Chemical vapor infiltration

Chemical vapour infiltration (CVI) is a ceramic engineering process whereby matrix material is infiltrated into fibrous preforms by the use of reactive gases at elevated temperature to form fiber-reinforced composites. The earliest use of CVI was the infiltration of fibrous alumina with chromium carbide. CVI can be applied to the production of carbon-carbon composites and ceramic matrix composites. A similar technique is chemical vapour deposition (CVD), the main difference being that the deposition process of CVD is on hot bulk surfaces, while the deposition process of CVI is on porous substrates. Chemical vapour infiltration (CVI) is a ceramic engineering process whereby matrix material is infiltrated into fibrous preforms by the use of reactive gases at elevated temperature to form fiber-reinforced composites. The earliest use of CVI was the infiltration of fibrous alumina with chromium carbide. CVI can be applied to the production of carbon-carbon composites and ceramic matrix composites. A similar technique is chemical vapour deposition (CVD), the main difference being that the deposition process of CVD is on hot bulk surfaces, while the deposition process of CVI is on porous substrates. During a chemical vapour infiltration process the fibrous preform is supported on a porous metallic plate through which a mixture of carrier gas along with matrix material is passed at an elevated temperature. The preforms can be made using yarns or woven fabrics or they can be filament wound or braided three-dimensional shapes. The infiltration process takes place in a reactor which is connected to an effluent treatment plant where the gases and residual matrix material are chemically treated. Induction heating is used in a conventional isothermal and isobaric CVI process.