Method for Producing a Wear-Resistant Aluminum Alloy,An Aluminum Alloy Obtained According to the Method, and Ues Thereof

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

TECHNICAL FIELD[0001]The invention relates to a method for producing a wear-resistant aluminum alloy, to aluminum alloys produced according to the method, and to the use thereof.BACKGROUND OF THE INVENTION AND RELATED ART[0002]Engine sliding couples having sliding elements produced from aluminum base alloy are found e.g. in a piston-piston ring-cylinder face assembly or a crankshaft-bearing shell assembly, especially in the form of crankshaft bearing shells, cylinder faces, piston rings, pistons and valve guides.[0003]In addition, the sliding surfaces of the sliding elements can be coated or thermo-chemically treated. Since the thirties of the past century, cylinder faces made of eutectic AlSi alloys (“Silumin”) with coarse Si primary crystals have been known and used in engines. They may include up to 1.3 wt % iron. The material matrix in these concepts is based on aluminum and silicon. With regard to the functional design of the cylinder face surface, an essential point is to rece...

AI Technical Summary

Benefits of technology

[0033]The present invention improves the wear resistance, the tribological load-bearing capacity and the heat resistance of aluminum base alloys. This may be caused by intermetallic phases deposited within the structure, such as AlFe3, Al3Fe (HV ˜9.8 GPa, , Al5Fe2 (η, HV˜10.5 GPa), Al6Fe, Al13Fe4, Al5Fe2 (η, HV˜10.5 GPa), Al3(Ti, Cr), Al3Ti, Al4(Cr, Fe), Al10(Cr, Fe), AlSi2 or Al8Fe2Si having microhard-nesses of from 4,000 to 8,000 MPa.

[0039]Following melting and homogenizing, between 0.5 and 0.8 wt % of one or more elements selected from the group of B, Ce, Sr, Sc, Mg, Nb, Mn or Zr can preferably be alloyed for grain refinement. Grain refinement predominantly reduces the size of the dendrites of intermetallic phases deposited during solidification, but also results in an increase of the crystal germ number / density during primary crystallization of aluminum.

[0041]Formation of dendrites from the intermetallic phases can also be prevented by magnetic stirring. In this way, magnetic stirring improves feeding the solidification front with fresh melt and aids in preventing voids (pores).

[0043]According to another preferred variant of the method, an alloy having 4-8 wt % Fe and / or 3-5 wt % X is provided. It is also preferred to preset X for the combination of elements (a) in such a way that the share of Si is smaller than or equal to 2 wt %, particularly smaller than or equal to 1 wt %. The measures mentioned above result in aluminum alloys having particularly favorable tribological behavior.

[0045]Finally, the temperature of the casting mold preferably ranges from 450° C. to 600° C. In this way, it is possible to produce aluminum alloys having particularly favorable tribological behavior.

Problems solved by technology

In total, however, it has been found that this well-tried couple of AlSi alloys can no longer withstand the load of new or future supercharged and / or hydrogen-operated engines in tribological terms.

Regarding the tribological high-pressure properties, the AlSi alloys are also limited in their tribological OK load or scuffing load.

However, the ceramic phases have a highly adverse effect on the piston ring wear.

), causing loss of the high strengths and entailing grain coarsening.

Using powder spinning, melt spinning or spray compacting with subsequent compacting and / or extruding, economic large-scale production of cylinder faces or engine blocks is not possible, especially when compared to competitive solutions such as thermal spraying or laser nitriding of gray iron.

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