Abstract A process for the production of valve seat rings by powder metallurgy wherein molybdenum disulfide in the range of about 0.5% to 1.5% by weight is added to a powder mixture containing 0.8% to 1.5% by weight graphite, 1.0% to 4% by weight lead, 0.5% to 5% by weight nickel, 1.2% to 1.8% by weight molybdenum, 9.6% to 14.4% by weight cobalt, and the remainder iron. The resulting powder mixture is pressed into valve seat rings at a pressing force between 40 and 60 and preferably 50 KN/cm 2 . The rings are then sintered in a neutral atmosphere at a temperature of 1100° C. to 1200° C., finally compressed at a pressing force above 120 KN/cm 2 and heat-treated if required. The resulting valve seat rings have greatly improved wear properties when used in internal combustion engines using lead-free gasoline.
In the process for the production of sintered valve seat rings wherein a powder mixture containing 0.8% to 1.5% by weight graphite, 1.0% to 4% by weight lead, 0.5% to 5% by weight nickel, 1.2% to 1.8% by weight molybdenum, 9.6% to 14.4% by weight cobalt, and the remainder iron, is pressed into valve seat rings at a pressing force of between 40 and 60 KN/cm 2 and are then sintered in a neutral atmosphere at a temperature of 1100° C. to 1200° C. and finally compressed at a pressing force above 120 KN/cm 2 ; the improvement in said process comprising adding to said powder mixture about 0.5% to 1.5% by weight molybdenum disulfide, whereby the molybdenum disulfide will disintegrate when sintering and form new compounds improving the homogeneous distribution of the cobalt powder in the sintered material.
Claim 2
Dependent Claim
139 words
In the process for the production of sintered valve seat rings wherein a powder mixture containing 0.8% to 1.5% by weight graphite, 1.0% to 4% by weight lead, 0.5% to 5% by weight nickel, 1.2% to 1.8% by weight molybdenum, 9.6% to 14.4% by weight cobalt, and the remainder iron, is pressed into valve seat rings at a pressing force of between 40 and 60 KN/cm 2 and are then sintered in a neutral atmosphere at a temperature of 1100° C. to 1200° C. and finally compressed at a pressing force above 120 KN/cm 2 ; the improvement in said process comprising adding to said powder mixture about 0.5% to 1.5% by weight molybdenum disulfide, whereby the molybdenum disulfide will disintegrate when sintering and form new compounds improving the homogeneous distribution of the cobalt powder in the sintered material.
Claim 3
Dependent Claim
24 words
The process of claim 1 wherein said powder mixture is pressed into valve seat rings at a pressing force of 50 KN/cm 2 .
Claim 4
Dependent Claim
13 words
An article of manufacture as is produced by the process of claim 1.