Patent Number: 
Section: description

A series of cylindrical extruded uranium rods about 8 inches long and 1.360 inches in diameter, after cleaning by a nitric acid pickling treatment, washing and drying as pre-viously described, were subjected to the following canning procedure: Each rod was immediately dipped through a xc2xdinch depth of potassium-sodium lithium chloride flux of the composition 53% potassiwm chloride, 42% lithium chloride and 5% sodium chloride, by weight, into a molten bronze bath consisting of 53 parts of tin and 47 parts of copper, by weight, at a tem-perature of 720xc2x0 C. for 45 seconds. Upon removal from the bronze bath each rod, which was uniformly coated with a bronze coating, was immersed in a bath of molten tin at 640xc2x0 C. for 20 seconds. Immersion in the tin bath was effected by dropping the rod onto the high end of a sloping wire rack sunk in the tin bath, allowing the rod to roll to the lower end, and removing it by a pair of tongs from the molten metal where the surface had just been carefully scraped to remove all traces of flux. Upon removal from the tin bath the rod was centrifuged at 640 rpm, in a centrifuge supporting the rod at about 6 inches from the axis of rotation, for 5 seconds to remove excess tin and then immersed in a bath of 0.1% sodium-modified, degassed 13X aluminum-silicon alloy (Federal specification AN-QQ-A-366, Amendment 4 Al-13X) at 600xc2x0 C. for 6 seconds. While the rod was being coated in this manner a 2S aluminum can which had an inside diameter 15 mils greater than the rod and had been cleaned by washing the can first with trichlorethene, then with an aqueous 0.1% soap solution containing 0.1% sodium pyrophosphate at 80xc2x0 C., and finally with aqueous 20% o-phosphoric acid solution for 5 minutes at 20xc2x0 C. was heated in a chromium steel supporting sleeve to a temperature of 640xc2x0 C. and 80 grams of 13X aluminum-silicon alloy and an aluminum plug xc2xdinch thick, with a hole through its center, preheated to about 630xc2x0 C. and about 640xc2x0 C., respectivey, were added to the can just before the metallic uranium rod was withdrawn from the aluminum-silicon bath. The plug was used to space the rod from the end of the can and provide good heat conduct-ivity at this location. It was inserted on the molten 13X alloy in the can by means of a rod having a tapered end fitting the hole in the plug snugly and having a sleeve for forcing the plug off the end. The coated uranium rod was passed from the bath immediately into the can and a slightly tapered aluminum cap about 5/16 inch thick, which had been preheated to a temperature of about 600xc2x0 C., was inserted into the molten aluminum-silicon alloy filling the open end of the can. The complete assembly was then immediately quenched by immersion in water and the canned rod was removed from its supporting sleeve. In this manner a firm uniform bond between the uranium rod and the protective metallic can was obtained. The total elapsed time from immersion of the uranium rods in the bronze bath to their immersion in the quench tank was about 80-90 seconds. FIG. 1 is photomicrograph at 500 magnifications show-ing a section of the bond between one of the uranium rods of this series and its protective can. Another series of uranium rods of the same size as employed in EXAMPLE 1 was canned under similar conditions with the following changes. After the rods were centrifuged to remove excess tin, they were dipped into a molten 1.0% sodium-modified, degassed aluminum-silicon alloy containing 88% aluminum and 12% silicon (before modifying) at 600xc2x0xc2x15xc2x0 C. for 6 seconds. They were then inserted in aluminum cans, containing 70 grams of 0.1% sodium-modified, degassed aluminum-silicon alloy of the same composition, maintained at 590xc2x0 C. The cans were capped and quenched as in the preceding example. A 1.360xe2x80x3xc3x978xe2x80x3 metallic uranium rod having its ends machined down to accommodate ferrules was coated as described in EXAMPLE 1. Upon removal of the coated rod from the alum-inum-silicon bath it was immediately capped by aluminum caps pressed over the machine ends, redipped in the aluminum-silicon bath for b 2 seconds, then placed in the valley formed by a pair of smooth xe2x80x9cTransitexe2x80x9d (asbestos cement) rollers rotating at about 200 ft. per minute peripheral velocity. Sixty-five grams of the modified degassed 88/12 aluminum silicon alloy at a temperature of 640xc2x0 C. was poured into the trough formed between the uranium rod and one of the xe2x80x9cTransitexe2x80x9d rollers. When all of the aluminum-silicon had solidified, the rod was removed from the rollers and quenched by immersing it in water. It was then machined down to a 1.42 inch diameter to provide a smooth, even 30-mil coating. A small metallic uranium rod, prepared for coating by pickling in nitric acid solution as previously described, was immersed for 45 seconds in a speculum metal bath (67% copper and 33% tin) at 810xc2x0 C. During this period the bath cooled to 795xc2x0 C. The rod was withdrawn from the bath and immersed in a eutectic bronze bath (47% copper and 35% tin) for about 1 