SINTERED ALLOY FOR VALVE SEAT AND MANUFACTURING METHOD OF EXHAUST VALVE SEAT USING THE SAME

A sintered alloy for a valve seat may be manufactured using a method including: mixing MnS with an alloy powder for a valve seat including C at 0.8-1.2 wt %, Ni at 2.0-4.5 wt %, Cr at 3.0-5.0 wt %, Mo at 16.0-20.0 wt %, Co at 9.0-13.0 wt %, V at 0.05-0.15 wt %, S at 0.2-0.8 wt %, Fe, and additional inevitable impurities; making a first shape by forming the mixed materials; pre-sintering the first formed shape; making a secondary shape by re-pressing the first pre-sintered shape; main-sintering the secondary shape; and tempering the main-sintered secondary shape. 1. A sintered alloy for valve seat , comprising:MnS is added to an alloy that comprises C at 0.8-1.2 wt %, Ni at 2.0-4.5 wt %, Cr at 3.0-5.0 wt %, Mo at 16.0-20.0 wt %, Co at 9.0-13.0 wt %, V at 0.05-0.15 wt %, S at 0.2-0.8 wt %, Fe, and additional inevitable impurities.2. The sintered alloy for valve seat of claim 1 , whereinan amount of MnS of 0.2-2.5 parts by weight with respect to 100 parts by weight of the sintered alloy is added.3. The sintered alloy for valve seat of claim 2 , whereinthe size of MnS particles is smaller than 12 μm.4. The sintered alloy for valve seat of claim 3 , whereinthe MnS comprises Mn at 60-65 wt % and S at 35-40 wt %.5. A manufacturing method of valve seat claim 3 , the method comprising:mixing MnS with an alloy powder for a valve seat comprising C at 0.8-1.2 wt %, Ni at 2.0-4.5 wt %, Cr at 3.0-5.0 wt %, Mo at 16.0-20.0 wt %, Co at 9.0-13.0 wt %, V at 0.05-0.15 wt %, S at 0.2-0.8 wt %, Fe, and additional inevitable impurities;making a first shape by forming the mixed materials;pre-sintering the first formed shape;making a secondary shape by re-pressing the first pre-sintered shape;main-sintering the secondary shape; andtempering the main-sintered secondary shape.6. The method of manufacturing a valve seat of claim 5 , whereinthe amount of MnS is from 0.2 to 2.5 parts by weight with respect to 100 parts by weight of the alloy powder.7. The manufacturing method of valve seat of ...