I. concept and classification of ceramics

1. Concepts of ceramics:

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 objects". Ceramics are materials closely related to human life and production.With the continuous development of productive forces and the continuous improvement of science and technology, the concept and category of "ceramics" endowed by each historical stage 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 Especially after the emergence of advanced ceramics, the definition focusing on traditional ceramics is no longer applicable.Broadly speaking, ceramic materials refer to all other materials except organic and metallic materials, namely inorganic non-metallic materials.In a narrow sense, ceramic materials mainly refer to polycrystalline inorganic non-metallic materials, namely inorganic non-metallic materials synthesized by high temperature heat treatment.The results of modern analytical techniques show that ceramics are a mixture of crystalline and glass phases, each of which has many different compositions.These components are mainly inorganic nonmetallic materials.Therefore, some countries regard inorganic non-metallic materials as the basic components of solid products called ceramics.Inorganic nonmetallic materials are often referred to as ceramic materials in the world. 

2. Classification of ceramics:

People are used to divide ceramics into two categories: traditional ceramics and advanced ceramics.Traditional ceramic is natural silicate minerals as raw materials (clay, feldspar, quartz, etc.), after the crushing process, molding, sintering process, such as products, so also called silicate ceramics, such as daily-use ceramics, art ceramics and industrial ceramics (power industry with high voltage electrical porcelain, chemical industry with the corrosion resistance of ceramic, and building the construction of industrial ceramics and sanitary ceramics, etc.).In contrast, various kinds of ceramics developed in modern times are generally called advanced ceramics. Advanced ceramics are inorganic non-metallic materials obtained through appropriate structural design, accurate stoichiometry, appropriate molding method and firing system and processed by synthetic compounds with high purity (such as al2o3.zr02.sic.Sic. Si3n4.bn).