Valve seat made of Fe-based sintered alloy excellent in wear resistance

A valve seat excellent in wear resistance made of Fe-based sintered alloy, the Fe-based sintered alloy comprising, as a whole composition, by weight

• C:
• 0.5-2%, Si:
• 0.05-1% Co:
• 8-16%, Cr:
• 2-8%, Mo:
• 1.5-6%, W:
• 1.5-6%, Ni:
• 0.5-2%, Nb:
• 0.05-1%, and
• calcium fluoride:
• 1-15%, with the balance Fe and the inevitable impurities, wherein the Fe-based sintered alloy has a structure in which Co-based alloy hard particles A, which comprise Co—Mo—Cr alloy and have high temperature wear resistance, and Cr-based alloy hard particles B, which comprise Cr—W—Co—Fe alloy and have ordinary temperature wear resistance, are dispersed and distributed in an alloy steel base in a total amount of 6-26 area percent when they are observed on a structure photograph recorded by an optical microscope, and wherein the amount of the hard particles A to total hard particles is 25-75 area percent and wherein the calcium fluoride particles are dispersed and distributed in the alloy steel base in an amount of 3-45 area percent, and the Fe-based sintered alloy has a porosity of 5-25%, and wherein the Fe-based sintered alloy is infiltrated with copper or copper alloy, or lead or lead alloy.

A valve seat made of Fe-based sintered alloy, the Fe-based sintered alloy comprising, on a weight percent basis:

• C:
• 0.5-2%, Si:
• 0.05-1% Co:
• 8-16% Cr:
• 2-8% Mo:
• 1.5-6% W:
• 1.5-6% Ni:
• 0.5-2% Nb:
• 0.05-1%, and
• calcium fluoride:
• 1-15%, with the balance Fe and the inevitable impurities, wherein the Fe-based sintered alloy has a structure in which Co-based alloy hard particles A, which comprise Co—Mo—Cr alloy having the composition of 20-35 wt. % Mo, 5-10 wt. % Cr and 1-4 wt. % Si, with the balance Co and impurities and have high temperature wear resistance, and Cr-based alloy hard particles B which comprise Cr—W—Co—Fe alloy having the composition of 0.5-3 wt. % C, 15-30 wt. % W, 15-30 wt. % Co, 5-15 wt. % Fe, 0.2-2 wt. % Nb and 0.2-2 wt. % Si, with the balance Cr and impurities and have ordinary temperature wear resistance, are dispersed and distributed in the alloy steel base in a total amount of 6-26 area percent when they are observed on a structural photograph recorded by an optical microscope, wherein, in the alloy, the ratio of hard particles A to total hard particles is 25-75 area percent, and wherein the calcium fluoride particles are dispersed and distributed in the alloy steel base in an amount of 3-45 area percent, and the Fe-based sintered alloy has a porosity of 5-25%, said valve seat having excellent wear resistance.