The blade of a knife can be made from materials such as high carbon steel, stainless steel, high carbon stainless steel, titanium, ceramic and plastic.
High carbon steel
One of the oldest materials used for producing knives, carbon steel blades are tough, can be very sharp and retain their sharp edge well. However, carbon steel is brittle which means that it can easily break under pressure. It is also susceptible to discolouration when exposed to acidic elements like citrus fruits and tomatoes. Discolouration and rusting can be minimised by coating the knife with flavour-free vegetable oil before storage. To maintain its performance, a light polish using fine grit steel wool or sandpaper from time to time will be sufficient.
This alloy of iron is made up of chromium, nickel and carbon. The ratio of chromium and nickel generally defines the quality of the stainless steel. The most common ratio would be 18% chromium and 10% nickel. Chromium contributes to rust resistance and shine while nickel gives it toughness. The edge created under factory conditions may be very sharp but it might be difficult to maintain and restore in a domestic kitchen.
High carbon stainless steel
The optimum combination of the best qualities from stainless steel and carbon steel. This blade has the toughness of carbon steel and the additional chromium makes it resistant to rusting and discolouration. Although slightly harder to sharpen compared to carbon steel, high carbon stainless steel are commonly used in high-quality kitchen knives.
This is the sturdiest material available for knife manufacture and holds a superb edge for the longest time. Zirconium oxide, a component used in ceramic, is second only to diamonds when it comes to sturdiness. However, it is also brittle and thus vulnerable to chipping and breaking. As such, it is more suited for slicing tasks rather than chopping. Given that the edge of the ceramic blade is thinner than the edge of a steel one, cutting through items will be much easier. Once the blades have dulled, they must be sharpened by a professional using a diamond sharpener.
The main purpose of using plastic blades is to prevent discolouration of vegetables and other ingredients from the blade of a knife. Usually serrated and not very sharp, some use of force is required when slicing.