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Thermally Stable Polycrystalline diamond (TSP)


This family of diamond products has been initially developed with one main objective, i.e. substitute naturally-mined diamonds, for which supply is irregular or even scarce, for synthetic diamonds.
Big natural stones, or drillings, originating from unstable areas, are subject to catastrophic failure due to cleavage, whereas Carbonado, the natural polycrystalline form of diamond, extremely tough and best suited for hard drilling, are very rare. That is how synthetic diamonds have become an interesting option. Being limited in size (for economic reasons), agglomerates have been designed.
These are called TSP, which stands for Thermally Stable Polycrystalline diamond products.

 

This material is almost as strong and hard as single crystal diamond and present one considerable advantage: in spite of its strength, single crystal diamond fractures relatively easily along cleavage planes. In polycrystalline diamond, crystals are randomly oriented, limiting cracks to the boundaries of each crystal.


This is one of the reasons explaining the high toughness of polycrystalline diamonds. Their exceptional strength also largely depends on the strength and extent of the diamond to diamond bonds.

TSP products consist of micron sized diamond crystals, combined to a bonding system usually made of silicon or a blend of silicon and other metal components, such as iron, aluminium, titanium,
As their name also clearly indicates it, TSP show a very high thermostability. They can withstand high temperatures of about 1200C (to a great extent because of the presence of silicon as bonding agent).
Thanks to this exceptional property, TSP products are best suited for manufacturing tools by means of high temperature - high pressure infiltration process.

From field observations, it has been established that, thanks to their specific characteristics, TSP diamond cutters are reducing overall system costs by increasing rates of penetration and bit life in abrasive and hard rock applications.


TSP Qualification method
Custodiam has developed, within its laboratory, a new method aimed at evaluating the quality of TSP products.
This quantitative method is based on the wear level observed after testing process.
The procedure could be described as follows:
Several TSP pieces are placed in a jar set in a kind of "spin dryer" at a speed maintained constant and controlled during the whole process by means of a tachometer.
During the process, TSP will move according to a specific scheme and be subject to wear by friction. In order to prevent any impact factor, several absorbing elements can be added to the testing procedure (for instance water).
After testing, pieces will present a weakening, more or less important (such as rounded edges), characterized by a weight loss (US value).
The same experiment will be applied on TSP pieces, which have previously been submitted to a heat treatment (USTh value). This treatment consists of heating the pieces at high temperature in a pipe hermetically closed, containing a fixed initial concentration of oxygen.
By combining wear results (before and after heat treatment), we are able to qualify the TSP product and attribute a performance index.

This testing procedure allows us to distinguish premium quality TSP from Standard quality (offering a good price/quality ratio), but to also identify low quality products. This difference has been clearly illustrated on the pictures here below.

WEAR EFFECTS CORRESPONDING TO PERFORMANCE INDEX

BEFORE TREATMENT


PERFECT SHAPE SHARP EDGES AND TIPS

P.I. 75


ALMOST INTACT

P.I. 65


SLIGHT CHANGES IN SHAPE AND EDGES

P.I. 50


NOTICEABLY ROUNDED
BLUNT EDGES

P.I. 30


ROUNDED SHAPE
NO EDGES

 

By means of SEM photos, we also observe the TSP structure, or rather the distribution and size of diamond grits within the TSP.
By burning the diamond contained, we are also able to isolate the structure of the bond, clearly showing the holes left by the burnt diamond grits, and so the grits distribution. A more regular structure and distribution is already a first indication of TSP quality and probably higher performance.

 


HUSQVARNA BELGIUM SA - CUSTODIAM
Avenue des Artisans, 50 - Zoning Industriel 2 - B-7822 Ath - Belgium
Tel: +32 (0)68 25 14 44 - Email: custodiam@husqvarnagroup.com