Thick film polycrystalline diamond has been produced since the mid 1950’s: a flat platform substrate of metal or ceramic is seeded with micron diamond and put in a chamber under vacuum. A mixture of gases, typically hydrogen and methane, is introduced and these are then heated rapidly. The gases react with each other and the seed diamond so that a diamond layer forms on the seed diamond and grows in a columnar manner. Thickness up to several millimetres are readily achievable.
There are three recognized methods of heating the gases that are currently employed: hot filament, microwave plasma and arcjet plasma
Each of these processes produces CVD diamond of differing characteristics and, together with the many other variables that can be selected, allows for the production of CVD that targeted at the two main industrial markets:
- Cutting Tools
- Grinding Wheel Dressing
For both these markets, NDP have identified the most suitable materials available and developed novel inspection procedures to ensure that only the highest quality material is supplied.
The adoption of CVD diamond for cutting tools has been driven by the increased used of composite materials. The abrasive nature of composites makes diamond the obvious choice for machining and CVD, with its extreme wear resistance and ability to maintain a very sharp cutting edge provides the best quality edge finish with low fibre pull-through. In tests it performs considerably better than Polycrystalline diamond.
CVD diamond has long been used in dressing tools. Extensive research over several years has enabled us to determine the most appropriate grades of CVD diamond for each dressing application and with careful control of quality to guarantee the performance of our products for this market.