Iron-based sintered alloy material for valve seat and valve seat made of iron-based sintered alloy

Abstract

An iron-based sintered alloy material for a valve seat, in which hard particles are dispersed in a base matrix phase, is characterized in that the base matrix phase is comprised of 5 to 40 vol. % of a pearlite phase and 10 to 40 vol. % of a high-alloy diffused phase and particles having hardness of Hv 600 to 1300 and particle diameter of 10 to 150 μm are dispersed as the hard particles, by the amount of 10 to 30 vol. %, in the base matrix phase. The hard particles are preferably at least one type of particles selected from the group consisting of intermetallic compound particles of Mo—Ni—Cr—Si—Co; intermetallic compound particles of Cr—Mo—Co; Fe—Mo alloy particles; and carbide-precipitated particles.

What is claimed is:  
     
         1 . An iron-based sintered alloy material for a valve seat, in which hard particles are dispersed in a base matrix phase, characterized in that the base matrix phase is comprised of 5 to 40 vol. % of a pearlite phase and 10 to 40 vol. % of a high-alloy used phase and particles having hardness of Hv 600 to 1300 and particle diameter of 10 to 150 μm are dispersed as the hard particles, by the amount of 10 to 30 vol. %, in the base matrix phase.  
     
     
         2 . An iron-based sintered alloy material for a valve seat, in which hard particles are dispersed in a base matrix phase, characterized in that a base portion which includes the hard particles has a composition comprised of 0.2 to 2.0 wt % of C; 1.0 to 9.0 wt % of Cr; 1.0 to 9.0 wt % of Mo; 0.1 to 1.0 wt % of Si; 1.0 to 3.0 wt % of W; 0.1 to 1.0 wt % of V; 3.0 to 15.0 wt %,as the total, of at least one type of element selected from the group consisting of Cu, Co and Ni; and the remainder which is substantially Fe, the base matrix phase is comprised of 5 to 40 vol. % of a pearlite phase and 10 to 40 vol. % of a high-alloy diffused phase and particles having hardness of Hv 600 to 1300 and particle diameter of 10 to 150 μm are dispersed as the hard particles, by the amount of 10 to 30 vol. %, in the base matrix phase.  
     
     
         3 . An iron-based sintered alloy material for a valve seat according to  claim 1  or  2 , wherein the hard particles are at least one type of particles selected from the group consisting of intermetallic compound particles of Mo—Ni—Cr—Si—Co; intermetallic compound particles of Cr—Mo—Co; Fe—Mo alloy particles; and carbide-precipitated particles.  
     
     
         4 . An iron-based sintered alloy material for a valve seat according to  claim 3 , wherein the carbide-precipitated particles have a composition which is comprised of: 0.2 to 2.0 wt % of C; 2.0 to 10.0 wt % of Cr; 2.0 to 10.0 wt % of Mo; 2.0 to 10.0 wt % of W; 0.2 to 5.0 wt % of V; and Fe and inevitable impurities as the remainder.  
     
     
         5 . An iron-based sintered alloy material for a valve seat according to  claim 4 , wherein the content of the carbide-precipitated particles, as is expressed as the proportion by volume thereof present in the base matrix phase, is less than 20 vol. %.  
     
     
         6 . An iron-based sintered alloy material for a valve seat according to  claim 4  or  5 , wherein fine carbides having particle diameter of 1 to 10 μm have been precipitated on said carbide-precipitated particles.  
     
     
         7 . An iron-based sintered alloy material for a valve seat according to any one of  claims 1  to  6 , wherein the base matrix phase contains solid lubricant particles by the amount of 0.1 to 10.0 vol. %.  
     
     
         8 . An iron-based sintered alloy material for a valve seat according to  claim 7 , wherein the solid lubricant particles made of are at least one type of compound selected from the group consisting of a sulfide, a fluoride and graphite.  
     
     
         9 . An iron-based sintered alloy material for a valve seat according to any one of  claims 1  to  8 , wherein sintered pores are infiltrated with one of the material selected from the group consisting of Cu, Cu alloy, Pb and Pb alloy or with a phenol-based resin.  
     
     
         10 . A valve seat made of an iron-based sintered alloy, characterized in that the valve seat is made of the iron-based sintered alloy material for a valve seat of any one of  claims 1  to  9 .