Cast Iron
Iron is a wildly popular and prolific metal used in many different industries and while it’s not quite as popular in the aftermarket parts market, we still use it a lot. Cast iron is not pure iron, pure iron will readily combine with the air which then causes the metal to corrode and rust very quickly. This is why almost nothing is made of pure iron.
Cast iron is iron combined with carbon, usually around 3-4 percent and poured into a mold. After that it’s allowed to cool and harden into shape.
Cast iron is easily poured into molds and it doesn’t shrink as much as steel, meaning it takes less material to fill the mold. This kind of iron is also relatively cheap compared to other metals and is fairly wear and corrosion resistant. But most importantly, cast iron absorbs vibrations, making the parts forged from it and the parts that work with parts made of it sturdier and more reliable. Without vibration damping, especially in places like an engine, vibrations can lead to squealing and broken parts. Most of the famous buildings and structures made of cast iron are from centuries past, back when steel wasn’t invented, but the benefits their makers looked for in a metal still remain today and is why we still use cast iron in some of our parts.
2618 High Tensile Forged Aluminum
2618 High Tensile Forged Aluminum is a fairly popular aluminum that contains both copper and magnesium. Copper has good strength, formability and corrosion resistance and magnesium has some of those same benefits and more as we discussed in more depth in Part 1.
This type of forged aluminum is commonly used for making pistons and rotating aircraft parts because it can take the punishment found in high temperature situations. Aftermarket parts, specifically pistons use this metal because of its ability to handle the heat coming from the higher horsepower generated from various performance parts.
If for some reason this metal is put in an extremely hot situation and this is a big IF, then it will melt rather than explode. Melting can damage some of the surrounding parts, but exploding will send shrapnel flying all over the place.
Nikasil
Nikasil is short for a Nickel and Silicon Carbide composite that was developed and trademarked by MAHLE (a company that offers innovative mobility solutions) in 1967. This composite binds together very tightly and provides a strong surface that can withstand the force coming from a piston. This material is extremely hard and is used to line engine components.
Nikasil is lighter, thinner and harder than iron and is often used in aluminum cylinder bores. Iron may be the cheaper option, but you’ll need to replace it more often compared to Nikasil because it’s easily chipped. Nikasil takes some finesse however, because it has to be applied very thin in cylinders. As Nikasil gets thicker, it loses its elasticity and strength, which are some of its best benefits.
As time goes on, new and innovative materials will be invented. The landscape is ever changing and aftermarket part suppliers will continue to provide amazing parts made of the most complicated sounding materials well into the future. That continued march forward will keep going until we find something that just doesn’t break.
Do you have any questions about all these different metals or some insight you’d like to share? Let us know in the comments.
Sources
- Cast Iron Vs. Cast Steel: http://www.reliance-foundry.com/blog/cast-iron-vs-...
- Aluminum 2618: http://www.aircraftmaterials.com/data/aluminium/26...
- Rotating Assembly 101, 4032 vs. 2618 Aluminum Alloy: http://dsportmag.com/the-tech/rotating-assembly-10...
- Cylinder Electroplating: http://www.electrosil.com.au/news3.htm
- The Flexhone for Nikasil Engine Cylinders: http://www.flexhoneblog.com/2012/11/the-flex-hone-...