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Developed Ceramic Pickup: Next development in pickup heads was the crystal cartridge utilizing the piezoelectric effect of rochelle salts, or similar crystal material, to produce the electrical impulses necessary for play¬ing a record. In this type of device, the stylus twists or otherwise distorts the crystal element, resulting in electrical output. This type of trans¬ducer, together with the more recently developed ceramic pickup, which uses barium titanate in the form of a ceramic as its active element, immedi¬ately gained widespread use because of low cost, high voltage output, and lack of susceptibility to hum pickup from the phonograph turntable motor. Crystal and ceramic reproducers offer good frequency response and are very widely used in commercial record players. But because of their relative instability under wide temperature and humidity variations, they are seldom incorporated in highest quality work.
Ceramic fuel elements are of increasing im¬portance in the generation of nuclear power. Ap¬proximately 90% of newly planned nuclear elec¬tric power installations will contain enriched uranium dioxide (UO»), a ceramic material, as the fuel element. Many of the structural elements of the reactors, from the construction materials to the control rods (which are usually boron com¬pounds or rare-earth oxides), are also ceramic materials.See Also Chinese Ceramic Authorities:Chinese ceramic authorities state that their pottery was first made during the reign of Hoang-ti, who ascended the throne in 2698 B.C. True porcelain, however, was probably not perfected until the beginning of the Sung dynasty (960-1279 A.D.) although porcelainlike pottery had been made much earlier. The Chinese also made enamelled ware. The cobalt blue colors used on such ware were learned from the Arabs. How¬ever, porcelain was the most common type of ce¬ramic, and it was used for centuries for all classes of wares. See also CHINA—75. Ceramic.'!.
The Egyptians were not the only people who made use of burial figures. This practice was also carried on by the ancient Chinese. Beautiful ceramic figures have been found in the tombs of wealthy Chinese. Among these are representations of horses, servants, musicians and dancers. It is believed these figures were placed in the tombs in order that they might serve the dead. See also CHINA—14. Art (Sculpture) ; 15. Ceramics.
On The Other Hand See Beneficiation Ceramic:Improvements in the beneficiation ceramic of ceramic w materials are probably no less important than ie development of new ceramic materials. For :ample, kaolins that have been subjected to caching and particle size selection are being used stead of the more expensive titanium dioxide in e coating of fine paper; and improved particle lection of flint has made possible the develop-ent of higher strength porcelains. There have :en improvements in the selection and grinding
nepheline syenite for fluxing glasses and ceramies. Potting clays have been improved by particle selection and purification.
Ceramic materials are being used in personnel mor to defeat the penetration of bullets. Alumi-jm oxide compounds are the most widely used ir this purpose. Such ceramic materials are also ;ing used as armor in helicopters and other air-
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