EP1943039A1

EP1943039A1 - Method for producing a wear-resistant aluminum alloy, an aluminum alloy obtained according to the method, and use thereof

Info

Publication number: EP1943039A1
Application number: EP06792791A
Authority: EP
Inventors: Mathias Woydt
Original assignee: Bundesanstalt fuer Materialforschung und Pruefung BAM
Current assignee: Bundesanstalt fuer Materialforschung und Pruefung BAM
Priority date: 2005-09-30
Filing date: 2006-08-11
Publication date: 2008-07-16
Anticipated expiration: 2026-08-11
Also published as: DE102005047037A1; EP1943039B1; ATE516094T1; US20080219882A1; WO2007039340A1

Abstract

The invention relates to a method for producing a wear-resistant aluminum alloy, to an aluminum alloy produced according to the method, and to the use thereof. The method comprises the steps of: (i) providing an aluminum alloy having the composition Fe: 3-10; X: 3-10; Y: 0-1.5; Z: 0-10; wherein X represents an element or combination of elements (a) V and Si; (b) Cr and Ti; (c) Ce; or (d) Mn; each time with the proviso that the proportion of the individual elements in the combinations of elements (a) and (b) is at least 0.5 wt %; Y represents one or more grain-refining elements selected from the group of B, Ce, Sr, Sc, Mg, Nb, Mn and Zr, unless already present as X; Z represents one or more additives increasing the heat resistance, selected from the group of ceramic fibers, particles and platelets, the figures referring to % by weight in the alloy, and Al and production-related impurities representing the remaining proportion in the alloy to make 100 wt %, with the proviso that the proportion of Al in the alloy is at least 80 wt %; (ii) melting the aluminum alloy, dissolving and homogenizing the alloy elements at temperatures of from 650° C. to 1,000° C.; and (iii) casting the melt into a casting mold at a casting temperature ranging from the melting temperature of the alloy up to a temperature 150° C. above the melting temperature.

Description

A process for producing a wear-resistant aluminum alloy, aluminum alloy obtained by the process and their use

Technical area

The invention relates to a process for producing a wear-resistant aluminum alloy, to aluminum alloys obtained by the process and to their use.

Background of the invention and prior art

Motorized bearings with sliding elements made from an aluminum base alloy are found, for example, in a piston-piston-ring-cylinder-track assembly or crankshaft-bearing shell assembly, particularly in the form of crankshaft bearing shells, cylinder liners, piston rings, pistons and valve guides.

The sliding surfaces of the sliding elements can additionally also be coated or treated thermochemically. Since the thirties of the last century, cylinder liners made of eutectic AISi alloys ("silumin") with coarse Si primary crystals have been known and used in motor applications, which can contain up to 1.3% by weight of iron For the functional design of the cylinder surface, it is essential to reset the aluminum matrix by 0.5 - 2 μm by chemical or mechanical treatment of the raceways, so that the hard silicon crystals (Hv -12-14 GPa) form the supporting component ,

The lowest system wear (piston ring and cylinder bore) is achieved by AISi raceways against nitrided piston rings, which are identical or partially identical to the wear expectation of highly carbonated cast iron cylinder liners (3.3 - 3.8 wt.% C). can also be better. The patent US 6,030,577 discloses AISi (17-35 wt.% Si) with 3-5 wt.% Fe.

Overall, however, it was found that this proven pairing of AISi alloys tribologically no longer withstand the load of new or future highly-charged and / or with hydrogen-powered engines. It turns out that this is true for both AISiI 7 (Alusil) and AISi25 alloys Furthermore, the AISi alloys are limited in the tribological good load or feeding load with regard to the tribological high-pressure properties.

The very readily castable material system Al-Si-Mg, e.g. Al-9.0Si-0.5Mg (A359) is characterized by a high temperature-dropping strength and by the following low temperature eutectic equilibria:

a. Al-Mg ₂ Si-Mg having a melting temperature of 555 ° C, b. Al-Mg ₂ Si-Al ₃ Mg ₂ having a melting temperature of 451 ° C or c. Al ₃₀ ^ Mg _{69 1} o Mg + Mg ₁₇ Al ₁₂ + Mg ₂ Si with a melting temperature of

437 ° C.

