Tools diamond-coated

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

Fig. 14. A scanning electron micrograph of a diamond coating on a siUcon nitride cutting tool (b) at higher magnification, the octahedral growth of...

Another approach is to coat the cutting tool material with a carbide former, such as titanium or siUcon or their respective carbides by CVD and deposit diamond on top of it. The carbide layer may serve as an iaterface between diamond and the cemented carbide, thus promoting good bonding. Yet another method to obtain adherent diamond coatings is laser-iaduced microwave CVD. By ablating the surface of the substrate with a laser (typically, ArF excimer laser) and coating this surface with diamond by microwave CVD, it is possible to improve the adhesion between the tool and the substrate. Partial success has been achieved ia this direction by many of these techniques. 

Oles, E. J., et al., The New Diamond-Coated Carbide Cutting Tools, Diamond Conference, Barcelona, Spain (Sept., 1995)... 

Some of the present industrial uses of diamond coatings include cutting tools, optical windows, heat spreaders, acoustic wave filters, flat-panel displays, photomultiplier and microwave power tubes, night vision devices, and sensors. Because its thermal conductivity and electrical insulation qualities are high, diamond is used for heat sinks in x- ray windows, circuit packaging, and high-power electroific devices. Moreover, the high chemical stability and inertness of diamond make it ideal for use in corrosive environments and in prosthetic devices that require biocompatibility. 

Fig.1 Some examples of diamond coated tools (Courtesy of sp and Crystallume Co.).

Despite high interest in using diamond coatings for diverse tribological applications, their widespread utilization for these purposes has not yet met expectations. Until now, only carbide and certain ceramic tools have been... 

Fig. 11 Morphology of cutting edge of diamond-coated tool insert.

Diamond-coated tools are primarily used in the machining of nonferrous metals, alloys, and composite materials that are inherently very difficult to cut or machine. The range of materials that are suitable for machining by diamond-coated tools include aluminum and its alloys (in particular high-silicon aluminum alloys) magnesium audits alloys copper, lead, and manganese alloys graphite carbon plastics ... 

When the performance and price of CVD tools compare favorably with those of PCD tools, CVD tools may displace PCD tools in some applications. Woodworking tools represent another major market segment for diamond coatings. Tungsten carbide blades already comprise a large part of the woodworking tool market. CVD-diamond-coated tools have yet to be used in woodworking and, thus, they offer an excellent business opportunity. 

Several companies are engaged in the production of CVD-diamond-coated tool inserts. DeBeers, Mitsubishi, Nachi-Fujikoshi, Norton, Kennametal, Sandvik, and Sumitomo are the major firms. Kennametal and Sandvik provide diamond-coated tools on a commercial basis. Based on the input of several tool insert manufacturers, the estimated world market for diamond-coated inserts is 10 to 20 million per year. As discussed above, CVD- diamond-coated inserts are primarily targeted for machining... 

Fig. 13 Extent of wear damage on (a) uncoated and (b) nanocrystalline diamond coated tool inserts after machining of hypereutectic aluminum-silicon alloy.

Fig. 14 Cutting performance of uncoated, PCD and CVD-diamond-coated tool inserts while milling graphite. ...

Other potential applications for CVD-diamond coatings include, woodworking tools. 

---