珲春How does diamond micro-powder affect the roughness of the polished surface?

In the field of ultra-precision machining, diamond micro-powder, due to its unique physical and chemical properties, has become a key material for improving the quality of polished surfaces. The synergistic effect of its particle size distribution, particle morphology and processing technology directly determines the roughness level of the processed surface. This dynamic process is constantly evolving along with breakthroughs in materials science and processing technology.

Particle size distribution: Nanoscale control initiates the era of ultra-smoothness

The particle size range of diamond micro-powder directly affects the material removal mechanism. When the particle size is less than 1 micron, the micro-powder is mainly cut by rolling, with a shallow embedding depth, and the resulting scratch width is less than 0.5 microns. For instance, in the polishing of silicon carbide (SiC) wafers, the surface roughness Ra value of the sample using 0.742-nanometer diamond micro-powder can be reduced to 0.742 nanometers, with only two deep scratches remaining. When the particle size was dispersed to 15 microns, the roughness soared to 2.41 nanometers, and the surface presented sand hole defects. This difference stems from the fact that the embedding depth of large particles increases with the cubic growth of particle size, resulting in an exponential increase in the amount of material removed.

Modern processes achieve a leap in surface quality through multi-level particle size control. A certain study adopted a three-step decreasing method: first, 10-micron micro-powder was used to rapidly remove the processing damage layer, then 3-micron micro-powder was used to correct the surface morphology, and finally 0.5-micron micro-powder was used to achieve atomic-level leveling. This strategy gradually reduced the roughness of the sapphire substrate from the initial 61.2 nanometers to 0.27 nanometers, reaching the optical grade standard.

Particle morphology: The crystal structure determines the processing accuracy

The crystal morphology of diamond micro-powder significantly affects the cutting efficiency. Single crystal particles are anisotropic, and the Angle between their cleavage surface and the processing surface determines the distribution of cutting force. A certain experiment shows that although the angular octahedral single crystal has a relatively high initial efficiency when polishing alumina ceramics, it is prone to form scratches as deep as 0.8 microns on the surface. The spherical polycrystalline micro-powder continuously generates new cutting edges through multi-directional crushing, stabilizing the surface roughness at 0.006 microns and eliminating directional textures.

Morphology control technology is breaking through traditional limitations. The isometric micro-powder developed by a certain enterprise is synthesized by directional blasting method, and its particle length-to-diameter ratio is strictly controlled within 1:1.2. This geometric uniformity enables the diamond spray polishing agent to reduce the scratch density by 75% and shorten the single polishing time by 60% in semiconductor processing.

Process innovation: Chemical and mechanical collaboration breaks through physical limits

Traditional mechanical polishing is confronted with the "hardness paradox" - although diamond is hard, large particles are prone to cause subsurface damage. Chemical mechanical polishing (CMP) technology solves this problem by introducing oxidants. In a certain study, a polishing solution prepared with K2FeO4 oxidant was used to form a carbon oxide softening layer on the surface of diamond at 50℃. Combined with the mechanical action of 0.5-micron micro-powder, the roughness was reduced to 0.478 nanometers without any scratch defects.

Photocatalytically assisted chemical mechanical polishing (PCMP) represents the latest breakthrough. A certain team utilized ultraviolet light to excite TiO2 polishing discs to generate hydroxyl radicals, thereby softening the surface of diamonds in real time. Experiments show that after 2 hours of PCMP treatment, the surface roughness of single-crystal diamond decreased from 1.35 nanometers to 0.19 nanometers, achieving atomic-level flatness. This technology has been applied to the preparation of diamond NV centers for quantum computing.

From nanoscale particle size control to chemical-mechanical synergy, the processing technology of diamond micro-powder is driving surface roughness into the sub-nanometer era. With the surging demand for ultra-smooth surfaces in high-end manufacturing fields such as 5G communication and quantum computing, the precise control technology of diamond micro-powder will continue to break through physical limits and redefine the standards of precision processing.