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This study investigates the critical maximum undeformed equivalent chip thickness for ductile-brittle transition ( DBh max -e ) of zirconia ceramics under different lubrication conditions. A DBh max -e model is developed through geometry and kinematics analyses of ductile-mode grinding. Result shows that DBh max -e decreases with increasing friction coefficient ( μ ). An experimental investigation is then conducted to validate the model and determine the effect of dry lubrication, minimum quantity lubrication (MQL), and nanoparticle jet minimum quantity lubrication (NJMQL) conditions on DBh max -e . According to different formation mechanisms of debris, the grinding behavior of zirconia ceramics is categorized into elastic sliding friction, plastic removal, powder removal, and brittle removal. Grinding forces per unit undeformed chip thickness ( F n/h and F t/h ) are obtained. The lubrication condition affects the normal force and ultimately influences the resultant force on workpiece. In comparison with dry grinding ( DBh max -e = 0.8 μm), MQL and NJMQL grinding processes increase DBh max -e by 0.99 and 1.79 μm respectively; this finding is similar to model result. The theoretical model is then assessed by different volume fractions of nanofluids under NJMQL condition with an average percentage error of less than 8.6%. [ABSTRACT FROM AUTHOR]