将羟基磷灰石复合涂层按照特征分为三类，即单层复合涂层、双层复合涂层和梯度复合涂层。

Hydroxyapatite composite coatings were classified into three kinds according to their feature, i. e. single layer composite coating, double layer composite coating and gradient composite coating.

youdao

将羟基磷灰石复合涂层按照特征分为三类，即单层复合涂层、双层复合涂层和梯度复合涂层。

Hydroxyapatite composite coatings were classified into three kinds according to their feature, i. e. single layer composite coating, double layer composite coating and gradient composite coating.

youdao