Electroless nickel plating is an electroless process in which a deposition that is true to the contours takes place on the entire surface. Even with complex shaped workpieces and in interior areas, an even distribution of layer thickness can be guaranteed. The nickel-phosphorus layer is characterized by hardness, wear resistance and very good corrosion resistance. In addition, the coating properties, such as magnetic/non-magnetic, can be controlled via the phosphorus content. For this purpose, we offer the electroless nickel processes Mid-Phos and High-Phos.
Our electroless nickel processes at a glance
Phosphorus content 6 - 9%
The Mid-Phos process is suitable for components that need to have a higher hardness and wear resistance. It should also be noted that workpieces nickel-plated with the Mid-Phos process are ferromagnetic. The Mid-Phos process produces good corrosion protection, which however does not equal the level of protection provided by the High-Phos process.
Phosphorus content 10-12%
The High-Phos process is suitable for components that need to be highly corrosion resistant and should also be non-magnetic. As the hardness of the nickel-phosphorus alloy decreases with increasing phosphorus content, a lower hardness and wear resistance is produced than with the Mid-Phos process. Hardness and wear resistance can be increased by thermal post-treatment.
The most economical variant for bulk goods
For bulk material such as contact and screw connections, coating in a barrel unit is the most economical method. Here the parts are filled into a perforated drum which rotates around its axis of rotation. The filled drum then passes through the individual steps of pre-treatment, coating and post-treatment. The rotation ensures that the entire surface of each component is refined in the drum.
For careful handling of precision parts
Components which are not suitable as drum material due to their size or geometry are individually placed on a frame or suspended from it. If possible, standard racks are used. For more complicated component geometries, our in-house fixture construction department will produce a suitable frame in the shortest possible time. The rack goods are carefully guided through the coating process, thus ensuring the integrity of precision parts.
With a transparent protective film
By sealing the electroless nickel-plated surface, the corrosion resistance can be additionally increased, the appearance improved and the sensitivity towards finger prints[Griffempfindlichkeit?] significantly reduced. For this purpose, an organic, transparent protective film is applied to the electroless nickel layer. The sealing protects the porous surface similar to a clear varnish and is recommended for casting moulds, for example.
Thermal Treatment Baking
For higher layer adhesion and hardness
During heat treatment, the components are tempered in a furnace between 230°C – 400°C after electroless nickel plating. The hardness of the electroless nickel layer can be increased to about 1000 (± 50) HV by thermal post-treatment. Baking also increases the coating adhesion and improves the wear behavior.
Electroless nickel and hard chrome coating
In hybrid coating, components are first electroless nickel-plated and then hard chrome-plated. In doing so, all the advantages of hard chrome and electroless nickel are being combined in one shift system.
The combination layer guarantees very good wear protection in conjunction with high corrosion protection and is ideally suited for use in an environment with high chemical and mechanical stress.
The layer thicknesses are based on the technical requirements, e.g. 0.030 mm electroless nickel and 0.040 mm hard chrome. Here you can learn more about our hybrid process.
Advantages of coating without external current
In comparison with electrolytic processes such as hard chrome plating, for example, the electroless process has a decisive advantage: the uniform distribution of the coating thickness.
Electroless nickel plating is an autocatalytic reduction process. The electrons required for deposition are not supplied by an external power source as in galvanic processes, but are generated by the chemical reaction of a reducing agent within the electrolyte. As a result, the same deposition conditions prevail on the entire surface of the component, resulting in a uniform layer structure.
Even with complex component geometries, a uniform layer thickness distribution at corners, edges and inner surfaces can be guaranteed.
Properties of your components
- Base material: all steels and non-ferrous metals
- Maximal dimensions: ⌀ 600 x 1100 mm
- Maximum weight: 250 kg
- Rack- or barrel plating
- Layer thickness: 0.003 bis 0.050 mm
- lead and cadmium free process (RoHS compliant)
- Sealing possible
- Phosphorus content: 6 - 9 %
- Hardness in the deposited state: ca. 600 HV 0.1
- Hardness after thermal treatment: ca. 1000 HV 0.1
- Corrosion resistance base material according to DIN EN ISO 9227-NSS: > 480 hours at s/min = 0.030 mm (without thermal treatment)
- Phosphorus content: 10 - 12 %
- Hardness in the deposited state: ca. 550 HV 0.1
- Hardness after thermal treatment: ca. 900 HV 0.1
- Corrosion resistance Base material according to DIN EN ISO 9227-NSS: > 500 hours at s/min = 0.030 mm (without thermal treatment)
The nickel-phosphorus layer is valued in a wide range of industrial sectors for its many functional properties. The properties of the coating thereby largely depend on the phosphorus content. Depending on technical requirements, the coating properties can be controlled by the concentration of phosphorus.
The nickel-phosphorus layer has a very high corrosion resistance against a large number of corrosive media, which increases with rising phosphorus content. In contrast, the hardness and wear resistance decreases with increasing phosphorus concentration.
In general, the hardness and wear resistance of the nickel-phosphorus layer can be increased with a subsequent heat treatment. The magnetic properties of the electroless nickel alloy also depend on its phosphorus content. Workpieces nickel-plated in the Mid-Phos process are ferromagnetic, whereas the High-Phos layer is non-magnetic.
The processes are free of lead and cadmium according to the RoHS directives. According to FDA standards, the material is qualified to get in contact with food.
For orders with increased time pressure, you have the option of using our express service. The express service is coordinated directly with our production control and invoiced via a surcharge.
Before the start of more complex series, we offer you an initial sampling at special conditions. This allows you to convince yourself of the quality of our services. In addition, together we coordinate our production processes ideally.
Tips for the delivery
The delivery condition of the components is one of the decisive factors for optimum coating quality and a short throughput time. Here you will find helpful tips for the delivery of your components.
Betz-Chrom – your partner for strong parts
In the sense of a trustful partnership, you will receive highly qualified technical advice from us that is tailored to your needs. We combine 70 years of experience in surface technology with an innovative and inquisitive corporate culture. Our quality awareness, our occupational health and safety management as well as our measures for environmental protection and energy saving are audited and certified according to DIN standards. As an on-schedule partner with high quality level, we constantly aim to find the optimal process solution for you.