minute at 710xc2x0 C. It was withdrawn from this bath and centrifuged for 8 seconds at about 640 rpm. It was then quenched by immersion in water. The bronze coated rod was dried and than dipped for 30 seconds in an aluminum-silicon bath comprising 88 parts of aluminum and 12 parts silicon at a temperature of 593xc2x0 C. The coated rod was rolled until the coating solidified, then washed with water. A firm over coating was obtained. A cross-section of the coated rod, showing the bond between the rod and the coating is illustrated in the photomicrograph, FIG. 2 of the drawing, at 100 magni-fications. A metallic uranium rod prepared for coating as previously described was immersed for 40 seconds in a bronze bath con-sisting of 47 parts of copper and 53 parts of tin at 730xc2x0 C. During the period of immersion the bath cooled from 730xc2x0 C. to 720xc2x0 C. The coated rod was then immersed in a tin bath at 420xc2x0 C. for 10 seconds. The tin bath was covered with a 53% KCl, 42% LiCl, 5% NaCl flux. Upon withdrawal from the tin bath the rod was centrifuged for 5 seconds at about 640 rpm. It was then dipped quickly into an aluminum-silicon alloy bath containing 88% aluminum and 12% silicon and quickly withdrawn. The rod was dipped seven times in this bath, which was held at a temperature of 615xc2x0 C. After the seventh dip it was withdrawn and laid on xe2x80x9cTransitexe2x80x9d rollers and 35 grams of additional aluminum-silicon alloy of the same composition was poured into the trough between the rod and the roller. The rod was rotated for 10 seconds until the aluminum-silicon had solidified and was then quenched by immersion in water. FIG. 3 of the drawing is a photomicrograph of a cross-section of the coated rod at 100 magnification. A small uranium rod, after pickling in nitric acid, washing and drying, as previously described, was immersed in a speculum metal bath at 850xc2x0 C. for 1xc2xd minutes during which the bath cooled to 840xc2x0 C. The rod, upon withdrawal from this bath, was immersed in peritectic bronze at 700xc2x0 C. for xc2xd minute, centrifuged for 15 seconds at 640 rpm, then quenched in water. The rod was coated with a continuous uniform protective bronze coating. Rods coated in this manner are afforded a substantial degree of corrosion resistance by the bronze coating. A bronze-coated rod prepared as described in EXAMPLE 6 was dipped in 88/12 almuminum-silicon alloy at 595-600xc2x0 C. for 30 seconds. Upon withdrawal from the aluminum-silicon alloy bath it was rotated at about 200 ft. per minute on xe2x80x9cTransitexe2x80x9d rollers for 15 seconds then quenched in water. The rod was coated with an aluminum-silicon coating over bronze. An extruded uranium rod was pickled for one minute in 50% HNO3 at room temperature, washed, dried and then dipped through a top flux of 50% NaCl and 50% KCl into a bronze bath containing 65% copper, 33% tin, and 2% nickel. After immersion in this alloy for 60 seconds, the rod was removed, dipped in a 50% LiCl, 40% KCl, 10% NaCl bath at about 550xc2x0 C. for about xc2xd minute then cooled. The rod was completely coated with a continuous corrosion-resistant bronze coating. An extruded uranium rod was dipped through a flux contain-ing 66% CaCl2, 29% NaCl, and 5% KCl into a molten bronze con-sisting of 53% copper and 47% tin to which 5% of nickel (based on the weight of the bronze) had been added. The bath was at 840xc2x0 C. After three minutes in the bath the rod was withdrawn, cooled and cleaned anodically in 98% H2SO4 solution. A polished protective bronze coating was thus obtained on the metal. A metallic uranium rod 1.1 inches in diameter and 4 inches long was first dipped through a chloride flux contain-ing 53% potassium chloride, 42% lithium chloride, and 5% sodium chloride, into a 47% copper 53% tin bath at a tempera-ture between 740xc2x0 and 760xc2x0 C. for 20 seconds. Upon withdrawal from the bronze bath the rod was centrifuged for 5 seconds to remove excess metal, it was then immersed in a salt bath having the same composition as the flux on the bronze bath and main-tained at 605xc2x0 C. After 20 seconds in this salt bath the rod was withdrawn and immersed in an unmodified 88% aluminum 12% silicon bath at 635xc2x0 C. for 20 seconds. The rod was then placed on xe2x80x9cTransitexe2x80x9d rollers and rolled slowly while 22 grams of the aluminum-silicon alloy was poured into the trough be-tween one of the rollers and the rod. Thirty-two grams of 88/12 aluminum-siliccn alloy modified by the addition of 1% of zinc and 0.02% of sodium was then poured on and the roll-ing was continued until the coating had solidified. The rod was then quenched by immersion in water. When cool the coat-ing was machined to a uniform 30 mil thickness. The resulting coating formed a protection for tle metal, which was resistant to the corrosive action of hot aqueous hydrogen peroxide solution. It will be understood that we intend to include variations and modification of the invention and that the preceding examples are illustrations only and in no wise to be construed as limitations upon the invention, the scope of which is defineed in the appended claims, wherein