Aluminium cast part and method for its fabrication

摘要

A cast aluminium part, with a honed cylindrical interior sliding surface having a roughness depth profile (DIN 4776) of Rk (core roughness depth) = 0.5 to 3.0 mu m, Rnk (reduced peak height) = 0.1 to 2.0 mu m and Rvk (reduced valley depth) = 0.5 to 5.0 mu m, is provided, on this sliding surface, with a gas phase deposited hard material layer having a roughness depth profile of Rk = 0.5 to 2.8 mu m Rnk = 0.1 to 1.8 microns and Rvk = 0.5 to 4.8 mu m. Also claimed are: (a) a process for producing the above cast aluminium part, in which the surface to be coated is cleaned by ion etching and is then immediately coated from the gas phase (preferably by PVD) at below 250 degrees C with a surface layer of more than 80 atom% hard material content; and (b) an apparatus for PVD coating of the cylindrical interior sliding surfaces of cast aluminium parts (3), the novelty being that (i) cathode rods (1) are mounted for longitudinal movement in a vessel cover (2a); (ii) gas and vacuum connections are located in the vessel base facing the cathode rods (1); and (iii) the vessel walls (4-8) are formed by the interior sliding surfaces to be coated and can be sealed vacuum tightly to the vessel cover (2a) and the vessel base (2b).