Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
  • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0242—Making ferrous alloys by powder metallurgy using the impregnating technique
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12014—All metal or with adjacent metals having metal particles
  • Y10T428/1216—Continuous interengaged phases of plural metals, or oriented fiber containing
  • Y10T428/12167—Nonmetal containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12014—All metal or with adjacent metals having metal particles
  • Y10T428/1216—Continuous interengaged phases of plural metals, or oriented fiber containing
  • Y10T428/12174—Mo or W containing

Definitions

• the present invention relates to iron-base sintered alloys having excellent wear resistance at high temperature, and more particularly to alloys adapted for fabricating valve seat rings of internal combustion engines.
• the alloys comprise metals having lubricating properties or alloys thereof infiltrated into pores of iron-base sintered alloys having high strength and wear resistance at high temperature;
• the present invention relates to sintered alloys resistant to wear at high temperatures.
• valve seat rings of internal combustion engines Materials such as special cast iron and heat resistant steel have usually been employed for valve seat rings of internal combustion engines. These materials are excellent when leaded gasoline is used as fuel since lead oxide formed from lead tetrachloride of antiknock agents ofiers lubricating action through its attachment onto the surface of valve seat rings. This prevents the valve seat rings from wearing away, and also results in full performance of the engine, However, these materials have the disadvantage that lubricating action by lead oxide is lost and the wearing away of the valve seat rings is thereby remarkably increased when LPG (liquefied propane gas) or lead-free gasoline is used as fuel. The engine suffers from the decreased output and abnormal operation.
• LPG liquefied propane gas
• the above mentioned disadvantage is overcome by using the alloys of the present invention.
• the valve seat rings made of the alloys of the present invention have excellent resistance to Wear even when LPG or lead-free gasoline is used as fuel. Moreover, the engine is maintained at a normal working condition. Also, the alloys of the present invention may be used to fabricate bearings for hot rollers or other parts that are exposed to or may reach high temperatures.
• the present invention relates to sintered iron-base alloys obtained by infiltrating types of metals or alloys thereof having lubricating action into the pores of the sintered iron-base body.
• the sintered iron-base body available for this purpose has a specific composition in which iron is contained as the principal constituent with 0.25 to 8 percent molybdenum, 0.1 to 1.0 percent carbon, and 0.2 to 2.0 percent of one or two or more types selected from tungsten, vanadium, titanium and tantalum, as the remaining constituents. Also, iron is contained as the principal constituent with 0.25 to 8 percent molybdenum, 0.1 to 1.0 percent carbon, and 1 to 20 percent nickel and copper used alone or in combination, as the remainder.
• iron is contained as the principal constituent with 0.25 to 8 percent molybdenum, 0.1 to 1.0 percent carbon, and 0.1 to 2.0 percent of one or two or more types selected from phosphorus, sulfur and boron, as the remainder.
• molybdenum 0.25 to 8 percent molybdenum, 0.1 to 1.0 percent carbon, and 0.1 to 2.0 percent of one or two or more types selected from phosphorus, sulfur and boron, as the remainder.
• the metals and alloys 3,806,325 Patented Apr.
• 1974 ice thereof having lubricating action include: copper or copper alloys mixed with one or two or more metals selected from chromium, tin and zinc, which are used for infiltration by 10 to 30 percent of the resulting sintered alloys; and copper-lead alloys, or copper-lead alloys added with one or two or more metals selected from chromium, tin and zinc, which are for infiltration by 5 to 30 percent of the resulting alloys; further lead, antimony or lead alloys added with one or two or more metals selected from bismuth, antimony and cadmium, which are used for infiltration by 1 to 25 percent of the resulting alloys.
• the percentages shown above and hereinafter are given by way of weight percent.
• the sintered alloys according to the present invention are characterized by infiltrating molten metals or alloys thereof having a lubricating action into the pores of the sintered ironbase body having high strength and Wear resistance at high temperature. These alloys are particularly suitable for valve seat ring constructions of internal combustion engines.
• molybdenum increases the resistance against softening of the alloys by temper, and their impact value as well. Moreover, molybdenum, as precipitated and pseudoprecipitated, forms an oxide at high temperature thereby lowering the coefficient of friction and raising the wear resistance. No substantial effect of such kind, however, is observed at less than 0.25% content, and by adding more than 8% the effect is not increased. Accord-.
