Interfacial Bonding Strength Between Brazing Alloys and CVD Diamond

Abstract

Three groups of brazing alloys were compared in brazing chemical-vapor-deposited (CVD) diamond, including two nickel-based alloys (Ni-3Fe-7Cr-3B-0.5Si-0.02C and Ni-14Cr-10P-0.02C), one copper-based alloy (Cu-10Sn-15Ti), and two silver-based alloys (Ag-5Cu-1Al-1.25Ti and Ag-34.25Cu-1In-1.75Ti). The nickel-based alloys catalytically transformed the sp 3 -bonded diamond into sp 2 -bonded carbon during hightemperature brazing operation though with the existence of Cr as the active metal. The bonding strength was very low and the fracture primarily propagated through the sp 2 -bonded carbon. For Cu-10Sn-15Ti brazing alloy, the transformation of the sp 3 -bonded diamond into sp 2 -bonded carbon during hightemperature brazing operation was marginal. The bond strength was adequate and fracture took place primarily through the brazing alloy bulk, due to the high concentrations of Sn and Ti that caused the precipitation of abundant intermetallic compounds in the brazing alloy bulk. For Ag-based alloys having very low concentrations of Ti, no visible degradation of diamond was observed and the bonding strength was very high. Crack primarily propagated through the brazed interface or even the CVD diamond bulk.

Fabrication of diamond conditioners by using a micro patterning and electroforming approach

“…To examine the catalytic reaction that occurs on the diamond surface during the manipulation process, two commercial brazing alloys, a Ni-based alloy (HBNi2: Ni-3Fe-7Cr-3B-0.5Si-0.02C) and a Cu-based alloy (Cu-10Sn-15Ti), were used as braze materials. The process conditions are similar to those reported previously [8,10]. Fig.…”

“…Fig. 9 shows the Raman spectrum of the diamond grits after removal of the metallic bonding matrix from the dressers via electrolysis in 20% H 2 SO 4 solution at 20 V. The Raman spectrum of the diamond grits removed from the electrodeposited Ni matrix solely comprised D-band at 1330 cm À1 [5,8], which is characteristic of a perfect diamond crystal, as shown in Fig. 9(a).…”

“…9(a). However, the Raman spectrum of the diamond grits removed from the Cu-based brazing alloy showed a graphite peak at approximately 1580 cm À1 [5,8] in addition to the D-band ( Fig. 9(b)).…”

“…In addition, the catalytic reactions associated with the brazing process tend to transform diamond to graphite, causing the degradation of the diamond grits [5][6][7][8][9][10]. Regarding the degradation of diamond to graphite, copper-based brazing alloys were found to be less harmful than nickel-based brazing alloys [5,8,10]. However, Raman spectroscopy still revealed the presence of the graphite phase in a diamond conditioner when copper-based brazing alloys were used.…”

A Review of the Diamond Retention Capacity of Metal Bond Matrices

“…Adding a small amount of Si to the preparation of cobalt-based bonding can enhance the abrasive resistance of the matrix, and lead to an increased adhesion of matrix to the diamond crystals, thus resulting in improved diamond retention [51]. The melting point of copper-based matrix materials can be decreased with the addition of elements P or B, which improves the wetting behavior of Cu and enhances the interfacial bonding strength [52,53]. The addition of element B can decrease the thermal expansion coefficient of diamond reinforced copper composites and strengthen the interfacial bonding [54].…”