Other Applications of Ceramics
Ceramics are used in the manufacture of knives. The ceramic stays sharp more than the steel knife but it is brittle and can be broken when dropped. In motor sports, ceramics are increasingly use in areas that needs insulation coating.
Ceramics also used as armored vest to repel large caliber rifle. It is commonly known as Small arms Protective Inserts (SAPI). Similar material is used to protect cockpits o some military airplanes, because of its light weight material.
Ceramic balls can be used to replace steel in ball bearings. The higher the hardness the less susceptible to wearing and also it can have longer life. It can deform less under load; they have less contact with the bearing retainer walls and can roll faster. In very high-speed applications, temperature from friction during rolling can create problems for metal bearings; problems which are lessen by the use of ceramics. Ceramics are also more chemically resistant and can be used in wet environments where steel bearings would rust. The two major drawbacks to using ceramics is a significantly higher cost, and susceptibility to damage under shock loads. In many cases their electrically insulating properties may also be valuable in bearings.
In the early 1980s, Toyota researched production of an adiabatic ceramic engine which can run at a temperature of over 6000 °F (3300 °C). Ceramic engines are made of lighter materials and do not need a cooling system and hence allow a major weight reduction. Fuel efficiency of the engine is also higher at high temperature. In a usual metallic engine, much of the energy released from the fuel must be dissipated as waste heat in order to prevent a meltdown of the metallic parts. Despite all of these desirable properties, such engines are not in production because the manufacturing ceramics parts require precision and durability is difficult. Imperfection in the ceramic leads to cracks, which can lead to potentially dangerous equipment failure. Such engines are possible in laboratory settings, but mass-production is not feasible with current technology.
Lately, ceramic advances which include bio-ceramics, such as dental implants and synthetic bones. Hydroxyapatite, the natural mineral component of bone, has been made synthetically from a number of biological and chemical sources and can be formed into ceramic materials. Orthopedic implants made from these materials bond prepared to bone and other tissues in the body without rejection or inflammatory reactions. Most hydroxyapatite ceramics are very porous and lack mechanical strength and are used to coat metal orthopedic mechanisms to aid in forming a bond to bone or as bone fillers. Also as fillers for orthopedic plastic screws that helps in reducing the inflammation and increase absorption of plastic materials.
Ceramic materials are valued by watchmakers for its light weight, scratch-resistance, durability and smooth touch which are used in watch cases.