Nucleation method

The outline of known diamond nucleation methods and process has been described in Section. 2.2, and it is briefly summarized below ... 

In conclusion, we have discussed the use of C clusters as diamond nucleation sites on Si substrates. This nucleation method substitutes the current practice of polishing surfaces with diamond grits. We have also demonstrated how C clusters can be used to selectively grow diamond on Si surfaces. In addition, our process provides a means of better understanding the mechanism of diamond nucleation. From our experiments, we can also speculate the reason why surface pretreatment is not necessary in the case of flame torch diamond deposition methods. We postulate that C clusters formed by the torch are helping to nucleate diamond on surfaces. The use of C clusters for diamond growth on other substrate materials, and the details of diamond nucleation will be reported elsewhere. 

With the exception of the nucleation method, non-mechanical methods to measure adhesion are not very well developed, and their field of application is severely limited. These methods can, in any case, only be used for basic investigations. 

A method independent of crack type is the minimum load-crack nucleation method. To operate this method the minimum load to nucleate cracks, P, has to be determined. By its nature this is a statistical method whereby about 20 indentations are made per load in a range from, say, 0.5 to 50 N. The number of indent corners where cracks appear are counted and expressed as a percentage of indent comers the minimum load for crack nucleation, P, is the load of which 50% of corners project a crack, and then equation (5.60) can be used... 

For substrates other than Si, and technologically more feasible, is the seeding of substrates with nanometer-sized diamond powder applied in an ultrasonic bath, for example. This is the nucleation method generally employed in the CVD synthesis of polycrystaUine films and coatings. 

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