Cylinder liner of a hypereutectic aluminum/silicon alloy for use in a crankcase of a reciprocating piston engine and process for producing such a cylinder liner

摘要

A cylinder liner cast into a reciprocating piston engine made of a supereutectic aluminum/silicon alloy which is free of mixed-in particles of hard material and which is composed in such a way that fine silicon primary crystals and intermetallic particles automatically form from the melt as hard particles. A blank is allowed to grow from finely sprayed melt droplets by spray compaction, with a fine distribution of hard particles being produced by setting the spray for small melt droplets. The blank can then be formed by cold extrusion to create a shape approximating the cylinder lining. After premachining, the surface is fine machined, honed in at least one stage and then the hard particles lying at the surface are mechanically or chemically exposed, forming plateau areas of hard particles which project above the remaining surface of the base microstructure of the alloy. The mechanical exposure of the primary crystals or particles is carried out by a honing process using felt strips which are cylindrically shaped on the outside and a slurry of SiC particles in honing oil. The chemical exposure of the primary crystals or particles is carried out by using aqueous alkali. The fine- grained, hard particles formed from the melt and also the mechanical exposure of the hard particles on the surface of the cylinder results not only in high wear resistance and high contact area of the surface, but also in gentle treatment of the piston and its rings.