Oxides formed during annealing of stainless steel strip are removed with abrasive brushes, in lieu of acid or molten salt based pickling. In some embodiments, the stainless steel strip is treated with a rare earth element or a related transition metal before annealing, and then brushed after annealing to remove any oxides. The selection of brushes can impart a finished appearance to conventionally polished stainless steel.

The invention relates to a fuel tank (1), in particular a hydrogen tank, for a fuel cell system, having a monolithic base body (10) made of a metal alloy, wherein the base body (10) has a first inner layer (11) having a first inner structure and a second outer layer (12) having a second inner structure, which differs from the first inner structure, and wherein the first inner structure is formed from a metastable austenite and the second inner structure is formed from a martensite.

The invention relates to a fuel tank (1), in particular a hydrogen tank, for a fuel cell system, having a monolithic base body (10) made of a metal alloy, wherein the base body (10) has a first inner layer (11) having a first inner structure and a second outer layer (12) having a second inner structure, which differs from the first inner structure, and wherein the first inner structure is formed from a metastable austenite and the second inner structure is formed from a martensite.

The invention relates to the rare metal smelting field, and particularly, the present invention relates to a tantalum powder for preparing capacitors and a process for preparing the tantalum powder, and to a sintered anode prepared from the tantalum powder. As to the tantalum powder as provided by the invention, its primary tantalum powder has a BET of from 3.0 to 4.5 m.sup.2/g. After the secondary agglomeration, the tantalum powder has a large particle size. The tantalum powder has an average Fisher sub-sieve size (FSSS) of 1.2 to 3.0 m wherein as measured with a standard sieve mesh, more than 75% of tantalum powder has a +325-mesh, and a particle size distribution D50 of more than 60 m, that is, the secondary particle size is high. A resultant capacitor anode prepared by sintering the tantalum powder of the invention at 1200 C. for 20 minutes and then being energized at the voltage of 20 V has the specific capacitance of from 140,000 to 180,000 FV/g and the residual current of less than 1.0 nA/FV. Meantime, the invention provides an economical process for making the tantalum powder.

The invention relates to the rare metal smelting field, and particularly, the present invention relates to a tantalum powder for preparing capacitors and a process for preparing the tantalum powder, and to a sintered anode prepared from the tantalum powder. As to the tantalum powder as provided by the invention, its primary tantalum powder has a BET of from 3.0 to 4.5 m.sup.2/g. After the secondary agglomeration, the tantalum powder has a large particle size. The tantalum powder has an average Fisher sub-sieve size (FSSS) of 1.2 to 3.0 m wherein as measured with a standard sieve mesh, more than 75% of tantalum powder has a +325-mesh, and a particle size distribution D50 of more than 60 m, that is, the secondary particle size is high. A resultant capacitor anode prepared by sintering the tantalum powder of the invention at 1200 C. for 20 minutes and then being energized at the voltage of 20 V has the specific capacitance of from 140,000 to 180,000 FV/g and the residual current of less than 1.0 nA/FV. Meantime, the invention provides an economical process for making the tantalum powder.

A method of processing a metal member having a passivation film on its surface is provided. The method includes a step of heating the metal member for a predetermined period at a temperature of 300 C. or higher.

The present invention provides iron powder for dust cores that has excellent compressibility and low iron loss after formation. In the iron powder for dust cores, Si content is 0.01 mass % or less, apparent density is 3.8 g/cm.sup.3 or more, the ratio of iron powder particles with a particle size of 45 m or less is 10 mass % or less, the ratio of iron powder particles with a particle size of over 180 m and 250 m or less is less than 30 mass %, the ratio of iron powder particles with a particle size of over 250 m is 10 mass % or less, and the Vickers hardness (test force: 0.245 N) of a powder cross-section is 80 Hv or less.

The present invention provides iron powder for dust cores that has excellent compressibility and low iron loss after formation. In the iron powder for dust cores, Si content is 0.01 mass % or less, apparent density is 3.8 g/cm.sup.3 or more, the ratio of iron powder particles with a particle size of 45 m or less is 10 mass % or less, the ratio of iron powder particles with a particle size of over 180 m and 250 m or less is less than 30 mass %, the ratio of iron powder particles with a particle size of over 250 m is 10 mass % or less, and the Vickers hardness (test force: 0.245 N) of a powder cross-section is 80 Hv or less.

A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.

A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.