Accession Number : ADA299243

Title :   'Nanocrystalline Processing and Interface Engineering of Si3N4-Based Ceramics'.

Descriptive Note : Final technical rept. 1 Apr 94-31 Mar 95,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMICAL ENGINEERING

Personal Author(s) : Ying, Jackie Y.

PDF Url : ADA299243

Report Date : 31 MAR 1995

Pagination or Media Count : 6

Abstract : Construction and modification of the novel tubular flow reactor for the synthesis of nanocrystalline materials by thermal evaporation in a forced flux of gas has been an ongoing process over the past year. The first version of the reactor was used to synthesize nanocrystalline silicon (Si). The incoming gas flow rate is set with a mass flow controller. Helium (He) enters at one end of the reactor and flows over the resistively heated crucible where Si is evaporating. The silicon supply is continually replenished with a magnetically coupled loader. An IR pyrometer is used for temperature monitoring and control of the evaporation crucible. A pumping system consisting of a roots blower (booster pump) backed by a single-stage mechanical pump continuously removes the Si particles in the He gas stream from the growth zone over the evaporation source. The pressure in the reactor is controlled by a throttle valve with a capacitance manometer input. The particles entrained in the gas stream flow down the glass tube and are deposited on a liquid nitrogen cooled disc mounted parallel to the gas flow in the center of the collection chamber. jg p.1

Descriptors :   *INTERFACES, *CERAMIC MATERIALS, *SILICON NITRIDES, INPUT, THROTTLING, SOURCES, TEMPERATURE, MECHANICAL PROPERTIES, MONITORING, SYNTHESIS, COMPOSITE MATERIALS, FLUX(RATE), GROWTH(GENERAL), CRYSTALS, GLASS, MASS FLOW, PARTICLES, FLOW RATE, ENGINEERING, HELIUM, VALVES, SUPPLIES, MAGNETIC DEVICES, EVAPORATION, PUMPS, HEAT, CHAMBERS, CAPACITANCE, GAS FLOW, TUBES, PYROMETERS, CRUCIBLES, MANOMETERS.

Subject Categories : Inorganic Chemistry
      Ceramics, Refractories and Glass
      Crystallography
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE