Book: Ceramics - Art or Science? Author: Dr. Stan Jones

14. Early Scientific Applications and the Role of Pottery Manufacturers

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The concentration was on alumina-based ceramic. Pure alumina has to be fired above 1800 ºC, has a melting point of 2050 and is usable up to 2000 ºC. The raw material for industrial alumina wares is usually corundum, a hard crystal form of alumina, which allows better control of the grain size of the fired ceramic. Alumina products have reasonable thermal conductivity and high electrical insulation properties. One problem that eases with high alumina scientific ceramics is the bubbles in a ceramic glaze. These depend on the silica content of the body, so there can be a high level of glaze bubbles in silica-rich earthenware, much fewer in bone china and none in pure alumina ware.

During the war a revolutionary new industrial product had been developed in Worcester, a high-grade alumina ceramic called Regalox. After a successful pilot production in Worcester, a new subsidiary, Royal Worcester Industrial Ceramics Ltd. was set up in 1959, based in Glamorgan, South Wales. It produced industrial high-alumina ceramics that were formed by extrusion to the shape required, and had a hardness between sapphire and diamond. It produced a wide range of products especially for the textile industry and for grinding. For the textile industry it produced thread guides and special porous ceramic spinarettes with minute holes for molten nylon to be forced through in the production of nylon fibres. Royal Worcester Industrial Ceramics produced many other components for various industries. 

There is some interesting correspondence between Royal Worcester Industrial Ceramics and overseas companies in 1968 concerning cooperation on ceramics for electric lamps (IET archives). One was a letter from Dr Zabel of Westinghouse, New Jersey to Mr Adlington at Royal Worcester Industrial Ceramics concerning exploratory talks about ceramic lamps. Another covered translucent ceramics for sodium streetlights for OSRAM (GEC), and on 29th May 1968 from GE (USA) Export Division concerning patent rights for LUCALOX ceramic material for lamps.

14.4 Welwyn and Worcester

Welwyn Electronics was started by E.B.Bull, who was an apprentice on Tyneside when called up to join the British Army during the First World War. He served in Italy and must have enjoyed the country because he returned there after the war to live and work. He acquired an agency for electrical and wireless equipment; principally selling wireless sets for an American Company. The technology was in its formative days in the early 30’s and electronic components were not very high in quality or reliability. It was in Germany that most significant development of high quality components was being carried out. In Milan a company called SECI had acquired the rights for ceramic vitreous enamel used in the manufacture of wirewound resistors developed by the Rosenthal porcelain factory in Germany, which were better quality than other British or US designs. The resistors were based on a ceramic former wound with wire and protected by a layer of glass or vitreous enamel, applied in powder form and fired at about 1000 ºC. Bull appreciated the potential of this product and expanded his electrical business in Italy by factoring all SECI products, including the vitreous enamel resistors.

In the middle 30’s the Fascists were in control in Italy so Bull made plans to return to the UK. He received information and a lot of help from SECI, so he could set up his own vitreous enamel resistor production. When he returned to UK he set up production in Welwyn Garden City as Welwyn Electrical Laboratories Ltd in April 1937. By 1938 the British Government had recognised the key importance of wireless and telecommunications equipment, especially high stability resistors, and needed to find a secure supply of components.

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