| 摘要 |
PURPOSE:To produce a valve seat for outboard motor excellent in wear resistance and corrosion resistance by using, as a stock, a sintered alloy where a hard Co-base alloy phase with a specific composition is dispersed into a Cu-Al alloy matrix. CONSTITUTION:First one part of Cu-50Al alloy powder is mixed with four parts of copper powder. Subsequently, 17 parts of hard grain powder of Co-8.5 Cr-28Mo-2.4Si are added to 100 parts of the resulting powder mixture, and these are mixed. Further, as the above hard grain powder, a pulverized powder of <=350 mesh grain size is used. Then, a compacting and lubricating agent is added by 0.5% to the resulting powder mixture, which is compacted into the prescribed shape and sintered at 990 deg.C. The resulting valve seat material has a composition consisting of 5.8-10.6% Al 3.3-5% Mo, 0.9-1.6% Cr, 0.3-0.5% Si, 7-10.7% Co, and the balance Cu, and further, this alloy has a structure where a hard phase having a composition consisting of 7.5-9.5% Cr, 27-30% Mo, 2.1-2.7% Si, and the balance Co is dispersed into a Cu-Al matrix having a composition consisting of 7-12% Al and the balance Cu. |
