Chemical vapor infiltration and deposition (CVI/CVD) is a known process for making composite structures such as carbon/carbon brake disks. The CVI/CVD process typically used for making carbon/carbon brake disks is sometimes referred to as “conventional” or “isothermal” CVI/CVD. This process involves passing a reactant gas or gas mixture (e.g., methane, propane, etc.) around heated stack of porous structures (e.g., carbonized stack of porous materials) at absolute pressures as low as a few torr (˜400 Pa or less). The gas diffuses into the stack of porous materials, driven by concentration gradients, and undergoes a CVD reaction such as thermal decomposition, hydrogen reduction, co-reduction, oxidation, carbidization, or nitridation to deposit a binding matrix.
During CVI/CVD, pores on the exterior of a stack of porous structures may become occluded. To resolve, one may remove the stack of porous structures from the process vessel and machine the stack of porous structures to open the pores. CVI/CVD may then be resumed.
USPTO Backgrounds
USPTO Backgrounds