| 摘要 |
PROBLEM TO BE SOLVED: To prevent separation between a tappet body and tip material by jointing the tip material made of a tungsten carbide base super alloy formed of a sintered body of specific composition, diffusedly to the cam contact face side top face of the tappet body made of low alloy steel formed of a specific composition. SOLUTION: A tappet body 1 is made of low alloy steel formed of a composition containing C: 0.13-0.5wt.%, Si: 0.15-0.35wt.%, Mn: 0.3-1.2wt.%, Cr: 0.4-3.5wt.% and Fe and unavoidable impurities forming the rest. Tip material 2 made of a tungsten carbide base super alloy formed of a sintered body composed of Co: 20-30wt.%, Ni: 3-15wt.% (Co + Ni: 25-35-wt.%), P: 0.1-1wt.%, chrome carbide: 0.5-10wt.% and tungsten carbide forming the rest is diffusedly jointed to a top face 1a on the cam contact face side of the tappet body 1 made of low alloy steel. As a result, wettability is improved by the mutual action of Si in tappet material and P forming the tip material, and the adhesion of the tip material to the tappet material is improved by the action of Cr3 C2 solid- solubilized in Co + Ni forming the binding phase of the tip material. |
