Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2003-01-17
2004-11-02
Zimmerman, John J. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S647000, C428S648000, C428S939000, C220S562000, C220S567200, C206S524300
Reexamination Certificate
active
06811891
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the art of corrosion-resistant metal materials such as a corrosion-resistant metal made of a corrosion-resistant metal alloy or a base metal which is coated with a corrosion resistant metal alloy, which corrosion-resistant metal materials can be used in a wide variety of applications such as, but not limited to, architectural or building materials such as roofing materials, siding materials, window frames, sheet metal, metal plates and the like; truck and automotive products such as, but not limited to, gasoline tanks, filter casings, body molding, body parts and the like; household products such as, but not limited to, appliance housings, electrical housings, light fixtures and the like; marine products such as, but not limited to, boat hulls, boat masts, dock system components; and/or other types of metal materials such as, but not limited to, tools, machinery, wires, cables, electrodes, solder and the like. The invention also relates to various metal alloy compositions or metal coating alloy compositions based upon metal alloys of tin and metal alloys of tin and zinc, and several novel methods and processes used therein for forming the metal alloy materials or base metals coated with the metal alloy composition, such as, but not limited to, wire or solder forming, metal strip forming, and coated metal forming by a plating process and/or a hot-dip process (i.e plating of metal alloy and subsequent flow heating, immersion in molten metal alloy, metal spraying of metal alloy, and/or roller coating of metal alloy), pretreatment of the base metal prior to metal alloy coating, applying an intermediate barrier metal layer prior to metal alloy coating, post-treating the metal alloy or coated base metal, and/or forming the metal alloy or coated base metal into a variety of different articles.
Over the last several years, there has been a trend in the industry to produce products which are higher in quality, are environmentally friendly, and are safe for use by humans, animals, and/or plants. This push for quality, safety and environmental friendliness is very apparent in the automotive industry wherein both consumer groups and environmental organizations are constantly lobbying for safer, higher-quality vehicles that are more fuel efficient and less detrimental to the environment. Recycling old vehicles has been one answer to resolving the environmental issues associated with vehicles which have run out their useful life. Automotive salvage markets have developed for these vehicles. The vehicles are partially dismantled and sold as scrap metal wherein the metal is melted down and reformed into various parts. Because of the environmentally-unfriendly nature of lead, the gasoline tanks of vehicles must be removed prior to the recycling of the vehicle. Gasoline tanks are commonly made of carbon or stainless steel that are coated with a terne alloy.
Terne or terne alloy is a term commonly used to describe a metal alloy containing about 80% lead and the balance tin. The terne alloy is conventionally applied to a base metal by immersing the base metal into a molten bath of terne metal by a continuous or batch process.
Although terne coated metals have excellent corrosion-resistant properties and have been used in various applications, terne coated materials have been questioned due to environmental concerns based on the high lead content of the alloy. Environmental and public safety laws have been proposed and/or passed prohibiting or penalizing the user of materials containing a significant portion of lead. As a result, these terne coated gas tanks must be disposed of in dumping yards or landfills. Not only does the terne coated gasoline tank take up space in the landfills, but there is a concern with the lead leaching from the terne coating into the landfill site and potentially contaminating the surrounding area and underground water reservoirs. Plastic gasoline tanks have been used as an alternative to terne coated materials, but with limited success. Although the use of plastic tanks eliminates the environmental concerns associated with lead, the plastic in-of-itself is a non-environmentally-friendly compound which does not readily degrade and therefore must be disposed of in a landfill. The plastic used to make the gasoline tanks is usually not the type that can be recycled. Plastics have also been found to be less reliable than metal gasoline tanks with respect to durability and safety. Plastic gasoline tanks have a tendency to rupture upon impact, such as from a car accident, whereas a metal gasoline tank tends to absorb much of the shock on impact by bending and slightly deforming. Furthermore, the plastic gasoline tanks are more susceptible to being punctured from roadside debris since the plastic skin is not as strong or malleable as the skin of a metal gasoline tank. Plastic gasoline tanks also require new materials, special tools and new assembly methods to fix and install the gasoline tanks due to the nature of plastic and its physical properties. These additional costs and shortcomings of plastic tanks have resulted in very little adoption of plastic gasoline tanks in present day motor vehicles.
The lead content in metal materials is also of some concern for building materials. This is especially a concern when the metal materials are in contact with drinking water. In many countries, lead pipe has been outlawed to reduce the amount of lead in the water. In many remote locations throughout the world, piped water or well water is not readily available. As a result, structures, such as portable roof systems, are built to capture rain and to store the rain water for later use. These potable roof systems supply an important water source for inhabitants utilizing such structures. Roof systems that are designed to collect rain water are typically made of metal to increase the longevity of the roofing system. Typically, the roof systems are made of carbon steel since such metal is the least expensive. The carbon steel is commonly coated with a terne alloy to extend the life of the roof system. Terne alloy is commonly used due to its relatively low cost, ease of application, excellent corrosion-resistant properties and desirable colorization during weathering. Roof systems have been made of other metals such as, but not limited to, stainless steel, copper, copper alloys and aluminun. Stainless steel, copper, copper alloys and aluminum were typically not coated with a terne coating since these metals have excellent corrosion-resistant properties. However, in some limited applications, these metals have been coated with terne to extend the life of these metals. However, as with lead piping, there is a concern that the lead in the terne coated roofing materials results in lead dissolving in the collected water.
Terne coated materials have typically been coated with a 6-8 lb. coating (7-11 microns), which is a very thin coating. This thin coating commonly includes pinholes. Terne coated materials that are drawn or formed in various types of materials such as, but not limited to, gasoline tanks, corrugated roofing materials and the like typically included one or more defects in the coating. The defects in the terne coating on the base metal which were designed to protect the base metal from corroding thus compromised the corrosion resistance provided by the terne coating. Due to the thin layer of the terne coating and the pinholes in the coating, the coating on the base metal, upon being drawn by a die or by being formed, tended to tear or shear the terne coating and/or elongate the pin holes on the coating thereby exposing the base metal. These exposed surfaces were subject to corrosion and over time compromised the structural integrity, safety and/or performance of the coated base metal. The non-uniform coating of stainless steel metal with the terne coating is especially evident since the terne alloy did not bond as well to the stainless steel. Another disadvantage of using a terne alloy coating is the softness of the tern
Carey, II Jay F.
Hesske Nicholas R.
Zamanzadeh Mehrooz
Fay Sharpe Fagan Minnich & McKee LLP
The Louis Berkman Company
Zimmerman John J.
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