| 摘要 |
<p>1296198 Growing whisker-like crystals PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 29 Jan 1970 [1 Feb 1969] 4360/70 Heading C1A Crystals in the form of whiskers, having an average thickness up to 100 millimicrons (mÁ) and a length at least 10 times larger than the thickness, are grown from a gaseous atmosphere containing the crystal material (or reagents which react to form the crystal material) on the surface of a substrate which is uniformly rough due to projecting crystallites, the lateral dimensions of which approximately correspond to the thickness of the whiskers to be grown. In an example, a plate formed by sintering silicon carbide powder is dusted with iron powder, having a grain size smaller than 1 mÁ, and is placed in a bed of quartz powder in a graphite crucible which is heated at 1280‹ C. in a quartz tube through which hydrogen is passed. Whiskers of silicon carbide, of diameter 1 mÁ and length 20 mm., grow on the plate in 10 hours. In another example, tablets 11 of compressed aluminium oxide powder, having a grain size of 0À01 to 0À1 mÁ, and alumina crucibles 12 filled with aluminium 13 are placed on a bed of quartz grains 14 in an alumina boat 15. The assembly is surrounded by an alumina tube 16 through which hydrogen is led, and heated at 1300‹ C. Crystallites of aluminium form on tablets 11, and ribbon-shaped aluminium oxide whiskers grow thereon. Other examples relate to the production of whiskers of silicon nitride, and of silicon.</p> |
