scholarly journals Wear resistance of strengthened layers with nanocrystalline structure in friction with boundary lubrication

2020 ◽  
Vol 6 (1) ◽  
pp. 83-90
Author(s):  
Volodymyr Gurey ◽  
Keyword(s):  
Surface Layer ◽  
Cast Iron ◽  
Contact Area ◽  
High Speed ◽  
Sliding Friction ◽  
White Layer ◽  
Friction Pair ◽  
Experimental Studies ◽  
Friction Treatment ◽  
Transverse Grooves

Friction treatment refers to surface strengthening (hardening) methods using highly concentrated energy sources. The source of thermal energy occurs in the contact area of the tool-part due to high-speed friction (60–90 m/s) of the tool on the treated surface. The heating rate of the metal surface layer is 105–106 K/s. After moving the energy source from the contact zone, high-speed cooling of the surface layer of the metal takes place. The cooling rate is 104–5∙105 K/s. Under the action of high-speed heating and cooling of the contact area of the tool-part in the surface layers, a strengthened (hardened) nanocrystalline (white) layer is formed. The formed nanocrystalline surface layer has other physical, mechanical, chemical properties in comparison with the base metal of the part. Studies have shown that in the process of friction treatment of working surfaces of parts made of Steel 40NiCr6 (quench hardening and low-temperature tempering) a strengthened layer with a thickness of 250–320 μm with a hardness of 7.6–9.2 GPa is formed. The grain size of the surface strengthened layer was 20–40 nm near the treated surface. The formation of the strengthened layer is influenced by the shape of the working surface of the tool. Thus, a strengthened layer of greater thickness and hardness is obtained when machining with a tool with transverse grooves on the working part than with a tool with a smooth working part. Experimental studies in friction with maximum lubrication of pair “Steel 40NiCr6 and Grey Cast Iron GG20” showed that the strengthened nanocrystalline layer significantly increases the performance during sliding friction. Only samples made of steel were strengthened, counter-samples made of gray cast iron were not strengthened. The wear intensity of strengthened pair is 2.2–3.1 times less compared to unstrengthened pair. During the friction of the strengthened pair, the coefficient of friction and the temperature in the sliding zone also decrease. The best results were obtained when studying the friction pair in which the samples were strengthened with a tool with transverse grooves on its working part.

scholarly journals Topography of the strengthened cylindrical surface after frictional continuous treatment

2020 ◽  
Vol 6 (3-4) ◽  
pp. 9-19
Author(s):  
Volodymyr Gurey ◽  
Keyword(s):  
High Speed ◽  
White Layer ◽  
Nanocrystalline Structure ◽  
Surface Friction ◽  
Continuous Treatment ◽  
Frictional Treatment ◽  
Friction Treatment ◽  
Transverse Grooves ◽  
Experimental Researches

Friction treatment refers to methods of surface strengthening (hardening) of the parts’ working surfaces using highly concentrated energy sources. Concentrated energy flow is formed during high-speed friction of the tool on the treated surface in the area of their contact. A strengthened (reinforced) white layer with a nanocrystalline structure is formed in the surface layer of the treated surface. Friction treatment of cylindrical surfaces of samples made of steel 41Cr4 (hardening and low-temperature tempering) was made on a lathe, and the device for the autonomous drive of the strengthening tool was installed instead of a toolpost. The tool was used with a smooth working part and with transverse grooves on the working part. Experimental researches of the strengthened surfaces’ topography were carried out on a profilometer “TALYScan 150” (Taylor Hobson Ltd, UK). The obtained data were processed in the software “Digital Surf MountainsLab Premium 8.2”. After friction treatment by using the tool with transverse grooves on its working part on the treated surface more evenly distributed peaks than after friction treatment by using the tool with the smooth surface. Analysing the spectral density of the peak’s distribution on the treated surfaces, it can be noted that after friction treatment by using the tool with transverse grooves, the area of the spectra is the lowest in comparison with friction treatment by using the tool with a smooth working part. When using the tool with cross grooves on its working part during frictional treatment allows to receive the best parameters of quality of the treatment surface in comparison with frictional treatment by the tool with a smooth working part. The parameters of the load-bearing capacity curve of the surface treated by the tool with transverse grooves on its working surface are better than after frictional treatment by the tool with a smooth working part. The treated surface by the tool with transverse grooves has a more favourable surface for wear, which was confirmed by research on wear resistance.

