the Elements. Additionally, one or more of the anions selected from the group consisting of water soluble salts and/or 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. Particularly desirable results can be obtained by using salts and oxides of silicon, aluminum and iron.
At least a portion of the resulting mineralized layer having oxide network attributes can be characterized by the following formula:
A
x
B
y
O
z
—nH
2
O
where A is termed a modifier cation and may be one or more ions selected from Group I, II and/or III metals, and B
Dalton William M.
Heimann Robert L.
McGowan Nancy M.
Price David L.
Webb David R.
Boyer Michael K.
Elisha Technologies Co LLC
Wu Shean C.
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