Similar phase equilibria also exist in the material system Al-Cu-Zn.

The heat resistance of AISi alloys can be improved by ceramic fibers, particles and / or platelets, such as AISiMg 30% by volume SiCp (Lanxide Corp., Al-7.0Si-0.3Mg) or A359-20% by volume. SiCp (p = platelet) or reinforced by particles of silicon carbide, such as DURALCAN F3S.20S, 20% by weight SiC) or AA6061 + 40% by volume Al ₂ O ₃ (Al-1% Mg + 30% by weight Al ₂ O ₃ (PRIMEX ™). However, piston ring wear is adversely affected by the ceramic phases.

For optimum combustion of H ₂ -driven engines, the high thermal diffusivity of aluminum (K ^RT -60-80 mm ² / s) is essential, which results in coatings of the cylinder liner with engineering ceramics, cermets or hard metals, despite proven, better wear resistance , exclude. For comparison: K ^RT = 16.6 mm ² / s of a lamellar gray cast iron with 3.7% by weight C.

The patent US 4,948,558 discloses a fabric system AIFeXY. In addition to the intermetallic phases, amorphous and crystalline aluminum phases characterize the microstructure morphology of the rapidly solidified Al special alloys. So far, these heat-resistant special alloys, eg. B. AI88.5 Fe8.5 V1, 3 Sil, 7 or AI84.5Fe7Cr6Ti2,5, technologically complex rapidly melted by melt atomization and then konnpaktiert and extruded or represented powder metallurgy. The alloys have hitherto not been mentioned in connection with wear-stressed components or with "classical" casting under the influence of gravity or pressure in molds or molds. US Pat. No. 5,318,641 to ALCOA discloses in the Al-Fe-Ce material system the alloy (X8019) having a tensile strength at RT of up to 1,600 MPa with crystalline nanoparticles precipitated in a partially amorphous matrix. The amorphous or partially amorphous structure above recrystallized 300-450 ⁰ C (AI90 _J 8Fe6,2Nb1 _J 0Si2,0 (at%), at 450 ⁰ C.) Is lost, whereby the high strengths. This is accompanied by a Komvergröberung. By powder atomization, melt spinning or Sprühkompak- animals with subsequent compacting and / or extrusion can be manufactured economically in a large series no cylinder liners or engine blocks, especially compared to competitive solutions, such as thermal spraying or laser nitriding of gray cast iron.

All ultra-high-strength Al special alloys with 800 MPa <σ _Tensile ^RT <1.600 MPa are produced either by powder metallurgy or by powder atomization or by melt spinning or spray compacting. They have a high volume fraction of intermetallic phases, which are present as fine dispersoids smaller than 50-100 nm due to the rapid solidification.

The patent application US 2003/0185701 (KL Sahoo et al.) Discloses casting parameters for the material system Al-Fe-V-Si. Thereafter, the casting temperatures of 800-1000 ⁰ C, wherein in a preheated to 350-500 ⁰ C mold is poured. The inoculum for the refinement consists of <1, 0 wt .-% Mg / Ni. A reference to tribologically stressed surfaces is neither refilled nor disclosed, nor the casting temperatures of the invention.

The publication by Sahoo et al., J. of. Materials Processing Technology 135 (2003) 253-257, presents for a Al-8, 3Fe-0, 8V-0, 9Si alloy the mechanical properties and grain morphologies grain-fined with 0.18 wt% Mg, which is 1 K / s to 14 K / s solidified.

The Al-8.3 Fe-0.8V-0.9Si alloys prepared according to US 2003/0185701 achieved between 43-143, with and without fine tuning by 0.1-1.0% by weight Mg Vickers hardness, which were significantly lower than those of the alloys of the invention.

