corrosion resistant ceramic hydraulic piston rod and axles coating

Lunac 2+ Verschleissschutz Deutsch

Semi ceramic Lunac 2+ (duplex) applied
to hydraulic pistons, shafts and axles

Nearly all important surface improvements can be achieved
in one treatment with the hard Lunac 2+ coatings on
hydraulic pistons, shafts and dredging equipment.



The ultimate semi-ceramic coating concept
for hydraulic cylinders, rods and shafts

After 14 years of continuous development, Lunac 2+ uniquely combines all the desired properties needed for a compromise-free coating for hydraulic cylinders. This, when combined with ductile nickel, has been declared by many users to be the best and most suitable material available, especially in their offshore use and with heavy-lifting applications. Apart from
becoming slightly tarnished after a long period of non-use, Lunac 2+ can be considered the first and only coating available that has no serious practical limitations; it is very hard, resistant to scratching and corrosion, seal-friendly, ductile, attractively priced and creates a weld-quality bond with the substrate. Early users report 12 years of uninterrupted service already.

heavy lifting cylinder coating

Enerpac heavy lifting crane, fully equipped with Lunac 2+ coated main strand jack and self erecting support cylinders


Since October 2011 Lunac 2+ duplo complies with following standards:

1-NBD 10300 (Rijkswaterstaat 2010) EPQ corrosion testing, based on ASTM G59-97 (2003) /G61-86 (2003) and ISO 17475 standards.


2-ASTM B117 1000 hours salt spray testing (and even > 2400 hours rating 10).

ceramic hydraulic piston coating Lunac 2+

The corrosion resistance of the very hard (Hv eff. 2200 ) Lunac 2+ coating is very durable, partly because unique compressive stresses keep Lunac 2+ coatings micro-crack free. The exceptionally high degree of bonding with the substrate (for these types of hard coatings) makes Lunac 2+ withstand the harshest environment (chipping, point loads). See the following picture displaying the Lunac 2+ surface after very harsh and 7 years outdoor application. The resistance to scratches is remarkable. Seals (and even the hardest hard fiber guide rings) barely interact with Lunac 2+. Because of this, another important application for Lunac 2+ is on the shafts of (slurry) pumps. The Lunac 2+ process is straightforward for these types of machine parts. Consequently the cost equals that of conventional chromium-nickel coatings and is consequently much more valuable than the most comparable HVOF ceramic plating. Normally finished Lunac 2+ coatings have a roughness of Ra = 0.1-0.3 ┬Ám (0.0039-0.0118") and do not need any post treatment. See the detailed report on the application of Lunac 2+ on hydraulic systems.

One of the most outspoken Lunac 2+ duplex characteristic is the damage resistance due to the anti-sub surface corrosion effect which is hardly ever recorded with a hard coating.

Sub-surface corrosion spot in a chromium-
nickel layer applied to S355J2 carbon steel after
3 years harsh offshore conditions. The lateral
sub-surface spreading is usually accelerated
by a 40-fold in relation to the natural corrosion



corrosion spot in damaged layer

Sub-surface corrosion inhibition effect of a locally damaged Lunac 2+ duplex coated S355J2 carbon steel rod after 4.5 years harsh (African) offshore conditions. The coating has completely been penetrated by a stone chip (picture below: steel corrosion visible in de botton of the spot). The applicant decided not to replace the rod because no oil leackage was recorded and the corrosion spot remained unchanged.





ceramic hydraulic piston coating

Pistons up to 3930 mm / 154.7" can (partially) be plated according
to the Lunac 2+ duplo system (50 + 70 µm / 1.97 + 2.76 mil) and
still be cut afterwards if necessary. Welding very close to the
coating zone is allowed as well as nitrogen cooling
for the benefit of shrinking.

corrosion resistant lock door coating

Lock door hinge-pins (Figure left: Amerongen, the Netherlands, Figure below: Kornwerderzand, the Netherlands) coated with Lunac 2+, operational in the sweet and salt water-air interfaces. Even this corrosion system does not inflict any extra damage to the Lunac 2+ duplex coating system. Mostly the Lunac 2+ system can be judged to be more corrosion resistant than high grade stainless steel. An additional advantage is the possible application of high tensile steel and reduction of the galvanic corrosion potential.

wear and corrosion resistance testing

Test construction lock door at TNO Delft, commissioned by Rijkswaterstaat (Dutch governmental water management). The Lock door pivot has been coated with Lunac 2+ duplex (on mild steel) and will be tested in various salt water concentrations at various speeds. The load is approximately 53 metric ton. Lunac 2+ duplex proved to be stable in this system and no corrosion appeared.

taatsmuts slijtage test

Lunac 2+ duplex lock door bearing (taatsmuts) on steel
foundation after the combined friction- and corrosion test.
Amount of real condition simulated swings: 8600 x