Le Carbone Lorraine

Jacques Fourre

Jacques Maire

Jean P Gervais

The present invention concerns a support of carbonaceous material for a rotary target of X-ray tubes. The support is formed of two parts which are fixed with respect to each other, one part being of a carbon/carbon composite which provides mechanical strength and the other part being of polycrystalline graphite for receiving a refractory metal, by virtue of its coefficient of expansion. A thermal contact is provided between the two parts. The invention is especially applicable to targets of X-ray tubes which rotate at a high speed, 20,000 RPM and above.

Support for rotary target of x-ray tubes

A dual-textured graphite has been produced having an apparent coarse strongly bonded grained structure (the macrotexture) in which each coarse grain is formed from a number of strongly linked ultrafine grains (the microtexture). The dimensions of the coarse grains are from 0.4 to 6.0 m.m. while those of the ultrafine grains are below 0.050 m.m. The fine grains are linked by graphitized pore-containing carbon having pores of less than 2.mu. diameter. The coarse grains are also linked by graphitized pore-containing carbon having pores of from 5 to 20.mu. diameter. Further characteristics of the graphite are a coefficient of linear expansion of 4-6.times.10.sup.-6 /.degree. C., thermal conductivity of 0.20 cal/cm/.degree. C./sec., electrical resistivity of 1500-2000.mu. ohms/cm and anisotropy factor not exceeding 1.4. A process for producing such product from pitch and petroleum or coal tar coke is described.

Artificial graphite

Dual pore-structured carbon and graphite consist essentially of a macroporous agglomeration of strongly bonded microporous grains of carbon or graphite the radii of the macropores therein being from substantially 10 to 350 .mu.m and those of the micropores from substantially 0.2 to 1.0 .mu.m, with the macropores being joined by intercommunicating channels which form a fluid permeable structure. Such carbon or graphite has a density of from 0.70 to 1.50 grams/cc., a permeability to gases of from 20 to 500 cm.sup.2 /sec/atmos and a porosity of from 30 to 50%. Such materials are produced by including in a mixture of tar or pitch and finely divided solid carbonaceous material in suitable proportions, a particulate eliminable non-carbon-forming material having a particle size of 10 to 350 .mu.m, which material is substantially insoluble in said mixture, in a proportion sufficient to secure the desired porosity, shaping and then heating the mixture to effect carbonization and/or graphitization thereof and, after the product has cooled, giving any appropriate after-treatment to eliminate any heat treated residue from said particulate material and leave the desired porous structure.

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Soisy-sous-Montmorency, France

Jacques Fourre