1、 Concept and classification of ceramics
1. Concept:
According to the composition, materials are generally divided into metal materials, inorganic non-metallic materials and organic materials. In 1968, the American Academy of Sciences defined ceramics as "inorganic non-metallic materials or articles". Ceramics is a material closely related to human life and production. With the continuous development of productivity and the continuous improvement of scientific and technological level, each historical stage is endowed with The concept and category of "ceramics" are constantly changing, especially after the emergence of advanced ceramics, the definition focusing on traditional ceramics is no longer applicable. Broadly speaking, ceramic materials refer to all other materials except organic and metal materials, that is, inorganic non-metallic materials. In a narrow sense, ceramic materials mainly refer to polycrystalline inorganic non-metallic materials, that is, inorganic non-metallic materials synthesized by high temperature heat treatment. The analysis results of ceramic products by modern analysis technology show that ceramic is a mixture of several crystalline phases and glass phases, each of which has many different compositions. These components mainly belong to inorganic non-metallic materials. Therefore, some solid products composed of inorganic non-metallic materials as basic components are called ceramics. Inorganic nonmetallic materials are often called ceramic materials in the world.
2. Classification:
People used to divide ceramics into two categories: traditional ceramics and advanced ceramics. Traditional ceramics are products obtained from natural silicate minerals (clay, feldspar, quartz, etc.) through crushing, forming, sintering and other processes. Therefore, they are also called silicate ceramics, such as daily ceramics, art ceramics and industrial ceramics (high-voltage electric ceramics for power industry, corrosion-resistant chemical ceramics for chemical industry, construction ceramics and sanitary ceramics for construction industry, etc.) 。 In contrast, all kinds of ceramics developed in modern times are collectively referred to as advanced ceramics. Advanced ceramics are inorganic non-metallic materials obtained by using synthetic compounds with high purity (such as Al2O3. Zr02. SiC. SiC. Si3N4. BN), appropriate structural design, appropriate stoichiometry, appropriate molding method and firing system, and processing.
