Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2001-01-12
2003-04-29
King, Roy (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C148S253000, C148S901000, C075S743000, C075S956000, C134S041000, C423S150100, C423S150300
Reexamination Certificate
active
06554915
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to preparation of what at least initially are aqueous solutions of nickel salts. It is known that in thermodynamic principle such solutions can be prepared by dissolving metallic nickel in aqueous solutions of acids, but it is also known that in practice such reactions are often impractically slow in most non-oxidizing acids and even in some oxidizing acids under certain conditions, under which the phenomenon known as “passivity” occurs.
Nickel cations dissolved in water (along with some counterions) are an important constituent of many of the important types of liquid metal surface treatment chemical compositions that are known as “conversion coating solutions” or a like term and are fundamentally characterized by their ability to react with surfaces of many corrosion prone metals to form on the metal surfaces a solid coating layer that includes anions from the conversion coating solution and at least some cations derived from the metal coated and that improves the corrosion resistance and/or lubricant carrying capacity of the surface so coated.
Dissolved nickel cations could of course be supplied to aqueous solutions desired to contain them by dissolving a water soluble nickel salt. However, all such salts that are readily available at an economically reasonable price are hydrated and are susceptible to various degrees of hydration dependent on the conditions under which they are stored. It is therefore difficult under large-scale manufacturing conditions to obtain reliable amounts of nickel from these salts without the inconvenience and expense of frequent chemical analysis to quantify their nickel content. Aqueous solutions with known and consistent concentrations of nickel cations are accordingly preferred, and a major object of this invention is to provide such solutions at an economically acceptable cost.
Except in the claims and the operating examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred, however. Also, throughout the description, unless expressly stated to the contrary: percent, “parts of”, and ratio values are by weight or mass; the term “polymer” includes “oligomer”, “copolymer”, “terpolymer” and the like; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description or of generation in situ within the composition by chemical reaction(s) noted in the specification between one or more newly added constituents and one or more constituents already present in the composition when the other constituents are added, and does not preclude unspecified chemical interactions among the constituents of a mixture once mixed; specification of constituents in ionic form additionally implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole and for any substance added to the composition; any counterions thus implicitly specified preferably are selected from among other constituents explicitly specified in ionic form, to the extent possible; otherwise such counterions may be freely selected, except for avoiding counterions that act adversely to an object of the invention; the word “mole” means “gram mole”, and the word itself and all of its grammatical variations may be used for any chemical species defined by all of the types and numbers of atoms present in it, irrespective of whether the species is ionic, neutral, unstable, hypothetical, or in fact a stable neutral substance with well defined molecules; and the terms “solution”, “soluble”, “homogeneous”, and the like are to be understood as including not only true equilibrium solutions or homogeneity but also dispersions that show no visually detectable tendency toward phase separation over a period of observation of at least 100, or preferably at least 1000, hours during which the material is mechanically undisturbed and the temperature of the material is maintained within the range of 18-25° C.
BRIEF SUMMARY OF THE INVENTION
It has been found that:
if metallic nickel is in large pieces, it will dissolve within a few hours in non-oxidizing acid aqueous solutions only if an oxidizing agent that is chemically different from the non-oxidizing acid is present in the non-oxidizing acid aqueous solutions in a substantial concentration;
if metallic nickel is in sufficiently finely divided powder form, most of the nickel will dissolve within a few hours in a non-oxidizing aqueous acidic solution that does not contain any separate oxidizing agent; much of any residual material will then dissolve within a few more hours if oxidizing agent is added to the aqueous acid solution in contact with the still-undissolved residue from the nickel powder;
metallic nickel derived from decomposition of nickel carbonyl is sufficiently pure to be satisfactory as a source of nickel cation solutions for conversion coating;
either large or small particles of nickel derived from decomposition of nickel carbonyl leave some insoluble residue when dissolved in aqueous non-oxidizing acid solutions, but when this residue is separated by filtration, the resulting solutions are satisfactory sources of nickel cations for high quality conversion coating solutions.
Accordingly, a process according to the invention comprises, preferably consists essentially of, or more preferably consists of, at least the following operations:
(I) providing a first mass of a solid, predominantly elemental nickel reagent;
(II) providing, separately from said first mass, a second mass of a precursor aqueous acidic liquid reagent that comprises, preferably consists essentially of, or more preferably consists of the following components:
(A) water;
(B) molecules of at least one non-oxidizing acid; and, optionally, one or both of the following components:
(C) an oxidizing agent component that contains molecules of at least one oxidizing agent that is distinct from said non-oxidizing acid; and
(D) dissolved nickel cations; and
(III) effecting contact between said first mass and said second mass under such conditions of temperature and relative motion between said two masses as will result in spontaneous chemical reaction between them, said spontaneous chemical reaction converting at least, with increasing preference in the order given, 80, 90, 95, or 98 percent of the elemental nickel present in said first mass to dissolved nickel cations in a final aqueous acidic liquid that includes some of the molecules of non-oxidizing acid originally present in said second mass within a time interval, beginning with the first contact between said first and second masses, that is not more than, with increasing preference in the order given, 24, 20, 16, 12, or 10 hours.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
Suitable and preferred non-oxidizing acids for use in a process according to this invention are formic, acetic, sulfuric, hydrochloric, hydrobromic, hydriodic, hydrofluoric, phosphorous and condensed phosphorous, and phosphoric and condensed phosphoric acids. At least for economy when preparing phosphate conversion coating solutions, orthophosphoric acid is most preferred.
The solid, predominantly nickel reagent (hereinafter usually more briefly described as “nickeliferous solid”) used as a starting material in a process according to the invention preferably contains at least, with increasing preference in the order given, 98.0, 99.0, 99.2, 99.4, or 99.6 percent by weight of nickel and independent
Harper Stephen D.
Henkel Corporation
King Roy
McGuthry-Banks Tima
Seifert Arthur G.
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