Surface Modification in Control SiO2 Fiber Fracture.
Abstract
It is known that corrosion resistance can be imparted to various materials by carefully controlling the chemical environment to which newly formed and atomically clean surfaces are initially exposed. We take the view that the embrittlement of silica (SiO2) is also a corrosion process, originating from the activated hydrolysis of siloxane (Si-O-Si) bonds by molecular water. Our approach considers that surface states of SiO2 can be altered by the presence of absorbed or chemisorbed gases so as to increase the activation energy required for the absorption of water vapor or alternatively to impede the dissociation of molecular water on silica surfaces. Either of these mechanisms should raise the activation energy involved in hydrolyzing siloxane bonds and thus lower the susceptibility for crack propagation. Gases containing straight or branched chain hydrocarbons are expected to reduce the absorption potential for H2O for the silics surface. Absorbed gases containing strong polar residues such as halogens are expected to establish a surface dipole layer which may repel the absorbing end of H2O and prevent its dissociation on the silica surface.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1981
- Accession Number
- ADA108796
Entities
People
- Roy Kaplow
Organizations
- Massachusetts Institute of Technology