5-8 September 2022
Wyndham Grand Salzburg Conference Center
Europe/Vienna timezone

PACVD- and nitriding processes as surface treatments to enhance corrosion- and wear resistance of piston rods for the hydraulic industry

7 Sep 2022, 14:45
Room 2

Room 2

Oral Presentation Coating technology (PVD, CVD, plasma, thermal spray,….) SURFACE ENGINEERING


Mr Volker STROBL (RÜBIG GmbH & Co KG)


Hydraulic cylinders are one of the main products in the fluid power industry. During their service life, piston rods are exposed to corrosive environments and wear stresses. Thus, a suitable surface treatment for enhancement of corrosion- and wear resistance is of high importance to guarantee a long lifetime of the parts. The main requirements to piston rod coatings include high surface hardness as well as a low and evenly distributed surface roughness to minimize wear of sealing and coating.
During the gas- or plasma nitriding process, atomic nitrogen diffuses into steels and leads to hardening of the surface and edge zone, where formation of nitrides with alloying elements such as Cr, Al and V represents the biggest contribution to hardness increase. Due to its ceramic character, the compound layer consisting of iron-nitrides, leads to an increased corrosion- and wear resistance. To reach a further increase in corrosion resistance, an oxidation step can be added after nitriding in the same process. Moreover, the slightly softer oxide layer can serve as a run-in layer to reduce sealing wear and the small pores act as a lubricant reservoir.
The PACVD technology can be used to deposit Si-doped amorphous carbon coatings (a-C:H:Si, “Diamond Like Carbon” - DLC). The Duplex DLC Xtended® process is a combination of plasma nitriding with subsequent DLC coating, enabling edge-zone hardening and coating in a single process.
Treatment of steels with RÜBIG technologies GASOX® or PLASOX® meet the requirements of 24-120h in the neutral salt spray test (NSS, ISO 9227). The Duplex DLC Xtended® thick coatings withstand more than 500h in the NSS test.
A comprehensive characterization of RÜBIG technologies in comparison with commercially available Cr- and Ni-Cr coatings including corrosion- and tribological testing with sealings as counterbody showed the applicability of of GASOX® and PLASOX® as alternatives for one layer Cr- coatings. For higher corrosion-requirements, Duplex DLC Xtended® coatings may be used.

Register for the Tom Bell Young Author Award (TBYAA)? Yes
Speaker Country Austria

Primary author

Annika WAGNER (RÜBIG GmbH & Co KG)


Mr Christian ÜBLEIS (RÜBIG GmbH & Co KG) Mr Matthias KRAWINKLER (RÜBIG GmbH & Co KG) Dr Christian DIPOLT (RÜBIG GmbH & Co KG) Mr Volker STROBL (RÜBIG GmbH & Co KG)

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