| 摘要 |
770,083. Travelling wave tubes. SPERRY CORPORATION. April 13, 1955 [May 4, 1954], No. 10641/55. Drawings to Specification. Class 39(1). [Also in Group XL(b)] The ceramic rods for supporting the helix in a travelling-wave tube are impregnated centrally with graphite attenuating material in the following manner: The rods are soaked in a solution of an organic non-volatile polyhydroxyl compound, e.g. a 40 per cent. solution of sucrose. The ends of the rods are protected by coatings of paraffin or the solution may be brushed on the central parts only. After drying, the rods are heated for 15 minutes at 400‹C. in an inert atmosphere to decompose the sucrose and leave a precipitate of colloidal carbon in the pores of the ceramic. The heating may be carried out in a confined space with the atmosphere constituted by. the vapours of decomposition. The rods are finally fired for 10 minutes at 1,000‹C. in a vacuum or a dry hydrogen atmosphere to convert the colloidal carbon to graphite. Other sugars such as lactose, glucose or dextrin may be used. The ceramic material may be aluminium or magnesium silicate. Specification 669,475 is referred to. |
