High machinability iron base sintered alloy for valve seat inserts
First Claim
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1. A sinter-hardenable powder metal valve seat material for internal combustion engines comprising a mixture of:
- a sinter-hardenable ferrous powder forming 75-90 wt. % of the mixture;
a tool steel powder;
a solid lubricant;
Cu added by infiltration during sintering, and wherein the ferrous powder is prealloyed with 2 to 5 wt. % Cr.
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Abstract
A ferrous sintered valve seat material is made of mixed powders comprising a sinter-hardenable phase and a finely dispersed carbide phase. The powder mixture comprises a sinter-hardening prealloyed powder forming 75 to 90 wt. % of the mixture and a tool steel powder with finely dispersed carbides forming 5 to 25% of the mixture. Machinability additives of MnS, CaF2 or MoS2 types are added in an amount of 1 to 5 wt. %. Improved thermal conductivity is obtained by infiltrating the compact with Cu up to 25 wt. %.
103 Citations
31 Claims
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1. A sinter-hardenable powder metal valve seat material for internal combustion engines comprising a mixture of:
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a sinter-hardenable ferrous powder forming 75-90 wt. % of the mixture;
a tool steel powder;
a solid lubricant;
Cu added by infiltration during sintering, and wherein the ferrous powder is prealloyed with 2 to 5 wt. % Cr. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
75 to 90% of the ferrous powder prealloyed with 2 to 5 wt. % Cr, 0 to 3 wt. % Mo and 0 to 2 wt. % Ni;
5 to 25 wt. % M2 tool steel powder;
1 to 5 wt. % of the solid lubricant selected from one or more of the group consisting of MnS, CaF2 and MoS2; and
the Cu added by infiltration during sintering amounting to 10 to 25 wt. % of the remaining constituents.
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7. The mixture of claim 6 wherein the ferrous powder is present in an amount of 89 wt. %.
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8. The mixture of claim 6 wherein the M2 tool steel is present in an amount of 8 wt. %.
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9. The mixture of claim 6 wherein the solid lubricant is present in an amount of 3 wt. %.
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10. The mixture of claim 6 wherein the Cu is present in an amount of 20 wt. % of the remaining constituents of the mixture.
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11. The mixture of claim 6 having the following composition:
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89 wt. % of the ferrous powder;
8 wt. % of the M2 tool steel;
3 wt. % of the solid lubricant; and
20 wt. % infiltrated Cu relating to the combined weight percentage of the ferrous powder, M2 tool steel and solid lubricant.
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- 12. A sintered valve seat insert material for internal combustion engines with improved machinability, wear resistance and high thermal conductivity, where said material consists of a mixture of a Cr-containing sinter-hardening ferrous alloy powder, a tool steel powder, a solid lubricant and Cu added by infiltration of compacts during sintering.
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16. A sintered valve seat insert for internal combustion engines exhibiting good machinability, wear resistance and high thermal conductivity, comprising:
a matrix of a sinter-hardening prealloyed or admixed Fe powder containing 2 to 5 wt. % Cr mixed and sintered with an amount of tool steel powder, a solid lubricant and an amount of Cu added by infiltration during sintering. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of making a sintered powder metal valve seat insert for internal combustion engines exhibiting good machinability, wear resistance and high thermal conductivity, comprising:
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mixing Cr-containing sinter-hardenable ferrous powder with tool steel powder and a solid lubricant;
compacting and sintering the mixture; and
during sintering, infiltrating the compact with Cu. - View Dependent Claims (27, 28, 29, 30, 31)
75 to 90 wt. % of the Cr-containing ferrous powder;
5 to 25 wt. % of M2 tool steel;
1 to 5 wt. % of the solid lubricant; and
wherein the Cu is infiltrated into the compacted mixture in an amount of 10 to 25 wt. % of the compact.
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30. The method of claim 29 wherein the Cr-containing ferrous powder comprises elemental admixed or prealloyed Fe powder combined with 2 to 5 wt. % Cr, 0 to 3 wt. % Mo and 0 to 2 wt. % of Ni.
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31. The method of claim 30 wherein the Cr-containing ferrous powder is present in an amount of 89 wt. %, the M2 tool steel present in an amount of 8 wt. %, the solid lubricant present in an amount of 3 wt. %, and the Cu infiltrated in an amount of 20 wt. % of the compact during sintering.
Specification