Diamond cutting tools with a Ni 3 Al matrix processed by reaction pseudo-hipping
- PDF / 411,399 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 34 Downloads / 200 Views
I. INTRODUCTION
TO attain a satisfactory cutting performance, the first requirement of the matrix of a diamond tool is adequate wear resistance. A wear rate that is too fast will cause premature pullout of the diamond particles, while a wear rate too slow will cause rounding of the sharp edges, commonly known as glazing, and subsequent loss of the cutting capability.[1,2] The second requirement is good retention of the diamond particles, particularly the protruding ones, which are cutting against the workpiece. The matrix must also have high hot strength and sufficient toughness to overcome the high heat and the interrupted vibrations that occur during cutting.[3,4,5] Among the various matrix materials that can meet these requirements, cobalt is the one most widely used.[4–7] However, cobalt is a strategic material and is costly. Thus, the replacement of cobalt binder phase by other materials has been the subject of many investigations. Since diamond is not a stable material under normal pressures, it can convert to graphite easily at high temperatures. Thus, to avoid deterioration of the diamond particles, refractory metals are seldom used as the matrix material because they require lengthy sintering time at high sintering temperatures. The self-propagating high-temperature synthesis (SHS) and reactive sintering, on the other hand, require minimal sintering time to attain high densities due to the high exothermic reaction between the constituents.[8,9] Several attempts have been made to produce diamond-containing SHS materials using titanium diboride (TiB2) and nickel aluminide (NiAl) matrix.[10,11,12] These studies indicated that the extent of diamond particle preservation depended on the time and the peak temperature that the diamond endured during the reaction.[10] As a result, several approaches were taken to reduce the diamond damages, K.S. HWANG, Professor, is with the Department of Materials Science and Engineering, National Taiwan University 1, Taipei, 106 Taiwan, Republic of China. Contact e-mail: [email protected] T.H. YANG, formerly Graduate Student, Department of Materials Science and Engineering, National Taiwan University 1, is Senior Engineer with Taiwan Semiconductor Manufacturing Co., Hsin-Chu, Taiwan R.O.C. S.C. HU, formerly Graduate Student, Department of Materials Science and Engineering, National Taiwan University 1, is Diamond Technology Center Manager with Kinik Co., Taipei, Taiwan R.O.C. Manuscript submitted February 24, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS A
such as adding titanium hydride to create a protective reducing atmosphere around diamond particles or using bilayer structures to adjust the combustion temperature.[10,12] Although these findings are encouraging, none of the previous studies have provided the needed information on the mechanical properties or the cutting performance of the tools thus prepared. This is probably because these two matrix materials are brittle in nature. Boron-doped nickel aluminide, Ni3Al, is an attractive material for structural applic
Data Loading...
