Abstract: A method for diffusion coating a surface of a metal substrate with zinc comprises the steps of: a1) applying a suspension, comprising a liquid and zinc and/or a zinc alloy as a diffusion source or zinc donor, onto the surface of the substrate to be coated, or a2) applying a liquid onto the surface of the substrate to be coated and subsequently applying zinc and/or a zinc alloy as a diffusion source or zinc donor onto the liquid; and b) drying the substrate obtained in step a1) or a2); c) carrying out a heat treatment of the substrate obtained in step b) at a temperature between 200 and 500° C., but below the melting temperature of the diffusion source in a shielding gas atmosphere; and d) removing the mixture applied in step a1) or a2).

Abstract: In a method for the coating of a surface of at least one substrate with zinc in which the at least one substrate to be coated is heat treated together with zinc as the coating agent at a temperature between 200 and 500° C., wherein, before the start of the heat treatment in the reaction space in which the substrate to be coated is heat treated, the oxygen content in the atmosphere contained in the reaction space is set to less than/equal to 5 volume percent and the heat treatment is then started in the atmosphere obtained in this manner in the reaction space and the heat treatment is carried out in the reaction space, with no gas being supplied into the reaction space during the heat treatment or with no gas containing oxygen being supplied or with gas being supplied which has been pretreated so that it has an oxygen content of a maximum of 100 ppm.

Abstract: The present invention relates to a hydraulic piston and a process for its surface treatment in order to improve above all the wear resistance and corrosion resistance at the surface of the piston. As a favorable manufacturing process for the surface treatment of an above-mentioned hydraulic piston, a multistage process is disclosed which arranges a nitrocarburization with a subsequent oxidation and a following mechanical solidification of the oxidized surface for the piston. As a result, several superposed layers—layer of oxide, connecting layer, diffusion layer—develop at the piston surface which exhibit the desired qualities.