What is Electroless Nickel?
Click here to access an article briefly describing Electroless Nickel written by ECS for a NZ engineering publication.
Since the process requires no applied DC electrical current ( as used in the electrolytic deposition of chromium or nickel ) the result is a very uniform coating – blind holes, threads, channels, recesses or internal areas receive the same amount of deposit thickness as sharp corners, edges or flat surfaces. The total as-plated thickness can often be maintained to a tolerance of <1 micron. Although the Electroless Nickel deposit can be machined, machining to size after plating is often eliminated. In certain applications EN can be used as a substitute for hard chromium.
Hardness & Wear Resistance
Two of the most important properties for many applications are hardness and wear-resistance. The as-plated hardness of Electroless Nickel is 45-49 RockwellC (HV450-500) and can be heat treated to 66-70 RockwellC (HV865-1050). The excellent wear resistance often allows it’s use as a replacement for high alloy materials and hard chrome.
Electroless Nickel is a barrier coating, which means it protects a substrate by sealing it off from a corrosive environment. EN exhibits corrosion resistance against ammonia, sea water, brine, organic acids and reducing inorganic acids. Therefore, it has many applications in the industries such as food, marine, chemical and oil.
Electrical / Thermal conductivity
The thermal and electrical properties of Electroless Nickel coatings will vary with phosphorus content. The electrical resistivity and thermal conductivity of high phosphorus EN is generally 50-200 micro ohms/cm and 0.08 w/cm2/k respectively. These properties make EN coatings an ideal solution for many electrical and electronic applications eg. for contacts and switch gear and are also of great benefit in such applications as heat sinks and heat exchanger tubing.
EN deposits are easily soldered but not welded.
The frictional characteristic of Electroless Nickel is excellent. It provides lubricity, minimizing heat build-up whilst reducing scoring and galling. This is very useful for applications such as plastic moulding. The non-stick properties have considerably improved plastic article release for our customers especially when our specially developed BorENide-H coating has been used.
Regarding galling, just 5 microns of EN will prevent galling between stainless steel parts(the male part would be plated).