Surface treatment is an efficient means for protection of various products against corrosion and also for increasing strength or resistance to wear or fatigue. Also certain electrical, chemical or optical properties may be achieved only by creating special surface layers. Many examples can be given: leaf springs with shot-peened surfaces; carburised and hardened tooth gears; coated cutting tips for machining; chemical appliances made of glass strengthened by ion exchange; enamelled vessels and containers; components for engines or turbines with heat insulating ceramic surface layers; chemical...