• the desirable range of molybdenum is between 0.25% and 8%.
• the range should preferably be between 1 0.2% and 2.0%.
• Nickel permeates into iron in the form of a solid solu-: tion and increases the mechanical strength and heat re-- sistance of the resulting alloys.
• Copper added to the sintered skeletons permeates, in part, into iron in the form of a solid solution and in-. creases the hardness and mechanical strength of the resulting alloys.
• the other part of the copper remains in. the pores of the sintered skeletons and takes the same.
• the range is desirably between 1% and 20%.
• Phosphorus or sulfur when added to the sintered skeletons, improves the machinability and lowers the coefiicient of friction thereby increasing the wear resistance. Further, the mechanical properties of the alloys are improved by addition of these elements up to 2%. At more than 2%, however, the fragility advances unsatisfactorily. To the contrary, addition of less than 0.1% will not bring appreciable effect.
• the desirable range of copper used for infiltration is between 10 and 30%
• the remaining part of the chromium disperses into copper and forms a thin oxide film on the surface of the alloys at high temperature which lowers the coeificient of friction thereby increasing the wear resistance.
• Lead used in Example 5 as one of the infiltrating materials, as explained below, is thinly coated onto the contacting surface of the alloys at high temperature and forms lead oxide which promotes the lubricating action thereby increasing the 'wear resistance.
• lead oxide which promotes the lubricating action thereby increasing the 'wear resistance.
• at less than 1% its effect is insufiicient and at more than 25% it is not useful in strengthening the sintered skeletons.
• Cadmium as added to lead, affects restraining lead from expansion when melting whereby lead may be more captured.
• Example 3 where 70% copper-30% lead alloys (Kelmet) are infiltrated, namely, copper and lead are simultaneously infiltrated, copper improves the wettability of lead toward the iron matrix thereby more uniformly and thinly attaching lead onto the contacting surface of the alloys than in the case of infiltrating with lead alone. This also increases the lubricating action by lead oxide.
• the simultaneous effect of copper and lead is in addition to the above noted individual influences of each of these metals.
• Tin as infiltrated simultaneously with copper, strengthens the copper matrix and increases the wear resistance. Zinc has a similar effect to tin.
• tin is used for infiltartion together with copper and lead. Tin contributes to a fine and uniform dispersion of lead in copper.
• Antimony has an affect similar to lead, and is particularly suitable for application cases using high temperature since the melting point of antimony (630 C.) is higher when compared with the melting point of lead (327 C.).
• the content of antimony is preferably between 1 and 25% because its effect is slight at less than 1% and the resulting alloys tend to lack strength at more than 25%.
• Example 6 where 80% lead and 20% bismuth are infiltrated, the bismuth is suitable for cases where low temperature is employed because addition of bismuth to lead lowers the melting tendency of lead.
• Example 8 where a lead-antimony alloy for infiltration is shown, this combination is suitable for the cases where relatively high temperature is employed because addition of antimony by about 25 or more to lead elevates the melting tendency of lead. (e.g. about 520 C. at 60% antimony content).
• the sintered alloys according to the present invention comprise, at first, providing iron molybdenum-carbon sintered skeletons with improved strength and wear resistance at high temperature through addition of (l) vanadium, titanium or tantalum which forms carbides such as WC, VC, TiC or TaC dispersed in the alloys; (2) nickel or copper which permeates into the alloys in the form of a solid solution to strengthen the alloys; (3) phosphorous of sulfur which has the lubricating action; or (4) boron which has wear resistance at high temperature.
• the resulting alloys are provided with greatly increased wear resistance at high temperature by infiltrating the pores of the sintered skeletons with soft metals or alloys thereof having lubricating action, specifically, copper or copper alloys added with one or two or more metals selected from chromium, tin and zinc; copper-lead alloys or copper-lead alloys added with one or two or more metals selected from chromium, tin and zinc; lead or antimony, or lead alloys added with one or two or more metals selected from bismuth, antimony and cadmium.
• these alloys are most suitable for materials in valve seat rings of internal combustion engines and in bearings which may reach or be exposed to high temperature.
