An apex seal consisting of 3.0 to 4.0 wt % of C, 1.5 to 2.5 wt % of Si, 0.3 to 1.0 wt % Mn, 0.05 to 0.3 wt % of P, less than 0.1 wt % of S, 0.005 to 0.025 wt % of Mg or Ce, 0.5 to 2.0 wt % of Cu and/or 0.5 to 3.0 wt % of Ni, 0.4 to 1.0 wt % of Cr, 1.0 to 2.0 wt % of Mo and/or 0.1 to 0.5 wt % of V with the balance of Fe, being formed in the sliding surface portion with a sorbite matrix structure in which carbides are dispersed in a matrix of sorbite and in the matrix portion of the material other than the sliding surface portion with a sorbite structure. The apex seal has an excellent bending strength and wear resistance.
A high temperature wear resistant sintered alloy suitable for the material of a valve seat in an automotive vehicle engine. The matrix of the sintered alloy consists essentially of carbon ranging from 0.45 to 1.15% by weight, nickel ranging from 5.4 to 27% by weight, molybdenum ranging form 0.4 to 2.7% by weight, cobalt ranging from 4.2 to 7.2% by weight and balance being substantially iron. The matrix is formed of a mixture of at least one of sorbite structure and bainite structure and austenite structure. Furthermore, the matrix includes hard phase dispersed therein and containing at least silicon, molybdenum and cobalt. The sintered alloy of such a structure can exhibit high strength and wear resistance at high temperatures regardless of type of engine and kind of fuel in case of being used as the material of the valve seat, while maintaining production cost thereof lower.
An iron cast having iron as a major component, and including C, Si, Mn, Cr, Mo and Ni, where the cast iron provides excellent heat resistance and oxidation resistance at high temperatures. The cast iron beneficially contains between 2.5 to 3.0% of C; 2.0 to 3.0% of Si; 0.8 to 1.2% of Mn; 1.7 to 3.0% of Cr; 0.025 to 0.06% of Mg; 0.15 to 0.4% of Mo; and 17.0 to 20.0% of Ni; but less than 0.1% of P; and less than 0.02% of S. The cast iron is suitable for extremely severe conditions at high temperatures, and can be used for an exhaust manifold for engines where temperature of the manifold may reach 850.degree. C.