The Chinese publication by Z.-H. Chen et al., J. Cent. South Univ. Technol. Vol. 7, no. 4, Dec. 2000, represents the manufacture of components from an AA8009 alloy according to the OSPREY process. Reference to tribologically stressed surfaces is neither refilled nor disclosed. - A -

The patent application US 2004/0156739 discloses for turbine applications aluminum alloys with up to 20 wt .-% of rare earths, which were cast at cooling rates of 10-100 K / s. A reference to tribologically stressed surfaces is neither refilled nor disclosed.

The patent application US 2004/0261916 discloses the dispersion-strengthening material system Al-Ni-Mn, wherein the alloys consisting of 0.5-6.0 wt .-% Ni and 1, 0-3.0 wt .-% Mn with up to 0 3% by weight Zr and / or Sc may be grain-finely ground. A reference to tribologically stressed surfaces is neither refilled nor disclosed.

The patent application US 2004/0140019 discloses the dispersion-strengthening material system Al + <11 wt .-% (Mg, Li, Si, Ti, Zr), which is enriched by cryogenic milling with up to 0.3 wt .-% nitrogen. From this, tubes are manufactured in US 2004/0255460 for guiding cryogenic media. Reference to casting technologies or tribologically stressed surfaces is neither refilled nor disclosed.

There is therefore a continuing need for a material that overcomes the described limitations of the prior art.

Summary of the invention

A first aspect of the invention, which helped to achieve the object, is to provide a method for producing a wear-resistant aluminum alloy. The method according to the invention comprises the steps:

(i) providing an aluminum alloy of the composition

Fe: 3 - 10;

X: 3 - 10;

Y: 0-1.5;

Z: 0-10; wherein

X for an element or an element combination

(a) V and Si;

(b) Cr and Ti;

(C) Ce; or

(d) Mn in each case with the proviso that the proportion of the individual elements in the element combinations (a) and (b) is at least 0.5 wt .-%; Y is one or more design elements selected from the group B, Ce, Sr, Sc, Mg, Nb, Mn and Zr, if these are not already present as X;

Z is one or more heat resistance additives selected from the group consisting of ceramic fibers, particles and platelets; and wherein the indications relate to wt .-% of the alloy and AI and manufacturing impurities take the remaining 100 wt .-% residual amount of the alloy, with the proviso that the proportion of

Al on the alloy is at least 80% by weight; (ii) melting the aluminum alloy, dissolving and homogenizing the aluminum alloy

Alloying elements at temperatures from 650 ⁰ C to 1000 ⁰ C; and (iii) casting the melt into a mold at a casting temperature ranging from a melting temperature of the alloy to a melting point

Temperature of 150 ° C above the melting temperature.

The present invention improves the wear resistance, the tribological load-bearing capacity and the heat resistance of aluminum-base alloys. This may be due to intermetallic phases precipitated in the microstructure, such as AIFe ₃ , Al ₃ Fe (H _v ~ 9.8 GPa, Θ), Al ₅ Fe ₂ (η, Hy-10.5 GPa), Al ₆ Fe, Al ₁₃ Fe ₄ , Al ₅ Fe ₂ (η, Hv-10.5 GPa), Al ₃ (Ti, Cr), Al ₃ Ti, Al ₄ (Cr, Fe), Al ₁₀ (Cr, Fe), AISi ₂ or Al ₈ Fe ₂ Si, which have microhardnesses of 4,000-8,000 MPa.

In the metallurgy according to the invention, no eutectic melt equilibria with liquidus temperatures below 600-620 ° C. are formed. Preferably, therefore, the silicon content should not exceed 2.0 wt%, more preferably not 1.0 wt% Si. The intermetallic phases are formed from eutectic (α-Al o Al ₃ Fe) and peritectic phase equilibria.

The alloys according to the invention differ morphologically, above all in the embodiment of the dendrites from intermetallic phases, from the silicon crystals precipitated in known AISi alloys. The silicon crystals are present in aluminum alloys as individual single crystals, while a dendritic network allows an excellent integration into the matrix for absorption for shear stresses from the tribological stress. The alloys according to the invention can be clearly characterized by their production process. A particular object of the present invention is also to represent the solid or non-soluble in the solid state alloying elements such as Fe, Ti, Cr, Mo or V, even by means of simple casting technology as a homogeneous, segregation-free structure. This is achieved in particular by the decoration with an element selected from the group B, Ce, Sr, Sc, Mg, Nb, Mn and Zr and by special casting temperatures.

