| 摘要 |
PROBLEM TO BE SOLVED: To provide a platinum or platinum alloy-made hollow tube in which the fear of the breakage caused by applying thermal stress or the stress due to external force in long term use as a duct under a high temperature atmosphere is suppressed. SOLUTION: The hollow tube is made from platinum or the platinum alloy and has projecting parts and recessed part alternately formed along the axial direction and continuously through the whole circumference in the circumferential direction of the hollow cylindrical body to satisfy the following relationship, 1/40≤(Y/X)×(X/L)<SP>1/2</SP>≤1/4 where in the relationship, X: the distance (mm) between the adjacent projecting parts (or recessed parts), Y: the height (mm) of projecting part (or recessed part) and L: the length (mm) of a region having the projecting and recessed parts in the axial direction of the hollow tube. COPYRIGHT: (C)2007,JPO&INPIT
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