Fundamental Studies of Thermal Plasma Chemical Vapor Deposition

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

Abstract-Girshick This is a fundamental study of thermal plasma chemical vapor deposition. (TPCVD) with the objective of developing TPCVD as a robust process for the high-rate deposition of high-quality hard films and coatings. An inductively coupled radio-frequency plasma at pressures of 1 Torr to 1 atmosphere is used to deposit films of boron carbide and silicon carbide. Reactants are the appropriate chloride vapor (boron trichloride or silicon tetrachloride) and methane, injected into an argon-hydrogen plasma. Films are characterized by several ex-situ techniques to determine elemental composition, crystallinity, morphology, chemical bonding, hardness and related mechanical properties. Film growth rates and properties are related to operating conditions, surface temperature, and the chemistry of the fluid boundary layer adjacent to the growth surface. Molecular-beam mass spectrometry (MBMS) is used to obtain on-line measurements of mole fractions of gas-phase species during deposition; this technique can provide absolute measurements of mole fraction for all species present above the detection limit (ppm) of the spectrometer. Numerical models of the chemically reacting boundary layer at the growth surface are developed and tested using MBMS measurements This topic is potentially a major enabling technology for production of coatings resistant to abrasion and chemical attack. Two graduate students are receiving interdisciplinary training in advanced experimental and computational methods involving heat transfer, plasma science, chemistry, and materials science. In addition, a new diagnostic (MBMS) for plasma deposition studies is developed.