Response of Infrared-Transparent Materials to Raindrop Impacts
Abstract
This investigation concentrates on the damage produced in chemically vapor deposited (CVD) zinc sulfide (ZnS) by water drop impacts on the order of 1 mm in diameter impinging over a velocity range from 222 to 684/ms (730 to 2240 fps). A combined experimental and analytical approach was pursued to determine the relationships between water drop impact damage and the material properties of CVD ZnS in order to evaluate and guide efforts to develop erosion resistant window materials for use at 8-12 micrometer wavelengths. Microscopic observations of the damage produced in three formulations of CVD ZnS representing variations in grain size, grain shape, and inclusion content indicated the fracture trajectories and penetration depths were essentially insensitive to the range of microstructural features which were investigated. The quality of the surface finish was found to be the dominant contribution to the fracture response of CVD ZnS. Further modification of the bulk material properties does not appear warranted: the present production material is satisfactory. Considerably greater latitude for increased resistance to rain erosion can be gained from improved polishing procedures and subsequent maintenance of the initial surface finish.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1979
- Accession Number
- ADA081542
Entities
People
- John C. Botke
- Timothy W. James
- William F. Adler