US2506327A - Article of tungsten and wrought copper joined by sintered copper - Google Patents

Description

May 2, 1950 R. H. HARRINGTON 2,595,327

ARTICLE OF TUNGSTEN AND WROUGHT COPPER JOINED BY SINTERED COPPER Filed Jan. 18, 1947 IhveY-rtor; Richards H. Harrington,

His Attorney.

Patented May 2, 1950 ARTICLE OF TUNGSTEN AND WROUGHT COPPER JOINED BY SINTERED COPPER Richards H. Harrington, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application January 18, 1947, Serial No. 722,798

1 Claim. (Cl. 250-149) The present invention comprises composite metal bodies consisting of members of refractory metal and copper joined in good heat-conducting relation and thereby being adapted for an X-ray apparatus has been found to be particularly troublesome in high voltage, high powered X-ray devices, such as shown for example in Fig. 1, and described in detail in Charlton and use as targets in X-ray devices. 5 Westendorp U. S. Patent 2,144,524, patented Target electrodes or targets as heretofore January 17, 1939. In such apparatus an extenfabricated have consisted of a charge-receiving sion tube i leads from the main evacuated champlate of a refractory metal, for example, tungber 2 and is terminated by a wall member which sten, imbedded in a backing plate of cast copper functions also as target. A source of cathode which functioned as a means for carrying away rays (electrons), as for example, an incandescent heat generated by the impingement of high vefilament (not shown in the drawing) is provided locity electrons on the tungsten plate during the in the main chamber. Abeam of electrons, which functioning of such target electrodes. may be suitably focussed by well understood In some forms of high-powdered X-ray devices means, is directed upon the end wall 3 of the a member of tungsten united with cast copper X-ray apparatus. The impact of the electrons has constituted both a discharge-receiving elecon the target generates X-rays which pass trode and a wall-member in the evacuated enough e a e nd a r d ed t0 t e 6X- velope in which the electron discharge for ro terior. It is important, therefore, that the target ducing X-rays was caused to operate. In such should be as thin as practicable. devices, it was found that leakage of gas occurred A indicated n 2 e target 5 817 of a through wall members which interfered with the plate l of highly refractory metal, as for example, proper functioning of the devices and in many tungsten 150 Which is joined a layer 5 of pp r cases caused complete fail re, which is consolidated from a finely divided or The entry of gas from the exterior into the pfl d State by heat and p s Will be evacuated space appears to be due to slow moexplained in connection with Fig. 2. As shown lecular diffusion of gas, ordinarily air, along the i F 3 h consolidated pp p w r pr rvery slightly open grain boundaries characteristic ably is mined externally to a plate 6 0f Wrought of interdendritic shrinkage which occurs in some (cold worked) c p In some cases the plate 6 degree in all forms of cast or resolidified metal, m y be Om tedthe gas thereupon diffusing around th t Cold worked, or annealed, copper does not have sten target int th ev cu t d space, the slightly open grain boundaries characteristic As a consequence of my present invention I f as pp r and h n s p r us to th have provided an improved cgmpggite body of molecular diffusion of gas from the atmosphere tungsten and copper through which such difinto the va uum chamber. fusion of gas can not occur. In accordance with H pressed or sintered pp r when fabri ated my invention composite metal articles ar 00 1- under the best methods of control approaches the structed of tungsten or other refractory metal nsi y and g smp vi u n s of worked metal joined t a body of wrought copper by an t as an ultimate limit. Hence, hot-pressing under mediate layer f finely divid d copper iideal conditions will provide a structure which dated under heat and pressure into a homogeis sealed again l a a but for most Practical neous sintered condition whichis free from leakpurp s i i d sirable to unite with the hotage paths. In the preferred embodiment of my pressed oppe an outer barrier 5 0f Cold-Worked invention a plate of forged copper is united ex- (wrought) copper as a guarantee against leakternally to the copper which is consolidated from e u de d a y a o y methOdS 0f p d cthe powder state and which functions as a bondtion. ing layer between the plate of refractory metal Although the hot pressing of copper is a known and the plate of forged copper. metallurgical procedure I have shown diagram- My invention is illustrated by the accompanymatically in Fig. 3 an apparatus for carrying out ing drawing in which Fig. 1 is a side elevation of the fabrication of a composite ta y a high voltage X-ray outfit in which a target aspressing. sembly of my invention is embodied; Fig. 2 is a A mold l of graphite, Fig. 3 is charged with sectional view of a preferred form of target and a plate 6 of cold-worked copper upon which is Fig. 3 is a sectional view of an apparatus which is superimposed a layer 8 of powdered copper and suitable for fabricating a composite target. in turn a plate 9 of tungsten, or other chosen re- Leakage of gas into the evacuated space within fractory target metal. In some cases the copper plate 6 is omitted. Upon these metal layers is placed a graphite plunger Ill. The mold 1 and its contents are heated to a sintering temperature, for example, to a temperature of about 1,000 to 1,050 C. The required heat conveniently is supplied electrically by passage of current supplied through water-coo1ed terminals H, [2 which, as conveniently indicated, are connected to electric conductors l3, l4, carrying suitable current. Pressure is applied as indicated by the arrow upon the powdered copper whereby the copper plate 6 the copper powder layer 8 and v the refractory plate 9 are united into a gas-impervious unitary structure.

As shown in Fig. 2 the resulting composite plate is joined to the end walls of the extension tube I and forms the end closure 3 which functions as a target.

What I claim as new and desire to secure by Letters Patent of the United States is:

An X-ray device comprising an evacuated envelope and an X ra'y target, said target con- REFERENCES ci rEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 'Name Date 2,013,411 Huifiri'il Sept. 3, 1935 2,019,599 Dri'ggs Nov. 5, 1935 2,096,924 Schwarzkopf Oct. 26, 1937 2,115,387 Briggs et al. May 3, 1938 2,172,207 Kolligs et al Sept. 5, 1939 2,297,317 Truxell, Jr., et al. Oct. 6, 1942 2,372,607 Schwarzkopf Mar. 27, 1945 2,390,452 Mudge r r Dec. 4 1945 2 ,410,512 Lindqvist Nov. 5, I946

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