Intumescent Reaction Mechanisms: An Analytic Model.
Abstract
Intumescent coatings are used to protect a substrate, such as warheads, from heat sources, e.g., fires. When subjected to heat, various mechanisms are activated to dissipate the incident heat. Characteristic of intumescent systems is the evolution of gases in a pyrolysis zone which causes the coating to expand or inflate, i.e., intumesce. A char is formed which is generally graphitic and resistant to burning, and which also acts as a further thermal barrier because of its low thermal conductivity. A mathematical model has been developed which describes the various physical processes by considering mass and energy control volumes. Expansion is explicitly accounted for by assuming it to be a function of mass loss. Thermodynamic data from thermogravimetric analysis and differential scanning calorimeter characterizes the chemical constituents of the coating. A computer program has been written to solve the system of equations, with appropriate boundary conditions, as a function of time. Experimentally determined parameters such as mass loss as a function of temperature requires a lagrangian formulation, but the computational grid is rezoned after each time step to re-establish an Eulerian grid for numerical accuracy in the difference equations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1983
- Accession Number
- ADA132586
Entities
People
- Charles E. Anderson Jr.
- Donna K. Wauters
Organizations
- Southwest Research Institute