Effect of the SiCl4 Flow Rate on SiBN Deposition Kinetics in SiCl4-BCl3-NH3-H2-Ar Environment

Abstract

To improve the thermal and mechanical stability of SiCf/SiC or C/SiC composites with SiBN interphase, SiBN coating was deposited by low pressure chemical vapor deposition (LPCVD) using SiCl4-BCl3-NH3-H2-Ar gas system. The effect of the SiCl4 flow rate on deposition kinetics was investigated. Results show that deposition rate increases at first and then decreases with the increase of the SiCl4 flow rate. The surface of the coating is a uniform cauliflower-like structure at the SiCl4 flow rate of 10 mL/min and 20 mL/min. The surface is covered with small spherical particles when the flow rate is 30 mL/min. The coatings deposited at various SiCl4 flow rates are all X-ray amorphous and contain Si, B, N, and O elements. The main bonding states are B-N, Si-N, and N-O. B element and B-N bonding decrease with the increase of SiCl4 flow rate, while Si element and Si-N bonding increase. The main deposition mechanism refers to two parallel reactions of BCl3+NH3 and SiCl4+NH3. The deposition process is mainly controlled by the reaction of BCl3+NH3.

Experimental Investigations into the Pyrolysis Mechanism and Composition of Ceramic Precursors Containing Boron and Nitrides with Different Boron Contents

“…The structural evolutions of the pyrolysis products were characterized by FTIR, and the results are shown in Figure 5 . There are a series of characteristic absorption peaks in the products of 15 M-400 °C, in which 3408 cm −1 belongs to the stretching vibration of N-H [ 30 ], 2960 cm −1 and 2900 cm −1 belong to the C-H bond of (Si-CH 3 ) silyl methyl [ 31 ], 2135 cm −1 belongs to the Si-H [ 32 ] bond, the broad peak near 1400 cm −1 belongs to the B-N structure [ 33 ], 1261 cm −1 belongs to the characteristic bending vibration of silyl methyl, and the wide peak near 900 cm −1 belongs to the Si-N structure [ 34 ]. During the heating up to 600 °C, the N-H signal increased and broadened obviously, while the silyl-methyl-related signal nearly disappeared, indicating that the ammonolysis process and decarbonization reaction occurred during heat treatment.…”

Machine learning and a computational fluid dynamic approach to estimate phase composition of chemical vapor deposition boron carbide

“…A novel approach that considers gas phase kinetics and heat and mass transfer, in combination with machine learning (ML), is proposed to better understand the actual deposition mechanism and design of the deposit composition. The approach was applied to a BCl 3 -CH 4 -H 2 system, which provides a useful foundation in understanding other precursor systems, such as SiCl 4 -BCl 3 -NH 3 -H 2 -Ar [21] and BCl 3 -MTS-H 2 [13].…”

Machine learning and a computational fluid dynamic approach to estimate phase composition of chemical vapor deposition boron carbide

“…A novel approach that considers gas phase kinetics and heat and mass transfer, in combination with machine learning (ML), is proposed to better understand the actual deposition mechanism and design of the deposit composition. The approach was applied to a BCl 3 -CH 4 -H 2 system, which provides a useful foundation in understanding other precursor systems, such as SiCl 4 -BCl 3 -NH 3 -H 2 -Ar [20] and BCl 3 -MTS-H 2 [13].…”