Aerospace would have problems without nickel. Although less than 1% of the weight of a typical airliner is nickel, it is vital for critical components in engines, landing gear and batteries. It is also being incorporated into many of the carbon fibre composites that are slowly replacing aluminium in airframes.
Although heavier than aluminium, nickel excels at temperature tolerance. It shrinks and expands far less than aluminium and its melting point is far higher. Despite this, it is easy to cast which helps to control costs. It is also four times as hard and therefore has great resistance to wear, even at high temperatures.
A particularly useful characteristic of nickel is the ease with which it forms alloys and composites with other materials. This means that many of the useful characteristics of nickel (which also include electrical and magnetic properties) can be transferred to other base materials.
Nickel composites
A popular material for mating with nickel is PTFE (polytetrafluoroethylene). Nickel-PTFE composites provide excellent dry lubrication suitable for hard wearing applications such as bearings. The material also repels water, oils and other liquids, adding to its already good corrosion resistance. You can read about some particularly useful composites of nickel here https://www.poeton.co.uk/apticote-450-nickel-polymer-composite/.
When even higher temperatures might be encountered, it is possible to combine nickel with boron nitride.
Nickel and nickel composite qualities can be transferred to other materials by a variety of surface treatments. One is chemical or “electroless” plating.
The many benefits in aerospace
Nickel alloys have increased the temperature at which engines can be operated and higher operating temperatures mean greater fuel efficiency. As a result, nickel saves fuel, lowers emissions and extends aircraft range.
Carbon fibre composites often incorporate about 36% of a nickel alloy called “invar”. Some find uses in airframes but they are more commonly encountered in the moulds used to build them. These nickel carbon composites can be constructed with high tolerances and can be baked at high temperatures and pressures.
The acceleration, deceleration and weight of aircraft taking-off and landing has to be carried through their landing gear. This is only possible because of a nickel-cobalt-steel composite that is highly resistant to cracking, chipping, twisting, fracturing or fatigue.
Nickel coatings also find uses in fasteners, circuit breakers, valves, pumps, extruders, clutches, splines and spindles.
