Abstract: Workpieces are very rapidly diffusion coated by heating the packed workpiece at a rate that brings the workpiece to diffusion-coating temperature and then completing the diffusion coating, all in less than 50 minutes, then cooling. Workpiece can have top coating layer of aluminum flake covered by a layer of extremely fine alumina or silica in a magnesium chromate binder, to provide surface having roughness at least about 10 micro-inches smoother than before the top coating. Used aluminized jet engine hot section members can be reconditioned by a fluoridizing treatment that deoxidizes and also removes residual aluminizing, so that the members can then be repaired if necessary and re-aluminized.

Abstract: Titanium and titanium alloy surfaces can be diffusion coated, and portions of the surface protected against such coating by localized powdered masking layer of about 43% titanium, aluminum in an amount equal to the aluminum content of the surface masked, as well as other metals in an amount about one-fifth of their content in the surface masked. Diffusion coating can be speeded by high heat input. Diffusion coating packs can be made with chemically reduced metal content of sludges. Diffusion aliminizing followed by caustic leaching to remove much of the diffused-in aluminum, yields catalytically and pyrophorically active porous surface that also accepts top coatings. Mixtures of aluminum powder with nickel and/or iron powders react when heated to form Raney-like product that can be leached to become pyrophoric, and when held on a metal foil or gauze web will adhere to the web so that leached product can be used as pyrophoric foil for decoying heat-seeking missiles.

Abstract: Iron and nickel are activated by diffusing aluminum into their surface at low temperature, and then leaching out some of that aluminum with caustic. So activated they are extremely pyrophoric and have their pyrophoric action improved by short dip in acid solution having pH about 2 to about 4. Foils of such metals so treated can be folded to further increase pyrophoric action.

Abstract: Self-supporting web of brass or similar cupreous metal is catalytically activated by diffusing aluminum into its surface at low temperatures and then leaching out some of that aluminum with dilute mineral acid, preferably HNO.sub.3, or ammonium persulfate. Resulting catalyst is very effective for reaction of CO with H.sub.2 to make methanol, and web provides very good thermal conductivity for improved temperature control. Activation can be confined to one face of web. Other self-supporting catalysts can be made similarly.

Abstract: Metals are made pyrophoric by diffusing aluminum or zinc into them and then leaching it out, or by reacting with aluminum and then leaching aluminum out. Powdered aluminum and powdered nickel, iron or cobalt, can thus be carried on an elongated support web and reacted by heating for a few seconds to a few minutes, after which leaching will provide elongated pyrophoric foil suitable for decoying heat-seeking missile.

Abstract: Very good masking of pack diffusion aluminizing or chromizing on any metal to keep portions from being diffusion coated is effected by localized coating of masking powder, the metal portion of which can have some composition as substrates. Chromizing can be performed before aluminizing for greater effects. Aluminizing of metals like iron and nickel followed by leaching out much of the diffused-in aluminum gives these substrates a pyrophoric and catalytic surface. Foil, wire or powder can be thus activated; very fine activated powder when discharged into the air forms a warm cloud that settles very slowly and decoys heat-seeking missiles.

Abstract: Plain iron and nickel can be activated to become extremely pyrophoric and can have their pyrophoric action improved by short dip in acid solution having ph about 2 to about 4. Foils of such metals so treated can be folded to further increase pyrophoric action.

Abstract: Very good masking of pack diffusion aluminizing on any metal to keep portions from being diffusion coated, is effected by localized coating layers the lowest of which is inert or depletion-reducing masking powder that can have same composition as substrates, mixed with non-contaminating film-former such as acrylic resin. The upper coating layer or layers can be of non-contaminating particles like nickel or Cr.sub.2 O.sub.3 that upon aluminizing or chromizing become coherently held together to form a secure sheath. Such sheath can also be used for holding localized diffusion-coating layer in place. Film-former can be dissolved in volatile solvent, preferably methyl chloroform, in which masking powder or sheath-forming powder is suspended. Chromizing can be performed before aluminizing for greater effects.

Abstract: Diffusion aluminizing with chromium or silver chloride, bromide or iodide that is not significantly soluble in or reactive with water. Hydrogen can be excluded from diffusion aluminizing atmosphere when aluminizing maraging steels or other substrates sensitive to hydrogen. Aluminized iron powders can be boronized to increase their exothermic heat upon exposure to air after leaching out aluminum.

Abstract: Diffusion aluminizing, when applied to titanium is effected with little or no activator to produce more uniform case and less etching.Workpieces are very rapidly pack-diffusion coated by using an excess of energizers in the pack, heating the retort containing the packed workpieces at a rate that brings the workpieces to diffusion-coating temperature and then completing the diffusion coating, all in less than 50 minutes, then cooling the retort.Diffusion aluminizing can also be applied to foils and powder to make pyrophoric product after leaching out much of the introduced aluminum. Powder can also be diffusion boronized. Pyrophoric boron-containing iron or nickel powder mixed with Ba(NO.sub.3).sub.2 will ignite to cause generation of large quantity of NO.sub.2 gas, and generation is improved when powdered boron and/or an oxidizer like NaClO.sub.3 is added.

Abstract: Low alloy steel tubes are decarburized, heavily diffusion chromized and heavily diffusion aluminized to protect them against sulfidation. For the diffusion they can be supported upright with one end on layer of diffusion-coating pack on floor of a retort. Surface portions that are to be welded are covered with masking layer that prevents diffusion coating, or with inert layer that reduces the amount of coating. Diffusion aluminizing can also be applied to foils and powder to make pyrophoric product after leaching out much of the introduced aluminum. Powder can also be diffusion boronized. Pyrophoric boron-containing iron or nickel powder mixed with Ba(NO.sub.3).sub.2 will ignite to cause generation of large quantity of NO.sub.2 gas, and generation is improved when powdered boron and/or oxidizer like NaClO.sub.3 is added.

