摘要:
A valve seat of an iron-based sintered alloy having high wear resistance in a wide temperature range, which can be used in direct injection engines with improved fuel efficiency, low emission and high power, is obtained by limiting the amount of a solid lubricant dispersed in the matrix of the valve seat of an iron-based sintered alloy, and dispersing at least two types of hard particles having different hardnesses in the matrix, thereby providing high strength and self-lubrication, as well as improved wear resistance under no lubrication in a wide temperature range.
摘要:
In a valve seat made of an iron-based, composite sintered alloy having hard particles and a solid lubricant dispersed therein to have high wear resistance and good machinability, which is usable in high-power fuel direct injection engines with improved fuel efficiency and low emission, relatively coarse solid lubricant particles in such an amount as not to drastically reduce the strength of a sintered body are dispersed to provide self-lubrication, and as fine solid lubricant particles as not hindering the bonding of matrix particles are dispersed to improve machinability.
摘要:
In a valve seat made of an iron-based, composite sintered alloy having hard particles and a solid lubricant dispersed therein to have high wear resistance and good machinability, which is usable in high-power fuel direct injection engines with improved fuel efficiency and low emission, relatively coarse solid lubricant particles in such an amount as not to drastically reduce the strength of a sintered body are dispersed to provide self-lubrication, and as fine solid lubricant particles as not hindering the bonding of matrix particles are dispersed to improve machinability.
摘要:
An iron-based sintered alloy having improved thermal and mechanical strength is provided. The iron-based sintered alloy with dispersed hard particles comprises: a matrix comprising, by weight, 0.4 to 2% silicon (Si), 2 to 12% nickel (Ni), 3 to 12% molybdenum (Mo), 0.5 to 5% chromium (Cr), 0.6 to 4% vanadium (V), 0.1 to 3% niobium (Nb), 0.5 to 2% carbon (C), and the reminder of iron (Fe); and hard particles comprising 60 to 70% molybdenum (Mo), 0.3 to 1% boron (B), 0.1% or less carbon (C), and the reminder of iron (Fe). The hard particles are dispersed in the matrix in an amount in the range of 3 to 20% based on the entire alloy. They are sintered to produce the iron-based sintered alloy. Addition of boron into the ferromolybdenum hard particles enhances the wettability of the ferromolybdenum hard particles to prevent the hard particles from falling off the matrix. Thus, the adhesive property between the matrix and the hard particles is improved, thereby enhancing the thermal and mechanical strength of the iron-based sintered alloy.
摘要:
An iron-based sintered alloy, which consists of from 0.5 to 5% of Ni, from 0.5 to 4% of Cr, from 0.5 to 2% of C, the balance being Fe and unavoidable impurities, and which has a micro-structure comprising an iron-based matrix containing Ni and a part of Cr as solutes and carbides containing the other part of Cr and dispersed in the matrix. The iron-based sintered alloy is appropriate for use as a valve seat of an internal combustion engine. Wear resistance is maintained at a moderate level while the additive amount of alloying elements is decreased to attain low cost.
摘要:
An iron-based sintered alloy having improved thermal and mechanical strength is provided. The iron-based sintered alloy with dispersed hard particles comprises: a matrix comprising, by weight, 0.4 to 2% silicon (Si), 2 to 12% nickel (Ni), 3 to 12% molybdenum (Mo), 0.5 to 5% chromium (Cr), 0.6 to 4% vanadium (V), 0.1 to 3% niobium (Nb), 0.5 to 2% carbon (C), and the reminder of iron (Fe); and hard particles comprising 60 to 70% molybdenum (Mo), 0.3 to 1% boron (B), 0.1% or less carbon (C), and the reminder of iron (Fe). The hard particles are dispersed in the matrix in an amount in the range of 3 to 20% based on the entire alloy. They are sintered to produce the iron-based sintered alloy. Addition of boron into the ferromolybdenum hard particles enhances the wettability of the ferromolybdenum hard particles to prevent the hard particles from falling off the matrix. Thus, the adhesive property between the matrix and the hard particles is improved, thereby enhancing the thermal and mechanical strength of the iron-based sintered alloy.