Dispersion Of Diamond Particles Research Articles

Titanium-Doped Copper-Diamond Composites Fabricated by Hot-Forging of Powder Mixtures or Cold-Pressed Powder Preforms

Cu-55 vol.%diamond-1 vol.%Ti composites were fabricated by hot-forging of powder mixtures (referred to as M-Cu/Dia) and cold-pressed powder preforms (referred to as P-Cu/Dia). Dispersion of diamond particles in the size range of 70–80 µm at 55% volume fraction was attained in the P-Cu/Dia composites while diamond agglomerations were observed in the M-Cu/Dia composites. TiC was observed at the copper/diamond interface in both composites, in which most diamond particle surfaces (> 95%) were enveloped by TiC. It was found that TiC formed preferentially on the diamond-{100} facets compared with the diamond-{111} facets, which can be attributed to the fact that the C atoms are bonded by two C–C bonds on the diamond-{100} facets (more active) while three C–C bonds on the diamond-{111} facets (less active). The dispersion of diamond particles and formation of a TiC interface layer contributed to the thermal conductivity (388 W/mK) of the P-Cu/Dia composites, which is nearly twice that of pure copper hot-pressed from powder.

Dispersion of micro diamond particles in electroless nickel solution

The dispersion behavior of micro-diamond particles ranging from 0 to 0.5 micron was compared between in DI water and in electroless nickel solution. The effects of the concentration of electroless solution, temperature, ultrasonic treatment, stirring speed, and baffles on the size distribution of micro diamond particles in electroless nickel solution were studied. Results show that the dispersion of micro diamond particles in DI water is obviously superior to that in electroless nickel solution. Micro diamond particles agglomerate evidently when the concentration of electroless solution V elect:V DI in dispersion media exceeds 5‰. Diamond particles agglomerate more and more seriously with the increase of the ion concentration. Applying ultrasonic, increasing stirring speed and adding baffles are helpful to improving the dispersion of diamond particles in the electroless nickel solution and its uniform distribution in the Ni-P coating.

Development of Ultrasound Exposure System of Four Piezoelectric Ceramic Vibrators with Operating Frequency of 150 kHz for Dispersion of Nanometer-Sized Diamond Particles

A novel ultrasound exposure system for the dispersion of nanometer-sized diamond particles was developed. The nanometer-sized diamond particles have a primary particle size of about 5 nm and are expected to be used as an abrasive agent in the future. However, the diamond particles are aggregated to a size of about 5 µm immediately after manufacture, and a hard disk surface is scratched by such aggregated diamond particles. It is important that the diamond particles are uniformly dispersed in water. Therefore, the dispersion of the diamond particles using an ultrasound exposure system with four lead titanium zirconate (PZT) piezoelectric ceramic vibrators and an acoustic matching layer was investigated. As a result, the diamond particles were dispersed to a particle size of about 75 nm by acoustic cavitation due to ultrasound exposure.

Effect of Diamond Dispersion on the Superplastic Rheology of Zinc Sulfide

The dispersion of diamond particles in superplastic zinc sulfide produces flow softening at low diamond concentrations, and hardening at high concentrations. The minimum in the flow stress is observed at 5 wt% (5.5 vol%) diamond content. The softening can be explained in terms of the grain refinement in the ZnS in the presence of diamond particles. The smaller grain size is shown to reduce the flow stress by enhancing the rate of diffusional creep. The hardening is believed to have been caused by the formation of a network among the diamond particles at high concentrations. The fact that the diamond particle size was approximately onethird the grain size of ZnS may have contributed to the network formation.

Fabrication of Diamond-Glass Composite under Micro-Gravity

Glasses containing a dispersion of diamond-particles were fabricated under micro-gravity and 1 G. Under micro-gravity, as the wettability between the sample and specimen capsule was significant, part of the fused specimen leaked out of the capsule. However, the microstructures and mechanical properties of the specimens fabricated in space were more isotropic than those of the samples fabricated under 1 G, and the particles were dispersed more homogeneously.