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SYNDAX3
| Despite
successes with standard cobalt-based PCD, the inability of
this material to withstand high temperatures limits the
choice of bit fabrication method. The problem of thermal
instability has, however, been solved with the introduction
of SYNDAX 3. An inert binder phase is used in SYNDAX 3,
which does not differ too greatly in its thermal expansion
coefficient from that of diamond. However, SYNDAX 3 is an
unbacked material, not bonded to a layer of tungsten carbide
as in the case of SYNDRILL, for instance. SYNDAX 3 is
manufactured from 15-390µm diamond starting material, using
techniques similar to those used for the synthesis of other
types of PCD product, but, instead of cobalt,
silicon-carbide is used as a matrix. The reslut is a PCD
material which is thermally stable up to 1200°C in a
reducing atmosphere. The microstructure of SYNDAX 3 is shown
in Fig. 1, below. |
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| Fig.
1, Scanning electron micrograph of SYNDAX 3 PCD
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Fig.
2, SYNDAX 3 PCD
products for rock drilling |
SYNDAX 3 is
currently produced in the form of discs up to 5mm thick,
from which a wide variety of sizes and shapes can be cut (see
Fig. 2, above),
including cubes, triangles and pins.
All bit manufacturers pay particular attention to gauge
protection, in order to extend bit life and to enhance drill
stability. It is important to maintain the hole diameter and
integrity and to prevent problems associated with
under-gauge holes. A typical PCD oil-well bit uses natural
diamond and/or SYNDAX 3 to enhance the gauge protection.
SYNDAX 3 and/or natural diamond can also be used in other
critical areas of the bit in order to back-up the PCD
cutting elements.
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