• EXAMPLE 1 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder of 3 to 6 in particle size, graphite powder and iron-tungsten alloy powder of minus 200 mesh and mixed to provide a composition of 92.4% iron, 5% molybdenum, 2% tungsten and 0.6% carbon.
• the mixture is formed under a forming pressure of 5 t./cm. to a density of 6.7 g./crn. After the formed mass is subjected to a sintering process at 1170 C. for one hour and a half in a reducing gas atmosphere, a sintered skeleton is obtained.
• the sintered skeleton is infiltrated with copper using an infiltrating material composed of cop per, 5% iron and 5% manganese at 1130" C. for one hour and a half in a reducing gas atmosphere.
• a sintered alloy of the present invention is obtained.
• EXAMPLE 2 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder of 3 to 6; in size, graphite powder and iron-titanium alloy powder of minus 200 mesh are mixed to provide a composition of 92.2% iron, 5% molybdenum, 2% titanium and 0.8% carbon. The mixture is then formed under a forming pressure of 5 t./cm. to a density of 6.7 g./cm. Thereafter, the formed mass is subjected to a sintering process at 1170 C. for one hour and a half in a non-oxidizing gas atmosphere and thus a sintered skeleton is obtained. After the sintered skeleton is infiltrated using copper-5% chromium alloy at 1130 C. for one hour and a half in a nonoxidizing gas atmosphere, a sintered alloy of the present invention is obtained.
• EXAMPLE 3 Reducing iron powder of minus mesh, fine electrolytic molybdenum powder of 3 to 6 in size, graphite powder and iron-vanadium alloy powder (30% iron and 70% vanadium) of minus 100 mesh are blended to provide a composition of 92.2% iron, 5% molybdenum, 2% vanadium and 0.8% carbon. After the mixture is formed under a forming pressure of 5 t./cm. to a density of 6.7 g./cm. the formed mass is subjected to a sintering process at 1170 C. for one hour and a half in a reducing gas atmosphere. A sintered skeleton is obtained. The pores of the sintered skeleton are infiltrated with a 70% copper-30% lead alloy (Kelmet) at 1050 C. for one hour in a reducing gas atmosphere. A sintered alloy of the present invention is obtained.
• Kelmet 70% copper-30% lead alloy
• EXAMPLE 4 Reducing iron powder of minus 100 mesh, fine electrdlytic molybdenum powder of 3 to 6p. in size, graphite powder and tantalum milled powder of minus 100 mesh are blended to provide a composition of 92.9% iron, 5% molybdenum, 1.5% tantalum and 06% carbon. After the mixture is formed under a forming pressure of 5 t./cm. to a density of 6.7 g./cm. the formed mass is subjected to a sintering process at 1170 C. for one hour and a half in a reducing gas atmosphere. A sintered skeleton is obtained. The pores of this sintered skeleton are infiltrated with a 60% copper-30% lead-10% tin alloy at 1050 C. for one hour, and a sintered alloy of the present invention is obtained.
• EXAMPLE 5 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder of 3 to 6p. in size, graphite powder and fine carbonyl nickel powder of about 4 in average size are mixed together to provide a composition of 89.7% iron, 5% molybdenum, 5% nickel and 0.3% carbon. This mixture is then formed under a forming pressure of 5 t./cm. to a density of 6.7 g./cm. After the formed mass is subjected to a sintering process at 1170 C. for one hour and a half in a reducing gas atmosphere, a sintered skeleton is obtained. The sintered g./cm.
• the formed mass is subjected to a sintering process at 1130 C. for one hour and a half in a reducing gas atmosphere. Thereafter, the pores of the sintered skeleton are infiltrated with antimony at 1100 C. for one hour in a reducing gas atmosphere.
• a sintered alloy of the present invention is obtained.
• EXAMPLE 8 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder, graphite powder and ironphosphorus alloy powder of minus 100 mesh are mixed to provide a composition of 94.1% iron, 5% molybdenum, 0.3% phosphorus and 0.6% carbon. The mixture is then formed under a forming pressure of 6 t./cm. to a density of 7.1 g./cm. The formed mass is subjected to a sintering process at 1130 C. for one hour and a half in a reducing gas atmosphere and a sintered skeleton is obtained. The pores of the sintered skeleton are infiltrated with a lead-60% antimony alloy at 1050 C. for one hour, and a sintered alloy of the present invention is obtained.
