For decades, ceramic fiber mats have been used to mechanically support substrates in catalytic converters. Intumescent mats, those that expand with heat, are composed primarily of ceramic fibers, vermiculite, and organic binder. The binder is required for manufacturing, handling, and installation. Unfortunately, under cool operating conditions, its effects on mat performance are often negative.
While residual binder is not an automatic precursor to premature failure, it can amplify the effects of other factors such as gap control and vibration. As the mat mount material is heated, sections can become soft and pliable. In the absence of sufficient heat for complete binder removal, regions of the mat may become rigid during the cooling cycle. This results in a decrease in mat resiliency.
Several tests can be used to show the relationship between binder level and material performance. These tests typically characterize expansion properties and pressure performance. By comparing test results of intumescent mats with various binder levels, one can quantify the deleterious effects of residual binder on mat performance.
This paper will present a possible failure mode associated when residual binder and other aggravating factors are present. It will also present how an intumescent mat with less binder can lead to improved mat performance.