A tool mold according to the invention may include any shape suitable for the metal casting technique. For test purposes, for example graphite molds can be used.

It should be noted that a prediction of the formation of intermetallic phases or dendrites during casting is not possible, but their presence significantly influences the tribological material properties. The lack of predictability of intermetallic phases, morphology and composition of the individual components of the microstructure as well as the problems arising from eutectic phase formation make purely theoretical considerations for the prognosis of suitable materials unsuitable. It has now been proven experimentally that holding the temperature of the melt above 650 ^° C. establishes a phase equilibrium over the entire volume of the material in a time period which is reasonable for commercial application.

After melting and homogenization, preferably between 0.5% by weight and 0.8% by weight of one or more of the elements selected from the group boron, Ce, Sr, Sc, Mg, Nb, Mn or Zr may be used for the refinement be alloyed. The refinement primarily reduces the size of the dendrites of the precipitated during solidification intermetallic phases, but also leads to an increase in the number of nuclei / density during the primary crystallization of aluminum.

A higher cooling rate of> 100 K / s achieves the same effect, so that the refinement is advantageously to be used for larger wall thicknesses of the cast parts in order to obtain a uniform microstructure. The still relatively large dendrites are favorable for a tribological sliding stress and for the connection of the intermetallic phases in the structure, but not for the Nachalimentierung the solidification front with melt. Therefore, an optimum in size must be sought in each case by grain refining elements optionally with the aid of magnetic stirring. The formation of the dendrites from the intermetallic phases can also be prevented by magnetic stirring. The magnetic stirring also improves the alimentation of the solidification front with fresh melt, thus helping to avoid voids.

Preferably, the casting temperature in step (iii) is in the range of 1 ° C to 80 ° C, in particular in the range of 10 ⁰ C to 50 ⁰ C, above the melting temperature of the alloy. The casting temperatures are preferably below 800 ° C.

According to a further preferred variant of the method, an alloy with 4-8 wt .-% of Fe and / or 3-5 wt .-% of X is provided. Furthermore, it is preferred that X for the element combination (a) is specified such that a proportion of Si is less than or equal to 2 wt .-%, in particular less than or equal to 1 wt .-%. The measures mentioned lead to aluminum alloys, with particularly favorable tribological behavior.

Preferably, steps (ii) and (iii) are part of a metallurgical melt casting process selected from the group of sand casting, die casting, continuous casting, strip casting, centrifugal casting and cold crucible casting. The methods mentioned can be implemented particularly simply in conjunction with the method according to the invention. The existing alloy workpiece can preferably be processed by drop forging. The workpiece is completely surrounded by the closed tool, the die, and the introduced into the die engraving determines the shape of the finished molding.

Finally, it is preferred if the temperature of the mold is in the range of 450 ° C to 600 ° C. As a result, aluminum alloys can be produced with particularly favorable tribological behavior.

A second aspect of the invention relates to an aluminum alloy produced or obtainable by the method described above.

A third aspect of the invention resides in the use of the abovementioned aluminum alloy for producing sliding elements in crankshaft bearing shells, cylindrical raceways, piston rings, pistons, valve guides, bearing bushes or bearing shells. The invention will be explained in more detail with reference to embodiments and the accompanying drawings. Show it:

1 to 3 sample cross sections through AlFeVSi alloys;

Figures 4 and 5 are etched and unetched SEM micrographs of a 88.5AI 8.5 Fe 1, 3V1, 7Si alloy;

6 shows a sample cross-section through an AlFeCrTi alloy;

FIGS. 7 to 9 are SEM images of the AlFeCrTi alloy;

10 shows a LOM image of the AlFeCrTi alloy;

11 shows a LOM image of a rapidly cooled AlFeCrTi alloy with residual melt;

FIGS. 12 and 13 show LOM images of an Al84.4Fe7Cr6Ti2.5Mg0.1 alloy and

14 to 16 test results for the tribological behavior of the alloys.

