A method has been developed for the uniform coating of graphite tubes with carbides of niobium, tantalum, and zirconinm by thermal decomposition of their respective halide vapors. Conditions of coating temperature and pressure are so chosen as to prevent the deposition of metal, but to permit the formation of the carbide as rapidly as carbon can diffuse to the surface. If the carbon diffusion can be made the rate-limiting step, the coating process becomes self- regulating and uniform thickness results. The limits of the temperature-pressure range have been determined experimentally for the thermal decomposition of zirconium iodide and of the chlorides and bromides of niobium, tantalum, and zirconium. With the successful development of coating equipment and definition of conditions, 99 blowpope test specimens were coated with uniform, continuous, and adherent layers of the carbides in three ranges of thickness, light (0.001 in.), medium (0.005 in.), and heavy (0.01 in.). Determinatlons were made of the coefficient for the diffusion of carbon in zirconium carbide as a function of temperature. Exploratory work on small specimens of graphite impregnated with 7 wt.% uranium indicated that the coating results were essentially unchanged, but that loss of uranium occurred. Means of avoiding the loss of …

This compilation includes the following subjects: (1) Spectroscopic studies, (2) Neutral carbon in the vacuum carbon arc, (3) Anode effects, doppler blast effects, and stark broadening, (4) Neutrals in the high-current carbon arc; (5) Photon breakup of N2 in the high-current carbon arc, (6) Ion density in the high current carbon arc, and (7) Recombination cross-section for fast hydrogen ions and slow electrons. Minor revisions have been made in the subject memoranda in incorporating them in the compilation.

Report presenting a brief compressor-surge and pressure-recovery program for the Convair YF-102 with a two-spool turbojet engine. The study covered a range of altitudes and Mach numbers.

"Slender-body aerodynamic theory is used in conjunction with thin-plate theory in the flutter analysis of low-aspect-ratio rectangular wings of constant thickness when chordwise variations of deflections are considered. The spanwise variation of deflection is given by a parabola, and the chordwise variation is allowed complete freedom. The results show the variation of flutter speed and mode shape with aspect ratio" (p. 1).

Abstract: This report presents the results of plant optimization studies and cost estimates of the reference design for a natural uranium, graphite moderated, gas-cooled reactor and power plant which was described in NAA-SR-1833.

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Report presenting an investigation of 6-percent-thick NACA 65-series compressor blade sections in a two-dimensional porous-wall cascade tunnel at several lift coefficients, angles of attack, and solidities. The useful operating angle-of-attack range was generally found to decrease as inlet angle increases.

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Tests have been completed on a combination heater-cooler unit for use in in-pile loops designed to operate in beam hole HN-1 of the ORR facility. The unit is designed to use air-water mixtures as the coolant. the coolant flows through a spiral of 3/8-inc. diameter tubing cast in aluminum around the 3/8-in. IPS loop pipe. four 1000-w calrod-type electric heating elements are cast into the aluminum, along with the cooling coils to provide loop heating.

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Transformation kinetics of binary U -Nb and ternary U-Nb-base alloys were investigated. Additions included zirconium, chromium, titanium, silicon, nickel, nnthenium, and vanadium. Encapsulated samples were given a homogenizstion anneal at 1000 or 1100/sup o/C, water-quenched from 906/sup o/C to retain the phase, and reheated to temperatures between 360 and 600/sup o/C. The metastability of the phase was examined by metallographic, hardness, resistometric, dilatometric and x-ray-diffraction techniques. The U -Nb system is characterized by a monotectoid decomposition of the high temperature allotrope at about 645/sup o/C to form alpha and /sub 2/, a niobium-rich cubic structure. Decomposition in U-Nb and in most U-Nb-X alloys occurred by a continuous precipithtion of alpha from the body-centered cubic phase with a resultant enrichment in niobium of until the equilibrium /sub 2/ composition was reached. In the U-Nb-Ti and U-Nb-V systems, alpha and /sub 2/ were coprecipitated. Annealing at 550 and 600/sup o/C produced decomposition products which, in most materials, originated at the grain boundaries; a fine precipitate which initiated throughout the matrix was observed at lower annealing temperatures. Increasing the niobium content resulted in greatly increased stability. The following elements added to a U-Nb base were found to retard transformation of the phase: zirconium, …