The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 20, 1984
Filed:
Apr. 07, 1982
Mahle GmbH, Stuttgart, DE;
Abstract
For a piston consisting of an Al-Si alloy having a mean linear grain diameter of the Silicon eutectic of more than 3 .mu.m for combustion engines and provided with a hard-oxidized top, the structure of the base material to be oxidized is subjected to a grain refinement in the depth to be oxidized so that the silicon eutectic has a mean linear grain diameter of less than 3 .mu.m, preferably less than 2.5 .mu.m. By this means, the resistance to erosion of the hard-oxide layer is improved. The grain refinement may be effected in the respective zones during the casting of the piston or thereafter by re-melting those zones prior to oxidizing. If the risk of erosion exists only in specific locally limited zones of a relatively large hard-oxide surface, then a grain refinement confined to these zones is sufficient.