Sintered valve guide and manufacturing method thereof

摘要

Disclosed is a sintered valve guide guide formed of a sintered alloy consisting essentially of 3.5 to 5 % copper, 0.3 to 0.6 % tin, 0.04 to 0.15 % phosphorus, 1.5 to 2.5 % carbon and the balance iron, by mass, and as occasion needs, further containing 0.46 to 1.41 % metal oxide, and MnS and/or magnesium silicate. The metallographic structure has: a matrix containing a pearlite phase, a Fe-P-C compound phase and a Cu-Sn alloy phase; pores; and a graphite of 1.2 to 1.7 % by mass of the sintered alloy. In the cross section, the ratio of the pearlite phase to the matrix is 90 area% or more, the ratio of the Fe-P-C com