17.doc
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
109
ZamotaТ.,*
Aulin V.**
*Volodymyr Dal East-Ukrainian National
University,
Lugansk, Ukraine
**Kirovograd National Technical University,
Kirovograd, Ukraine
E-mail: aulin52@mail.ru
DIMINISHING OF MACRO-GEOMETRICAL
ERROR OF DETAIL′S FORM AND FRICTION
TORQUE BY ELECTROCHEMICAL-
MECHANICAL RUNNING-IN
UDC 631.354:621.43:62-24
The processes of ECMR pass in the environment of electrolyte, which influences efficiency of process, mode of
friction at running-in pair and speed of electrochemical reactions. The essence of ECMR consists of the following: working
motion for details of mechanism is given, between details an electrolyte is pumping and cutoff alternating current. Due to
joint electrochemical-mechanical influence there is a rapid adaptation of one surface to other. The most effective factor of
ECMR is electrochemical, at which it is easy to electrochemical stripping of material from the run-in surface due to anodal
dissolution at the hydrodynamic lubrication rate.
Key words: running-in, electrochemical - mechanical running-in (ECMR), engines, friction torque.
Introduction
Unfortunately, macro - geometry of units of friction considerably differs from correct. In many cases
space tapering of surfaces is broken. A roughness after tooling frequently falls short of optimum values. It results
in higher specific pressures in the area of contact, to the direct contact of metal surfaces and, as a result of it, to
the teasers, grasping and enhanceable wear of the running-in surfaces. Defects have an effect of increase of con-
tact pressure on small area and further in more rapid tribological processes as compared to a contact without a
defect. For example, by the result of the unlubricated contact of surface on a ring, in which warped steel on
bronze, diminishing of the time of running-in with the increase of defect was marked. It talks about complication
of flowing processes and necessity of further study of influence of defects on running-in of the sliding surfaces.
For renewal of precision pairs, abrasive grinding in is used. At many positive moments, the abrasive
grinding (polishing) has substantial failings. The conducted analysis allows exposing the following failings, re-
lated to the abrasive polishing of precision details: presence of technological contaminations; danger of carica-
turing of abrasive particles in soft materials; disparity of roughness to the conditions of work; incomplete form-
ing of actual area of spot of contact; negative gradient of mechanical properties on depth.
On this basis it is possible to conclude that the abrasive polishing does not allow to form necessary mi-
cro- and macro-geometry, physical and mechanical properties that would allow shortening time of running-in
and increasing quality of the recovered surfaces. In addition, a presence of technological contaminations is rea-
son of enhance able wear of connections and decline of their technical and economical indexes of hydraulic ag-
gregates.
Therefore the details of connections of machines must not be exposed to abrasive grinding in. One pos-
sible type of grinding in, there is the chemical-mechanical planarization (CMP) [1 - 3] and another one is elec-
trochemical– mechanical planarization (ECMP) [4 - 7]. ECMP found a wide use as method of clean (final)
grinding-in of details, workings in the conditions of friction, mechanical loadings, corrosions because this proc-
ess is related to the change of micro roughness and physical and chemical state of surface. The electrochemical
polishing provides the best friction properties of the ground pair, by comparison to the mechanical polishing; it is
confirmed by a number of researchers.
ECMP requires application of special equipment (adaptation, instrument), exact maintenance of the
mode of electrolysis, control and adjustment of solution, temperature condition of work of bath, careful cleaning
of surfaces of details before treatment (chemical treatment is in organic solvents, electrochemical depriving of
fat). For intensification of process, the electrochemical polishing must be conducted in a running electrolyte, and
it requires more advanced equipment, than stationary baths. In addition, this method does not allow correcting
macro geometrical defects.
One direction in polishing and reduction of time of running-in is a key-in of electric current directly
through connections of details, part the layer of electrolyte which is give working motion. The electrochemical-
mechanical running-in (ECMR) method is used for running-in of basic units of engines and is one of perspective
directions in research [8].
Application of the electrochemical - mechanical running-in has a number of substantial advantages be-
fore other types of final grinding in. Unlike the abrasive polishing in ECMR formation, abrasive particles are
fully eliminated as products of wear. Affecting material is made by imposition of current on an environment and
details and takes a place at ionic level. As a result, products of output are in an environment as atoms and mole-
cules. As well as at the electrochemical polishing, at ECMR there is a removal of internal tensions both in micro-
mailto:aulin52@mail.ru
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
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and macro-volume of surface of material. ECMR allows making the local output of metal, but the surface pas-
sivation, characteristic for electrochemical process, absent here. In addition, ECMR provides joint running-in of
details without application of the special instruments unlike abrasive and electrochemical processes, due to it
there is rapid structural, micro- and macro-geometrical adaptation of the surfaces under friction.
Present efficiency of ECMR is enhanceable due to additions of oleic acid in an electrolyte. It enabled
considerably to improve tribotechnical characteristics of the runnig-in surfaces at the different types of friction.
Further research must be directed on opening of mechanism of forming of running-in surfaces of details of basic
machines’ units on the different types of friction.
