Hitachi Metals, Ltd.

Proterial, Ltd.

Tsunehiro Kawata

Toshio Ishii

Hiroshi Ueda

Yoshinori Kobayashi

Futoshi Kuniyoshi

Takeshi Nishiuchi

Shigeyuki Hamayoshi

Hirohisa Suwabe

Kimio Uchida

Rintaro Ishii

Hisayuki Imamura

Masayuki Gonda

Masahisa Sobue

Katsuhiko Kojo

Mitsuaki Mochizuki

Hideya Yamane

Takayuki Fukaya

Yoshio Igarashi

Seiichi Endo

Osamu Tokudome

Michihisa Shimizu

Masao Murakawa

Kenichiro Sekiguchi

Masahiro Miyake

Youichiro Kazama

Toshihiko Tsujimura

A sintered ferrite magnet comprising metal elements of Ca, La, Fe and Co, whose atomic ratios are represented by the general formula of CaLaFeCo, wherein x and y, and n representing a molar ratio meet 0.3&#x2266;x&#x2266;0.6, 0.25&#x2266;y&#x2266;0.5, and 3&#x2266;n&#x2266;6, and further comprising 0.2% to 0.35% by mass of SiO.

Sintered ferrite magnet and its production method

A sintered ferrite magnet having a main phase composed of ferrite having a hexagonal, M-type magnetoplumbite structure, a grain boundary phase containing Si and Ca with a lower atomic ratio of La than in said main phase, and a third phase containing La at a higher atomic ratio than in said main phase, and a method for producing a sintered ferrite magnet having said third phase by calcining starting materials with more La than Ca, adding more than 1% and 1.8% or less by mass of SiOand 1-2% by mass (calculated as CaO) of CaCOto the calcined body, and pulverizing, molding and sintering it.

A graphite-containing, heat-resistant cast iron for exhaust equipment members used at temperatures exceeding 800&#xb0; C., comprising 3.5-5.6% of Si and 1.2-15% of W on a weight basis, and having intermediate layers, in which W and Si are concentrated, in the boundaries of graphite particles and a matrix. An exhaust equipment member formed by this heat-resistant cast iron has an Atransformation point is 840&#xb0; C. or higher when measured from 30&#xb0; C. at a temperature-elevating speed of 3&#xb0; C./minute, and a thermal cracking life of 780 cycles or more in a thermal fatigue test, in which heating and cooling are conducted under the conditions of an upper-limit temperature of 840&#xb0; C., a temperature amplitude of 690&#xb0; C. and a constraint ratio of 0.25.

Heat-resistant cast iron and exhaust equipment member formed thereby

In a ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls, the cell walls have a porosity of 55-75%, with an average pore diameter Da of 10-30 &#x3bc;m and a pore area ratio Sa of 10-30% on their surfaces, and the average length La of the pores at their openings and the average width Lb of the pores at depth La from the surfaces of the cell walls meet the condition of 1.1&#x3c;Lb/La&#x3c;5 in an arbitrary vertical cut surface of the cell walls. In the cordierite-based ceramic honeycomb structure, the ceramic contains Fe and a spinel, the amount of the spinel being 4% or less by an X-ray diffraction intensity ratio, and most of the spinel having particle sizes in a range of 0.01-5 &#x3bc;m.

Ceramic honeycomb structure and moldable material usable for its extrusion molding

A silicon nitride sintered body comprising Mg and at least one rare earth element selected from the group consisting of La, Y, Gd and Yb, the total oxide-converted content of the above elements being 0.6&#x2013;7 weight %, with Mg converted to MgO and rare earth elements converted to rare earth oxides REO. The silicon nitride sintered body is produced by mixing 1&#x2013;50 parts by weight of a first silicon nitride powder having a &#x3b2;-particle ratio of 30&#x2013;100%, an oxygen content of 0.5 weight % or less, an average particle size of 0.2&#x2013;10 &#x3bc;m, and an aspect ratio of 10 or less, with 99&#x2013;50 parts by weight of &#x3b1;-silicon nitride powder having an average particle size of 0.2&#x2013;4 &#x3bc;m; and sintering the resultant mixture at a temperature of 1,800&#xb0; C. or higher and pressure of 5 atm or more in a nitrogen atmosphere.

