Fabrication of carbon-carbon composites by forced flow-thermal gradient chemical vapor infiltration

Abstract

Carbon fiber-carbon matrix composites were fabricated using the forced flow-thermal gradient chemical vapor infiltration (FCVI) process. The preforms for the infiltration were prepared by stacking 40 layers of carbon cloth in a graphite holder. The preforms were infiltrated with carbon using propylene or methane as a reactant, with hydrogen as a diluent. Composites with porosities as low as 7% have been processed within 8-12 h. The highest deposition rate obtained in the present study was ∼3 μm/h, which is more than an order of magnitude faster than the typical value of 0.1-0.25 μm/h for the isothermal infiltration process.

Methodologies of Application of Sol-Gel Based Solution onto Substrate: A Review

“…Although CVD process is a very complex process, but due the following advantages the process is being considered as one of the widely used and highly sophisticated techniques for the thin film formations. For this reason this method has been extensively studied and well documented [45,[63][64][65][66][67][68][69][70]. Coating with highly dense and pure materials is obtainable.…”

Chemical Vapor Infiltration Rates of ZrO2 into MoSi2 Porous Bodies and Comparison with Model Calculation

“…The experimental conditions are shown in Table I. Long CVI processing times are common 31,32 during the industrial fabrication of composites. However, in our study, short CVI processing times were used to keep the process pressure constant during the experiments.…”

Modelling of the CVI Processes

“…Most of them rely on the use of a thermal gradient, because this can help monitoring the chemical reaction and make it happen at the right place first -that is, at the centre of the preform, or at its extremity which lies farthest from the impinging gas flux [8,9]. The forced CVI (F-CVI) process was initially based on the intent of accelerating chemical deposition by forcing the gases through the pores with a pressure drop [10], but it has been rapidly found out that the superposition of a thermal gradient would enhance the quality and processing time [6,[11][12][13]. Golecki et al have implemented a "rapid densification" process [14,15] based on isobaric conditions and the creation of a "hot side" and "cold side" on the preforms.…”