Platinum is known for being durable and resistant to tarnish and wear.
Which is Harder?
You can look at the harness of a material and easily gauge
how it will hold up to wearing. There are many different kinds of hardness though.
- How well does it hold up when scratched against something? This is determined by the Mohs hardness test.
- Does it get dented when you bang it against something hard? This is determined by the Vickers hardness test.
Palladium has a Mohs hardness of 4.75 and Vickers hardness of 461MPa. Platinum, on the other hand, has a Mohs hardness of 4.25 and Vickers hardness of 549MPa. That means if you rub palladium and platinum, the former will scratch the latter. However, platinum will resist dents more easily.
When it comes to measuring the resistance to tarnish, it is seen that on heating to around 850 degrees Celsius, palladium tarnishes easily. However, platinum only develops a very thin layer of oxide at the same temperature.