The present invention generally relates to a process for diffusing titanium and nitride into a material. More specifically, a process is provided for diffusing titanium and nitride into a material having a coating thereon.
The present invention relates to a low temperature process for diffusing titanium and nitride into a base material having a coating thereon in the presence of electrolyzed titanium. A low temperature process is preferred in that it prevents or lessens warping and twisting of the material. Titanium is considered a generally inert, light-weight material which has very high tensile strength (or toughness) and excellent corrosion resistance. Accordingly, because of their inert nature, increased hardness, increased tensile strength and increased resistance to wear, products containing titanium may be used in various applications including industrial, biomedical, aerospace, automotive, defense, jewelry, tools, tool-making, gun-making applications and other such applications.
U.S. Pat. No. 6,645,566, which is incorporated by reference herein and made a part hereof, describes a process for diffusing titanium and nitride into a variety of base materials including steel and steel alloys, aluminum and aluminum alloys, titanium and titanium alloys. Nevertheless, U.S. Pat. No. 6,645,566 does not describe a method for diffusing titanium and nitride into a material having a coating thereon.
Various materials (e.g., carbide, metal and metal alloys) are used in applications which require hardness, tensile strength and/or resistance to wear. Although these materials may inherently include these attributes, it is desirable to further enhance such. Accordingly, various surface treatment and coating processes have been applied to these materials. Conventional surface treatment and coating processes may include, but are not limited to, heat treatment, nanocoating, ceramic coating, Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Ion Assisted Coating (IAC), and other suitable surface treatments or coating. These conventional processes are typically preferred because they extend the life of the material at a lower cost than replacement of such.
Nevertheless, a coating is only as good as the strength of the bond between the coating and the substrate material. Good adhesion is an important prerequisite in engineering a commercially useful coating process. For this reason, a number of coating processes have been developed, each attempting to improve the interfacial strength between the coating and the base material.
In one example, conventional surface treatments and coating processes have been typically applied to steel and steel alloys. Steel and steel alloys are generally known to contain a high content of iron. Some conventional surface treatment processes, such as in some Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD) and Ion Assisted Coating (IAC) processes, involve nitriding, wherein nitrogen is introduced such that it reacts to iron in the steel or steel alloy to form a hardened ferrous nitride layer. This reaction causes the formation of a hardened ferrous nitride layer, which serves as a suitable coating on the base material.
These nitriding processes, however, are generally deficient when treating materials which contain a relatively low content of iron (e.g., carbide). As such, when applying these processes to such materials, there is generally not enough iron for nitrogen to react with. Accordingly, conventional nitriding surface treatments cannot generally form a hardened ferrous nitride layer on the base material due to its low iron content. Instead, a coating is formed which has a weak adhesion with the base material surface, thereby causing it to be susceptible to chipping.
It is therefore an object of the present invention to diffuse titanium and nitride into a material having a coating thereon, in order to enhance the coating in and of itself. It is also an object of the invention to provide a process which allows for the implementation of the enhanced properties of titanium in both the coating and the base material.
USPTO Backgrounds
USPTO Backgrounds