EP0018377A1 - Composite materials - Google Patents

Composite materials

Info

Publication number
EP0018377A1
EP0018377A1 EP79900490A EP79900490A EP0018377A1 EP 0018377 A1 EP0018377 A1 EP 0018377A1 EP 79900490 A EP79900490 A EP 79900490A EP 79900490 A EP79900490 A EP 79900490A EP 0018377 A1 EP0018377 A1 EP 0018377A1
Authority
EP
European Patent Office
Prior art keywords
layers
piston
layer
skirt
article
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP79900490A
Other languages
German (de)
French (fr)
Inventor
Evan John Nestorides
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Internal Combustion Engine Research Institute
Original Assignee
British Internal Combustion Engine Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Internal Combustion Engine Research Institute filed Critical British Internal Combustion Engine Research Institute
Publication of EP0018377A1 publication Critical patent/EP0018377A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/10—Pistons  having surface coverings
    • F02F3/12—Pistons  having surface coverings on piston heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
    • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
    • C22C32/0036—Matrix based on Al, Mg, Be or alloys thereof
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/341—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one carbide layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C23C28/3455—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F2200/00—Manufacturing
    • F02F2200/04—Forging of engine parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/02—Light metals
    • F05C2201/021—Aluminium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2251/00—Material properties
    • F05C2251/04—Thermal properties
    • F05C2251/042—Expansivity

Definitions

  • the present invention relates to the formation of articles, particularly but not exclusively pistons, of composite materials comprising two or more layers.
  • an object of the invention is to provide a layered article which is less subject to the above mentioned difficulties but avoids the need of a mechanical connection.
  • the invention provides in one aspect an article comprising two or more layers of different material compositions there being a controlled graded change of composition between layers or within at least one of the layers.
  • the thickness of the graded change may be from about one millimetre to several centimetres, or even greater.
  • Por composite materials with three or more layers, the material or materials of one or more of the layers can be a controlled mixture or a controlled graded mixture providing controlled graded discontinuous or continuous changes of thermal and mechanical properties within the composite layer.
  • one or more of the layers can have a greater mechanical strength than the other layer or layers.
  • One or more of the layers can have a low thermal conductivity.
  • One or more of the layers can have a low, medium or high value of mechanical elongation at rupture.
  • the region of the controlled graded layer contiguous to the second layer may have a thermal expansion coefficient and/or a value of elongation at rupture which are intermediate between the value of the thermal expansion coefficient and/or the value of elongation at rupture for the second layer and the value of the thermal expansion coefficient and/or the value of elongation at rupture in the noncontiguous regions of the controlled graded layer.
  • at least one intermediate layer can have a thermal expansion coefficient and/or a mechanical elongation at rupture which are intermediate between the values of the corresponding coefficients and elongations for the contiguous layers.
  • the properties of low thermal conductivity, high mechanical strength and non-negligible elongation may apply individually or jointly to a given layer, to contiguous layers or to non-contiguous layers, and a layer with one, two or all three of these properties can be an outer layer, an intermediate layer, or the innermost layer. In some cases, however the different layers may be provided by different zones of the article having a graded change of composition from one zone to the next.
  • the invention provides in a further aspect a method of manufacturing an article, comprising the steps of starting with at least two layers of different material compositions, there being a controlled graded change of composition between layers or within at least one of the layers, and subsequently bonding the layers together.
  • One or more of the layers may be of a material or materials produced by casting, forging, stamping, rolling produced as a single material or as a controlled mixture of materials bonded to the contiguous layer or layers.
  • One or more of the layers may be bonded to another layer or layers by sintering, casting or by friction welding.
  • One or more of the layers may be produced by existing methods used for coatings, which include roll-bonding, diffusion-bonding, spraying (including fusion spraying), sintering, deposition (including explosive deposition, electro-deposition, electro-static deposition, electroless deposition), brushing and dipping, without or with surface treatment of the layers, or the contiguous layer or layers.
  • the layers can have the same thickness or different thicknesses, depending on design and operating requirements.
  • the invention has particular application to pistons for use in internal combustion engines.
  • the skirt has a first composition and the crown has a second composition, and between the skirt and the crown the piston has an intermediate zone in which the relative proportions of the materials lies intermediate those in the skirt and the crown.
  • thermal conductivity, mechanical strength and other properties can be graded between the skirt and the crown.
  • the piston may comprise three or more distinct layers, each having different proportions of said materials, the proportions being substantially uniform throughout each layer and the relative proportions of the materials being graded from one layer to the next. However there may be a continuous grading of the materials throughout part or the whole of the piston. The proportion of one of the materials in one or other of the outer layers may be zero.
  • aluminium or an aluminium alloy for example silicon-aluminium
  • the crown having a significant proportion of alumina
  • the intermediate layer or layers having a smaller proportion of alumina
  • the skirt having a still smaller proportion of alumina, which may be zero.
  • the proportion of alumina to aluminium or aluminium alloy may vary from the skirt to the crown with the range 0 to 30% by weight.
  • Figure 1 is a vertical section of a piston having three uninterrupted layers and showing two half-sections at right angles to each other;
  • Figure 2 is a similar view to Figure 1 of a piston comprising uninterrupted layers.
  • a piston primarily for an internal combustion engine is made as a composite-material design with three uninterrupted layers 1, 2, 3.
  • the outermost layer 1 i.e. at the crown end of the piston is a layer with a high percentage of alumina mixed with aluminium or silicon-aluminium, this layer providing most of the mechanical strength and having a lower thermal conductivity than the other two layers.
  • the layer 1 extends from the crown 4, to the peripheral edge 5 of the piston, and down along the side of the piston to the region 6 below the bottom compression ring.
  • the intermediate layer 2 extends down below the region 6 of the layer 1 and consists of a medium percentage of alumina with aluminium or silicon-aluminium, the layer having intermediate mechanical and thermal properties between those of the outer layer 1 and the inner surface layer 3 which extends downwardly beyond the region of the intermediate layer 2 below the area of the bottom compression ring groove and further downwardly along the side of the piston to a gudgeon pin boss 7 and to an area 8 in the bottom region of the piston skirt.
  • the layer 3 is made of aluminium or silicon-aluminium or a mixture of a low percentage of alumina with aluminium or silicon-aluminium, and has a lower high-temperature mechanical strength and a higher thermal conductivity than the layer 2.
  • layer 3 may contain from 0 to 10% by weight alumina, layer 1 up to 30% alumina, (and greater than in layer 3), and layer 2 an intermediate amount of alumina.
  • the layers 1, 2, and 3 may be made by compacting and sintering. Alternatively layers 2 and 3, or layer 3, may be cast or sprayed on layer 1 or on layers 1 and 2 respectively.
  • a piston is made as a composite-material design with three uninterrupted layers.
  • the layer 9 in the crown 4 provides low thermal conductivity and comprises a mixture of aluminium or silicon-aluminium with a significant proportion of alumina.
  • a lower layer 10 comprises a mixture of aluminium or silicon-aluminium with a smaller proportion of alumina, and can be either a homogeneous mixture or a controlled continuously graded layer having a higher proportion of alumina near the layer 9 and a lower proportion of alumina away from the layer 9.
  • An insert 11 containing the compression ring grooves provides low thermal conductivity and/or mechanical strength and may be of the same material as the uppermost layer 9, or of other suitable materials.
  • Layer 10 may be sprayed, sintered or cast.
  • the lower layer 12 of the piston comprising the piston bosses and the skirt, may be of aluminium or silicon-aluminium but may also include a small proportion of alumina.
  • This layer 12 may be made, for example as a separate casting. It can then be bonded, e.g. by friction welding, to the upper section of the piston.
  • the layer 12 may comprise a continuously graded layer with a higher proportion of alumina near the layer 10 and a lower proportion of alumina (which may be zero) at the skirt end of the piston.
  • the layer 10 may extend to the skirt end of the piston and be in the form of a single graded layer with a higher proportion of alumina nearer the layer 9 and a lower proportion of alumina (which may be zero) at the skirt end of the piston.
  • the piston may be continuously graded throughout, the proportion of alumina increasing from the skirt towards the piston.
  • pistons made from aluminium or siliconaluminium have been described it will be appreciated that other materials could alternatively be used. Moreover although the invention is especially applicable to pistons, clearly other articles may be made within the scope of the invention, such as, inter alia, cylinders with or without ribs or flanges, casings, turbi blades and combustors.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Un produit, par exemple un piston d'un moteur a combustion interne est forme de deux ou plusieurs couches de compositions de materiaux differentes dans lesquelles le degre de variation de la composition entre les couches ou dans au moins une des couches est controle. La jupe (3) d'un piston possede une premiere composition, la couronne (4) possede une seconde composition (1) et entre la jupe et la couronne se trouve une zone intermediaire (2) dans laquelle les proportions relatives des materiaux se situent entre celles de la jupe et de la couronne.A product, for example a piston of an internal combustion engine is formed from two or more layers of compositions of different materials in which the degree of variation of the composition between the layers or in at least one of the layers is controlled. The skirt (3) of a piston has a first composition, the crown (4) has a second composition (1) and between the skirt and the crown is an intermediate zone (2) in which the relative proportions of the materials are located. between those of the skirt and the crown.

Description

The present invention relates to the formation of articles, particularly but not exclusively pistons, of composite materials comprising two or more layers.
In some cases different parts of an article may be subjected to different conditions in use, and it is known to form an article of two or more layers of different materials chosen to withstand respective operating conditions. However difficulties can arise due to differences between the physical properties of the materials forming the layers, which can lead to separation of the layers after a period of use.
Whilst it is possible to form a mechanical connection between adjacent layers, this is not always convenient, and an object of the invention is to provide a layered article which is less subject to the above mentioned difficulties but avoids the need of a mechanical connection.
Accordingly the invention provides in one aspect an article comprising two or more layers of different material compositions there being a controlled graded change of composition between layers or within at least one of the layers.
Thus it is possible to provide a controlled graded continuous or discontinuous change of thermal and mechanical properties from one layer to the other. By this means a more satisfactory bond between layers can be achieved. The thickness of the graded change may be from about one millimetre to several centimetres, or even greater. Por composite materials with three or more layers, the material or materials of one or more of the layers can be a controlled mixture or a controlled graded mixture providing controlled graded discontinuous or continuous changes of thermal and mechanical properties within the composite layer.
For composite materials with two, three or more layers, one or more of the layers can have a greater mechanical strength than the other layer or layers. One or more of the layers can have a low thermal conductivity. One or more of the layers can have a low, medium or high value of mechanical elongation at rupture. For composite materials with two layers, the region of the controlled graded layer contiguous to the second layer may have a thermal expansion coefficient and/or a value of elongation at rupture which are intermediate between the value of the thermal expansion coefficient and/or the value of elongation at rupture for the second layer and the value of the thermal expansion coefficient and/or the value of elongation at rupture in the noncontiguous regions of the controlled graded layer. For composite materials with three or more layers, at least one intermediate layer can have a thermal expansion coefficient and/or a mechanical elongation at rupture which are intermediate between the values of the corresponding coefficients and elongations for the contiguous layers.
The properties of low thermal conductivity, high mechanical strength and non-negligible elongation may apply individually or jointly to a given layer, to contiguous layers or to non-contiguous layers, and a layer with one, two or all three of these properties can be an outer layer, an intermediate layer, or the innermost layer. In some cases, however the different layers may be provided by different zones of the article having a graded change of composition from one zone to the next.
The invention provides in a further aspect a method of manufacturing an article, comprising the steps of starting with at least two layers of different material compositions, there being a controlled graded change of composition between layers or within at least one of the layers, and subsequently bonding the layers together.
One or more of the layers may be of a material or materials produced by casting, forging, stamping, rolling produced as a single material or as a controlled mixture of materials bonded to the contiguous layer or layers. One or more of the layers may be bonded to another layer or layers by sintering, casting or by friction welding. One or more of the layers may be produced by existing methods used for coatings, which include roll-bonding, diffusion-bonding, spraying (including fusion spraying), sintering, deposition (including explosive deposition, electro-deposition, electro-static deposition, electroless deposition), brushing and dipping, without or with surface treatment of the layers, or the contiguous layer or layers.
The layers can have the same thickness or different thicknesses, depending on design and operating requirements. The invention has particular application to pistons for use in internal combustion engines.
Thus according to another aspect of the invention in a piston formed of at least two different materials, the skirt has a first composition and the crown has a second composition, and between the skirt and the crown the piston has an intermediate zone in which the relative proportions of the materials lies intermediate those in the skirt and the crown.
By this means the thermal conductivity, mechanical strength and other properties can be graded between the skirt and the crown.
The piston may comprise three or more distinct layers, each having different proportions of said materials, the proportions being substantially uniform throughout each layer and the relative proportions of the materials being graded from one layer to the next. However there may be a continuous grading of the materials throughout part or the whole of the piston. The proportion of one of the materials in one or other of the outer layers may be zero.
Preferably aluminium or an aluminium alloy, for example silicon-aluminium, is a major constituent throughout the piston, the crown having a significant proportion of alumina, the intermediate layer or layers having a smaller proportion of alumina, and the skirt having a still smaller proportion of alumina, which may be zero. Thus the proportion of alumina to aluminium or aluminium alloy may vary from the skirt to the crown with the range 0 to 30% by weight.
Two embodiments of the invention will now be described with reference to the accompanying drawings, wherein : Figure 1 is a vertical section of a piston having three uninterrupted layers and showing two half-sections at right angles to each other; and
Figure 2 is a similar view to Figure 1 of a piston comprising uninterrupted layers. In Figure 1 a piston primarily for an internal combustion engine is made as a composite-material design with three uninterrupted layers 1, 2, 3. The outermost layer 1 (i.e. at the crown end of the piston) is a layer with a high percentage of alumina mixed with aluminium or silicon-aluminium, this layer providing most of the mechanical strength and having a lower thermal conductivity than the other two layers. The layer 1 extends from the crown 4, to the peripheral edge 5 of the piston, and down along the side of the piston to the region 6 below the bottom compression ring.
The intermediate layer 2 extends down below the region 6 of the layer 1 and consists of a medium percentage of alumina with aluminium or silicon-aluminium, the layer having intermediate mechanical and thermal properties between those of the outer layer 1 and the inner surface layer 3 which extends downwardly beyond the region of the intermediate layer 2 below the area of the bottom compression ring groove and further downwardly along the side of the piston to a gudgeon pin boss 7 and to an area 8 in the bottom region of the piston skirt.
The layer 3 is made of aluminium or silicon-aluminium or a mixture of a low percentage of alumina with aluminium or silicon-aluminium, and has a lower high-temperature mechanical strength and a higher thermal conductivity than the layer 2. As an example, layer 3 may contain from 0 to 10% by weight alumina, layer 1 up to 30% alumina, (and greater than in layer 3), and layer 2 an intermediate amount of alumina.
The layers 1, 2, and 3 may be made by compacting and sintering. Alternatively layers 2 and 3, or layer 3, may be cast or sprayed on layer 1 or on layers 1 and 2 respectively. In Figure 2 a piston is made as a composite-material design with three uninterrupted layers. In this example the layer 9 in the crown 4 provides low thermal conductivity and comprises a mixture of aluminium or silicon-aluminium with a significant proportion of alumina. A lower layer 10 comprises a mixture of aluminium or silicon-aluminium with a smaller proportion of alumina, and can be either a homogeneous mixture or a controlled continuously graded layer having a higher proportion of alumina near the layer 9 and a lower proportion of alumina away from the layer 9. An insert 11 containing the compression ring grooves provides low thermal conductivity and/or mechanical strength and may be of the same material as the uppermost layer 9, or of other suitable materials. Layer 10 may be sprayed, sintered or cast. In this example the lower layer 12 of the piston, comprising the piston bosses and the skirt, may be of aluminium or silicon-aluminium but may also include a small proportion of alumina. This layer 12 may be made, for example as a separate casting. It can then be bonded, e.g. by friction welding, to the upper section of the piston. In some cases the layer 12 may comprise a continuously graded layer with a higher proportion of alumina near the layer 10 and a lower proportion of alumina (which may be zero) at the skirt end of the piston.
In an alternative arrangement the layer 10 may extend to the skirt end of the piston and be in the form of a single graded layer with a higher proportion of alumina nearer the layer 9 and a lower proportion of alumina (which may be zero) at the skirt end of the piston.
Also in some cases the piston may be continuously graded throughout, the proportion of alumina increasing from the skirt towards the piston.
Although pistons made from aluminium or siliconaluminium have been described it will be appreciated that other materials could alternatively be used. Moreover although the invention is especially applicable to pistons, clearly other articles may be made within the scope of the invention, such as, inter alia, cylinders with or without ribs or flanges, casings, turbi blades and combustors.

Claims

1. An article of composite materials and comprising two or more layers of different material compositions, there being a controlled graded change of composition between layers or within at least one of the layers.
2. An article as claimed in claim 1, wherein the article comprises two layers, one of the layers having a controlled graded region therein contiguous to the other layer, said controlled graded region having at least one property the value of which is intermediate the values of said property in the other layer and the non graded region of said one layer.
3. An article as claimed in claim 1, wherein the article comprises three layers, the intermediate layer having at least one property the value of which is intermediate the values of the corresponding property of the layers contiguous to said intermediate layer.
4. An article as claimed in any one of the preceding claims, wherein the article is a piston.
5. A piston for an internal combustion engine formed of at least two different materials wherein the skirt has a first composition and the crown has a second composition, and between the skirt and the crown there is an intermediate zone in which the relative proportions of the materials lies intermediate those in the skirt and the crown.
6. A piston as claimed in Claim 5 wherein the intermediate zone has properties of thermal conductivity and mechanical strength which are intermediate those at the skirt and the crown.
7. A piston as claimed in Claim 5 or 6 wherein the piston comprises three or more distinct layers each having different proportions of said materials, the proportions being substantially uniform throughout each layer and the relative proportions of the materials being graded from one layer to the next.
8. A piston as claimed in Claim 5 or 6 wherein there is a continuous grading of materials throughout part or the whole of the piston.
9. A piston as claimed in Claim 5 wherein aluminium or an aluminium alloy is a major constituent throughout the piston, the crown has a significant proportion of alumina, the intermediate zone has a smaller proportion of alumina, and the skirt has a still smaller proportion of alumina.
10. A piston as claimed in Claim 9 wherein the proportion of alumina to the aluminium or aluminium alloy is between 0% to 10% by weight at the skirt and is up to 30% by weight at the crown.
11. A piston as claimed in Claim 9 or 10 wherein the region of the piston containing the piston ring grooves comprises a mixture of aluminium or aluminium alloy with a significant proportion of alumina.
12. A method of manufacturing an article, comprising the steps of starting with at least two layers of different material compositions, there being a controlled graded change of composition between layers or within at least one of the layers, and subsequently bonding the layers together.
13. A method as claimed in Claim 12 wherein the bonding is achieved by sintering.
14. A method as claimed in Claim 12 wherein the bonding is achieved by casting.
15. A method as claimed in Claim 12 wherein the bonding is achieved by friction welding.
16. A piston for an internal combustion engine substantially as herein described with reference to and as shown in Figure 1 or Figure 2 of the accompanying drawing.
17. A method of manufacturing a piston for an internal combustion engine substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawing.
EP79900490A 1978-05-23 1979-12-17 Composite materials Withdrawn EP0018377A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2149578 1978-05-23
GB2149578 1978-05-23

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EP0018377A1 true EP0018377A1 (en) 1980-11-12

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EP79900490A Withdrawn EP0018377A1 (en) 1978-05-23 1979-12-17 Composite materials

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EP (1) EP0018377A1 (en)
JP (1) JPS55500363A (en)
AU (1) AU4732779A (en)
BE (1) BE876507A (en)
DK (1) DK21980A (en)
ES (1) ES480829A1 (en)
IT (1) IT7968102A0 (en)
NL (1) NL7904066A (en)
NO (1) NO791675L (en)
SE (1) SE8000505L (en)
WO (1) WO1979001103A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU6744381A (en) * 1980-02-27 1981-09-03 British Internal Combustion Engine Research Institute Limited, The Sintered piston
JPS59218342A (en) * 1983-05-26 1984-12-08 Honda Motor Co Ltd Fiber reinforced light alloy piston for internal- combustion engine
GB8328576D0 (en) * 1983-10-26 1983-11-30 Ae Plc Reinforcement of pistons for ic engines
GB8413800D0 (en) * 1984-05-30 1984-07-04 Ae Plc Manufacture of pistons
DE4221448A1 (en) * 1992-06-30 1994-01-13 Mahle Gmbh Reinforcement material for pistons of internal combustion engines
US8757124B2 (en) 2009-01-23 2014-06-24 Man Diesel, Filial Af Man Diesel Se, Tyskland Movable wall member in form of an exhaust valve spindle or a piston for internal combustion engine, and a method of manufacturing such a member

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE943917C (en) * 1944-09-10 1956-06-01 Dr Joseph Dornauf Piston head covered with a heat-insulating layer
DE837467C (en) * 1946-07-17 1952-04-28 Aluminium Ind Ag Process for the production of light metal bodies
GB671606A (en) * 1948-10-01 1952-05-07 Maschf Augsburg Nuernberg Ag Piston for internal combustion engines
FR1226350A (en) * 1958-06-09 1960-07-11 Ind De L Aluminium Sa Manufacturing process of composite bodies formed of aluminum and sintered aluminum
US3911891A (en) * 1973-08-13 1975-10-14 Robert D Dowell Coating for metal surfaces and method for application

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO7901103A1 *

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Publication number Publication date
NL7904066A (en) 1979-11-27
SE8000505L (en) 1980-01-22
AU4732779A (en) 1979-11-29
BE876507A (en) 1979-09-17
DK21980A (en) 1980-01-18
ES480829A1 (en) 1980-10-01
WO1979001103A1 (en) 1979-12-13
IT7968102A0 (en) 1979-05-23
NO791675L (en) 1979-11-26
JPS55500363A (en) 1980-06-26

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