Synthesis and characterization of carbon-based MWCNT combined with CaO to improve the surface characteristics of DED-processed Ti64 alloy machined under MQL conditions

•Analyzed wettability, viscosity, density, and thermal conductivity of MWCNTs (0.25%-1.25%).•Conducted milling tests: dry, flood, CaO-MQL, and nanofluid-MQL (N-MQL).•MWCNTs in CaO reduced contact angle to 15.53° at 1.00 wt.%.•MWCNTs enhanced fluid properties; N-MQL showed superior surface quality. The capacity of additive manufacturing (AM) to create intricate geometries and minimise material waste has drawn a lot of attention. Nevertheless, post-processing steps like machining are frequently needed for AM components to improve their functional surfaces. High temperatures are produced at the tool-workpiece-chip contacts during cutting operations, which lowers tool life and efficiency. Although petroleum-based cutting fluids (CFs) are commonly used to control these temperatures, they pose environmental, health, and cost concerns. Minimum quantity lubrication (MQL) with vegetable oil (VO) has emerged as a promising alternative that offers improved machining performance and environmental friendliness. However, MQL’s effectiveness of MQL may be limited under aggressive machining conditions, necessitating the use of nanoparticles (NPs) to enhance performance. In this investigation, the wettability, dynamic viscosity, density, and thermal conductivity of multi walled carbon nanotubes (MWCNT) at varying wt. concentrations (0.25% to 1.25%) are examined. Following that, the milling tests are conducted in the following conditions: dry, flood, MQL (CaO), and nanofluid-MQL (N-MQL). The outcomes show that the addition of NPs to CaO reduces the contact angle to 15.53° at 1.00 wt%, indicating better wettability. Furthermore, the incorporation of MWCNTs results in a significant improvement in the dynamic viscosity, thermal conductivity, and density of the VO. N-MQL, on the other hand, results in an enhancement in surface quality in contrast to other cutting strategies.