Suppression of Polycrystalline Diamond Tool Wear with Mechanochemical Effects in Micromachining of Ferrous Metal

A mechanochemical effect is investigated to reduce diamond tool wear by means of applying a surfactant to low-carbon magnetic iron during diamond turning. Orthogonal microcutting demonstrates the manifestation of the mechanochemical effect through the reduction of cutting forces by 30%, which supports the notion of lower cutting temperatures for reduced tribo-chemical wear. This is affirmed by the reduction in tool flank wear by up to 56% with the mechanochemical effect during diamond turning. While wear suppression increases by 9.4–16.15% with feeds from 5–20 μm/rev, it is not proportional to the reduction in cutting forces (31–39.8%), which suggests that the reduction in cutting energy does not directly correspond with the reduction in heat energy to sustain tribo-chemical tool wear. The strain localization during chip formation is proposed to serve as a heat source that hinders the wear mitigation efficiency. Finite element simulations demonstrate the heat generation during strain localization under the mechanochemical effect, which counteracts the reduced heat conversion from the plastic deformation and the transfer from tool–chip contact. Hence, this paper demonstrates the effectiveness of the mechanochemical method and its ability to reduce tool wear, but also establishes its limitations due to its inherent nature for heat generation.

Mechanochemical effect of ultrasound on sweet potato starch and its influence mechanism on the quality of octenyl succinic anhydride modified starch

The purpose of this study is to reveal the mechanism of preparing high quality modified starch by ultrasonic technology. In this paper, ultrasonic modified starch and octenyl succinic anhydride modified starch with low degree of substitution were prepared under ultrasonic conditions, using sweet potato starch as raw material. The effects of ultrasound on the structure and properties of native sweet potato starch were studied to see whether ultrasound could produce mechanochemical effect on starch. Then the mechanism of ultrasonic effect on quality of octenyl succinic anhydride modified starch was studied by mechanochemical effect. The results showed that after ultrasonic treatment for 1 min, the crystallinity decreased from 37.6 to 33.8% and reaction efficiency increased from 49.43 to 54.39%, while after ultrasonic treatments for 8 and 32–60 min had different changes. These changes showed that ultrasonic treatment produced significant mechanochemical effect on native sweet potato starch. Ultrasound significantly improved the quality of octenyl succinic anhydride modified starch, and its influence mechanism was revealed using the theory of mechanochemistry. This study provides a feasible method for the research of high quality modified starch and lays a theoretical foundation for expanding the application of ultrasound in various fields.

Опыт кулонометрической оценки коррозионноактивной поверхности аустенитной стали в агрессивном электролите при знакопеременной деформации

Исследовано коррозионное поведение сложнолегированного сплава в растворе 3М НСl при статической деформации переменного знака. Результаты, полученные методом кулонометрической регистрации продуктов коррозии в начальный период взаимодействия металла со средой, обеспечили количественную оценку специфики растворения сплава. Полученные результаты позволили объемным методом в сочетании с методом кулонометрической регистрации продуктов коррозии разработать методологию селективной оценки коррозионного поведения многофазных сплавов в условиях агрессивной среды REFERENCES Berenshtein G. V., Dyachenko A. M., Rusanov A. I. Mekhanohimicheskij effekt rastvoreniya [Mechanochemical effect of dissolution] Report Academy of Sciences of the USSR, 1988, v. 298 (6), pp. 1402–1404. (in Russ.) Rusanov A. I., Uriev N. В., Eryukin P. V., Movchan T. G., Esipova N.E. Effect of the strain sign in corrosion under stress. Mendeleev Commun., 2004, v. 14(2), рр. 58–59. https://doi.org/10.1070/mc2004v014n02abeh001875 Rusanov A. , Ur’ev N. B., Eryukin P. V., Movchan T. G., Esipova N. E. Otkrytie effekta znaka deformacii v yavleniyah korrozii pod napryazheniem [Discovery of the sign deformation effect in stress corrosion phenomena]. Report Academy of Sciences, 2004, v. 395(3), pp. 364-366. (in Russ.) Esipova N. E., Blinov E. B., Movchan T. G., Bannykh O. Corrosion Resistance of a Bent Plate from a High-Nitrogen Nonmagnetic 05Kh22AG15N8M2F Steel in Aggressive Media. Russian metallurgy (Metally), 2007(2), pp. 148-75. Movchan T. G., Esipova N. E., Eryukin P. V., Uryev N. B., Rusanov A. I. Mechanochemical effects in processes of corrosion of metals. Russian Journal of General Chemistry, 2005, v. 75(11), pp. 1681–1686. https://doi.org/10.1007/s11176-005-0491-8 Rusanov A. I. Termodinamicheskie osnovy mekhanohimii [Thermodynamic principles of mechanochemistry]. Saint Petersburg, Nauka Publ., 2006, 221 p. (in Russ.) GOST 9.908-85. Metals and alloys. Interstate standard. (in Russ.) Kuzmak A. E., Kozheurov A. V., Efi menko L. A., Ilyukhin V. I. Kulonometricheskaya ocenka korrozii okoloshovnoj zony svarnogo shva pri deformacionnom starenii [Coulometric corrosion assessment of the heat-affected weld zone during strain aging]. Korroziya: Materialy, Zashchita, 2009(1), pp. 43–46. (in Russ.) Kuzmak A. E., Kozheurov A. V. Kulonometricheskaya ocenka skorosti korrozii uglerodistoj stali [Coulometric corrosion rate assessment for carbon steel]. Zashchita Metallov, 2004, v. 40(3), pp. 315–320. (in Russ.) Kuzmak A. E., Kozheurov A. V., Marin A. V. Coulometric evaluation of infl uence of the welding technology of 12Kh18N10T steel on welded zone corrosion. Korroziya: Materialy, Zashchita, 2005(1), pp. 43-46. (in Russ.)

Some Observations on How Mechanochemical Effect Determines Deformation Mode and Chip Morphology in Cutting of Metals

We analyze unsteady plastic flow modes in cutting of metals using high-speed imaging of the deformation zone, in situ. For metals which exhibit high levels of strain hardening, the commonly assumed steady (smooth) flow is inherently unstable. Instead, the cutting is characterized by unsteady sinuous flow, with large-amplitude folding, that is triggered by a plastic buckling instability linked to the material microstructure. A mechanochemical effect caused by Al-Alcohol chemical reaction on workpiece surface, which is coupled to the unsteady flow mode, is highlighted. Experimental results reinforce the hypothesis pertaining to flow stability governing the deformation mode and chip type.