氧化铝陶瓷和氧化锆陶瓷都有很多种。天然氧化铝是刚玉，莫式硬度为9 ，立方氧化锆的莫式硬度为8.5 。因此纯氧化铝和氧化锆来说氧化铝的硬度更高，也更耐磨。但是氧化铝陶瓷是混合体，它人工经过配料然后烧结而成的，并非纯脆的刚玉。因此要看陶瓷的氧化铝含量，有的厂家有95%氧化铝陶瓷，97%氧化铝陶瓷，99%氧化铝,99.7%氧化铝陶瓷等多种陶瓷。而氧化锆陶瓷硬度也非常高。
如果在离心作用力下工作的研磨介质材料好选用氧化锆，其单斜晶型密度为5.85。而氧化铝的密度只有3.9-4.0。因此选氧化锆做研磨介质会产生更大的剪切力，提高研磨效率。 如果做为研磨罐，或轴承等部件的材料，则选择硬度更高的高纯氧化铝陶瓷效果会更好。（图/文www.cddnvga.cn）
中译英：
Alumina ceramic and zirconia ceramic has many kinds. Natural alumina corundum, Mohs hardness of 9, cubic zirconia mullite hardness is 8.5. Thus pure alumina and zirconia, alumina higher hardness, is more resistant to. But is it a mixture of alumina ceramics, artificial after dosing and then sintered, not pure corundum. So to see ceramic alumina content, some manufacturers have 95% alumina ceramic,97% alumina ceramics,99% alumina,99.7% alumina ceramics and other ceramic. The zirconia ceramic hardness is very high.

If the centrifugal force of the grinding medium material work under the best selection of zirconium oxide, its monoclinic density of 5.85. While alumina density only 3.9-4.0. So choosing zirconia do grinding medium will produce greater shear stress, to improve the grinding efficiency. If as a grinding tank, or bearing and other parts of the material, choosing higher hardness of high purity alumina ceramic, the effect will be better.