Carbon fiber insulation typically has a high resistance to decomposition, especially under vacuum conditions where oxidative reactions are limited due to the absence of oxygen. However, it can degrade or decompose under certain conditions such as exposure to high temperatures beyond its tolerance limit, or when subjected to reactive chemicals that may be present in the vacuum furnace’s environment.

In a vacuum furnace, the primary cause of degradation for carbon fiber insulation would be the high temperatures, which can cause pyrolysis (thermal decomposition in the absence of oxygen). The specific temperature at which carbon fiber insulation starts to decompose will depend on the type of carbon fiber and the materials used to bind the fibers together.

For precise information on the decomposition temperature and conditions for a specific type of carbon fiber insulation, it would be necessary to consult the material’s technical data sheet or contact the manufacturer. They can provide detailed information about the material’s properties and its resistance to high temperatures, especially in a vacuum environment.