Development and machinability evaluation of MgO doped Y-ZTA ceramic inserts for high-speed machining of steel

ABSTRACT

In current high productivity manufacturing era, it is necessary to develop non-conventional newer tool materials. Here, an attempt has been made for developing MgO doped zirconia-toughened alumina (Mg-ZTA) using powder metallurgy process route. The 3 mol% yttria stabilized zirconia (YSZ) (10 wt%), alumina (Al₂O₃) (90 wt%) with varying percentage of magnesium oxide (MgO) (0–1 wt%) are mixed to study the phase transformation and uniaxially pressed into square inserts with 0.8 mm nose radius and sintered at 1,600ºC for 1 h in pressure less condition. The maximum hardness of 17.04 GPa, fracture toughness of 5.09 MPa m^1/2 and flexural strength of 502 MPa, respectively, has been reached at 0.6 wt% of MgO due to more metastable tetragonal phase. The performance of the insert has been evaluated by machining AISI 4340 steel (radius 75 mm) in lathe. The performance with respect to flank wear, cutting force and surface roughness is quite impressive at different cutting speed even after 20 min of machining. It can be inferred that MgO doped ZTA insert can be used for medium to high-speed machining in current manufacturing scenario and is very promising to replace carbide or coated carbide inserts in coming days.

KEYWORDS:

• Alumina zirconia ceramics
• cutting insert
• flank wear
• fracture toughness
• hardness

Acknowledgment

The authors would like to thank Prof. (Dr) Harish Hirani, Director, CSIR-Central Mechanical Engineering Research Institute, Durgapur, for his kind approval to publish the article in a reputed journal. The authors also gratefully acknowledged Mr. Palash Chowdhury, Staff members and research fellows of Centre for Advanced Materials Processing (CAMP) for their continuous effort in the experimentation part. The author also thanks to Central Research Facility, Indian Institute of Technology, Kharagpur and CSIR-CMERI, Durgapur for helping us to carry out the characterization study like XRD, FESEM, etc.

Additional information

Funding

Authors are highly grateful to the Science and Engineering Research Board (SERB) of Department of Science and Technology (DST), Govt. of India, New Delhi for the financial support (SB/S3/MMER/0035/2014 dated 22-05-2014).