Iron-based sintered alloy valve seat insert for internal combustion engine

Abstract

An iron-based sintered alloy valve seat insert for an internal combustion engine having excellent wear resistance, has a composition wherein Si—Cr—Ni—Fe type Mo-based intermetallic compound particles having a hardness of 700 to 1300 HV in terms of Vickers hardness and a composition containing Si: 1.5% to 3.5%, Cr: 7.0% to 9.0%, Mo: 35.0% to 45.0%, and Ni: 5.0% to 20.0% in terms of mass %, with a remainder being Fe and inevitable impurities are dispersed as hard particles in a base matrix phase that includes hard particles, solid lubricant particles, and contains C: 0.5% to 2.0%, Si: 0.2% to 2.0%, Mn: 5% or less, Cr: 0.5% to 15%, Mo: 3% to 20%, and Ni: 1 to 10% in terms of mass %, and further contains V: 0% to 5%, W: 0% to 10%, S: 0% to 2%, and Cu: 0% to 5%, with a remainder being Fe and inevitable impurities.

1 . An iron-based sintered alloy valve seat insert for an internal combustion engine which is a valve seat insert press-fitted into a cylinder head of an internal combustion engine,
 wherein the valve seat insert has a double-layer structure in which a valve contacting face material side layer and a supporting material side layer are integrally sintered,   the valve contacting face material side layer is made of an iron-based sintered alloy material having a structure including a base matrix phase and 10% to 40% of hard particles in terms of area ratio and 0% to 5% of solid lubricant particles in terms of area ratio dispersed in the base matrix phase, in which the hard particles are Si—Cr—Ni—Fe type Mo-based intermetallic compound particles having a hardness of 700 to 1300 HV in terms of Vickers hardness and having a composition consisting of Si: 1.5% to 3.5%, Cr: 7.0% to 9.0%, Mo: 35.0% to 45.0%, and Ni: 5.0% to 20.0% in terms of mass %, with a remainder being Fe and inevitable impurities, and a base matrix part including the base matrix phase, the hard particles, and the solid lubricant particles has a base matrix part composition containing C: 0.5% to 2.0%, Si: 0.2% to 2.0%, Mn: 5% or less, Cr: 0.5% to 15%, Mo: 3% to 20%, Ni: 1% to 10%, in terms of mass %, and further containing V: 0% to 5%, W: 0% to 10%, S: 0% to 2%, Cu: 0% to 5%, with a remainder being Fe and inevitable impurities,   the supporting material side layer is made of an iron-based sintered alloy material having a structure including a base matrix phase and 0% to 5% of solid lubricant particles in terms of area ratio and 0% to 5% of hardness improving particles in terms of area ratio dispersed in the base matrix phase, and having a composition in which a base matrix part including the base matrix phase, the solid lubricant particles, and the hardness improving particles contains C: 0.3% to 1.3%, and further contains Ni: 0% to 2.0%, Mo: 0% to 2.0%, Cu: 0% to 5.0%, Cr: 0% to 5.0%, Mn: 0% to 5.0%, S: 0% to 2.0% in terms of mass %, with a remainder being Fe and inevitable impurities, and   a density of the valve seat insert is 6.70 to 7.20 g/cm 3 .   
     
     
         2 . An iron-based sintered alloy valve seat insert for an internal combustion engine which is a valve seat insert press-fitted into a cylinder head of an internal combustion engine,
 wherein the valve seat insert has a single-layer structure formed of a valve contacting face material side layer,   the valve contacting face material side layer is made of an iron-based sintered alloy material having a structure including a base matrix phase and 10% to 40% of hard particles in terms of area ratio and 0% to 5% of solid lubricant particles in terms of area ratio dispersed in the base matrix phase, in which the hard particles are Si—Cr—Ni—Fe type Mo-based intermetallic compound particles having a hardness of 700 to 1300 HV in terms of Vickers hardness and having a composition consisting of Si: 1.5% to 3.5%, Cr: 7.0% to 9.0%, Mo: 35.0% to 45.0%, Ni: 5.0% to 20.0% in terms of mass %, and the remainder being Fe and inevitable impurities, and a base matrix part including the base matrix phase, the hard particles, and the solid lubricant particles has a base matrix part composition containing C: 0.5% to 2.0%, Si: 0.2% to 2.0%, Mn: 5% or less, Cr: 0.5% to 15%, Mo: 3% to 20%, Ni: 1% to 10%, in terms of mass %, and further containing V: 0% to 5%, W: 0% to 10%, S: 0% to 2%, Cu: 0% to 5%, with a remainder being Fe and inevitable impurities, and   a density of the valve seat insert is 6.70 to 7.20 g/cm 3 .   
     
     
         3 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 1 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 10% to 90% of a fine carbide precipitation phase and 0% to 30% of a high-alloy phase, with a remainder being pearlite, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         4 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 1 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 15% of a high-alloy phase, with a remainder being a fine carbide precipitation phase, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         5 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 1 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 25% of a high-alloy phase, with a remainder being a bainite phase, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         6 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 1 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 30% of a high-alloy phase, with a remainder being pearlite, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         7 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 3 ,
 wherein the fine carbide precipitation phase is a phase from which fine carbide having a particle diameter of 10 μm or smaller is precipitated and which has a hardness of 400 to 600 HV in terms of Vickers hardness.   
     
     
         8 . The iron-based sintered alloy valve seat insert according to  claim 1 ,
 wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .   
     
     
         9 . The iron-based sintered alloy valve seat insert according to  claim 1 ,
 wherein the hardness improving particles are iron-molybdenum alloy particles.   
     
     
         10 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 4 ,
 wherein the fine carbide precipitation phase is a phase from which fine carbide having a particle diameter of 10 μm or smaller is precipitated and which has a hardness of 400 to 600 HV in terms of Vickers hardness.   
     
     
         11 . The iron-based sintered alloy valve seat insert according to  claim 10 ,
 wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .   
     
     
         12 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 2 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 10% to 90% of a fine carbide precipitation phase and 0% to 30% of a high-alloy phase, with a remainder being pearlite, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         13 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 2 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 15% of a high-alloy phase, with a remainder being a fine carbide precipitation phase, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         14 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 2 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 25% of a high-alloy phase, with a remainder being a bainite phase, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         15 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 2 ,
 wherein the base matrix phase of the valve contacting face material side layer has a structure including 0% to 30% of a high-alloy phase, with a remainder being pearlite, in terms of area ratio where an area of the base matrix phase excluding the hard particles and the solid lubricant particles is 100%.   
     
     
         16 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 12 ,
 wherein the fine carbide precipitation phase is a phase from which fine carbide having a particle diameter of 10 μm or smaller is precipitated and which has a hardness of 400 to 600 HV in terms of Vickers hardness.   
     
     
         17 . The iron-based sintered alloy valve seat insert according to  claim 2 ,
 wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .   
     
     
         18 . The iron-based sintered alloy valve seat insert for an internal combustion engine according to  claim 13 ,
 wherein the fine carbide precipitation phase is a phase from which fine carbide having a particle diameter of 10 μm or smaller is precipitated and which has a hardness of 400 to 600 HV in terms of Vickers hardness.   
     
     
         19 . The iron-based sintered alloy valve seat insert according to  claim 18 ,
 wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .