Classifications

• • 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
• • 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
• • 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
• • 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
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49229—Prime mover or fluid pump making
  • Y10T29/49298—Poppet or I.C. engine valve or valve seat making
  • Y10T29/49306—Valve seat making
• • 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

Definitions

• the present invention relates to iron-base sintered a1- loys having excellent wear resistance at high temperatures, and more particularly to alloys adapted for fabricating valve seat rings of internal combustion engines.
• the alloys of the present invention are characterized by infiltrating selected metals having lubricating properties or the alloys thereof into the pores of iron-chromium-carbon base sintered alloys having significant mechanical strength and heat resistance.
• the present invention relates to sintered alloys having wear resistance at high temperatures.
• the sintered alloys of the present invention exhibit superior wear resistance at high temperatures.
• the valve seat rings made of the present alloy do not wear away even when LPG or lead-free gasoline is used as fuel. The engines are therefore maintained at normal working conditions.
• the alloys of the present invention are suitable for use in fabricating bearings for hot rollers and other parts that are exposed to or reach high temperatures during use thereof.
• the primary object of the present invention is to provide alloys having excellent wear resistance at elevated temperatures.
• carbon content is between 02 and 1.0 percent.
• Chromium melts into iron in the form of a solid solution and makes iron tough by forming composite carbides such as (Fe C), Cr C, (Fe C) Cr C and Fe C.Cr C. These carbides are coexistent with Fe C, and quite useful in increasing the hardness of the steels and their wear resistance. Furthermore, chromium remains stable at high temperatures. It diminishes the deterioration of the materials caused by arise in temperature and increases their heat resistance. However, at less than 0.2 percent content there is little if any effect, while at more than 15 percent very little effect results when compared with the amount added. The machinability of the resulting alloys is also poor. Both cases should be avoided. Thusfthe chromium content is between 0.2 and 15 percent.
• the preferred copper content is between the above two percentages.
• Lead used for infiltration turns into lead oxide during actual use of the alloys.-
• the lead oxide adheres in a thin layer on the surface of the alloys, and thereby produces a lubricating action which increases the wear resistance of the alloys.
• the secondary effect of lead is to remarkably increase the machinability of the alloys. However, at less than 1 percent the effect is very slight and a uniform distribution oflead is unobtainable. At more than 25 percent of the amount for infiltration the strength of the alloys drops. Therefore, the preferred range of lead is l to 25 percent.
• antimony is similar to lead. Since the melting point of antimony is higher than that of lead (melting point of antimony is 630 C., lead 327 C.), antimony is suitable for alloys used at higher temperatures when compared with the alloys infiltrated with lead. As in the case of lead infiltration, at less than 1 percent antimony the effect is slight, while at more than 25 percent the strength of the alloys drops. Therefore, the preferred range of antimony is l to 25 per cent.
• Example 2 a percent copper 30 percent lead alloy (Kelmet) is used for infiltration.
• Kelmet a percent copper 30 percent lead alloy
• Example 4 a copper-lead base alloy added with tin is used for infiltration.
• the tin has the effect of partly melting into copper in the form of a solid solution and increasing the strength and the wear resistance of copper.
• Tin also has the effect of dispersing lead in a fine and uniform state in copper and further increasing the wear resistance of the alloys.
• Zinc added to copper reacts similar to tin. Moreover, zinc forms afilm ofits oxide at high temperature during practical use of the alloys and lowers the coefficient of friction which increases the wear resistance.
• Example 3 infiltration with a copper-chromium alloy is explained. A portion of the chromium melts into copper in the form of a solid solution and strengthens the copper, while the remaining portion forms a film of its oxide on the surface at high temperature and gives the alloy a reduced coefficient of friction which increases the wear resistance of the alloys even more.
• Example 6 Infiltration with a 90 percent lead percent bismuth alloy is explained in Example 6.
• the bismuth reduces the melting tendency of lead, and increases the lubricating action by lead in cases where lower temperature and load are employed with valve seats or bearings.
• Cadmium is effective in restraining lead from its expansion at melting whereby lead may be more captured.
• the sintered alloys according to the present invention are provided with greatly increased wear resistance at high temperatures by infiltrating metals or alloys thereof having significant lubricating properties into the pores of iron-chromiumcarbon base alloys having superior strength and wear resistance at high temperature.
• the metals or alloys thereof used for infiltration are: copper, lead; antimony; copper-base alloys added withone or two or more metals selected from tin, zinc, lead and chromium; lead-base alloys added with one or two or more metals selected from antimony, bismuth and cadmium.
• lead is premixed with iron powder and graphite powder as a means of adding lead.
• the infiltration according to the present invention has the advantage of obtaining a uniform distribution and a satisfactory capture of lead and other substances. Therefore, alloys of uniform quality are obtained in mass production.
• EXAMPLE 2 Using the sintered skeleton of Example 1, the pores of the skeleton are infiltrated with a 70 percent copper 30 percent lead alloy (Kelmet) at 1,050 C. for one hour in a reducing gas atmosphere. A sintered alloy of the present invention is obtained.
• Kelmet copper 30 percent lead alloy
• EXAMPLE 3 Using the sintered skeleton of Example I, the pores of the skeleton are infiltrated with a percent copper 5 percent chromium alloy at 1,130 C. for one hour in a reducing gas atmosphere. A sintered alloy of the present invention is obtained.
• EXAMPLE 4 Using the sintered skeleton of Example 1, the pores of the skeleton are infiltrated with a 60 percent copper 30 percent lead 10 percent tin alloy at l,050 C. for one hour in a reducing gas atmosphere. A sintered alloy'of the present invention is obtained.
• EXAMPLE 5 Reducing iron powder of minus mesh, ironchromium alloy powder of minus 100 mesh and graphite powder are mixed to provide a composition of 93.2 percent iron, 6 percent chromium and 0.8 percent carbon, each by weight percent. The mixture is formed under a forming pressure of 6 t/cm to a density of 7.1 g/cm Thereafter, the formed mass is sintered at 1,300 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 lead at 1,000 C. for 45 minutes in a reducing gas atmosphere. A sintered alloy of the present invention is obtained.
• EXAMPLE 6 EXAMPLE 7 Using the sintered skeleton of Example 5, the pores of the skeleton are infiltrated with antimony at l,lO0 C. for one hour and a half in a reducing gas atmosphere. A sintered alloy of the present invention is ob- .tained.
• the alloys of the present invention as obtained in Examples 1 through 7 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 lead-base alloy infiltrant includes at least one metal selected from the group consisting of bismuth, antimony and cadmium.
• a valve seat for an internal combustion engine fablar specimens fixed to cast iron are rotated times a 5 i d f th wear resistant metal f l i 5,
• a wear resistant metal comprising a sintered skele- TABLE Composition by weight) Tensile strength Hardness (Hv.0.2) Quantity of wear (mm) Alloys of the Present Invention
• Example 6 Fe-6Cr0.8C-9(90Pb- 60 262-321 037 103i) infiltrated Example 7 (Fe-6Cr-0.8C)-9Sb 62 276-329 0.38
• a wear resistant metal comprising a sintered skeleton consisting essentially of iron having 0.2 to percent by weight chromium and 0.2 to 1.0 percent by weight carbon, 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 percent by weight lead, 1 to 25 percent by weight lead-base alloy, and l to 25 percent by weight antimony.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 1.
• a valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 3.
• the wear resistant metal of claim 1 in which the ton consisting essentially of iron having 0.2 to 15 percent by weight chromium and 0.2 to 1.0 percent by weight carbon, 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 7.
• valve seat for an internal combustion engine fabricated of the wear resistant metal of claim 9.

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

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Cited By (10)

Citations (3)

• 1971
  • 1971-06-28 JP JP4699471A patent/JPS5341082B1/ja active Pending
• 1972
  • 1972-01-11 US US00217031A patent/US3790352A/en not_active Expired - Lifetime

Patent Citations (3)

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