John A. Hanigofsky

Chemical vapor deposition of silver films for superconducting wire applications

Abstract Chemical vapor deposition (CVD) was used to deposit silver films for superconducting wire applications. AgI, silver trifluoroacetate (Ag(TFA)), and perfluoro-1-methylpropenylsilver (Ag(PF)) produced the most promising silver films. CVD processing was optimized on these three precursors using thermodynamic calculations performed using a modified version of the SOLGASMIX-PV computer program. Ag(PF) produced the highest quality silver films at low temperatures and pressures. A fiber tow which contained a silver barrier layer and a YBa2Cu3Ox overlayer was found to be a superconductor at 72 K.

Thermodynamic analysis for the chemical vapor deposition of composite coatings from the Al–B–Ti–N–H–Cl–Ar system

Thermodynamic calculations were performed for chemical vapor deposition in the Al–B–Ti–N–H–Cl–Ar system in order to determine the feasibility of multiphase deposition. Reagent species used were BCl 3 , AlCl 3 , TiCl 4 , NH 3 , H 2 , and Ar; B 2 was substituted for BCl 3 to determine changes in deposition efficiency. Temperature and input molar concentrations were varied over a range of values to establish relationships among solid deposits. Through deposition diagrams, molar efficiency plots, and partial pressure graphs, several two and three phase regions were found to exist. The calculations indicate that the following dispersed phase composites could be prepared: A1N + BN + TiN, BN + TiN, BN + TiB 2 , BN + TiB 2 + TiN, and TiB 2 + TiN.

Grain structure and growth of dispersed phase BN-AlN coatings grown via chemical vapor deposition

This paper discusses the variation in microstructures encountered during the separate depositions of boron nitride (BN) and aluminium nitride (AlN) as well as during the codeposition of BN-AlN dispersed phase ceramic coatings. This combination was chosen in order to take advantage of the self lubricating properties of hexagonal BN along with the hard, erosion resistance of AlN. Films were characterized using scanning and transmission electron microscopy (SEM and TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD). A range of coating microstructures are possible depending on the conditions of deposition. The best films produced, in terms of hardness, density, and tenacity, were a fine mixture of turbostratic BN and preferentially oriented A1N whiskers aligned with the whisker axis perpendicular to the substrate surface as seen by both electron microscopy and x-ray diffraction. 4 refs., 9 figs., 1 tab.