The Characteristics of Ceramic Ball Valve and Its Application Prospect Part I
Summary :The structure and classification of ceramic ball valves are introduced here. This paper analyzes the problems of product structure and processing technology of ceramic ball valves, and gives the development prospect of integral ceramic ball valve and its breakthrough direction.
Ball valves are widely used in all fields of modern industry. However, in some complex, severe and even extreme environments and applications, the traditional metal seated ball valve has been unable to break through the limits due to the materials limitation, so that they can not meet the special requirements of the severe applications. Therefore, the use of new ceramic materials into the traditional ball valve industry is an inevitable choice. New ceramics, also known as advanced ceramics, fine ceramics, including structural (or engineering) ceramic and functional ceramics, due to different chemical components and crystal structure, it has different special properties and functions, such as high strength, hgih Hardness, anti-high temperature, corrosion resistance, abrasion resistance, insulation and a variety of electrical, magnetic, optical and biocompatibility, can be widely used in machinery, electronics, chemicals, metallurgy, electricity, medicine, aerospace and other aspects of modern cutting-edge science, become an important part of the technology.
In the 1980s, the research and development of new ceramic materials with the development of industrial technology, formed a boom, the new special structural ceramic materials and thus in the industrial field began a large-scale application. At present, all kinds of engineering ceramics in the world some developed countries and regions have formed a broad and stable growth of the market.
(1) High pure alumina ceramics
The first material introduced into the traditional ball valve industry is the high pure alumina ceramics (Al2O3) as the main body of the ceramic material, the hardness of 88 HRA, bending strength of 350MPa, although the brittle, but the molding, sintering performance is better, high yield strength. Due to their strength and brittle restrictions, in addition to some of the requirements of the strength is not high (such as faucet spool, etc.) can be made directly into the overall valve with Al2O3 ceramics, in the harsh industrial environment, generally through the mosaic, bonding And so on the Al2O3 ceramics coated to the metal surface, both the use of metal as a support skeleton to solve its brittle, low strength of the shortcomings, while playing its ultra-high hardness of metal materials play a protective role.
Due to the structure and shape of the restrictions in the design and manufacture of ceramic ball valve, it should not be used when the usual mosaic, bonding, etc., the most feasible and reliable method is to use the overall solid core ceramic structure to prepare all ceramic ball valve. After isostatic pressing, hot pressing sintering and other process, the ceramic products inherent defects greatly reduced, the overall strength and reliability has been greatly improved.
To be continued......