Wear resistant valve seat ring - consists of a sintered, low-alloy iron substrate and a wear-resistant, sintered, iron alloy top coating

摘要

The ring, which is wear-resistant at high temp., is prepd. by powder metallurgy and is composed of a substrate of sintered low-alloy iron and a wear resistant top coating of smaller thickness than that of the substrate, which consists of a sintered high alloy iron or a sintered mixt. of low alloy iron (Ie and an alloy (II) based on Co, Mo, Si or Cr. The prepn. comprises filling a die with the substrate powder and covering this powder with a wear-resistant coating powder. The mixt. is compacted, sintered, opt. cold or warm post-compacted, and opt. heat treated. Pref. the low-alloy iron powder contains Ni, Mn, B and graphite. The wear-resistant layer is composed of 70-95% (I) and 5-30% (II). Prodn. of the ring is economical as a small amt. of costly alloying element is required i.e. for the wear-resistant layer only. The substrate retains its high strength.