Advanced medium for Diamond synthesis
The MEDIUM used during synthesis of Polycrystalline Diamond Compact, shall best simulate the natural condition, under which, diamond structure is formed and stabilized inside the formation-rock under high pressure (over 5 GPa) and high temperature (2000°C). To withstand and behave properly under such sever condition, the following characteristics are considered on selection of material used as the synthesis MEDIUM:
High plasticity in isostatic condition with grain sliding characteristics
High volumetric modulus to achieve higher isostatic pressure when anvils get closer to each other
High ultimate compressional strength to prevent explosion of cell assembly and anvils overrunning and destruction
Creating a high pressure molten bath
The PDC shall be exposed to pressure isotropically. Any imbalance force may conclude to the deformation of PDC face or ovality of its peripheral surface. A molten bath has been designed around the pre-comps (Capsule assembly) to apply a uniform pressure to its external surfaces. The molten bath secures complete bonding of diamond particles and eliminates any unbounded zone in PDC structure due to the localized pressure deficiency. Uniform pressure over the molten bath guarantees the homogenous properties all over the product.
Capsule assembly sequence
Apart from the materials used to make different cups, their numbers, shapes and the way to assemble them are proprietary for each cutter manufacture. SCT has reached to its own innovative arrangement of the cups and an efficient assembly and sealing methods.
Design of an efficient synthesis temperature cycle
The synthesis temperature cycle and the accurate control of it, during PDC cutter production, has a great impact on the quality of final product. Pre-heating of anvils and Capsule assembly, the through put electrical power capacity, selection of new type of insulators and special composition for the graphite elements are some of unique adjustments innovated by SCT as the temperature control and cycle design.
Thermal insulation of the encapsulated cutter during heating cycle
To avoid excessive heat being transferred to the anvils, special insulation system has been designed and superior insulators have been selected. Heat transfer control during Diamond compact production will have direct impact on anvils lifetime and it make the process costs remain in an optimum level.
The grain size of Tungsten Carbide substrate, its Cobalt content (as the binder) and other additives have noticeable effects on the quality of a PDC cutter. SCT has reached to an advanced grade, composition and grain size for the WC substrate.
Diamond particles are the main ingredient composes PDC layer. The following parameters are essential to make a superior layer:
Grain size and shape
Mixing method and procedure
Activating and preservation methods
In HPHT process, the anvils are used as the pressure intensifier to concentrate the cubic press force into a small space. Effective area, relief angles at the tip of the anvils depend on the size of cell assembly cube. It is desired to have constant pressure on the cell cube surfaces. Axial movements of vertical and horizontal anvils and their speed during the pressurizing cycle greatly affect how the isostatic pressure is obtained. Anvil design is proprietary and each company has its own design. We have our own too.
Synthesis pressure has a significant role on the quality characteristics of PDC product. As the pressure of diamond sintering increases, the superiority of the diamond layer improves. However while coming by the higher pressure, the anvils will be exposed to the higher risk of destruction. To produce the premium cutters, the most reputable suppliers are applying around 6Mpa pressure during diamond sintering process.
Thanks to a talented anvil design, SCT has been successful to obtain superior PDC cutter prototypes with 30% higher durability by applying 8MPa in the sintering pressure. The repeatability of the process has been checked and approved as well.
Higher synthesis pressure
Leaching process improvement
In leaching process, the type of acids solution, the sealing of protected area of cutters, fixture design, time and temperature of the process and implying accelerated methods can enhance the depth of leaching and its pattern. We have used barrel leaching process which is more effective than the face leach.
Conclusively, the final quality of a PDC cutter, greatly depends on the tailor-made manufacturing know how
What is innovative with SCT product are:
Using a mixture of natural diamond powders with different sizes
Implementing a state of the art mixing method and procedure
Adding some ingredients (such as graphite) to improve process implications
Utilizing special surface treatment for preservation/activation of diamond particles