自润滑陶瓷刀具切削过程中的减摩机理研究

采用热压法CaF2作为添加剂,Al2O3/TiC(LT55)作为基体制备出了自润滑陶瓷刀具,并对其进行了干切削试验.在切削过程中,在刀具前刀面上能形成自润滑膜,从而使刀具具有减摩性能.用扫描电镜观察了前刀面和后刀面微观结构.LT55在切削加工45钢时,Al2O3/TiC/CaF2(ATF)自润滑陶瓷刀具前刀面的平均摩擦系数比未添加固体润滑剂的LT55陶瓷刀具显著降低,其主要原因是在ATF自润滑陶瓷刀具的前刀面上形成了一层固体润滑膜,这层润滑膜可起到减摩作用.自润滑刀具在切削过程中,自润滑膜经历生成、破损、脱落、再生成的循环过程,因此,ATF自润滑陶瓷刀具在其整个生命周期内都具有自润滑效果.自润滑刀具后刀面不存在固体润滑膜,具有较明显的磨料磨损特征.

SELF-LUBRICATING MECHANISM OF A SELF-LUBRICATING CERAMIC CUTTING TOOL

An Al2O3/TiC(LT55)self-lubricating ceramic tool with the addition of CaF2 was produced by hot pressing.Dry cutting tests were carried out with respect to 45 steel and Al2O3/TiC/CaF2(ATF)self-lubricating ceramic cutting tools.The friction of the ATF tool was reduced by forming a film on the tool rake face.The morphologies of the rake face and rear face of the tool cutting the steel in air were observed by a scanning electron microscope.It was found that the friction coefficient of ATF tool was lower than that of LT55 due to a lubricating film generated on the rake surface of ATF tool.The film follows the forming,destroying,falling off and reforming circle processes,therefore,ATF tool has self-lubricating function in its whole lifecycle.There was no a lubricating film on the rear face of the ATF tool,where existed a obvious wear feature.