Study On Cutting Performance And Tribological Behavior Of Al₂O₃-base Ceramic Tool With Water Vapor As Coolant And Lubricant

Green cutting technology is a developing trend of modern manufacturing industry; both the cutting performance and tribological behavior of tool material are the most important research fields on green cutting technology. This dissertation focuses on the cutting performance and tribological behavior of Al2O3-base composites ceramics tool with overheated water vapor as coolant and lubricant cutting (OWVCL) and dry cutting as compared one. Using tribology, materials science and metal cutting theory, adopting analytical calculation, experimental study, computer simulation and other methods, under different cooling and lubricating conditions, the effects of tribological behavior of the tested ceramics tool materials with different toughening mechanisms, their wear mechanisms, and the work hardening in cutting process are all studied. The above researches to Al2O3-base composites provide theoretical and practical support for the application of Al2O3-base ceramics tools in green cutting.This paper presents three ways, thermal shock testing, theoretical calculation and finite element analysis to estimate the thermal shock resistance of four kinds of Al2O3-base composites ceramics tool, which provides the experimental and theoretical foundation for the wear behaviors of cutting tools with thermal stress on the cutting process. It was found that, by means of phase transformation-toughening, ZrO2adding can effectively improve the thermal shock performance of Al2O3-base ceramics, but the particle toughening one has a poor effect. And the thermal shock performances of three kinds of Al2O3-base composites ceramics were clearly better than that of the single-phase Al2O3ceramics.Using OWVCL technology, the results of fretting wear experiments of Al2O3-base composites ceramics show that the friction coefficient and wear of ceramics materials were all significantly reduced compared to dry friction, which provided the experimental and theoretical foundations to study the wear behaviors of the ceramics tools in cutting process.Adopting the analytic method, a friction model between tool and chip, based on appropriate simplification, was developed for the oblique cutting process under dry cutting and OWVCL technology, which provide the foundation for studying the tools wear behaviors on different coolant and lubricant conditions.composites ceramics was selected as the testing tools, which has good comprehensive properties; the cutting performance of Al2O3-TiC tools was studied in turning ZGMn13and AISI4340. The results showed that, compared to the dry cutting, reduction in the cutting force, surface roughness and cutting temperature were observed with OWVCL technology.With OWVCL technology, the results of wear experiments of the three kinds of Al2O3-base composites ceramics tools in cutting process show that the wear of Al2O3-TiC and Al2O3-SiC tools were markedly reduced, compared to dry cutting. On the contrary, wear of Al2O3-ZrO2tools was increased compared to dry cutting.The work hardening behaviors of ZGMnl3and AISI304in turning using Al2O3-TiC Ceramic tool were studied, compared to the tensile test of AISI304, the results showed that, with OWVCL technology, the work hardening extent was obviously decreased, compared to dry friction. Under the same condition, the work hardening extent of AISI304was considerably lower than ZGMn13, and the quantity of strain-induced martensite of the former is considerably less than the one of the latter, too.