Ceramic manufacturing is responsible for fabricating and sintering powdered composites and slurries of inorganic minerals into extremely hard nonmetal parts for a large number of diverse, high-impact applications. Ceramics encompass a broad range of materials and products used for applications from consumer to aerospace, but all ceramics share characteristics of having a crystalline structure, extreme hardness, extreme wear resistance and extreme heat resistance.
Ceramic products can be broken up into four main categories: structural ceramics such as bricks and tiles; refractories for kiln linings, crucibles and other high-heat applications; whitewares such as bone china for dining and other decorative pottery and technical ceramics, also known as engineering ceramics, or advanced ceramics. Advanced ceramics such as silicon carbide are high-performance ceramic parts used in aerospace, nuclear power, bio-medical, military, defense and automotive applications that require exceptional heat resistance or insulation, wear and corrosion resistance. Ceramic manufacturers provide ceramic machining and ceramic grinding services as well as industrial ceramics products such as ceramic armor, ceramic balls, ceramic bearings, ceramic insulators, ceramic rods and heat-insulating ceramic spacers and ceramic tubes.
Among extreme high-impact aerospace and military applications, ceramics have found uses in automotive, power generation, refractory, industrial, food processing, chemical and construction industries. Electric motors use ceramic parts and ceramic magnets to withstand engine heat; wind turbines and jet engines use ceramic blades and rotary bearings; construction industries use ceramic bricks and tiles, and countless industrial heating and cooling applications use ceramic insulators. Bio-medical industries have begun to use ceramic as an optimal material for bone and teeth replacements and prosthetic limbs, and alumina ceramic and boron carbide ceramic plates are used as body armor by U.S. soldiers. Ceramic coatings are used to coat engine components to reduce chemical corrosion or surface temperature of the parts, extending part life. Ceramic insulators, capacitators, magnets and superconductors are known as electrical ceramics. Additionally, there are other types that include ceramic coatings for engine components and industrial wear parts, and chemical and environmental ceramics used as fibers, membranes and catalysts.
Ceramic bearings are extremely hard and are much less dense than other materials, lowering centrifugal force, increasing maximum rotation speed and reducing friction and wear. Ceramics used as bearings, rods, tubes, insulators and other moving parts are nonconductive and in general have a long operating life. Ceramics can be used in environmental applications to absorb toxic materials and decrease pollution or to help with water purification. In the medical field, ceramics are used as bone and teeth replacements as well as blood sugar sensors for diabetics. Trains in Japan use the Meissner effect with ceramic magnets to create levitation. With all these new developments and research, there is little that ceramics may not be used for in the future. Advanced ceramics used in industrial, aerospace and other high-impact applications are made from materials that fall into three categories: oxides such as alumina and zirconia; non-oxides such as carbide, boride, nitride and silicide; and composites of both oxides and non-oxides. These comprise ceramic parts' raw materials, which begin the manufacturing process as fine powders. Other minerals and materials may be added to enhance certain properties. After this, the material is prepped in ceramic manufacturing for forming by adding water or another liquid additive. The slurry or liquid material is then slip cast, pressed, extruded or injection molded into the desired shapes known as greenware, which are then placed in an extremely high heat oven and sintered. The greenware then become rigid products that can then be glazed or further processed by polishing, cutting or machining for advanced ceramic applications. Oxides and non-oxides hold different properties of translucency, hardness, corrosion resistance, heat resistance, wear, weight, microwave absorption and heat insulation. Aluminum oxide and boron carbide, for example, both have qualities of exceptional hardness that are used in armoring applications; boron carbide has a hardness that is close to that of diamonds and is used in body armor.
These materials have a wide range of applications from artificial bones to space shuttle tiles and are desirable because of their many excellent properties: high melting points, oxidation resistance, high hardness and light weight. Many of the desirable properties of various metals, polymers and rubbers are combined in ceramic materials along with properties of intense heat insulation and resistance. Ceramics are often corrosion resistant like stainless steel; some varieties can be harder than titanium; some can be injection-molded or cast like polymers and rubbers, and many are lightweight like aluminum or polymers. Ceramic parts are often more expensive than traditional metal, polymer or rubber materials, an obstacle which has discouraged many engineers from switching to ceramic materials. The long-term benefits of ceramics include reliable part performance, which often triples that of other materials, making ceramic materials a more cost-effective choice in many applications. Ceramic manufacturing does have its limitations, however; unlike polymers, some ceramics cannot be blown or stretched, nor can they be forged and worked like metals, making ceramics susceptible to breakage. It is also difficult to reach high precision tolerances and complex designs with ceramic molding and sintering, although progress is being made to reach tighter tolerances with ceramic manufacturing every day. Advanced ceramics are able to outperform metals in many situations, especially in harsh environments, and are also sometimes able to conduct electricity better than copper. There are many processes that are made possibly solely by ceramics, such as space shuttles and missile cones, which would crack without heat-insulating ceramic casings.
|General Characteristics of Structural Materials|
|Density||Low to High||Low to High||Low|
|Tensile Strength||Low to Medium||High||Low|
|Compressive Strength||High||Medium to High||Low to Medium|
|Young's Modulus||Medium to High||Low to High||Low|
|Melting Point||High||Low to High||Low|
|Dimensional Stability||High||Low to Medium||Low|
|Thermal Expansion||Low to Medium||Medium to High||High|
|Thermal Conductivity||Medium||Medium to High||Low|
|Thermal Shock||Low||Medium to High||High|
|Chemical Resistance||High||Low to Medium||Medium|
|Oxidation Resistance||Medium to High||Low||Low|
Ceramic Manufacturing Terms
The act of one material adhering to another. In the case of clay and water,
water is held on the surface of clay by a loose bonding force.