Besides our series and unitary batch production of hydraulic distributors, we also provide surface treatments.

Zinc - Nickel

We provide our customers with Zinc-Nickel treatments for all our steel and casted parts assuring a resistance of 3,356 hours in salt spray camera test which is considerably higher than a C5H (1,500 hours in salt spray camera).


This coating has the following properties and characteristics:

  • It is produced through immersion with uniform black shiny ferrous oxide coatings which are applied on polished and matte sandblasted or stripped iron.
  • The blueing layer has a moderate corrosion resistance and it fulfills the MIL-C-13924 A, Class 1 specifications. The lower the coal is, the better the resistance will be.
  • These layers have a two to six-hours resistance in salt spray camera test at a 20% which is more than enough for indoor parts. An extra resistance can be obtained through the application of an extra oil, wax or lacquer.
  • The blueing layer that is obtained has between 1 and 2 microns.
  • This application is recommended for steel parts which have low chromium content.
  • The blueing process is made under a temperature of 150 degrees, so no deformation problems can be found in the parts.

In general terms, the application of this layer implies an improvement in the parts, an increase in the part’s life as well as a reduction in material costs due to the fact that less expensive materials can be used for machining the parts.


The electroless nickel is a technical surface treatment which is made of a nickel and a phosphorus compound (9-12%). This is applied in a chemical process in which electric power is not used. It is a non-electrolytic process.
The electroless nickel process is an auto-catalytic reduction in which the nickel ions, which are in the presence of phosphorus, transform themselves into a combination between the metallic nickel and the phosphorus which is applied on the part.
The surface treatment is applied without electricity. The part’s thickness is uniform and regular. For this reason, this treatment can be applied in parts which are geometrically complex without any further machining of the part. This process is applied at a very low temperature which makes it possible not to have any deformations in the parts even if the nickel-phosphorus layer is a heat-treated one.
The advantages that our customers can obtain are the following:

  • A good protection against corrosion
  • High hardness: from 450 HV /45 HRC) to 900 HV (62 HRC) with a heat treatment in the applied layer.
  • A good resistance against erosion.
  • A low friction coefficient.
  • Good physical properties for its application in many of the industrial areas.



The phosphate treatment that is applied in metallic parts, mainly steel parts, is used for avoiding corrosion, to improve the oiling or as a pre-treatment to other surface treatment’s application. The blueing is based on a phosphoric acid solution (H3PO4) and phosphate salts. This is applied through immersion or spraying and reacts to the metal’s surface creating a non-soluble crystal clear phosphate coating.
These surface treatments can also be applied to other metals, such as aluminium, zinc, cadmium and tin. The types of phosphates that are mainly applied are made of manganese, iron and zinc. The manganese phosphate is used in order to avoid corrosion and to improve the metal’s oiling. This is only applied through immersion. The iron phosphate is generally used as a pre-treatment for later treatments. Its application is made either applied through immersion or spraying. The zinc phosphate is used for avoiding rusting and as an oiling layer or pre-treatment to other later surface treatments. Its application is made either through immersion or spraying.


The anodizing technique is used to modify the aluminium’s surface through aluminium rusting which protects the part. This is also known as alumina.

This layer is obtained through electrolysis obtaining a layer in microns which provides the aluminium a higher resistance and durability.

The aluminium’s protection level will depend on the microns’ layer that will be obtained in the part.


  • Decorative: it allows the application of colour layers in the part: red, blue, black, green etc.
  • Resistance: hardness. It provides the part a high resistance level against corrosion in industrial and marine environments and even resistance against abrasion.
  • Thermal and electrical insulation.

Rulisa Hydraulic Blocks es el número 1 en fabricación de bloques hidráulicos con un único objetivo: la más alta calidad.