Saffil Fibres
→Benefits
→Chemical Resistance

SAFFIL fibres contain 95 to 97 percent alumina, produced by a novel solution spinning process from the highest purity raw materials and an aqueous medium. In the design phase of the SAFFIL project, the team took the advice of expert toxicologists to develop the fibre diameter and chemical composition specifications.

SAFFIL alumina fibres contain very low levels of non-fibrous material (shot)
The chemistry was determined to avoid the presence of free silica, which might transform to cristobalite at high temperatures. The dimensions were specified to avoid fibres of diameter less that one micron, to minimise biological activity, and to minimise the level of fibres greater than 6 microns, which can cause skin irritation. To meet the thermal and mechanical performance targets required the development of a unique spinning process to achieve a narrow diameter distribution around a median value of about 3.5 microns. The fibre design principle was tested and confirmed in a comprehensive toxicological package. A feature of the process is the ability to restrict the level of non-fibrous particles (shot) to extremely low levels treatment of fine porcelain and highest quality steels. This is in marked contrast to processes used for making vitreous refractory ceramic fibres, RCFs.

Key properties
A number of key properties of Saffil fibre make the product a versatile material for automotive applications. These include:

• Excellent thermal stability
  
• Good chemical resistance
  
• Low shrinkage
  
• Low shot (non-fibrous material) content
  
• High resilience
  
• High tensile strength and modulus
  
• Manufacture

The manufacturing process for Saffil fibres involves collection of the as-spun gel fibre and passing it through a series of heat treatment stages to develop the crystalline microstructure. The presence of a small amount of silica (3 to 4 percent) is effective in controlling crystal growth, allowing the gradual removal of porosity to optimise thermal mechanical properties. The flexibility of the process enables various grades to be produced, each one tailored to meet the specific needs of the application.