The following Figures 1-13 describe the production parameters with the then adjusting and the Gefömgemorphologien of alloys of the invention based on AIFeVSi and AIFeCrTi in argon atmosphere.

Embodiment 1 - AlFeVSi alloys

Figures 1-3 show sample cross-sections of AlFeVSi alloys cast under various conditions. The 12mm sample cross-section of Fig. 1 shows a AI88,4Fe8,5V1, 3Si 1, 7ZrO, 1 alloy, which was poured into a preheated to 600 ⁰ C graphite mold at a melt temperature of 750 ⁰ C and the Zr was added as Komfeinungselement , The sample cross-section (14 mm) from FIG. 3 is based on an Al88.5 Fe8.5 V1, 3 Si1.7 alloy, which was poured without preheating into a graphite mold at a melting temperature of 700.degree. Fig. 2 shows the same alloy but under the process variant that the melting temperature was 750 ° C and the graphite mold was heated to 500 ° C. The latter alloy offers an E modulus at room temperature (RT) of E ^RT = 85.7 GPa and at 500 ⁰ C still E ^{500 ° C} = 65 GPa. Such values of the modulus of elasticity are that is, comparable to those of a high-carbon, lamellar gray cast iron (-3.7% by weight C, GL11) and significantly larger than that of AISi alloys. It should be noted for both exemplified Al-casting alloys according to the invention that the high moduli of elasticity were achieved without the addition of ceramic fibers, particles or platelets. Alone due to the high modulus of elasticity, the alloys according to the invention can substitute gray cast iron material mechanically, since, moreover, it decreases in a similar manner with increasing temperature, as with high-carbon cast iron. The decrease in strength of the alloys of the invention is also shifted to higher temperatures.

3 illustrate that the uniform formation of the microstructure of the AI88,5Fe8,5V1, 3Si1, 7-alloy is achieved over the cross-section through a pre-heated to 500 ⁰ C graphite mold, however, these conditions promote the growth of large dendrites of Al - Figs. 1 ₃ Fe (X-ray diffraction chart JCPDS NR .: 001-1265) several millimeters long. Only the grain refinement with 0.1 wt .-% Zr, a pre-heated to 600 ° C graphite mold in conjunction with a casting temperature of 750 ⁰ C achieved a much finer structure image which is pronounced homogeneously over the cross section.

In addition to the excretion of "primary" dendrites of Al ₃ Fe (001-1265) and Al ₈ oVi ₂ Fe ₇ , ₅ (JCPDS No .: 040-1229) in the 88.5AI 8.5 Fe 1.3V1, 7Si alloy show the SEM images of Fig. 4 (unetched) and Fig. 5 (etched) the fine "pearlite" pattern from the eutectic decay of the residual melt, which consists of AISi ₂ (aluminum disilicide). This forms the key to the formation of the high hot strength of a "classical" cast AIFe-XY alloy without the use of rapid solidification techniques.

Embodiment 2 - AlFeCrTi alloys

Fig. 6 shows a grain morphology of an Al84.5Fe7Cr6Ti2.5 alloy cast at 700 ° C, with no coalescing elements added to the alloy and cast into a non-preheated graphite mold (0 = 14mm). The alloy of AI84.5Fe7Cr6Ti2.5 has a modulus of elasticity of E ^RT = 104.1 GPa, which at 500 ⁰ C drops to E ^50trc = 83 GPa.

The alloy system AI84,4Fe7,0Cr6,0Ti2,5 separates a dense, but closed, primary dendrite (see Fig. 6) which by means of EDX as an AI ₄ (Fe ₁ Cr) was analyzed. In addition, the SEM images (FIG. 7 (Unetched); Figure 8 (etched)) in addition to the Al ₃ Fe dendrites precipitates of Al ₄ (V ₁ Fe). Within the lamellar drendrites one finds a globular substructure. In addition, one finds in the same microstructure further precipitates of Al ₃ (Ti ₁ Cr) (Figure 9, SEM image, etched).

As with the 88,5AI8,5Fe1, 3V1, 7Si alloy AlFeCrTi alloy of the AI84 _J 4Fe7,0Cr6,0Ti2 _J shows a fine, "perlitartiges" pattern of the eutectic decomposition of the residual melt 5 alloy (Fig. 10 For comparison, Figure 11 shows a LOM image of lamellar intermetallic dendrites in a rapidly cooled AlFeCrTi alloy with the residual melt.

By reducing the difference between casting and mold temperature to 250K and refining it with 0.1 weight% Mg, the dendrite network appears somewhat finer in an Al84.4Fe7.0Cr6.0Ti2.5Mg0.1 alloy (Figure 12) is caused in particular by their branching or branching (Fig. 13). The AI84,4Fe7 0Cr6,0Ti2 _J _J _J 5Mg0 1 alloy was cast (14 mm) at 750 ⁰ C in a mold preheated to 500 ⁰ C graphite mold. The 88.5AI8.5Fe1, 3V1, 7Si alloys tend to form stem-like crystals rather than the Al84.4Fe7.0Cr6.0Ti2.5Mg0.1 alloy with a dendrite network.

Overall, it has also been found that the AlFeXY alloys according to the invention advantageously have a low excess temperature of max. 150K above the melting temperature of the alloy.

Tribological behavior

The off-engine characterization of the tribological behavior of the AlFeXY alloys according to the invention was carried out according to the BAM test technique, which is the reference "Woydt M. and N. Kelling, Characterization of the tribological behavior of lubricants and materials for the tribosystem" piston ring / cylinder liner, in : ASTM STP 1404, "Bench testing of industrial fluid lubrication and wear properties used in machinery applications," June 2000, Seattle, ISBN 0-8031-2867-3, p.153 ". FIG. 14 shows the wear coefficient or rate of rotating samples of two AIFeXY and of different piston rings under mixed / boundary friction in first filling straight running oils SAE OW-30 (FUCHS "PCX") and 5W-30 (Castrol "SLX"). ) (F _N = 50 N, s = 24 km, T = 170 ° C). Both AlFeXY alloys used in Figure 14 were vacuum cast and the intermetallic phases were not exposed by chemical or mechanical (honing) release. The tribological functional surfaces were on R _PK -0.43 microns at AI88.4Fe8.5V1, 3Si I JZrO ₁ I and R _PK ~ 0.37 microns at

AI84 _J 4Fe7.0Cr6 _J 0Ti2 _J 5Mg0 _J 1 lapped.

FIG. 14 shows the test results obtained in the form of the wear coefficient of the main body (piston ring) separated from the counterbody (rotating sample or cylinder bore) with the mixing / boundary friction coefficient belonging to the respective pairing. Hydrocarbon-based SAE 5W-30 and SAE OW-30 first fill oils used in FIG. 14 have a high temperature high shear viscosity (HTHS) of 3.0 mPas. The GG20HCN is a 3.66 wt% carbon high carbon gray cast iron with lamellar graphite. The piston ring designations "MKP81A", "MKJet502 (WC / Cr ₃ C ₂ ," superpolished ")" and "CKS36" are brand names of Federal Mogul Burscheid GmbH. "Nitriert" means in the diagrams a "standard nitration" by the company Federal Mogul Burscheid GmbH. The atmospheric, plasma sprayed (APS) Ti _n O _2n-I and Ti _n-2 Cr ₂ θ _2n- i ring _coatings represent experimental _coatings for piston rings from CIE Automotive (Tarabusi, Barrio Urquizu 58, ES-48140 Igorre) AlFeXY alloys Al84.4Fe7.0Cr6.0Ti2.5Mg0.1 and 88.4AI8.5Fe1.3V1, 7SiZrO, 1 were poured off in vacuo at 750 ° C in a preheated to 600 ° C graphite mold.

In the BAM test arrangement, nitrided rings are considered to be wear-resistant against AISiI 7 (AISiI 7Cu4Mg, "Alusil" from Kolbenschmidt) or AISi25Ni4 ("Silitec" from PEAK Werkstoff GmbH) up to 25 N normal force or are in wear low position ~ 25 N (oil-dependent!) Go into the wear high position. The following table shows the mixing / coefficient of friction of AlSi alloys (chemically optional) in the BAM test arrangement (T = 170 C ^0; s = 24 km; v = 0.3 m / s) compared to the AI84,4Fe7Cr6Ti2, 5Mg0,1 to remove.

* First fill oil, ** Polypropylene glycol monobutyl ether motor oil formulation of BAM.

On average in the BAM test set, the average wear coefficient at F _N = 50 N of GGL20HCN is 4.8 10 ^{~ 8} mπϊVNm on average of more than 200 trials with high-carbon gray cast iron GGL20HCN. The wear resistance of the 0.1% by weight Mg grain refined AI84.4Fe7Cr6Ti2.5Mg0.1 alloy achieves a wear resistance and load capacity comparable to high carbon black cast iron compared to the molybdenum based MKP81A piston ring.

Conspicuous in the table are the higher coefficients of friction with the first filling oil SAE 5W-30 under mixed / boundary friction of the AlFeXY alloys compared to the GGL20HCN.

The relatively high mixed friction numbers can be determined by the use of a polyalkylene glycol (PAG46-4 + 2.6 Phopani, HTHS = 3.6 mPas) or a polypropylene glycol monobutyl ether (PPG32-2 + 2.6 Phopani; HTHS = 2.87 mPas ) are reduced (see Fig. 15). The metal-free friction reducer contained in the first filling oil SAE OW-30 ("PCX") with an HTHS of 3.0 mPas does not work with the AIFeCrTi. 1 -Legierunglaufbahnseitig, with the same normal force of F _N = 50 N, in the context of the precision limits of the test method in terms of wear coefficient with the highly carbonated gray cast iron is comparable (s = 24 km, T = 170 ° C.) Especially in the PPG32-2 is the Overall wear of the piston ring and raceway comparable to those of GG20HCN.

Referring only to the "nitrided" piston ring, Fig. 16 shows that the AIFeVSi, in particular the AIFeCrTi, in the FUCHS PCX OW-30 oils and the PPG32-2 + 2.6 Phopani polyglycol has comparable wear resistance to the high carbon gray cast iron GGL20HCN (F _N = 50 N, s = 24 km, T = 170 ^° C.) In Fig. 16 is still the wear coefficient of a long-term experiment (108 km) reproduced, whereby a strong, wear-reducing run-in behavior of AlFeCrTi alloy is documented.

Crankshaft plain bearing shells made of "electric" AISiI 2CuNiMg (Karl Schmidt GmbH, KS 1275 (material number 3210.9), today Kolbenschmidt AG with 11-13.5% Si, 0.5-1, 3 Cu, 0.8-1, 3 Mg , 0.5-1, 3 Ni, -0.25 Zn, -0.1% Cr, remainder AI) were used in the double-star aircraft engine BMW 801 application (Ing. Buske, The dependence of the bearing load capacity of the bearing design, report on the Lubricant Conference, Part 1: Friction and Wear, Cold Behavior, 11 / 12.12.1941, Berlin-Adlershof, pp. 119-148), wherein the crankshaft journal was made of a "nitriding steel" with HRC 58. Such a material solution is The current running surfaces of plain bearing shells made of AISn14Cu8, AISn20, PbSn10Cu3, GZ-CuSn7ZnPb or lead bronzes, as well as bonded coatings require corrosion inhibiting additives in the lubricants for federal metals, which significantly impair the ecotoxicological properties AISi or AlFeXY alloys are all together with less risk of corrosion and allow a waiver or a significant reduction in the concentration of anti-corrosion additives. Known in the prior art is still an AI96 (Ni, Mn) alloy (Glyco-172) with a maximum allowable geometrical bearing pressure of 80 MPa, which is fatigue and corrosion resistant, but it tends to malfunction due to insufficient lubrication due to the AlFeXY metallurgy is suppressed.

The tribological limit load capacity of 100 MPa (geometrical surface pressure) of the sliding combination "AISi12CuNiMg / Nitrierstahl" in the BMW801 double star motor at an oil inlet temperature of 99 ° C of the fully synthetic lubricant "SS-1600" based on an adipic ester and ethylene oil is remarkable, as it with a kinematic Viscosity ηiooc ~ 6.2 mm ² / s was still significantly "thinner" than today's light-running oils with ηiooc ~ 9-12 mitf / s.

Another advantage of an AlFeXY system is that the wear protection and high pressure additives in engine and gearbox oils, also due to the metallurgy of the specimens in Tribometem, are matched to iron and not to silicon.

Valve guides require high thermal diffusivity because they dissipate heat from the valve stem into the cylinder head, with associated wear resistance. Therefore, valve guides are preferably made of copper base alloys, such as CuZn36Mn3AI2SiPb (≡ CuZn40AI2 according to DIN 17660 or CW713R) with λ _RT ~ 63 W / mK or K ^RT ~ 19.7 mm ² / s. At the surfaces in the lower part of the guide of the exhaust valve temperatures of 500 ⁰ C are not uncommon. The aluminum alloys according to the invention offer a 3-4 times higher thermal diffusivity combined with the necessary temperature resistance without melt equilibria up to> 600 ° C.

Aluminum piston materials consist of eutectic AISi12CuXX alloys or over-eutectic AISiI 8CuXX alloys also containing up to 0.85% by weight iron. The thermal diffusivities are between 55 mitf / s <K ^RT <61.7 mm ² / s.

Claims

claims

A method of making a wear resistant aluminum alloy, comprising the steps of: (i) providing an aluminum alloy of the composition

Fe: 3 - 10; X: 3 - 10; Y: 0-1.5; Z: 0-10; wherein

X for an element or an element combination

(a) V and Si;

(b) Cr and Ti;

(c) Ce; or (d) Mn, in each case with the proviso that the proportion of the individual elements in the element combinations (a) and (b) is at least 0.5% by weight; Y is one or more grain refining elements selected from the group B, Ce, Sr, Sc, Mg, Nb, Mn and Zr, if these are not already present as X;

Z is one or more heat resistance additives selected from the group consisting of ceramic fibers, particles and platelets; and wherein the data refer to wt .-% of the alloy and AI and production-related impurities to 100 wt .-% remaining

Occupy residual amount of the alloy, with the proviso that the proportion of Al in the alloy is at least 80 wt .-%;

(ii) melting the aluminum alloy, dissolving and homogenizing the alloying elements at temperatures from 650 ^° C to 1000 ^° C; and (iii) casting the melt into a mold at a casting temperature that is in a range from a melting temperature of the alloy to a temperature of 150 ° C above the melting temperature.

2. The method of claim 1, wherein the casting temperature in step (iii) in the range of TC to 80 ⁰ C above the melting temperature of the alloy.

3. The method of claim 2, wherein the casting temperature in step (iii) is in the range of 10 ° C to 50 ° C above the melting temperature of the alloy.

4. The method according to any one of the preceding claims, wherein a temperature of the mold in the range of 450 ⁰ C to 600 ⁰ C.

5. The method according to any one of the preceding claims, wherein the alloy contains 4-8 wt .-% of Fe.

6. The method according to any one of the preceding claims, wherein the alloy contains 3 - 5 wt .-% of X.

A method according to any one of the preceding claims, wherein the alloy contains 0.5-0.8% by weight of Y.

8. The method according to any one of the preceding claims, wherein X is the element combination (a) and a proportion of Si is less than or equal to 2 wt .-%.

9. The method of claim 1, wherein X is the element combination (a) and a proportion of Si is less than or equal to 1 wt .-%.

10. The method according to any one of the preceding claims, wherein the steps (ii) and (iii) are part of a metallurgical Schmelzgießprozesses selected from the group of sand casting, die casting, continuous casting, thin strip casting, centrifugal casting and cold crucible method.

11. Aluminum alloy produced or obtainable by a process according to one of claims 1 to 10.

12. Use of the aluminum alloy according to claim 11 for the production of sliding elements in crankshaft bearing shells, cylinder liners, piston rings, pistons, valve guides, bearing bushes or bearing shells.