| 摘要 |
1,210,299. Diamond powder dispersions. ALLIED CHEMICAL CORP. 3 July, 1968 [3 July, 1967], No. 31714/68. Heading C1A. [Also in Division C4] A dispersion, for use as an abrasive lapping composition, for example, comprises 5-15 wt. per cent of shock-formed synthetic diamond powder, whose particles have an average diameter of 7 x 10<SP>-4</SP> to 1 x 10<SP>-2</SP> microns, in a liquid dispersion medium, (said medium preferably having a viscosity of 0À5-100 centipoise), said dispersion being stable for more than 24 hours, a surfactant being present if the surface tension of the medium is less than 35 dyne/cm. and, if the medium is water, the pH being 5-10À2. Such a dispersion may be made by dispersing the diamond using rotating blades which give a high shear stress of at least 0À83 watt/c.c. for at least 2 minutes. The blades, which may be in a rotating blade homogenizer or blender, preferably rotate at 8000-20,000 r.p.m. The dispersion is preferably done at above 40‹ C. The liquid may be water, ethanol, olive oil, glycol, glycerine, hydrocarbons or commercial solvent mixtures. The surfactant may be an alkyl aryl sulphonate. The diamond used preferably has a surface area of 40-400 m.<SP>2</SP>/gm., at least 10% of its surface containing hydroxyl, carboxyl and carbonyl functional groups. |
