Damage resulting from single and multiple waterdrop impacts on coated and uncoated LWIR substrates

The amount and type of damage a sample receives during waterdrop impact experiments depends not only on the size and impact velocity of the waterdrop, but also on the microstructure of the underlying substrate, and its impact history. The geometry of the ring fractures resulting from single impacts is strongly affected by the morphology (i.e. grain size and orientation) of the substrate material. Furthermore, repeated impacts on or near previously impacted sites will create damage which depends not only on the morphology of the substrate material, but also on nature of the previous damage. Impact resistance refers to a previously unimpacted samples ability to withstand damage from individual waterdrop impacts. Durability refers to a samples ability to withstand extended exposures to high speed rain fields. Rain protective coatings can be applied to substrates to significantly enhance their survivability. Coating have been shown to increase a substrate's Damage Threshold Velocity (DTV) and to significantly reduce the cumulative damage that samples receive during prolonged exposures to high speed rain fields.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.