• the alloys of the present invention as obtained in Examples 1 through 8 are tested for their properties and quantities of wear at high temperature.
• the results are shown in the following table.
• quantities of wear are indicated by the worn away quantities in millimeters in the direction of the height of the specimens measured after the testing has been continued for 100 hours by a so-called sliding high-cycle impact tester, wherein 2500 shocks a minute are given to the angular specimens under a surface pressure of 30 kg./cm. by means of a jig made of heat resistant steel, while the angular specimens fixed to cast iron are rotated 10 times a minute at an elevated temperature of 500 to 550 C.
• EXAMPLE 6 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder, graphite powder and electrolytic copper powder of minus 100 mesh are mixed to provide a composition of 87.7% iron, 5% molybdenum, 7% copper and 0.3% carbon. The mixture is then formed under a forming pressure of 5 t./cm. to a density of 6.7 g./cm. Thereafter, the formed mass is subjected to a sintering process at 1150 C. for one hour and a half in a reducing gas atmosphere. The pores of the resulting sintered skeleton are infiltrated with 80% lead-20% bismuth alloy at 1000 C. for 45 minutes in a reducing gas atmosphere. A sintered alloy of the present invention is obtained.
• EXAMPLE 7 Reducing iron powder of minus 100 mesh, fine electrolytic molybdenum powder of 3 to 6p. in size, graphite powder and sulfur powder for chemical use are mixed to provide a composition of 93.2% iron, 5% molybdenum, 1% sulfur and 0.8% carbon. The mixture is then formed under a forming pressure of 6 t./cm. to a density of 7.1
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 0.2 to 2.0 percent by weight at least one metal selected from the group consisting of tungsten, vanadium, titanium and tantalum, and an infiltrant selected from the group consisting of 10 to 30 percent by weight copper, 10 to 30 percent by weight copper-base alloy, 1 to 25 percent by weight lead, 1 to 25 percent by weight lead-base alloy, and 1 to 25 percent by weight antimony.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 1.
• the lead-base alloy infiltrant includes at least one metal selected from the group consisting of bismuth, antimony and cadmium.
• valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 7.
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 1 to 20 percent by weight at least one metal selected from the group consisting of nickel and copper, and an infiltrant selected from the group consisting of to 30 percent by weight copper, 10 to 30 percent by weight copper-base alloy, 1 to 25 percent by weight lead, 1 to 25 percent by weight lead-base alloy, and 1 to 25 percent by weight antimony.
• valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 9.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 11.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 13.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 15.
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 0.1 to 2.0 percent by weight at least one metal selected from the group consisting of phosphorous, sulfur and boron, and an infiltrant selected from the group consisting of 10 to 30 percent by weight copper, 10 to 30 percent by weight copper-base alloy, 1 to 25 percent by weight lead, 1 to 25 percent by weight lead-base alloy, and 1 to 25 percent by weight antimony.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 17.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 19.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 21.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 23.
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 0.2 to 2.0 percent by weight at least one metal selected from the group consisting of tungsten, vanadium, titanium and tantalum, and an infiltrant consisting of 5 to 30 percent by weight copper-lead base alloy.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 25.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 27.
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 1 to 20 percent by weight at least one metal selected from the group consisting of nickel and copper, and an infiltrant consisting of 5 to 30 percent by weight copper-lead base alloy.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 29.
• the wear resistant metal of claim 29 in which the copper-lead base alloy infiltrant comprises 5 to 30' percent by weight copper-lead alloy.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 31.
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.25 to 8 percent by Weight molybdenum, 0.1 to 1.0 percent by weight carbon, and 0.1 to 2.0 percent by weight at least one metal selected from the group consisting of phosphorous, sulfur and boron, and an infiltrant consisting of 5 to 30 percent by weight copper-lead base alloy.
• valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 33.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 35.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
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• General Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)

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Cited By (12)

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• 1971
  • 1971-06-28 JP JP4699571A patent/JPS549127B2/ja not_active Expired
• 1972
  • 1972-01-10 GB GB106572A patent/GB1355291A/en not_active Expired
  • 1972-01-11 US US00217030A patent/US3806325A/en not_active Expired - Lifetime
  • 1972-01-13 DE DE2201515A patent/DE2201515C3/de not_active Expired

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