超硬とサーメットの違いは何ですか？

What is the relationship between hardness and strength?

Hardness affects resistance to abrasion, and harder the material the more resistant it is to abrasion.
However, amount of abrasion is not only determined by hardness, but could be affected by adhesions caused by workpieces of certain materials.
Thickness also affects the life of material, and so the environment and manufacturing process must be taken into consideration when selecting cemented carbide grade.
There are many factors related to strength, such as transverse rupture strength, impact strength, fracture toughness value and others, therefore material selection must be made in consideration of these factors.

Why is there a 50% change in volume?

Carbide is a material made by compacting powder during sintering, and there are some gaps inside the carbide where air and particles collide.
Through sintering, the cobalt liquefies, and a 50% reduction in volume occurs when tungsten particles are attracted due to the capillary phenomenon. The contacting surfaces of different powdered particles try to mix and homogenize, inducing the atoms to move in an attempt to create new compounds.