Surface Science for Advanced Propulsion.
Abstract
Complex composite structures are prevalent throughout the propulsion industry. Unavoidable are the many interfaces between materials of differing physical and chemical properties. In applications where nut-and-bolt fasteners are not appropriate, the 'adhesive' quality of the interface becomes a serious consideration with regard to overall system integrity and reliability. Indeed, it is the ability of the structure to transfer or distribute stress when subjected to, for example, thermal and mechanical loading, that will help determine performance and failure criteria. If the materials on each side of the interface are also chemically complex (as is the case with solid propellants), then other issues such as surface segregation, diffusion, solubility, and reactivity of chemical constituents also affect the interfacial region and overall system aging. The project objective was to examine the structure, function and dynamics of the interfacial regions of advanced propulsion materials. Before the principal author joined the project, the primary focus of the program was on the ammonium perchlorate (AP)/bonding agent interaction. As the propellant community sought to lower hydrochloric acid (HCI) emissions in rocket plumes and therefore eliminate AP as an oxidizer in new propellant systems, the focus of the program shifted entirely toward the annealing phenomenon exhibited by thermotropic liquid crystal polymers (LCP): an exciting candidate material for structural applications and the subject of current research. Ammonium perchlorate presents a challenge because of its delicate, reactive nature as revealed by its low heat of formation of approximately -70.7 kcal/mole. Ion and electron beam techniques were found to be too damaging to either the ammonium perchlorate substrate and/or the organic bonding agent overlayer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1996
- Accession Number
- ADA316997
Entities
People
- John J. Rusek
- Kevin P. Chaffee