Key Engineering Materials Vol. 661

Abstract: Boron nitride films were deposited on silicon substrate by a hot filament assisted chemical vapor deposition (HFCVD) system. The tris (dimethylamino) borane (B[N(CH₃)₂]₃) was used as the single source precursor which has both the boron and nitrogen source, ammonia gas was used as the assisted gas to increase the nitrogen concentration in the films. The films deposited by different ratios of precursor to ammonia gas flow rate and filament temperatures were investigated. The boron-carbon-nitrogen (BCN) compound films were deposited under lower filament temperature. With increasing the ammonia gas flow rate, the carbon concentration in the films decreased. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) image reveal that hexagonal boron nitride (hBN) films were deposited at the higher filament temperature of 2000°C. Moreover, the crystallization degree of the films became better with the filament temperature increased.

Abstract: In the present study, a plasma spray coating for titanium particles was studied using software simulations. The governing equations to solve the velocity and temperature distributions of plasma flow and titanium particles considered the effects of electric/magnetic inductions. Seven controlling factors were included in order to investigate their effects on the velocity and temperature of titanium particles colliding with the specimen substrate and the colliding scope of the effective particle depositions. The velocity and temperature distributions of the plasma flow predicted in the present study were expressed in a power form. The results predicted by the present governing equations were thus trustworthy. In general, either a small particle diameter in collaboration with a low electric potential or a large particle diameter in collaboration with a high electric potential is advantageous for a high melting and boiling points.

Abstract: An analytical thin film thickness model based on the geometry of a commercial vacuum coating system is proposed. This model can calculate the profiles of linear variable filters (LVFs), which are used to eliminate overlapping orders of spectra due to the use of a diffraction grating and which are fabricated using a local mask, producing a linearly variable thickness. While the filter transmits the first-order wavelength and blocks the second-order wavelength. The 75% and 25% relative thicknesses deviation between the evaporated film and the theoretical model is less than 5%, indicating good suitability for LVF design and fabrication.