Sintered material for valve guides and production method therefor
AssigneeHitachi Powdered Metals Co., Ltd.
InventorsHiroki Fujitsuka, Hideaki Kawata
Life of this patent
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Abstract
A sintered material for valve guides consists of, by mass %, 0.01 to 0.3% of P, 1.3 to 3% of C, 1 to 4% of Cu, and the balance of Fe and inevitable impurities. The sintered material exhibits a metallic structure made of pores and a matrix. The matrix is a mixed structure of a pearlite phase, a ferrite phase, an iron-phosphorus-carbon compound phase, and a copper phase, and a part of the pores including graphite that is dispersed therein. The iron-phosphorus-carbon compound phase is dispersed at 3 to 25% by area ratio, and the copper phase is dispersed at 0.5 to 3.5% by area ratio, with respect to a cross section of the metallic structure, respectively.
Claims11
A sintered material for valve guides, consisting of, by mass %, 0.01 to 0.3% of P, 1.3 to 3% of C, 1 to 4% of Cu, and the balance of Fe and inevitable impurities,
- the sintered material exhibiting a metallic structure made of pores and a matrix, the matrix being a mixed structure of a pearlite phase, a ferrite phase, an iron-phosphorus-carbon compound phase, and a copper phase, and a part of the pores including graphite that is dispersed therein,
- wherein the iron-phosphorus-carbon compound phase is dispersed at 3.1% to 25% by area ratio, and the copper phase is dispersed at 0.5 to 3.5% by area ratio, with respect to a cross section of the metallic structure, respectively.
A production method for a sintered material for valve guides, comprising:
- preparing an iron powder, an iron-phosphorus alloy powder, a copper powder, and a graphite powder;
- mixing the iron-phosphorus alloy powder, the copper powder, and the graphite powder with the iron powder into a raw powder consisting of, by mass %, 0.01 to 0.3% of P, 1.3 to 3% of C, 1 to 4% of Cu, and the balance of Fe and inevitable impurities;
- filling a tube-shaped cavity of a die assembly with the raw powder;
- compacting the raw powder into a green compact having a tube shape;
- and
- sintering the green compact at a heating temperature of 970 to 1070° C. in a nonoxidizing atmosphere so as to obtain a sintered compact.
Dependencies are inferred from the claim text.