Bøger af M. Terpstra

'!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.

The present study complements the study on patents, patent applications and other literature on rare earth metals based permanent magnets by Frits Andriessen and Marten Terpstra, published by Elsevier Applied Science in 1989, and complements in part the book on Nd-Fe permanent magnets edited by LV. Mitchell, which was the result of a workshop organized by the Commission of the European Communities and held in Brussels on 25 October 1984. The difference between the content of the first book and that of the present study is that the first is more specifically directed to various kinds and compositions of alloys used in newly developed magnets, while the present book emphasises the improvements obtained when using particular alloys. The study edited by Mitchell deals more specifically with the economic, physical and chemical aspects of rare earth metals based magnet alloys, their properties compared with the more common and classical magnets such as ferro-cobalt alloy magnets, and their applications to various fields of technology. From the present study it has become apparent that there exist only a few patents and patent applications covering a specific use of particular magnets having specific properties to a circuit, arrangement, device or electric motor. This appears to be due to the fact that every manufacturer of such circuits or arrangements applying magnets naturally wants to employ the most effective magnets.

The present study of patents and patent applications published in the United States, Japan and the countries of Western Europe, and of other technological about 1980, is the result of a comprehensive analysis literature published since of documents which reveal various processes for reinforcing composite materials by metals, the atoms of which have been arranged according to predetermined matrices. Pre-searches were conducted by the Patent Information Office of TNO in Rijswijk, The Netherlands, which also provided copies of the documents needed to carry out the analysis. The International Patent Classification System (IPC) was employed to determine proper entries to the documents on the respective subject-matter. These classes are: C 22 C 1/09 relating to alloys containing metallic or non-metallic fibres or filaments; by subjecting to pressure and heat an assembly comprising at /09B least one metal layer or sheet and one layer of fibres or filaments; /09C by contacting the filaments or fibres with molten metal, e. g. by impregnation; /09D by using a powder-metallurgical method; characterized by the material used respectively for the metal /09F matrix or the reinforcing fibres; matrix formed of a light metal such as AI, Mg, Be, Ti; /09F2 matrix formed of a refractory metal such as Ni, Co, Cr, Mo. /09F4 Classifying patents or patent applications is actually a very difficult matter, particularly when it has to deal with processes for the production of composites, metal alloys or pharmaceuticals.