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 Type-90 The Type-90, also known as the MZD-2, is a Chinese submunition used in the 122 mm Type-81 cluster rocket. It is made by Norinco. Type-81 rockets with Type-90 submunitions were used by Hezbollah against Israel in the 2006 Lebanon War, and they have been used in the Syrian Civil War as bombs dropped by weaponized Hezbollah quadcopters. Each Type-90 resembles a small cylindrical bell with a ribbon at one end. A plastic band full of 3mm steel spheres wraps horizontally around the middle of the cylinder. Inside is an armor-piercing shaped charge. Each Type-81 rocket contains 39 Type-90 submunitions.