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What are the Most Corrosion Resistant Metals

Wednesday, October 16, 2019
Categories : Design

Metals form the bedrock of modern society and commerce in so many ways that it can sometimes be easy to take them for granted. Manufacturers using vast quantities of metals as their raw materials take great care to make the right material choices. This becomes true especially when dealing with metals for delicate and vital applications, like circuits and other microelectronic components. Corrosion resistance is one of the most important factors in selecting the perfect alloy.

Let’s take a look at the most corrosion-resistant metals, including those most appropriate for a few of the more interesting applications commonly seen by AMETEK ECP:

Iridium and tungsten: Tougher than the rest

Understanding of iridium - which, as Scientific American noted, is more common in space than on Earth - as the strongest, most corrosion-resistant metal dates back to the 1800s. In his textbook Platinum Metals Review, L.B. Hunt identifies Smithson Tennant and William Hyde Wollaston as the discoverers of iridium in 1803, though the former is responsible for its name. Numerous attempts by scientists and metallurgists to melt the substance- in the interest of finding practical applications for it - would follow. But it wasn't until physicist Otto Feussner in 1993 that its melting point became known: 2,000 degrees Celsius, or 3,632 degrees Fahrenheit.

indium resistant metal

Pure tungsten has a higher 3,422 Celsius (6,192 F) melting point, and carbon arc is even greater at 5,530 Celsius (9,980 F), but iridium is superior to both for corrosion resistance. It's not prone to problematic oxidation, can't be damaged by acid or silicates and is all but invulnerable to cold. Only potassium or sodium cyanide compounds can significantly damage it. As such, it's highly useful in spark plugs and related electrical contacts, as noted by J.R. Handley in another piece from Platinum Metals Review.

Tungsten's higher melting point results in it being slightly more commonly used - and, in some cases more affordable - than iridium. The two are also included as trace elements in more cost efficient alloys.

Using either one will do wonders for the strength of many electric components.

The nobility of metals?
Noble metals represent a bit of an anomaly on the periodic table. According to the Encyclopaedia Brittannica, the vast majority of scientists believe that gold, platinum, silver, palladium, osmium, rhodium, rhenium, iridium, and ruthenium make up the full list of noble metals. Tungsten, niobium, tantalum and titanium do not make the cut, despite their massive resistance to corrosion. Nor does copper, for that matter, even though copper withstands corrosion reasonably well. (Its only real danger is oxidation; hence its somewhat selective application.)

tungsten resistant metal
A broad spectrum of options

AMETEK ECP uses a wide variety of metals to construct our components, running the gamut from lead and tin to tungsten and pure gold. Additionally, as can be seen in our alloy list, the expert metallurgists at our Coining facility have created hundreds of different combinations of metals to meet the demands of a wide range of challenging applications over the years. If it doesn't already exist on our standard list, chances are high that we can design a solution to meet your needs.

The matter of practicality

In the day-to-day world of manufacturing, metallurgy, electronics and various other related trades, the specific classifications of things don't always matter when it's a question of simply getting the job done - and getting it done quickly, safely and cost effectively. For example: If a standard gold or silver alloy will effectively serve a customer's intended function, it is often best to use off the shelf material.  But if your needs are more specific, we have the design and production capability to create an ideal custom solution to get the job done.

This is yet another example of the attention to detail and exemplary customer service that keeps AMETEK ECP at the head of the electronic and microelectronic components industry. Take a look at our knowledge page to learn more about the metals we offer and the products they help us build.



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