| 摘要 |
PURPOSE:To obtain a valve seat with high hardness and high corrosion resistance by a method wherein the seat surface of a valve head is formed with seating member harder than the base material of a valve and high corrosion resistant member combined with each other. CONSTITUTION:A seating member is composed of a composite structure consisting in installing high hard material 14 over the whole outer peripheral surface and high corrosion resistant material 15 over the whole inner peripheral surface of the seating part 13 of a valve head. No indentation is easily formed, even when combustion residue is caught on the outer peripheral surface 14 by burning inferior quality oil. Even when indentation is formed after long time running and high temperature corrosion develops from the indentation, the development of the corrosion is stopped by the corrosion resistant material 15 installed on the inner peripheral surface lying next to the outer peripheral surface and no blow- off is resulted. SUH3 or the like is employed as the base material of the valve, stellite or the like as the high hard material, and an alloy of Ni-20%, Cr-2.5%, Ti-15%, Al the remainder; or an alloy of Ni-30%, Cr-2%, Ti-1%, Al the remainder or the like as high corrosion resistant material is employed. |
