Abstract: A production method for a sintered valve guide includes preparing a raw powder which is primarily made of an iron powder and which includes at least a copper alloy powder and a graphite powder. The production method further includes compacting the raw powder into a green compact having an approximately cylindrical shape and sintering the green compact at 950 to 1050° C. The iron powder includes particles, which do not pass through a sieve of 240 mesh, at not less than 40 mass %, and not less than 70 mass % of the powder particles have not more than 0.5 of degree of circularity.

Abstract: Valve guides made of ferrous sintered alloy for internal combustion engines have improved durability of the valve stem without soft nitriding process. The valve guides include Cu: 8 to 20 mass %, C: 0.8 to 1.5 mass %, and at least one of MnS, WS2, and MoS2: 0.5 to 2 mass % and the balance of Fe, the valve guides have many pores, have a metal structure in which the copper phase dispersed in an iron pearlite matrix exists, and have a structure in which metal sulfides are dispersed between particles between the matrix and the copper phase.

Abstract: Disclosed is a sintered valve guide guide formed of a sintered alloy consisting essentially of 3.5 to 5% copper, 0.3 to 0.6% tin, 0.04 to 0.15% phosphorus, 1.5 to 2.5% carbon and the balance iron, by mass, and as occasion needs, further containing 0.46 to 1.41% metal oxide, and MnS and/or magnesium silicate. The metallographic structure has: a matrix containing a pearlite phase, a Fe—P—C compound phase and a Cu—Sn alloy phase; pores; and a graphite of 1.2 to 1.7% by mass of the sintered alloy. In the cross section, the ratio of the pearlite phase to the matrix is 90 area % or more, the ratio of the Fe—P—C compound phase is 0.1 to 3 area % of the cross section, the ratio of the Cu—Sn alloy phase to the cross section is 1 to 3% by area, and the ratio of a portion of the Fe—P—C compound phase having a thickness of 15 microns or more is 10 area % or less of the whole Fe—P—C compound phase.

Abstract: A production method for a sintered component made of stainless steel with high corrosion resistance has steps of preparing a perovskite composite oxide powder made of rare earth element, transition metal element and oxygen, and a stainless steel powder or a mixed powder having a stainless steel composition, mixing the perovskite composite oxide powder and the stainless steel powder or the mixed powder, whereby a raw powder in which the rare earth element is 0.1 to 12 mass % is prepared, compacting the raw powder in a predetermined shape, whereby a green compact is obtained, and sintering the green compact. The sintered component obtained by the production method is a component in which corrosion resistance can be increased without parts of decreasing Cr concentration and precise production processes and process control are not necessary.

Abstract: Valve guides made of ferrous sintered alloy for internal combustion engines have improved durability of the valve stem without soft nitriding process. The valve guides include Cu: 8 to 20 mass %, C: 0.8 to 1.5 mass %, and at least one of MnS, WS2, and MoS2: 0.5 to 2 mass % and the balance of Fe, the valve guides have many pores, have a metal structure in which the copper phase dispersed in an iron pearlite matrix exists, and have a structure in which metal sulfides are dispersed between particles between the matrix and the copper phase.

Abstract: Disclosed is a sintered alloy material for valve guides, containing: 1.5% to 4% by mass of carbon; 1% to 20% by mass of copper; 0.1% to 2% by mass of tin; 0.01% or more than 0.01% and less than 0.1% by mass of phosphorus; and an iron base. The metallographic structure of the sintered alloy material has a matrix phase composed mainly of pearlite, and a free carbon phase being dispersed in the matrix phase.

Abstract: Disclosed is a sintered alloy material for valve guides, containing: 1.5% to 4% by mass of carbon; 1% to 20% by mass of copper; 0.1% to 2% by mass of tin; 0.01% or more than 0.01% and less than 0.1% by mass of phosphorus; and an iron base. The metallographic structure of the sintered alloy material has a matrix phase composed mainly of pearlite, and a free carbon phase being dispersed in the matrix phase.

Abstract: Disclosed is a valve guide which is manufactured by a sintered alloy and used for an engine, and more particularly, to a valve guide which has high wear resistance and can prevent appearance of scuffing on a surface of a valve stem associated with the valve guide, and to a process for manufacturing the valve guide. The valve guide comprises an inner surface sliding with a valve stem, the inner surface finished by machining and exposing pores. Area-ratio of the pores with respect to the inner surface is 2.7 to 10.7%, and at least one pore having pore size of not less than 80 .mu.m exists per 1 mm.sup.2 of the inner surface.

Abstract: A sintered metal part has a magnesium metasilicate mineral, or a magnesium metasilicate mineral and a magnesium orthosilicate mineral, or at least one of a magnesium metasilicate mineral and a magnesium orthosilicate mineral and at least one of boron nitride and manganese sulfide dispersed throughout the metal matrix. An iron-based sintered sliding member is of a structure that free graphite and an intercrystalline inclusion have been dispersed throughout the metal matrix that consists essentially of, in weight ratio, 1.5 to 4% of carbon, 1 to 5% of copper, 0.1 to 2% of tin, 0.1 to 0.5% of phosphorus, 0.