Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
1999-08-31
2002-11-05
Koehler, Robert R. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C106S001120, C106S001130, C106S001150, C106S001180, C106S001210, C106S001270, C205S080000, C205S170000, C205S181000, C205S187000, C205S188000, C205S191000, C205S197000, C205S261000, C427S005000, C427S304000, C427S305000, C427S405000, C427S437000, C428S680000, C428S686000, C428S457000, C428S926000, C428S935000, C428S936000, C604S509000, C606S007000
Reexamination Certificate
active
06475644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to radioactive coating solutions, radioactive sols and sol-gels, methods used to form radioactive coatings on a variety of substrates, and to radioactive coated substrates. In particular, the present invention relates to a medical device, or a component thereof, having at least one radioactive coating layer thereon.
2. Description of Related Art
Metal coatings are used in a variety of industrial and engineering applications to provide, for example, resistance to corrosion and wear, enhanced lubricity and decorative appearance. Several methods are used to form metal coatings, including electrodeposition and electroless deposition. Electrodeposition depends on the use of applied voltage to produce metal deposition, while electroless deposition depends on chemical reactions (including the chemical reduction of a metal) independent of applied voltage. See, e.g., Dini, J. W., Developments and Trends in Electrodeposition, SAMPE Quarterly (1989) 28-32; and Ohno, I. Electrochemistry of Electroless Plating, Materials Science and Engineering, vol. A146 (1991) 33-49.
A wide variety of solutions for electrodeposition and electroless deposition are known, as theoretically any element or combination of elements, including metals and non-metals, can be added to a carrier metal to provide a suitable coating solution, wherein the carrier metal is present as an ion. In particular, metalloids including phosphorus and boron can be added to a carrier metal to provide a coating solution. Commonly used carrier metals include nickel, copper, cobalt, platinum, palladium, chromium, gold and silver. Particularly common are nickel and nickel alloy coating solutions, including nickel-phosphorus, nickel-boron, palladium-nickel, nickel-chromium, nickel-cobalt, nickel-phosphorus-boron, and copper-nickel chromium. Solutions are typically aqueous.
Electroless coatings are significantly more uniformly deposited than electrodeposited coatings, and are particularly desirable for coating complex shapes, including tubes and large components. Electroless deposition of nickel-phosphorus coatings, in particular, is well known. In general, electroless nickel phosphorus (ENP) coatings are dense, non-porous metal glass structures resembling polished stainless steel. ENP coatings typically contain between 3 and 13% by weight phosphorus, with the percentage significantly influencing both the chemical and physical properties of the coating. High phosphorus ENP coatings provide superior corrosion protection and are generally more continuous that lower phosphorus ENP coatings. R. P. Tracey, Practical Guide to Using N-P Electroless Nickel Coatings, Materials Selection and Design, 1990. ENP coatings are generally highly adhesive, providing resistance to chipping and peeling under extreme conditions. Electroless coatings may be amorphous or crystalline in structure
Materials to be coated by electroless deposition are commonly metal. Electroless coatings can be applied to most metals and alloys, including steel and stainless steel, iron, aluminum, titanium, magnesium, copper, brass, bronze and nickel. In some cases, in addition to cleaning and removing surface oxides, the metal or alloy must be pre-treated to provide a catalytic surface for the electroless coating. For example, for coating Elgiloy™ with ENP, the surface must be coated (i.e., by electrodeposition or electroless deposition) with Ni prior to being coated with ENP. Electroless deposition may also be used to coat a variety of materials that are generally non-conductive, including plastics, glasses and ceramics, and composite materials. Coating of polymers genereally requires additional steps to activate the polymer surfaces. A variety of processes are known for making polymer surfaces catalytic to the coating process. A tin-palladium catalyst, for example, can be absorbed onto the surface of the substrate, or applied as a catalytic coating.
Electroless deposition is carried out by immersing the substrate to be coated in an coating solution or bath comprising a carrier metal ion and a reducing agent. In ENP coating solutions, the most common reducing agent is hypophosphite ion (H
2
PO
2
−
). (Tracey, 1990). The metal ions are chemically reduced in the presence of the reducing agent and deposited onto the substrate surface. Deposition rates are typically 10-20 microns per hour. Typical commercial ENP coating are from about 2.5 to about 125 microns thick. (Tracey, 1990). Thicker coatings are typically required for rough surfaces.
Metal coatings may also be formed by electrodeposition. For example, nickel-phosphorous coatings may be produced by electrodeposition, and have comparable properties to those prepared via electroless deposition. Weil et al., Comparison of Some Mechanical and Corrosion Properties of Electroless and Electroplated Nickel-Phosphorous Alloys, Plating and Surface Finishing (Feb. 1989) 62-66.
Materials to be coated by electrodeposition include most metals and alloys, which in some cases must be clean and oxide free to provide a catalytic surface for electrodeposition. In certain circumstances, polymers may also be coated by electrodeposition. For example, plastics incorporating conductive particles can be coated by electrodeposition. Intrinsically conductive polymers may also be coated by electrodeposition. Generally, electrodeposition rates of Ni—P are higher than normally obtained via electroless methods. Also, electroplating solutions are more stable and have fewer replenishment problems. However, electrodeposited Ni—P does not coat complicated shapes with as uniform a thickness as ENP.
Electrodeposition is carried out by immersing the substrate to be coated in a coating solution or bath comprising a carrier metal ion and a radioisotope. Unlike electroless deposition, electrodeposition requires an applied current. In general, a reducing agent such as is necessary for electroless deposition is not required for electrodeposition, although reducing agents are not uncommonly present for electrodeposited Ni—P coatings, for example.
Methods for producing radioactive metal articles are also known. For example, it is known to manufacture a metal article comprising a radioisotope, e.g., by alloying the radioisotope with a metal or alloy or by ion implantation with a radioactive element It is also known to manufacture non-radioactive metal articles which are subsequently made radioactive, e.g., by neutron bombardment. Each method of preparing radioactive metal articles, however, is associated with particular disadvantages. Manufacture of alloys using radioactive elements, for example, is problematic because many of the most desirable radioisotopes (e.g., P) show limited solubility as equilibrium alloying ingredients. Moreover, health physics safety issues associated with the manufacture of various articles effectively prohibit certain methods of manufacture.
The use of neutron bombardment to produce radioactive metal articles is similarly problematic, given limited access to nuclear reactors and tremendous costs. Neutron bombardment also constrains the size of components which can be irradiated. Moreover, neutron bombardment activates all components of the metal article that are susceptible to neutron activation, so that undesirable and potentially dangerous radioisotopes may be generated. Many standard alloy components, including Fe and Cr, form undesirable radiation reaction products. Thus, metals and alloys subject to neutron bombardment must be extremely pure and free of problematic elements, e.g., Na.
It is one object of the present invention to provide a radioactive coating that can be produced from less than extremely pure materials, and without placing the coated article into a nuclear reactor.
It is a further object of the present invention to provide a radioactive coating comprising any of a wide variety of radioisotopes, including insoluble radioisotopes.
It is another object of the present invention to provide a radioactive coating solution which permits sep
Hampikian Janet M.
Scott Neal A.
Koehler Robert R.
Radiovascular Systems, L.L.C.
LandOfFree
Radioactive coating solutions methods, and substrates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radioactive coating solutions methods, and substrates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radioactive coating solutions methods, and substrates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2984878