Metal fusion bonding – Process – Metal to nonmetal with separate metallic filler
Reexamination Certificate
1999-01-25
2001-04-10
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Process
Metal to nonmetal with separate metallic filler
C228S124500, C228S005100, C228S121000
Reexamination Certificate
active
06213380
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of bonding a diamond compact to a cemented carbide substrate.
Diamond compacts consist of a polycrystalline mass of diamond produced under diamond synthesis conditions. Diamond compacts have a high diamond content, for example, higher than 80 percent by volume, and generally contain a second or bonding phase. An example of a second or bonding phase is one which contains silicon, with or without a diamond catalyst/solvent. The silicon will be present largely as silicon carbide, although some residual elemental silicon will also be present.
Diamond compacts are brittle and are generally bonded to a substrate, particularly a cemented carbide substrate, for cutting and other similar operations. Bonding of silicon-containing diamond compacts to substrates presents problems. Where a braze is used for the bonding, the strengh of the braze joint can be reduced by impurities which diffuse from either the substrate or the compact into the braze layer. More particularly, for siliconcontaining compacts, even minute quantities of residual, unreacted freesilicon from the binder phase reacts preferentially with the braze producing a highly inconsistent and weakened braze joint between the compact and the substrate.
SUMMARY OF THE INVENTION
According to the present invention, a method of bonding a diamond compact comprising a polycrystalline mass of diamond and a bonding phase which contains free-silicon to a substrate includes the steps of contacting a surface of the compact with carbon or nitrogen or a mixture thereof under conditions suitable to cause free-silicon in the surface to react with the carbon and/or nitrogen and thereafter bonding that surface to the substrate, preferably by means of a braze.
The source of the carbon may be graphite or amorphous carbon or it may be produced in situ by decomposition or pyrolysis of a carbon-containing gas, e.g. a hydrocarbon. A silicon carbide or sub-carbide compound will be formed.
The source of nitrogen may be solid or gaseous and a silicon nitride or subnitride compound will be formed.
The invention has particular application to diamond compacts comprising a polycrystalline mass of diamond particles present in an amount of 80 to 90 percent by volume of the compact and the bonding phase present in an amount of 10 to 20 percent by volume of the compact, the bonding phase consisting essentially of silicon or silicon carbide or a combination thereof. An example of such a compact is that described in U.S. Pat. No. 4,793,828. An example of a commercially available form of such a compact is that sold under the trade name SYNDAX 3®.
In one preferred form of the invention, the surface of the diamond compact which is bonded to the substrate is acid cleaned after contact of the surface with the carbon or nitrogen, or mixture thereof and before bonding to the substrate. The acid treatment is preferably carried out with a strong acid such as sulphuric acid or chromic acid and more preferably with fuming sulphuric acid. It has been found that the presence of an oxidizing agent such as a nitrate improves the acid cleaning. Thus, a typical acid cleaning may involve the steps of treating the diamond compact surface with the acid in the presence of an oxidizing agent and thereafter washing the acid cleaned surface with water, e.g. deionised water.
Where a braze is used to bond the treated diamond compact surface to the substrate, any known commercially available braze may be used. Examples of such brazes are a titanium/copper/silver braze (e.g. Ti 4,5%, Cu 26,7%, Ag 68,8%) and a silver/copper/indium braze (e.g. Ag 75%, Cu 20%, In 5%).
The substrate will generally be a cemented carbide substrate. Cemented carbide substrates are known in the art and comprise a mass of carbide particles, for example, tungsten carbide particles, bonded into a hard, coherent form by means of a binder metal such as cobalt, iron, nickel or an alloy containing one or more of these metals.
REFERENCES:
patent: 4793828 (1988-12-01), Burnand
patent: 4871377 (1989-10-01), Frushour
patent: 5010043 (1991-04-01), Ringwood
patent: 5127923 (1992-07-01), Bunting et al.
patent: 5151107 (1992-09-01), Cho et al.
patent: 5348108 (1994-09-01), Scott et al.
patent: 5547121 (1996-08-01), Kapoor et al.
patent: 5635256 (1997-06-01), Olson
patent: 5645937 (1997-07-01), Noda et al.
patent: 0 329 954 (1989-01-01), None
patent: 2 163 144 (1986-02-01), None
Collins John Lloyd
Dufferwiel Graeme David
Sweeney Charles Gerard
Wort Christopher John Howard
Elve M. Alexandra
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ryan Patrick
LandOfFree
Bonding a diamond compact to a cemented carbide substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bonding a diamond compact to a cemented carbide substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bonding a diamond compact to a cemented carbide substrate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2536566