Abstract: An anti-bonding material is placed in a desired pattern onto a first sheet of conductive material. A second sheet of conductive material is roll bonded with the first sheet of material. Fluid is injected between the bonded first and second sheets of material to expand the sheets of material at the desired pattern. A flow channel is formed at the desired pattern between the first and second sheet during fluid injection.

Abstract: A method is provided for forming a precursor layer of aluminum oxide on a cold-rolled ferritic stainless steel substrate having an aluminum content of less than five weight percent, and more preferably as low as 1.5 weight percent, by exposing the stainless steel to a hydrogen atmosphere containing controlled quantities of water vapor to provide a controlled hydrogen-to-water vapor ratio of less than about 1400. The aluminum can be provided either as a constituent of the ferritic stainless steel chemistry, or it can be provided as a coating on a ferritic stainless steel which contains essentially no aluminum itself. The resulting oxidation environment is extremely oxygen-poor, having a partial pressure of oxygen between about 2.7.times.10.sup.-23 and 1.9.times.10.sup.-18 atmospheres. In addition, the environment has a relatively high water vapor content of up to about 10,000 ppm.

Abstract: A method for producing aluminum-containing ferritic stainless steel from a magnesium-contaminated melt such that the steel is suitable for growing oxide whiskers to cover the surface thereof is disclosed. The method comprises adding sulfur to the contaminated melt in an amount sufficient to increase the sulfur content not less than 1.3 time the magnesium content, whereupon the sulfur reacts with the magnesium to render the magnesium inert to whisker growth. The method also preferably comprises an addition of titanium, zirconium of hafnium in amounts sufficient to react with residual sulfur in excess of the amount required for magnesium reaction, thereby mitigating the adverse affect of sulfur on oxide adhesion.

Abstract: An accelerated method for growing oxide whiskers on aluminum-containing stainless steel foil comprises heating the foil in air at an initial temperature suitably less than 960.degree. C., preferably between 900.degree. C. and 950.degree. C., to initiate whisker growth and thereafter increasing the temperature to above 960.degree. C., preferably between 960.degree. C. and 990.degree. C., to continue whisker growth at an accelerated rate and thereby reduce the time and processing expense required to grow mature whiskers of a desired size.

Abstract: A peeling billet of the type for producing a thin metal foil by a metal peeling process and composed of an aluminum-containing ferritic stainless steel, that is, iron-chromium-aluminum alloy, is manufactured from cast alloy. A casting is forged at an elevated temperature in a manner sufficient to work the metal by an amount equivalent to forging along an axis to produce at least a 50 percent reduction in dimension. The forged billet is annealed at a temperature at least 80 degrees greater than the forging temperature, but not greater than 1100.degree. C., to recrystallize the metal to produce a refined grain microstructure conducive to peeling.

Abstract: In aluminum-containing stainless steel foil, the presence of magnesium impurity in an amount greater than about 0.002 weight percent has been found to inhibit formation of a preferred oxide surface layer characterized by multitudinous oxide whiskers of a type suitable for tightly bonding an applied coating. A method for purifying magnesium-contaminated foil comprises heating the foil to selectively vaporize the magnesium while avoiding incipient melting of the base alloy, preferably between about 1000.degree. C. and 1150.degree. C. The magnesium vapors escape into a suitable ambient phase such as a vacuum or a dry hydrogen gas. Thereafter, the foil is oxidized under conditions effective to produce the desired whiskers. A preferred steel is composed of an iron-base alloy comprising about 15 to 25 weight percent chromium and 3 to 6 weight percent aluminum, and optionally may contain cerium or yttrium in an amount effective to promote oxide adherence.