Al2O3/TiC/CaF2自润滑陶瓷刀具切削过程中的减摩机理

在Al2O3/TiC陶瓷刀具基体内加入固体润滑剂CaF2来改善其摩擦学特性,制备出Al2O3/TiC/CaF2自润滑陶瓷刀具.以该陶瓷刀具对45钢进行干切削试验,结果表明添加固体润滑剂的Al2O3/TiC/CaF2自润滑刀具的摩擦因数比未添加固体润滑剂的Al2O3/TiC陶瓷刀具显著降低,表现出了良好的减摩效果.在切削过程中,Al2O3/TiC/CaF2自润滑陶瓷刀具中的固体润滑剂由于受到摩擦和挤压作用而析出,能在刀具前刀面上形成润滑膜,可阻止刀-屑间的粘着,显著降低前刀面与切屑间的平均摩擦因数.对自润滑陶瓷刀具切削后磨损表面显微分析表明,前刀面在切削过程中形成了自润滑膜的生成、破损、脱落和再生的循环过程.因此,Al2O3/TiC/CaF2自润滑陶瓷刀具在其整个生命周期内始终具有润滑效果.

FRICTION REDUCING MECHANISMS OF Al2O3/TiC/CaF2 SELF-LUBRICATING CERAMIC TOOLS IN MACHINING PROCESSES

CaF2 solid lubricants are added to Al2O3/TiC ceramic tool matrix to improve its tribological behaviors. Al2O3/TiC/CaF2 self-lubricating ceramic tools are produced successfully. Dry cutting tests are carried out on 45 steel with this kind of ceramic tool. Results show that the friction coefficient between the tool-chip interface of Al2O3/TiC/CaF2 self-lubric- ating ceramic tool is greatly decreased compared with that of common Al2O3/TiC ceramic tool. A self-lubricating film, which can be acted to reduce the friction coefficient and adhesion, is formed between the tool-chip interface during machining processes for Al2O3/TiC/CaF2 self-lubricating ceramic tool. Microstructure analysis of the wear surface show the self-lubricating film on the tool rake face experiences a four stage cycle, ie. forming, fracture, falling off and re-forming, Therefore, this kind of ceramic tool has self-lubricating behaviours during its full lifetime.