Conventional Micron Diamonds

Micron diamonds are indispensable for polishing industrial products including metals, ceramics, and plastics. There are several types of micron diamond fines. Most micron diamond fines are

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Figure 5.10. The turning of hydrophilic diamond to hydrophobic by heating in hydrogen atmosphere (left). The conversion of hydrophilic diamond from hydrophobic one by heating in nitrogen atmosphere (right). Source: Satoru Hosomi, Hiroshi Yamanaka, Rev. High Pressure Science and Technology, 2003, V13, No. 1, 31-35.

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Figure 5.10. The turning of hydrophilic diamond to hydrophobic by heating in hydrogen atmosphere (left). The conversion of hydrophilic diamond from hydrophobic one by heating in nitrogen atmosphere (right). Source: Satoru Hosomi, Hiroshi Yamanaka, Rev. High Pressure Science and Technology, 2003, V13, No. 1, 31-35.

Figure 5.11. The size effect on the mass loss and specific surface area by heat treatment at 800°C under hydrogen atmosphere (left). The emission of gas by thermaographic analysis of micron diamond (Tomei Dia's MD150) in air (right). Source: Hiroshi Yamanaka, Satoru Hosomi, J. Soc. Mater. Sci., Japan, 2003, V52, No. 6, 592-595.

Figure 5.11. The size effect on the mass loss and specific surface area by heat treatment at 800°C under hydrogen atmosphere (left). The emission of gas by thermaographic analysis of micron diamond (Tomei Dia's MD150) in air (right). Source: Hiroshi Yamanaka, Satoru Hosomi, J. Soc. Mater. Sci., Japan, 2003, V52, No. 6, 592-595.

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Figure 5.12. The comparison of X-ray diffraction patterns of different diamond origins. Source: Satoru Hosomi, Hiroshi Yamanaka, Rev. High Pressure Science and Technology, 2003, V13, No. 1, 31-35.

Figure 5.13. The comparison of FTIR spectra of different diamond origins. Source: Satoru Hosomi, Hiroshi Yamanaka, Rev. High Pressure Science and Technology, 2003, V13, No. 1, 31-35.

produced by crushing and pulverizing low valued larger diamonds. Such diamonds are formed due to the gradients of pressure and temperature existed in the high pressure cell. Other micron diamond is formed by shock wave compression of graphite, or by CVD nucleation of diamond.

A typical pulverized micron diamond powder contains angular corners that may cause scratch to the smooth surfaces. Hence, it is critical to remove irregular shaped micron particles (Figs. 5.14 and 5.15).

Figure 5.14. Micron diamond of different origin including pulverized natural diamond (top left), pulverized synthetic diamond (top right), shock wave compressed diamond (bottom left), and CVD micron diamond (bottom right).

There have been no micron diamond that show euhedral morphology, i.e. with grown crystallographic faces. However, recently, the author developed a CVD process that can grow near perfect diamond crystals in high concentration (Fig. 5.16). Such euhedral micron diamond has the lowest amount of specific surface area of all micron diamonds, so they are the cleanest. Moreover, the high symmetry can allow them to be sorted in very tight size distribution. Moreover, because all solid angles are obtuse, these micron jewels will not scratch the work piece even when the polishing is performed under high pressure to achieve a high removal rate of the work piece.

Figure 5.15. The typical morphology of conventional micron diamond made by pulverizing unwanted large diamond.
Figure 5.16. Euhedral micron diamond grown by CVD method with different magnification. The top left figure shows more diamond crystals (1011) than stars in the entire Milky Way galaxy.
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