[en] A coated article of manufacture is described comprising: a substrate selected from the groups consisting of iron base alloys and nickel base alloys; a coating metallurgically bonded to the substrate and having a thickness between 7.5 and 100 microns; the coating formed by the process steps comprising: electro-spark depositing a first material from a cemented carbide electrode consisting essentially of chromium carbide in a matrix selected from the group consisting of nickel and binary nickel-chromium alloys. The matrix forms about 5 to 25 wt.% of the cemented carbide electrode. A layer of the first material is deposited on the substrate and is alloyed therewith; and electro-spark depositing a second material from an electrode selected from the group consisting of aluminium, aluminium alloys containing at least 95 wt.% aluminium, and nickel-molybdenum-chromium alloys containing greater than 20 wt.% molybdenum. A layer of the second material is deposited on the layer of the first material and is alloyed therewith; and the coating formed by the process characterized by a combination of excellent wear resistance and a low average dynamic friction coefficient when in rubbing contact with an identically coated component in a liquid, low oxygen, sodium environment at temperatures below about 650⁰C

[en] Poorly controlled wear and friction affects energy conservation, material conservation, and the reliability and safety of mechanical systems, and is estimated to cost U.S. industries $16 billion/yr. ERDA's National Friction, Wear, and Self-Welding Program and its accomplishments are described. This program includes studies of wear and friction problems in high temperature and unusual environments, e.g., as experienced by LMFBR components, and common to much technology involving energy conversion using fossil-fuel, geothermal, nuclear, and solar resources. Program activities for tribology information handling and wear and friction testing are discussed

[en] Several types of metallurgical coatings are used in the unique environments of the fast breeder reactor. Most of the coatings have been developed for tribological applications, but some also serve as corrosion barriers, diffusion barriers, or radionuclide traps. The materials that have consistently given the best performance as tribological coatings in the breeder reactor environments have been coatings based on chromium carbide, nickel aluminide, or Tribaloy 700 (a nickel-base hard-facing alloy). Other coatings that have been qualified for limited applications include chromium plating for low temperature galling protection and nickel plating for radionuclide trapping

[en] Thermophysical properties of 13 selected wear-resistant materials, including specific heat, thermal conductivity, thermal diffusivity, and thermal expansion (instantaneous, mean, and linear) are provided. The Center for Information and Numerical Data Analysis and Synthesis (CINDAS) at Purdue University supplied properties data

[en] This paper describes some of the essential performance measures used to qualify materials for tribological applications in liquid sodium environments and summarizes relative properties of some of the newer tribological materials now qualified for use in sodium systems

[en] Electro-spark deposition (ESD) is a pulsed-arc micro-welding process using short-duration, high-current electrical pulses to deposit an electrode material on a metallic substrate. It is one of the few methods available by which a fused, metallurgically bonded coating can be applied with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. The short duration of the electrical pulse allows an extremely rapid solidification of the deposited material and results in an exceptionally fine-grained, homogenous coating that approaches (and with some materials, actually is) an amorphous structure. This structure is believed to contribute to the good tribological and corrosion performance observed for hardsurfacing materials used in the demanding environments of high temperatures, liquid metals, and neutron irradiation. A brief historical review of the process is provided, followed by descriptions of the present state-of-the-art and of the performance and applications of electro-spark deposition coatings in liquid-metal-cooled nuclear reactors

[en] The friction, wear, and corrosion performance of several metallurgical coatings in 200 to 650⁰C sodium are reviewed. Emphasis is placed on those coatings which have successfully passed the qualification tests necessary for acceptance in breeder reactor environments. Tests include friction, wear, corrosion, thermal cycling, self-welding, and irradiation exposure under as-prototypic-as-possible service conditions. Materials tested were coatings of various refractory metal carbides in metallic binders, nickel-base and cobalt-base alloys and intermetallic compounds such as the aluminides and borides. Coating processes evaluated included plasma spray, detonation gun, sputtering, spark-deposition, and solid-state diffusion

No abstract available

[en] The self-welding behavior of two similar materials, Stellite 6 and Stellite 156, in sodium are discussed. The materials were tested at temperatures from 850 to 1140⁰F for time periods up to six-months while immersed in flowing sodium. Contact stresses ranged from 6000 psi to 16,000 psi on contact areas from 0.35 to 0.47 square inches. All separation tests to determine the extent of self-welding were conducted in a tensile mode. The surface morphologies of the samples before and after each test were measured. At temperatures of 1115⁰F and above, almost all the Stellite 6 specimens indicated a significant tendency toward self-welding within a relatively short period of time (one week). Stellite 156 couples also developed a strong self-weld bond at 1060⁰F after six-month exposure

No abstract available