Cobalt is pretty easy to come across!

Cobalt is pretty easy to come across!

Despite pure cobalt metal (Co), as show in the form of electrolytic flakes below not being all that easy to get outside specialized sources, cobalt ions and alloys are rather widely available.

Flakes and pieces of pure electrolytic Co metal.

First of all, cobalt metal is an alloying element in many steel types, such as high speed steels (HSS-Co in this case). Addition of cobalt works well in increasing the overall hardness and wear resistance of steels, but also helps keep these characteristics in high temperatures the tools are working in.

Cobalt, however hinders the ability to create martensitic microstructure in steels through increasing the critical speed of cooling required to fully transform the microstructure. Therefore this metal is mostly added in small amounts and in applications that require the benefits.

HSS-Co drilling-tapping bit with TiN coating.

Another way to come across cobalt, this time in the form of Co2+ and Co3+ ions, is to go to an antique store or just look through glass items in your house. My samples of cobalt glass are in the form of a tiny glass bottle and a marble from a well over 100 year old set. The deep blue color is usually achieved through addition of cobalt oxides or other compounds, like carbonates to molten glass. Depending on the saturation of the additives, such glass can look almost opaque and black, but looking through it at a light source will usually reveal the wonderful color.

Cobalt glass bottle.

Cobalt glass marble.

Cobalt doped zirconia.

I've also learnt that cobalt 3+ ions are used to give synthetic gemstones, particularly cubic zirconias (c-ZrO2) a light violet/lilac color. That's why I also included a photo of such stone from my collection.

Thermite cobalt metal (or Co-Fe alloy).

Before owning any pure samples of cobalt metal, I had been trying to produce it myself through an aluminothermic reduction of cobalt oxide with fine aluminum powder. I used a sparkler to initiate the reaction, as it needed a fair bit of encouragement to start, and as a result, I received some small beads of cobalt and a light blue coating on every surrounding surface. The metal is without a doubt heavily contaminated though, as the steel rod inside the sparkler has partially melted from the heat of the reaction.