THE EFFECT OF NANOCRYSTALLINE LAYERS ON THE WEAR RESISTANCE OF GREY CAST IRON DURING FRICTION IN AN OIL-ABRASIVE MEDIUM

Tribologia ◽  
2018 ◽  
Vol 282 (6) ◽  
pp. 37-42
Author(s):  
Ihor HUREY ◽  
Tetyana HUREY ◽  
Volodyr GUREY
Keyword(s):  
Surface Layer ◽  
Cast Iron ◽  
Sliding Friction ◽  
Friction Pair ◽  
Grey Cast Iron ◽  
High Rate ◽  
Unit Load ◽  
Abrasive Medium ◽  
Friction Hardening ◽  
Grey Cast

Friction hardening is one of the surface hardening methods with the use of highly concentrated energy sources. In the “tool-treated surface” contact area, the surface layer of a metal is heated at a very high rate to phase transition temperatures, and then it is cooled at a high rate, which results in the formation of hardened nanocrystalline layers. The studies carried out have shown that a hardened nanocrystalline layer is formed in the surface layer in the course of friction hardening of cast-iron (EN-GJL-200) components. The layer thickness is 90–120 μm, and the microhardness is 7–8 GPa. Grain size of the hardened surface layer was equal to 20–40 nm near the treated surface. It is shown that the hardened layer significantly increases the serviceability of the pair “grey cast iron-grey cast iron” during sliding friction in the lubricated-abrasive medium. When increasing the unit load from 2 to 6 MPa, the wear rate of the hardened pair decreased by 2.6–4.2 times in comparison with an unhardened pair. Only one component of the friction pair was hardened.

scholarly journals The gradient structure in the surface layer of an Al-Zn-Mg-Cu alloy subjected to sliding friction treatment

2019 ◽  
Vol 13 ◽  
pp. 102318 ◽  
Author(s):  
G.Y. Zheng ◽  
X. Luo ◽  
Y.Q. Yang ◽  
Z.D. Kou ◽  
B. Huang ◽  
...  
Keyword(s):  
Surface Layer ◽  
Sliding Friction ◽  
Gradient Structure ◽  
Cu Alloy ◽  
Friction Treatment

scholarly journals Analysis of the Heating of Steel Wires During High Speed Multipass Drawing Process/ Analiza Nagrzewania Się Drutów Stalowych W Procesie Ciągnienia Wielostopniowego Z Dużymi Prędkosciami

2014 ◽  
Vol 59 (4) ◽  
pp. 1475-1480 ◽  
Author(s):  
M. Suliga
Keyword(s):  
Surface Layer ◽  
High Speed ◽  
Heated Surface ◽  
Experimental Studies ◽  
Drawing Process ◽  
Heat Accumulation ◽  
Steel Wires ◽  
Drawing Speed ◽  
The Wire ◽  
Surface Layer Thickness

Abstract The analysis of the heating of the wire including theoretical studies showed that in the multistage drawing process a increase drawing speed causes intense heating of a thin surface layer of the wire to a temperature exceeding 1100°C, which should be explained by the accumulation of heat due to friction at the interface between wire and die. It has been shown that with increasing of drawing speed the heated surface layer thickness measured at the exit of the wire from the dies is reduced significantly and at drawing speed of 25 m/s is equal to about 68 μm. The decrease in the thickness of this layer can be explained by a shorter time of heat transfer to the wire, which causes additional heat accumulation in the surface layer. Thus fivefold increase in drawing speed caused an approximately 110% increase in the temperature in the surface layer of the wire. Experimental studies have shown that the increase of drawing speed of 5 to 25 m/s will increase the temperature of the wire after coiled on the spool more than 400%.

INFLUENCE OF ENGINE OIL ON THE FRICTION AND WEAR OF A SURFACE LAYER WITH BORON

Tribologia ◽  
2017 ◽  
Vol 272 (2) ◽  
pp. 107-112
Author(s):  
Janusz LUBAS ◽  
Wojciech SZCZYPIŃSKI-SALA
Keyword(s):  
Surface Layer ◽  
Contact Area ◽  
Friction And Wear ◽  
Friction Pair ◽  
Mineral Oil ◽  
Engine Oil ◽  
Synthetic Oil ◽  
Start Up ◽  
Higher Temperature ◽  
Bearing Alloy

The aim of the present work is to determine the influence of surface layers with boron and engine oil on the processes of friction and wear in friction pairs. The ring samples with a borided surface layer cooperated under test conditions with counterparts made with CuPb30 bearing alloy. During the tests, the friction pairs were lubricated with 15W/40 Lotos mineral oil and 5W/40 Lotos synthetic oil. The friction pairs lubricated by Lotos synthetic oil a generate stronger friction force and higher temperature in the contact area of friction pairs, as compared to the pairs lubricated by Lotos mineral oil. Lubrication of the friction pairs by mineral oil in the start-up phase causes faster stabilization of the friction conditions than in the case of lubrication by synthetic oil. The wear of bearing alloy was lower when lubricated by Lotos mineral oil than by Lotos synthetic oil. The process of friction in the contact area of the friction pair leads to the destruction of the lubricant and the reduction of its operational properties, especially at high temperatures.

