S.P23 Share of friction and lubrication under microindentation of number of metals
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ZHITARU, Raisa, PARSHUTIN, Vladimir, PARAMONOV, Anatolii, KOVALI, Alexandr, AGAFII, Vasile. S.P23 Share of friction and lubrication under microindentation of number of metals. In: Materials Science and Condensed Matter Physics, 13-17 septembrie 2010, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2010, Editia 5, p. 299.
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Materials Science and Condensed Matter Physics
Editia 5, 2010
Conferința "Materials Science and Condensed Matter Physics"
Chișinău, Moldova, 13-17 septembrie 2010

S.P23 Share of friction and lubrication under microindentation of number of metals


Pag. 299-299

Zhitaru Raisa, Parshutin Vladimir, Paramonov Anatolii, Kovali Alexandr, Agafii Vasile
 
Institute of Applied Physics
 
Disponibil în IBN: 22 aprilie 2021


Rezumat

Taking into account wide application of microhardness it is important to understand the physical nature of microindentation process and evolution of this process with variation in the external deforming force and friction force at indentor penetration into material. Therefore, in this paper are studied: the microhardness dependence on external force of miroindentation and the influence of lubrication of surface of some metals on this dependence. The investigations were carried out on steel 45(quenched and unquenched), steel 3, cupper (pure) and aluminum. Microhardness was measured by means of PMT-3 device. The load value ranged within 0,1-2 N. Polyalphaolefine oil, petrolatum oil, and pentaerythritol estere were used as lubricants. The friction force between the indentor and material varied using the lubrication oils. Investigations were carried out at room temperature. The results obtained allow concluding that lubrication leads mainly to microhardness decrease and only in some cases to its increase. The first effect is pronounced for hard metals and large loads on indentor and, quite the reverse, for soft metals at small loads, fig. It is known that the state of the deformed zone near indentation undergoes significant changes with increase of load. In this case the strain mechanism also changes; gradual transition from the dislocation mechanism to displacement along boundaries (grain-boundary slipping) is observed; that is, the dominant role is played by rotation strain along with translational ones. The changes of initial structure of metal and the strain mechanism under indentation result in the friction force change too. The results obtained allow proposed that effects revealed are stipulated by the evolution of structure and stress state of metal layer under microindentation process. It is assumed that the lubrication influence on microhardness value is determined by two interconnected stages of microindentation process: at the loading stage, by the modification of structural condition of the surface metal layer in the region of indentor- metal contact; at the unloading stage, by value of elastic recovery of stresses formed at the loading stage. The joint action of the both factors determines variations in the microhardness with the use of lubrication. The same factors determine the microhardness dependence on indentor load value in lubricant media.figureFig. Microhardness dependence on indentation load for the unquenched (a) and quenched (b) samples of steel 45. Curves (1) correspond to the case of indentor penetration without lubrication; curves (2, 3, 4) with lubrication.