Kawasaki Steel Corporation

Mazda Motor Corporation

Minoru Nitta

Ichio Sakurada

Shunji Ito

Yoshihiro Kajinaga

Kuniaki Ogura

Hiroshi Ohtsubo

Hiroyuki Ishikawa

Yoshiaki Maeda

Takeo Omura

Yoshisato Kiyota

Yasuhiro Habu

Toshio Watanabe

Shigemi Ohsaki

Yutaka Yoshii

Kenichi Otsuka

Yukio Makiishi

Sumio Kamino

Yutyaka Yoshii

Yasuaki Morioka

This invention is to control the diffusion of C (carbon) from added graphite to particles of iron powder in the sintering to thereby improve the accuracy of dimensional change in the sintered body by using iron powder for powder metallurgy and a mixed powder thereof as a starting material in the production of sintered mechanical parts by adding the iron powder with Cu powder and graphite powder and companying and sintering them, in which 0.008-0.5 wt % in total of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/l mol of O.sub.2 is included in the iron powder and not less than 20% of the element is rendered into an oxide, or 0.01-0.20 wt % in total of an oxide powder of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/l mol of O.sub.2 is added to the mixed powder.

Iron powder and mixed powder for powder metallurgy as well as method of

There is provided alloy steel powders for the injection molding use manufactured by the atomizing method which are characterized by their substantially spherical particle shape and average particle diameters of 20 microns or less, a compound for the injection molding use which contains the alloy steel powders and one or more organic binders, a process for manufacturing sintered materials in performing injection molding of compound and subsequently debinding the obtained injection molded part followed by sintering the debound part, at least the first stage of the sintering step is performed in reduced pressure atmosphere, and the sintered material having a relative density ratio of 92% or more.

Alloy steel powders for injection molding use, their compounds and a

In a process for preparing a spherical copper fine powder having an average grain size ranging from 0.1 .mu.m to a few .mu.m, by use of chemical vapor deposition of cuprous chloride vapor with a reducing gas, the vapor deposition zone is maintained at a temperature ranging 900.degree. C. to less than 1,150.degree. C. and the generated particles are quenched subsequently. The generated powder is utilized as a conductive powder which is the main component of a conductive paste.

Process for preparing spherical copper fine powder

A method of producing ferrous sintered alloys comprises the steps of preparing mixed alloy powder containing Fe-P-C eutectic alloy powder which includes phosphorus within the range of 2.0% to 3.0% by weight, carbon not more than 4.0% by weight and one of molybdenum within the range of 8.0% to 11.0% by weight and boron within the range of 0.5% to 3.0% by weight, graphite, and ferroalloy powder containing chromium within the range of 11% to 14% by weight; causing the mixed alloy powder to be subjected to compression molding to have a green compact; and sintering the green compact to have a ferrous sintered alloy containing compound carbides in a matrix structure thereof. The graphite is so selected that the sum total of the graphite and the carbon included in the Fe-P-C eutectic alloy powder constitutes a part within the range of 5% to 8% by weight of the sum total of the graphite and the Fe-P-C eutectic alloy powder. Further, the ferroalloy powder is so selected as to constitute a part within the range of 30% to 70% by weight of the whole mixed alloy powder.

Method of producing ferrous sintered alloys with superior abrasion

An alloy steel powder having a basic alloy composition, which is composed of at least one of manganese, chromium, molybdenum and vanadium, and the remainder being iron, and having low carbon, nitrogen and oxygen contents is excellent in the compressibility and moldability at the press molding and further excellent in the carburizing property and hardenability in its sintered steel or powder forged steel.

Alloy steel powder having excellent compressibility, moldability and

A process and an apparatus for producing low-oxygen iron-base metallic powder are disclosed. The low-oxygen iron-base metallic powder is produced by alloying and/or admixing iron-base metallic raw powder to be subjected to a final reduction, which has an apparent density in filled state corresponding to 16-57% of theoretical true density, an oxygen content of not more than 6% by weight and a particle size of not more than 1 mm, with carbon or carbonaceous granule in an amount corresponding to not more than an target alloying carbon content of a final product (% by weight) + an oxygen content of the powder just before the final reduction (% by weight) .times. 1.35 to form a starting powder, preheating the starting powder at a temperature of 780.degree.-1,130.degree. C. in a non-oxidizing atmosphere having a theoretical oxygen partial pressure of not more than 2.1.times.10.sup.-1 mmHg and a dew point of not more than +5.degree. C. to form a preheated and sintered cake (P-cake), induction heating the P-cake at a temperature of 850.degree.-1,400.degree. C. in the same atmosphere by applying an alternating power of 50 Hz to 500 kHz from power supply to effect deoxidation and decarburization to form an induction heated cake (I-cake), and then cooling and pulverizing the I-cake.

Apparatus for producing low-oxygen iron-base metallic powder

A shaft furnace for producing low-oxygen iron-base metallic powder for metallurgy is disclosed. The shaft furnace comprises a zone of storing and feeding a metallic raw powder, a preheating zone, an induction heating zone and a zone of cutting and cooling a product cake in a vertical array from top to bottom. The preheating zone and induction heating zone have a special structure for ensuring a smooth descent of the raw powder and the cake.

Shaft furnace for producing low-oxygen iron-base metallic powder for

A process for producing low-oxygen iron-base metallic powder are disclosed. The low-oxygen iron-base metallic powder is produced in a shaft-type apparatus comprising a preheating zone and an induction heating zone by alloying and/or admixing iron-base metallic raw powder to be subjected to a final reduction, which has an apparent density corresponding to 16 to 57% of theoretical true density, an oxygen content of not more than 6% by weight and a particle size of not more than 1 mm, with carbon or carbonaceous granule in an amount corresponding to not more than a target alloying carbon content of a final product (% by weight)+ an oxygen content of the powder just before the final reduction (% by weight).times. 1.35 to form a starting powder, preheating the starting powder at a temperature of 780.degree. to 1,200.degree. C. in a non-oxidizing atmosphere having a thermodynamically calculated oxygen partial pressure of not more than 2.1.times.10.sup.-1 mmHg and a dew point of not more than +5.degree. C. in the preheating zone to form a preheated and sintered cake (P-cake) with cylindrically sintered shell layer wherein the volume ratio of the shell layer is at least 20%, induction heating the P-cake at a temperature of 850.degree. to 1,400.degree. C. in the same atmosphere by applying an alternating power of 50 Hz to 500 kHz from power supply to effect deoxidation and decarburization to form an induction heated cake (I-cake), and then cooling and pulverizing the I-cake.

Process for producing low-oxygen iron-base metallic powder

Iron or iron alloy powders having a low oxygen content to be used for powder metallurgy are produced by subjecting iron or iron alloy powder materials having an oxygen content of not more than 8% by weight and a total carbon amount including carbon alloyed in said powders being not more than 6% by weight corresponding to the oxygen content to an induction heating under a relative density of 5-65% based on a density of the molding steel of said powders by means of an alternating current of 50 cycles-1 megacycle to heat said powders at a temperature of 750.degree.-1,400.degree.C to effect reduction rapidly.

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Chiba, Japan

Minoru Nitta