Accession Number : AD0733292

Title :   A Mechanistic Approach for the Preparation of Chemical- Vapor-Deposited Isotropic and Anistropic Boron Nitride.

Descriptive Note : Research and development technical rept.,

Corporate Author : ARMY ELECTRONICS COMMAND FORT MONMOUTH N J

Personal Author(s) : Branovich,Louis E. ; Long,Martin L. ; Fitzpatrick,William B. P.

Report Date : AUG 1971

Pagination or Media Count : 25

Abstract : The properties, such as density and dielectric constant, of materials prepared by the CVD depend upon reaction parameters, such as pressure and temperature. The degree of anistropy of the CVD products depends primarily upon the initial reactants and secondarily upon the reaction parameters of temperature and pressure. In the report the preparation of anistropic and isotropic boron nitride (BN) is described. Two methods of preparation of the anistropic material have been investigated. One method uses ammonia and boron trichloride as the starting materials while the second method begins with beta-trichloroborazole. It will be shown that beta-trichloroborazole is a logical intermediate of the ammonia-boron trichloride system and that the two methods are, therefore, essentially equivalent. A theory is presented that not only accounts for the fact that BN formation occurs only at the hot substrate but is capable of predicting the requirements for the formation of the isotropic or anistropic forms. It should be shown that at the hot substrate a surface reaction takes place that results in the deposition of BN in an ordered anistropic form. In the reaction used for the formation of anistropic BN, water vapor is not present to disturb the initial anistropy. (Author)

Descriptors :   (*BORON COMPOUNDS, VAPOR PLATING), DEPOSITION, NITRIDES, CHEMICAL REACTIONS, CHLORIDES, SURFACES, AMMONIA, CRYSTAL STRUCTURE, MOLECULAR STRUCTURE

Subject Categories : Mfg & Industrial Eng & Control of Product Sys
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE