Standard_Parts_Catalogue

| Surface Treatments Page 2171 Electropolishing Galvanizing Nano-Passivation This electrochemical process reduc- es surface roughness and removes impurities, microfissures, and micro- structural defects in stainless steel parts. The workpiece is placed into an immersion bath containing mate- rial-specific electrolytes and forms the anode from which a thin metallic layer is removed after direct current is applied. Electropolishing operates on the mi- cro-scale and removes rough peaks, while generating increased abrasion at the edges, which also makes elec- tropolishing ideal for fine deburring. The process is gentle on the structure since there is neither thermal nor me- chanical stress. In addition to decorative applications, electropolished elements are used, for example, in the chemistry and food industry, in container construc- tion, or in medical technology. This general term stands for various processes for the application of pure zinc layers to steel. In all cases, the objective is to protect the substrate against corrosion for as long as pos- sible. The galvanic zinc-coating most com- monly used by Ganter uses a bath in which an electrolyte connects the workpiece which acts as the cathode to an anode made of pure zinc. Depending on process parameters, the layer thicknesses which are de- posited in this way range from 2.5 to a maximum of 25 μm. The process, which is standardized according to DIN 50979, is mainly suitable for cor- rosion protection of small parts. The zinc which is present on the sur- face may also be exposed to corro- sion depending on ambient condi- tions and is therefore subsequently protected by additional passivation to prevent zinc corrosion (white rust). In addition, treatment with suitable chromium(VI)-free solutions creates a chromate layer, which considerably improves the corrosion resistance of the zinc coating. Dyes can also be in- troduced in this process step. Blueish or black transparent coloring is most commonly observed. This process provides exceptionally good corrosion protection with min- imal layer thicknesses for die-cast zinc parts. The passivation layer is only 0.3 to 0.5 µm thick and does not affect dimensional accuracy. Ganter, usually uses an anthracite-colored layer. The passivation consists of a chro- mium(III) layer and an overlying layer consisting of nanoscale SiO 2 parti- cles which have self-healing proper- ties. If the surface becomes damaged down to the metallic substrate, the SiO 2 particles migrate through the potential differences in a mobilized way to the unprotected area to re- close the layer. Nano-passivation can be performed quickly and economically as a spray or immersion process—and is also a good primer for subsequent, further coatings, such as powder coating. Finishes continued