Generally speaking, in the process of ball milling, the wear of balls will decrease with the increase of hardness. At the same time, the deformation of the balls is small, which reduces the energy absorbed by the balls during impact, and uses more energy to impact particles, thus increasing the efficiency of ball milling.
But the fact is that the grinding balls are not the harder the better, but has an optimum range. The grinding balls with higher hardness has lower wear rate, but for the grinding efficiency, when the hardness exceeds the optimum value, it will have a negative impact.
There are two negative impact of high hardness of grinding balls in laboratory ball mill: the rebound of grinding balls is aggravated after impact, which leads to some energy loss and reduces the energy used for ball milling; the grinding balls with higher hardness are sliding badly when they extrude particles between balls, which can not effectively grind materials.