Source: http://www.google.com/patents/US8091765?ie=ISO-8859-1
Timestamp: 2015-01-30 04:52:50
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Patent US8091765 - Method of bonding titanium to stainless steel - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA method of bonding a stainless steel part to a titanium part by heating a component assembly comprised of the titanium part, the stainless steel part, and a laminated titanium-nickel filler material placed between the two parts and heated at a temperature that is less than the melting point of either...http://www.google.com/patents/US8091765?utm_source=gb-gplus-sharePatent US8091765 - Method of bonding titanium to stainless steelAdvanced Patent SearchPublication numberUS8091765 B2Publication typeGrantApplication numberUS 11/336,596Publication dateJan 10, 2012Filing dateJan 20, 2006Priority dateApr 7, 2004Also published asUS8177116, US20050224558, US20060113357, US20120073114, US20120237785Publication number11336596, 336596, US 8091765 B2, US 8091765B2, US-B2-8091765, US8091765 B2, US8091765B2InventorsGuangqiang Jiang, Atilla AntalfyOriginal AssigneeAlfred E. Mann Foundation For Scientific ResearchExport CitationBiBTeX, EndNote, RefManPatent Citations (8), Classifications (19) External Links: USPTO, USPTO Assignment, EspacenetMethod of bonding titanium to stainless steelUS 8091765 B2Abstract A method of bonding a stainless steel part to a titanium part by heating a component assembly comprised of the titanium part, the stainless steel part, and a laminated titanium-nickel filler material placed between the two parts and heated at a temperature that is less than the melting point of either the stainless steel part or the titanium part. The component assembly is held in intimate contact at temperature in a non-reactive atmosphere for a sufficient time to develop a hermetic and strong bond between the stainless steel part and the titanium part. The bonded component assembly is optionally treated with acid to remove any residual free nickel and nickel salts, to assure a biocompatible component assembly, if implanted in living tissue.
1. A method of making a living tissue implantable component assembly, comprising the steps of:
selecting a biocompatible 316L stainless steel part;
selecting a biocompatible titanium part that is comprised of Ti-6Al-4V;
selecting a laminated filler material that is less than about 0.010 inches thick that is comprised of a 22% to 98% nickel portion and a remaining titanium portion, said laminated filler material comprising at least two nickel layers surrounding at least one titanium layer,
selecting said laminated filler material having a melting point that is lower than the melting point of said titanium part and said stainless steel part;
positioning said filler material between said stainless steel part and said titanium part;
applying a force to said stainless steel part and said titanium part to place said filler material in compression, thereby creating intimate contact between said stainless steel part, said filler material, and said titanium part;
heating the assembly to a temperature between said melting point of said laminated filler material and said melting point of said titanium part;
holding the assembly at said bonding temperature for a predetermined time to form a bond between said stainless steel part and said titanium part;
cooling the assembly; and implanting the component assembly in a human body.
2. The method of claim 1 wherein said step of applying a force creates compression between about 5 and 50 psi.
3. The method of claim 1 wherein said step of applying a force creates compression between about 5 and 7 psi.
4. The method of claim 1 further comprising the step of forming said filler material from metallic particulate.
5. The method of claim 1 further comprising the step of placing the assembly in a non-reactive atmosphere is placing in a vacuum less than 10−5 Torr.
6. The method of claim 1 further comprising the step of placing the assembly in a non-reactive atmosphere is placing in argon gas.
7. The method of claim 1 wherein said bonding temperature is between approximately 940� and 1260� C.
8. The method of claim 1 wherein said predetermined time is between approximately 5 and 60 minutes.
9. The method of claim 1 additionally comprising the step of cleaning said component assembly after bonding to remove elemental nickel and nickel salts.
10. The method of claim 9 additionally comprising the step of cleaning said component assembly after bonding by placing it in an acid bath.
11. A method of making a living tissue implantable component assembly, comprising the steps of:
selecting a biocompatible stainless steel part from the group consisting of corrosion resistant stainless steels;
selecting a biocompatible titanium part comprised of Ti-6Al-4V;
positioning a laminated filler material between said stainless steel part and said titanium part;
applying a force to said stainless steel part and said titanium part to place said filler material in compression between 5 and 7 psi, thereby forming said component assembly;
heating said component assembly to between approximately 940� and 1260� C. for between approximately 5 and 60 minutes;
cooling said component assembly;
cleaning said component assembly after cooling to remove elemental nickel and nickel salts; and
implanting the component assembly into a human body. Description
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a side view of the component assembly with filler material as a foil between the stainless steel part and the titanium part.
FIG. 8 illustrates a bonded device with a crimp-attached wire.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 presents component assembly 2 having a titanium part 4, a stainless steel part 6, and a filler material 8. Component assembly 2 is heated to a specific process temperature that is below the melting point of titanium part 4 or of the melting point of stainless steel part 6, for a specific period of time, at a pressure that is created by force 10, that is exerted to place filler material 8 in intimate contact with the titanium part 4 and stainless steel part 6.
Filler material 8 is preferably a laminate metal foil having a thickness of approximately ten-thousandths (0.010) of an inch and more preferably less than 0.010 inches. Filler material 8 is selected from the group of materials that are compatible with the stainless steel chosen for stainless steel part 6 in that they wet the surface during the bonding process and enter into a diffusion process with the stainless steel part 6, thereby creating a strong bond joint during processing. Filler material 8 is further selected from the group of materials that are compatible with the titanium part 4. Filler material 8 forms a bond between titanium part 4 and stainless steel part 6 at the bonding temperature and pressure utilized during processing. The group of filler materials that are compatible with both the stainless steel part 6 and the titanium part 4 includes substantially pure titanium and nickel laminate compositions, preferably comprised of filler materials of about 22% to 98% nickel and the balance titanium. In a preferred embodiment, FIG. 3, filler material 8 is preferably comprised of alternating foil layers 12 and 14. Preferably, for example, as shown in FIG. 3, a laminate stack of commercially pure nickel layer 12 on the top outer surface 42 and a similar nickel layer 12 on the bottom outer surface 44. Sandwiched between the nickel layers 12 is a titanium layer 14. The nickel layer 12 having at least 99.0% nickel and less than 1.0% of other elements with a thickness of greater than approximately 0.0003 inches and the titanium layer 14 comprised of commercially pure titanium foil having at least 99.0% titanium and less than 1.0% of other elements with a thickness of greater than approximately 0.0003 inches.
