Diamond segments and saw blades have been prepared using both uncoated and coated saw grit and the relationship between the coating, diamond, metal matrix and performance in application is examined. It is shown that the relative retention of diamond grit in a metal matrix during saw blade application testing can be predicted by relating the results from segment fracture analysis to a Weak Link Model for predicting retention of grit in metal matrices. In addition, the protection offered by a coating against diamond graphitisation can be assessed by analysing recovered diamond after segment manufacture. It is shown that a range of coatings is needed in order to successfully match a coating with the matrix material, method of tool production and application.
Conclusions
1. Fracture analysis and its relationship to the weak link model can be used as a method to predict the retention of uncoated and coated grits in metal matrices.
2. It has been shown that in a high copper pre-alloyed matrix hot pressed at 700oC the use of S1 coated grit extends the life of a saw blade over uncoated grit due to an increase in diamond retention during sawing.
3. It has also been shown that in a cobalt matrix hot pressed at 800oC, S2 coated grit extends the life of a saw blade over both uncoated and S1 coated grit due to an increase in diamond retention and also protection of the diamond against graphitisation.
4. In a partially sintered iron compact infiltrated with liquid nickel-bronze, a S3 coating protects the diamond from graphitisation better than either a S1 coated or uncoated diamond.
5. In order to increase saw blade performance, it is important to ensure that the coating selected for a diamond is both compatible with the matrix material and protects the diamond from graphitisation during tool manufacture.

K. Greene, D. Egan, S. Kelly, S. Nailer, S. Melody
Element Six Ltd., Shannon Airport, Co. Clare, Ireland.