REACH compliant coatings:

Hard chrome
alternatives

Functional hard chrome alternatives in line with legislation


CIDETEC has developed coatings that are an alternative to hard chrome, which in addition to complying with the properties of hardness, wear, friction and resistance to corrosion also comply with the applicable regulations to which the restriction of chromium VI refers.

Concept

Hard chrome plating has been one of the most commonly employed processes to obtain coatings with good properties with respect to their capacity to resist the most extreme conditions, while maintaining its quality, in very varied industries.

An additional advantage is that it is a simple, versatile and cheap process. The main inconvenience is that due to the presence of hexavalent chromium in its formulation it is classed as carcinogenic by the International Agency for Research on Cancer (IARC) and regulated by REACH, which has forced us to find an alternative coating.

In order to respond to this need CIDETEC has developed multilayer coatings using electroless nickel, composite electroplating processes and coating usings nickel and tugnsten, which all show high resistance to wear and abrasion. They have anticorrosive and innocuous properties which enables their use as a real alternative to the current coatings made of hard chrome.

Aspect

Hardness

Wear
resistance

Abrasion
resistance

High
melting point

Our approach

REACH

REACH (Regulation on registration, evaluation, authorization and restriction of chemicals) was adopted by the European Union with the purpose of improving the protection of human health and the environment against the risks chemical products can pose, while at the same time it boosts the competitiveness of the chemical industry in the EU.


Electroless nickel multi-layers

Electroless nickel is a process based on chemical reduction of metal ions precursor. The resulting coatings contains significant proportions of the active element present in this reducing agent, obtaining nickel-phosphorus (NiP) alloys in hypophosphite baths.

The alternative to hard chrome are those with a low P content. However they have limited corrosion resistance. In order to increase the corrosion resistance of this type of coating, CIDETEC has developed a multi-layer process. The generated interfaces act by avoiding the propagation of cracks and defects along the thickness, improving the performance of the coating and maintaining the mechanical properties.

This is a very versatile technology as it also makes possible to combine layers of a different nature, allowing different functionalities to be combined in a single coating.


Ni ELECTROLESS COATING CRYOFRACTURE


Article:

A. Salicio-Paz, H.Grande, E.Pellicer, J.Sort, J.Fornell, R.Offoiach, M.Lekka, E.García-Lecina, “Monolayered versus multilayered electroless NiP coatings: impact of the plating approach on the microstructure, mechanical and corrosion properties of the coatings”, Surface and Coatings Technology 368 (2019) 138.

Composites

Composite coatings are obtained by including particles (usually polymeric, ceramic or oxides) in an electrolytically deposited metal matrix. These coatings synergistically combine the properties of the two materials to obtaining a coating with superior properties to each component.

CIDETEC has developed formulations based on nickel/silicon carbide (Ni/SiC), cobalt/chromium carbide (Co/CrC), nickel/ tungsten carbide (Ni/WC) and nickel/alumina (Ni/Al2O3) composites, all with excellent wear and abrasion resistance.


COMPOSITE COATINGS ON AERONAUTIC GEARS

ALUMINA PARTICLES INTEGRATED IN THE COATING

SEM image in section of composite coating of metal matrix.

Article:

- E. García-Lecina; I. García Urrutia; J. A. Díez; J. Fornell; E. Pellicer; J. Sort. Codeposition of Inorganic fullerene-like WS2 nanoparticles in an electrodeposited nickel matrix under the influence of ultrasonic agitation. Electrochimica acta. 114, pp. 859 - 867. Elsevier, 2013.

- E. García-Lecina; I. García-Urrutia; J.A. Díez; J. Morgiel; P. Indyka. A comparative study of the effect of mechanical and ultrasound agitation on the properties of electrodeposited Ni/Al2O3 nanocomposite coatings. Surface & Coatings Technology. 206, pp. 2998 - 3005. 2012.

- E. García-Lecina; I. García-Urrutia; J.A. Díez; F. Smeacetto; G. Gautier; R. Seddon; R. Martin. Electrochemical preparation and characterization of Ni/SiC compositionally graded multilayered coatings. Electrochimica Acta. 54, pp. 2556 - 2562. 2009.

Nickel-tungsten coatings

CIDETEC has developed NiW formulation that has excellent hardness properties and corrosion resistance, even at high temperatures, as well as an electroplating process adapted to its characteristics.


NiW ADVANTAGES

PropertyHard chromiumNiW
Pre-treatment In the hard chrome bath, this process can generate problems with high-alloy steels Degreasing and stripping line. By controlling the process parameters it is possible to treat high alloy steels
Efficiency 20-25 % 45-50 %
Thickness Between 25 and 100 μm. For pieces that require a thickness between 80-300 μ Good property results with a thickness of 25-30 μm. Allows later correction using a higher thickness (tested approx. 100 μm)
Hardness 800 - 1000 Hv 1100 Hv with heat treat-ment at 400 °C for 1 hour
Uniformity of deposit Accumulation in zones of high current density Good uniformity
Adherence Easily propagation of cracks. Poor on sharp edges Good on all surfaces of the piece. Tested on steel (type F1 and F124)

Abrasion/wear at 10 000 cycles
Good. Taber Index: 3.8 Slightly superior to hard chromium. Taber Index: 5.4
Corrosion resistance Resistance inferior to 200 h neutral salt spray for coatings of 25-30 μm Excellent. More than 400 h in neutral salt spray for coatings of 25-30 μm

Article:


- I. García-Urrutia; L.A. Jones; J.A. Díez; C. Müller. Effect of bath stabiliser on performance of electrodeposited Ni–W coatings. Transactions of the Institute of Metal Finishing. 89, pp. 132 - 136. 2011.

- I. García-Urrutia; J.A. Díez; C. Müller; P. Calvillo. Estudio en célula Hull de un baño electrolítico de NiW y evaluación de sus propiedades. Metalurgia. 45(2), pp. 92 - 99. 2009.

- N. Imaz, J.A. Díez, M. Ostra, M. Sarret, E. García-Lecina, “Advanced Ni-W coatings obtained by the combination of pulse plating and chemometric techniques”, Transactions of the Institute of Metal Finishing 92 (2014) 305

/ - N. Imaz, J.A. Díez, J. Sort, E. Pellicer, H. Grande, E. García-Lecina, “Thermal treatment effect on the mechanical, tribological and corrosion properties of Ni-W alloy obtained by direct and pulse plating electrodeposition”, Transactions of the Institute of Metal Finishing 95 (2017) 31-38.

Opportunities

PETROCHEMICAL
AND CHEMICAL
INDUSTRY

AUTOMOTION

MOLDS
AND DIES

AEROSPACE

MINERY

More info


 

Dr. Eva García-Lecina

DIRECTOR OF THE CIDETEC INSTITUTE FOR SURFACE ENGINEERING

 

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