Contact angle a contact angle of 0°. This is often the case for water on bare metallic or ceramic surfaces, although the presence of an oxide layer or contaminants on the solid surface can significantly increase the contact angle. Generally, if the water contact angle is smaller than 90°, the solid surface is considered hydrophilic and if the water contact angle is larger than 90°, the solid surface is considered hydrophobic. Many polymers exhibit hydrophobic surfaces. Highly hydrophobic surfaces made of low surface energy (e.g. fluorinated) materials may have water contact angles as high as ~120°. Some materials with highly rough surfaces
Type 90 Kyū-maru leading to higher per unit costs than comparable models from NATO countries such as the M1 Abrams and the Challenger 2. Development of upgrades to the Type 90 suffered both as a result of limited budget, which caused procurement delays, and funding prioritization in favor of the Type 10 Main Battle Tank. Due to a perception that Type 90s are unsuited to operations in the tight confines of Japan's urban areas, they are preferentially assigned to the JGSDF Fuji School Brigade and the 7th Armored Division based in Hokkaido, where there is sufficient room for maneuver. With the exception of