The inventors prefer the term �laminated� versus other descriptive, but equally applicable, terms such as �layered�, �clad�, or �composite� material. The laminated filler material is not an �alloy� of nickel and titanium. An alloy, which is defined as a homogeneous mixture of two or more metals, where the atoms of one replace or occupy interstitial positions between the atoms of the other, of nickel and titanium, for example, does not demonstrate the depressed melting point that is available at a eutectic composition when nickel and titanium are in intimate contact. The laminate material supplies substantially pure nickel to initiate bonding with other metals, such as titanium or stainless steel, for example, at relatively low eutectic temperatures. For example, the lowest liquidus temperature (also referred to herein as the melting point) in the nickel-titanium phase diagram occurs at 28% by weight nickel and is 942� C. Therefore, the optimum braze temperature will be greater than this temperature.
In a further preferred embodiment, FIG. 4, the metal foil layers 15, 15′, and 15″, which are comprised of nickel, are placed in laminated filler material 8 as the top outer surface 42 and as the bottom outer surface 44, thereby making the nickel available to react directly with the stainless steel part 6 and the titanium part 4. Alternating layers of inner mating foil layer 17 and 17′, which are comprised of titanium, are placed between the metal foil layers 15, 15′, and 15″.
Titanium part 4 may be comprised of a titanium alloy and is comprised of Ti-6Al-4V, i.e. an alloy of titanium with 6 weight percent aluminum and 4 weight percent vanadium, in a preferred embodiment. Stainless steel part 6 may be comprised of one of the corrosion resistant stainless steels, such as, 304 stainless steel, or a 200, 300, or 400 series stainless steel, and in a preferred embodiment stainless steel part 6 is comprised of 316L stainless steel. This configuration of components offers the advantage of being biocompatible and of being capable of forming hermetic seals.
Yet another alternate embodiment of forming a bonded component assembly 2 utilizes the compact filler material 8′, as presented in FIG. 5, that is comprised of layered discrete particle 19, preferably spheres, comprised of layered or laminated composition, as shown in FIG. 6. In a preferred embodiment, layered discrete particle 19 is comprised of alternating layers of primary particle laminate layer 18 and secondary particle laminate layer 40, where primary particle laminate layer 18 is preferably comprised of nickel and secondary particle laminate layer 40 is comprised of titanium. The overall bonding methods and processes are analogous to those employed for the several embodiments.
In step 26, the assembly to be heat processed is placed in a furnace in a non-reactive atmosphere, which is preferably vacuum, but which, in an alternative embodiment, can be any of several atmospheres that are known to those skilled in the art, such as argon, nitrogen or hydrogen. A non-reactive atmosphere is applied before the furnace is heated to the processing temperature in step 28. A preliminary holding temperature may be utilized to allow the thermal mass of the parts to achieve equilibrium before proceeding with heating. In a preferred embodiment, the vacuum is less than 10−5 torr, to assure that the filler material 8 and titanium part 4 do not oxidize. Component assembly 2 is held at the selected temperature, which is between approximately 940� and 1260� C., for approximately 5 to 60 minutes, while force 10 continues to be exerted on filler material 8. The exact time, temperature and pressure are variable with each other so as to achieve a strong bond between titanium part 4 and stainless steel part 6. For example, in a preferred embodiment, a 316L stainless steel part is bonded to a Ti-6Al-4V part in vacuum at 10−6 torr at approximately 1000� C. for 10 minutes with a pressure of about 50 psi on a nickel-titanium foil of approximately 0.002 inches total thickness.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS3994430 *Jul 30, 1975Nov 30, 1976General Electric CompanyEutectic alloyUS4433230 *Jun 3, 1981Feb 21, 1984Tokyo Shibaura Denki Kabushiki KaishaMethod of manufacturing a vacuum vessel provided with a radiation-permeable windowUS6109339 *Nov 8, 1996Aug 29, 2000First Company, Inc.Heating systemUS6521350 *Oct 6, 2001Feb 18, 2003Alfred E. Mann Foundation For Scientific ResearchApplication and manufacturing method for a ceramic to metal sealUS6722002 *Dec 16, 2002Apr 20, 2004Engineered Materials Solutions, Inc.Method of producing Ti brazing strips or foilsUS6875949 *Mar 19, 2003Apr 5, 2005Edison Welding InstituteMethod of welding titanium and titanium based alloys to ferrous metalsUS7201973 *Dec 10, 2003Apr 10, 2007Honeywell International, Inc.Bimetallic plate-fin titanium based heat exchangerUS20040105999 *Aug 12, 2003Jun 3, 2004Stanley AbkowitzBi-metallic macro composite* Cited by examinerClassifications U.S. Classification228/203International ClassificationB23K35/02, B23K35/00, A61N1/375, B32B15/00, B23K20/02, B23K1/20, A61N1/372Cooperative ClassificationB23K35/004, A61N1/372, B23K2203/24, A61N1/3752, B23K20/023, A61N1/37205, B23K35/0238, B23K35/005European ClassificationA61N1/372, B23K35/00B6, B23K20/02DRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services