Silicon nitride powder, silicon nitride sintered body, sintered silicon nitride substrate, and circuit board and thermoelectric module comprising such sintered silicon nitride substrate

The permanent magnetic alloy of the present invention comprises an R&#x2014;Fe&#x2014;B alloy wherein R is at least one element selected from rare earth elements including Y. The R&#x2014;Fe&#x2014;B alloy has a composition mainly comprising Fe, substantially containing no N, and containing 4 at. % or more of B. The permanent magnetic alloy substantially comprises a TbCuhard magnetic phase (main phase) and a fine crystal having an average crystal grain size of less than 5 nm and/or an amorphous phase, and has high magnetic properties.

Permanent magnetic alloy and bonded magnet

A silicon nitride sintered body comprising Mg and at least one rare earth element selected from the group consisting of La, Y, Gd and Yb, the total oxide-converted content of the above elements being 0.6-7 weight %, with Mg converted to MgO and rare earth elements converted to rare earth oxides REO. The silicon nitride sintered body is produced by mixing 1-50 parts by weight of a first silicon nitride powder having a particle ratio of 30-100%, an oxygen content of 0.5 weight % or less, an average particle size of 0.2-10 &#x3bc;m, and an aspect ratio of 10 or less, with 99&#x2212;50 parts by weight of &#x3b1;-silicon nitride powder having an average particle size of 0.2-4 &#x3bc;m; and sintering the resultant mixture at a temperature of 1,800&#xb0; C. or higher and pressure of 5 atm or more in a nitrogen atmosphere.

An R&mdash;T&mdash;B sintered permanent magnet having a composition including 28-33 weight % of R, and 0.5-2 weight % of B, the balance being substantially T and inevitable impurities, wherein R is at least one rare earth element including Y, at least one heavy rare earth element selected from the group consisting of Dy, Tb and Ho being indispensable, and T is Fe or Fe and Co, the permanent magnet having a crystal structure comprising first R T B-type, main-phase crystal grain particles having a higher heavy rare earth element concentration than that of a crystal grain boundary phase, and second R T B-type, main-phase crystal grain particles having a lower heavy rare earth element concentration than that of the crystal grain boundary phase.

R-T-B sintered permanent magnet

An alumina coated tool comprising a plurality of refractory layers and a substrate body. The refractory layers comprise a non-oxide layer on the surface of the substrate body, a bonding layer having a face-centered-cubic structure on the non-oxide layer, and an oxide layer on the bonding layer. The non-oxide layer is at least one of carbide, nitride and carbonitride of a metal selected from the group consisting of the Groups IVa, Va and VIa of the Periodic Table. The bonding layer is a single- or multi-coating of oxide, oxycarbide, oxynitride, oxycarbonitride of a metal selected from the group consisting of the Groups IVa, Va and VIa of the Periodic Table. The oxide layer is substantially .alpha.-Al.sub.2 O.sub.3. The epitaxial relationship between the non-oxide layer and the bonding layer enhances the bonding strength of the oxide layer to provide an alumina coated tool resistant to flaking of the oxide layer.

Alumina coated tool and production method thereof

Stainless steel member for semiconductor fabrication equipment having a passive state coating on the surface of the stainless steel comprising, in weight percent, 0.1% or less of C, 2.0% or less of Si, 3.0% or less of Mn, 10% or more of Ni, 15 to 25% of Cr, 1.5 to 4.5% of Mo, 0.5% or less of one or more rare earth element and Fe for substantially the whole remainder. Said passive state coating has a pitting potential of at least 900 mV (when the current density of the anode polarization curve determined with a potentiostat in 3.5% aqueous sodium chloride solution is 10 .mu.A/cm.sup.2) and has a thickness of 0.5 to 20 nm. The invention also includes a surface treatment method for the stainless steel.

Growing community of inventors

Saitama-ken, Japan

Tsunehiro Kawata