Characteristics and Application of CVD Diamond Tools
Compared with PCD tools, CVD diamond has high purity. The CO contained in PCD material makes it have strong anti fragmentation and fracture properties, but the presence of
CO reduces the hardness of PCD, and will accelerate the transformation and oxidation of diamond to graphite at high temperature. CVD diamond is pure diamond without any added
composites, so it has higher hardness, thermal conductivity, compactness, sharp edge, wear resistance, high temperature resistance, chemical stability, non conductivity and lower
friction coefficient than PCD.
Diamond particle size is an important factor to determine the properties of PCD materials. Coarse PCD tools have good wear resistance, but the cutting edge is rough; Fine grained
PCD tools have sharp edges and are easy to process good part surface texture, but the wear resistance is slightly poor. CVD diamond is a continuous material because it does not
contain bonding phase, and its properties are hardly affected by the internal diamond grain size.
With the rapid development of automobile, aviation, aerospace and other industries, the requirements for cutting tools for machining various high-performance materials are increasing.
Although the service performance of PCD tools has been significantly improved compared with traditional cemented carbide tools and has been widely used in machining, they still can
not fully meet the requirements for machining efficiency and workpiece surface integrity in many processing plants. In addition, because PCD material is composed of diamond particles
and bonding, its edge characteristics are not ideal. CVD diamond and PCD material are polycrystalline materials, and its internal grains do not have directionality. Therefore, it can be
oriented arbitrarily when making cutting tools, which is not affected by crystal characteristics. The most promising use of CVD diamond tools is to process graphite. CVD insert can also
be used to turning high silicon aluminum alloy, non-ferrous metal, plastic and composite materials. CVD diamond thick film cutting tool has sharp cutting edge and almost no initial rapid
wear. It can be used for ultra precision cutting. However, CVD diamond thick film tool has more edge collapse and larger fluctuation of wear curve in the cutting process, so it is more
suitable for continuous cutting.
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