Is normal steel harder than stainless steel

chemistry Which is the hardest metal?

In the past, what scratched the other was considered harder

Colloquially, we know very well what we mean by "hard": the harder something is, the more it hurts when you bump your head on it. In the past, hardness was mainly defined in relative terms: one material was used to scratch another. And the material that each other scratched - that is, left scratches - was the harder material.

According to this, plaster of paris is harder than chalk or talc, glass is harder than plaster of paris, quartz is harder than gold, ruby ​​is harder than quartz and diamonds are the hardest of all. The result is a scale from 1 to 10. Talc has a hardness of 1, diamond has a hardness of 10 and osmium has a hardness of over 7.

Exact procedures for the depth of penetration into a material

Today, hardness is usually defined a little differently. Hardness describes the resistance that a material has to oppose a penetrating body. To the annoyance of the owner, if I throw a stone on a car sheet, it penetrates deeply and leaves a permanent dent. A car sheet is therefore not as hard as a steel plate, for example. And so there are precisely defined procedures for measuring the depth of penetration into a material.

Osmium is one of the platinum metals

There are a number of fairly hard metals that chemically belong to the platinum group. They have the property that they are quite dense; one cubic centimeter of platinum weighs about 20 grams - that is, twenty times that of water. One can imagine that the density of a metal also has to do with how hard it is. Platinum is quite a hard metal, but there are a few elements that are not far from platinum in the periodic table of the elements and are similarly dense, but much harder.

These include tungsten or iridium. They are not much less hard than osmium. And because these metals are so dense - which means nothing else than that the individual atoms are very dense and compact - they also have a high melting temperature: Osmium only melts at around 2,800 ° C.

This high melting temperature was one reason why osmium, but also tungsten, was used primarily as a conductive metal in incandescent lamps. We know the well-known incandescent lamp company Osram - the name is derived from this combination: osmium and tungsten.