Abstract: Pyrophoric preparations made of crushable open-celled metal skeleton such as honeycomb, metal foam or expanded twisted foil, filled with pyrophoric powder, so that when crushed to make a compact disc the metal skeleton is deformed and helps lock the powder particles in place.

Abstract: Heating or heat generation in general can be from activated aluminides of molybdenum, zirconium or other similar ignitible metals. Activation is by leaching out some of the aluminum and leaves a product which is highly pyrotechnic but not pyrophoric. Activation of such alloy renders activated surface porous so it car receive impregnants such as lubricants to thus act as a bearing. Pyrotechnic webs for use as decoys against heat-seeking missiles can be folded so that portions interfere with the free radiation of other portions, to thus extend the time the webs remain at high temperature. The folding also improves the trajectory through which the webs fall when discharged into the air. The web can be coated with a thin layer of powdered silica, alumina or zirconia to increase the proportion of its radiation in the 8 to 14 micron range.

Abstract: Metals like iron and nickel are pyrophorically activated by continuous or batch treatment. Activated metal can be coated with material that increases, or tempers by partial blocking, pyrophoric action. Pyrophoric powder can be compacted with ignitable powders or fibers to produce self-supporting bodies having different degrees of pyrophoric activity.

Abstract: Very good masking of pack diffusion aluminizing or chromizing on any metal to keep portions from being diffusion coated, is effected by localized coating the lowest layer of which is depletion-reducing masking powder the metal portion of which can have same composition as substrates, mixed with inert refractory diluent and non-contaminating film-former such as acrylic resin. The upper coating layer can be of non-contaminating particles like nickel or Cr.sub.2 O.sub.3 that upon aluminizing or chromizing become coherently held together to form a secure sheath. Such sheath can also be used for holding localized diffusion-coating layer in place. Film-former can be dissolved in volatile solvent, preferably methyl chloroform, in which masking powder or sheath-forming powder is suspended. Chromizing can be performed before aluminizing for greater effects. Aluminizing of metals like iron and nickel followed by leaching out much of the diffused-in aluminum, gives these substrates a pyrophoric and catalytic surface.

Abstract: Diffusion coatings can be masked from portions of a workpiece by combination of layers the outer one of which forms coherent strong shell that holds inner layer or layers in place. All ingredients of these layers can be materials such as nickel, nickel aluminide, chronium, chromic oxide (Cr.sub.2 O.sub.3) and inert diluent, that do not contaminate superalloys or even low alloy or plain carbon steels. Layer can be deposited from suspension in a solution of film-former like and acrylic resin in readily volatilizable solvent such as methyl chloroform or chloroform. Innermost layer can be depletion-preventing and can be omitted. Such a holding shell can also be used to retain on a workpiece surface a layer that causes formation of a diffusion coating. Chromizing can be performed before aluminizing. Low alloy steel conduit can be internally chromized and/or externally chromized or aluminized to make it more desirable for use as high pressure steam boiler heat exchange tubing.

Abstract: Workpieces are very rapidly pack diffusion coated by using an excess of energizers in the pack, heating the retort containing the packed workpieces at a rate that brings the workpieces to diffusion-coating temperature and then completing the diffusion coating, all in less than 50 minutes, then cooling the retort. Workpiece can have top coating layer of aluminum flake covered by a layer of extremely fine alumina or silica in a magnesium chromate binder, to provide surface having roughness at least about 10 micro-inches smoother than before the top coating. More active diffusion coated products are also produced.

Abstract: Diffusion coatings can be masked from portions of a workpiece by combination of layers the outer one of which forms coherent strong shell that holds inner layer or layers in place. All ingredients of these layers can be materials such as nickel, nickel aluminide, chromium, chromic oxide (Cr.sub.2 O.sub.3) and inert diluent, that do not contaminate superalloys or even low alloy or plain carbon steels. Layer can be deposited from suspension in a solution of film-former like an acrylic resin in readily volatilizable solvent such as methyl chloroform or chloroform. Innermost layer can be depletion-preventing and can be omitted. Such a holding shell can also be used to retain on a workpiece surface a layer that causes formation of a diffusion coating. Chromizing can be performed before aluminizing. Low alloy steel conduit can be internally chromized and/or externally chromized or aluminized to make it more desirable for use as high pressure steam boiler heat exchange tubing.

Abstract: In the pack diffusion coating of chromium into the surface of a superalloy, the formation of undesirable oxide inclusion is reduced when the diffusion coating pack contains at least about 3% Ni.sub.3 Al. Also the formation of alpha-chromium is reduced when the pack diffusion is carried out in a retort effectively not over five inches in height. On the other hand an alpha-chromium-rich layer at least 0.2 mil thick can be deliberately formed and the superalloy thus coated subjected to an aluminizing treatment to convert the alpha-chromium into islands that provide very high sulfidation resistance. Pack aluminizing in the presence of chromium makes a very effective aluminum- or chromium-containing top coating over platinum plated or platinum coated nickel-base superalloys. Depletion of diffusible material from workpieces heated in a powder-pack can also provide a surface on which aluminizing produces a highly impact-resistant coating.

Abstract: Low alloy steel tubing is decarburized, chromized and then aluminized with or without masking at the sites at which the tubing is to be welded in place, to greatly increase resistance of the tubing to high temperature oxidation and sulfidation. Low surface aluminum content after aluminizing makes it easier to weld at that surface.