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Workpiece surface integrity deterioration is a bottleneck in minimum quantity lubrication (MQL) grinding cemented carbide. However, nanofluids prepared by adding nanoparticles with excellent antifriction and antiwear properties achieve improved lubrication characteristics. In this study, a surface grinding experiment under four working conditions (i.e., dry, flood, MQL, and nanofluid minimum quantity lubrication (NMQL)) with cemented carbide YG8 is conducted to confirm the effectiveness of NMQL grinding. Results show that the minimum specific grinding force (Ft′ = 13.47 N/mm, Fn′ = 2.84 N/mm), friction coefficient (μ = 0.21), specific grinding energy (U = 17.02 J/mm3), and the largest G ratio of 6.52 are obtained using NMQL grinding. Furthermore, no evident furrow and large deformation layers are found on the surface of the workpiece. Moreover, the scanning electron microscope (SEM) images display that the debris is strip-shaped and slenderer than that under the other working conditions. Meanwhile, the blockage of the wheel pore is improved. Therefore, the validity of NMQL in grinding cemented carbide is verified.

To overcome environmental problems, nanofluid minimum quantity lubrication (NMQL) has been utilized as a burgeoning alternative technique to conventional flood machining, which consumes a large quantity of cutting fluid. Furthermore, spraying parameter optimization is a prerequisite of an effective NMQL grinding and a key to achieving a new sustainable grinding process. However, the spraying parameters of NMQL are multifarious and have varying degrees of influence on lubri-cooling performance. The main objective of this work is to first obtain good spraying parameters in NMQL grinding through the analysis of signal-to-noise ratio and analysis of variance based on orthogonal experiment results. Furthermore, an experimental verification is carried out on the basis of the relative optimization of several groups of spraying parameters from the orthogonal experiments. Power spectral density function (PSDF) and energy spectrum are used to analyze the workpiece and debris microtopography. Consequently, the optimal spraying parameter is obtained. The spraying parameter (palm oil as the base oil, 2 vol% nanoparticle concentration, 0.6 MPa air pressure, and 0.4 gas–liquid flow ratio) achieved the lowest proportionality coefficient (0.245) of PSDF in the low-frequency band and the highest (0.142) in the high-frequency band. Meanwhile, the optimal grinding performance is validated by the workpiece and debris microtopography and long-strip debris morphology.

An investigation into the effect of nanofluid minimum quantity lubrication (MQL) on the temperatures in surface grinding is presented and discussed. Six types of nanoparticles, namely molybdenum disulfide (MoS 2 ), zirconium dioxide (ZrO 2 ), carbon nanotube (CNT), polycrystalline diamond, aluminum oxide (Al 2 O 3 ), and silica dioxide (SiO 2 ), are considered to mix individually with a pollution-free palm oil in preparing the nanofluids. A commonly used Ni-based alloy is chosen as the workpiece material. It is shown that CNT nanofluid results in the lowest grinding temperature of 110.7 °C and the associated energy proportionality coefficient of 40.1%. Furthermore, the relevant physical properties of the nanofluids such as the coefficient of thermal conductivity, viscosity, surface tension and the contact state between the droplets and workpiece surface (contact angle) are discussed to shine a light on their effect on the cooling performance. A mathematical model for convective heat transfer coefficient is then developed based on the boundary layer theories. The model calculation indicates that the CNT nanofluid has the highest heat transfer coefficient (1.3 × 10 4 W/(m K)) which to some extent explains why CNT nanofluid MQL gives the lowest grinding temperature.

The polymorphisms of soil fungal rDNA Internal Transcribed Spacer regions were studied in Korean pine forests of various ages (10–100-year-old trees) by means of cloned libraries, and analyzed to determine the effects of the trees’ developmental stage on soil fungal community structure. The obtained Shannon diversity index (H) and richness (S) indicated that the diversity of the soil fungal community increased significantly with the development of Korean pines (P