Resistance to cast iron seizure determined by the technological condition of the surface layer

2015 ◽  
Vol 67 (1) ◽  
pp. 17-21
Author(s):  
Stanislaw Laber
Keyword(s):  
Surface Layer ◽  
Cast Iron ◽  
Design Methodology ◽  
Friction Pair ◽  
Ground Surface ◽  
Technological Condition ◽  
Bearing Surface ◽  
Content Type ◽  
The Moment ◽  
Surface Curve

Purpose – The aim of this study was to evaluate a surface layer of the condition resistance to seizure. The surface layer was shaped in the processing grinding and burnishing. Design/methodology/approach – The resistance to seizure tests were carried out on a test station specially designed by the author. It is possible to simultaneously test the same two pairs of pivot–pan kinematic pairs on this station. Moreover, the time, route and the temperature of the friction area were registered. The time of sliding group operation from the moment when a lubricant is no longer added to the friction pair to the moment the sliding group reaches the critical temperature T = 418 K (145°C) is taken as a seizure indicator. Findings – The structure and state of the surface layer have an influence on the seizure of the surface of cooperating elements. Greater resistance to the seizure of the burnished surface in comparison to the ground surface is associated with differences in the state of the surface layer. The burnished surface has a smaller surface roughness and a higher value of the bearing surface curve, and the compressive stress occurs more often in the surface layer. Originality/value – There have been no studies on the effects of burnishing machining and grinding of cast iron in resistance to seizure.

Study of Dry Sliding Friction and Wear Characteristic of High-Speed Steel/ Ti6Al4V Alloy under Direct Steady Magnetic Field

2011 ◽  
Vol 50-51 ◽  
pp. 348-352
Author(s):  
Yong Hui Wei ◽  
Yong Zhen Zhang ◽  
Yue Chen
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Friction And Wear ◽  
Sliding Friction ◽  
Friction Pair ◽  
High Speed Steel ◽  
Wear Loss ◽  
Dry Sliding ◽  
Steady Magnetic Field ◽  
Dry Sliding Friction

The influence of DC steady magnetic field on dry-sliding friction and wear characteristics of friction pair of high-speed steel (HSS) ring / Ti6Al4V pin is studied by use of improved MPV-1500 type under normal temperature. It is shown that the wear loss of ferromagnetic materials can be decreased by applying a steady magnetic field. Under the load of 250N and the friction velocity of 0.6m/s, the wear loss of the sample HSS ring keeps decreasing along with the enhancement of magnetic field intensity, and in the scope of 64mT-160mT, the average friction coefficient becomes smaller and smaller. Magnetic field can accelerate debris refinement. The wear mechanism covers oxidative wear and adhesive wear mainly.

scholarly journals Simulation modelling of dynamic processes due discontinuous frictional treatment of the flat surfaces

2020 ◽  
Vol 6 (2) ◽  
pp. 23-33
Author(s):  
Volodymyr Gurey ◽  
◽  
Vitaliy Korendiy ◽  
Ihor Kuzio ◽  
◽  
...  
Keyword(s):  
Contact Area ◽  
High Speed ◽  
Chemical Properties ◽  
Nanocrystalline Structure ◽  
Simulation Modelling ◽  
Dynamic Processes ◽  
Shock Loads ◽  
Flat Surfaces ◽  
Frictional Treatment ◽  
Friction Treatment

Friction treatment refers to surface strengthening (hardening) methods using highly concentrated energy sources. In the course of this processing in the surface layers of the processed surfaces of parts the strengthened layer with nanocrystalline structure is formed. The formed layer has specific physical, mechanical, chemical properties, as well as improved performance properties, which are significantly different from the base metal. A highly concentrated energy source is formed in the contact area of the tool-part due to the high-speed friction (60–90 m/s) of the tool on the treatment surface. Frictional treatment of flat parts according to the kinematics of the process is similar to grinding. The strengthening process was carried out on an upgraded surface grinder. The tool is a metal disk made of stainless-steel. Transverse grooves are formed on the working surface of the tool to intensify the process of forming a strengthened (reinforced) layer with a nanocrystalline structure. The grooves form additional shock loads in the contact area of the tool-treatment surface of the part. These shock loads increase the shear deformation of the metal of the parts’ surface during treatment, which affects into formation the quality parameters of the parts’ surface and surface layer. To study the friction treatment process, the calculation scheme of the elastic system of the machine was developed. A simulation model for the study of dynamic processes that take place during the friction treatment of flat surfaces was built. This model gives possibility to determine the displacements and velocities of the machine table on which the part is fixed and the tool, and to determine their mutual displacement and also calculate the reaction of the machine table.

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