'!he present survey is the result of a ccrnprehensive study of patents and patent applications suhnitted in France, the Federal Republic of Gennany, the United Kingdan and Europe (Munich), p..!blished since 1976 and canprising !lOre than 750 publications, classified in accordance with the INl'ERNATICNAL PATENT CLASSIFI~TION, classes C 01 B; sub-classes 21, 33, 35; C 01 G, sub- class 25; C 04 B, sub-class 35. '!he Ill3.jor part of the patents was granted to applicants fran the United Kingdan, the Federal Republic of Gennany, France, the United States of America and .Japan. Alt:hcA1gh the I.P.C. of basic refractories and ceramics produced therefran is !lOSt useful in assessing validity and in supporting "prior art" searches, it does not satisfy the requirements of scientists and technicians Who work in this field and Who are also interested in the oanposition of such Ill3.terials and the methods for producing them. As regards Part III, relating to finished products, it was decided to follow a classification based on specific parts of Ill3.chines and installations Where ceramics are !lOSt CClTITOnly applied. It should be observed that ceramic Ill3.chine parts and other ceramic canp:Jsitions are widely spread over the I.P.C. system, canprising !lOre than 10,000 docurrents published since 1975.