A research object is choosing the process of the electrochemical - mechanical running-in of surfaces of
details of basic machines’ units. The most running-in surfaces at ECMR pass three basic stages of running-in
process. Knowing that the Sommerfeld criterion which is evened Sm = 10-5 corresponds transient regime of fric-
tion, easily to set the change of types of lubrication at running-in surfaces. In an initial period of time there is
mechanical elimination or driving back of plastic materials, forming an initial area of contact (I stage). With its
growth, a transition is possible from a semiliquid friction to hydrodynamic (II stage), and at the hydrodynamic
regime of friction the spot of contact is finally formed in examined tribosystem (III stage).
Objects and problems
The aim of this paper was to study the influence of electrochemical mechanical running-in to change the
nature of friction and wear in a pair of friction with reciprocating characteristic of the piston-liner interface,
working in conditions with distortions of their axes. Сhanges in friction, temperature and rate of wear are com-
monly observed shortly after the start of sliding contact between fresh, unworm solid surfaces [9]. The studies
were conducted on a model representing the slider-crank mechanism that copy the friction pair of cylinder-piston
sleeve. The design system is shown in Fig. 1(a). Installation was mounted on the friction machine. Drive installa-
tion from the shaft friction machine. The effects of the friction in the slide were estimated friction torque, taken
from the machine shaft potentiometer included with the machine. Friction torque recorded on graph paper plotter
N 306. For the initial (zero) value of the frictional moment taken its value corresponding to the time of friction
with the shaft of the machine impaled on it without a crank rod. Assessing the friction and wear of the slide were
performed on samples-rings, to strengthen it from both sides (fig. 1, b). Two rings made of aluminum (outer di-
ameter of 42 mm and a width of 11 mm) are pushed on slider. Frictional resistance created by these rings and the
amount of wear and tear are estimated.
The moment of friction and wear rings were determined at different skew axis slide and barrel. Skewed
axes provides a turn of the stage in the horizontal plane perpendicular to the plane of the swing rod, using a
micrometer screw (fig. 1, a). For the initial value of the distortion, value was taken within the clearance between
the piston and the sleeve length in mm/100 mm piston (Δn = 0,19 mm/100 mm length).
a b
Fig. 1 – Device for study the effect of piston warps to ECMR of slider-liner pairing (a) and the slider with two rings (b)
Before the experiment the ring was cleaned, thoroughly washed, dried, weighed on an analytical bal-
ance WA-31 with an accuracy of 0,1 mg, and then mounted on a slide. The slide was collected from the liner.
Slider joint movements were performed with sleeve liner along its axis together with the stage. An electrolyte
was given in the area of friction. An alternating current (AC) was connected to the piston (slider) and liner
(fig. 1, a). For comparison, experiments were carried out under the same conditions, but without current flow be-
tween the friction surfaces.
In the latter case, the experiments showed that the time fixed by friction during operation without con-
necting current slide significantly depended on the tilt axis of slide and liner. The corresponding value of the
friction torque was achieved almost immediately after starting the device for study the effect of piston warps to
ECMR of slider-liner pairing and did not undergo further changes (fig. 2).
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
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The friction torque is increased with increasing bias. Changing the friction torque in time in connection
with the current pair had a different character with a small warp (0,38 and 0,76 mm/100 mm of long slide). As in
the previous case, immediately after the start time, friction increased sharply and then decreased at these distor-
tions to patterns shown in the diagram. However, during the experiment, the friction torque is not reached the
value corresponding to a zero skew. The greater difference the greater the resulting distortion was observed.
When distortions 1,14; 1,52 mm, length 100 mm (curves 4 and 5, fig. 2, a) decreased friction torque was ob-
served. Pattern is similar to that observed in friction without current.
a b
Fig. 2 – The change in the friction torque versus time during running
by the standard method (a) and at ECMR (b):
1 - 5 – for piston misalignments 0; 0,38; 0,76; 1,14; 1,52 mm to 100 mm in length
Character study of wear patterns energized and de-energized showed that more wear rings occurred in
the experiments with the passage of current. This indicates that the action of the electrochemical process in-
creases the material removal from rings, the removal increased with increasing bias to a greater extent than those
without current. This phenomenon provides for a fast burn-rings to the sleeve, which leads to a decrease in the
friction torque. The passing current through the bearing surfaces provided them quickly (within 4 minutes)
macro running-in. Changing the friction torque in time it is possible to explain of high speed of diminishing of
macro-geometrical error of form of detail at ECMR.
It is known that the basic pair of friction of machines has different character of the mutual moving. The
tribounits of piston-cylinder group are working at crank motion (fig. 3), and the sliding bearing – at rotator
movement (fig. 4). Obviously in first case, speed of the mutual moving of details changes from zero to the
maximum speed, determined the structural parameters of knot and frequency of rotation of crankshaft. In the
second - speed depends only on frequency of rotation and on the set modes is constant.
For analytical determination of the mode of friction, presence and thickness of electrolyte film between
the ground details apply the criterion of Sommerfeld Sm [10]. For running- in of details of type of piston-rings in
the interfaces of rings-liner (with the recurrently-forward mutual moving) it is equal:
bP
V
Sm ⋅
⋅µ
= , (1)
where µ – dynamic viscosity of lubricating material (electrolyte), MPa·s;
V – moving speed of piston, m/s;
P – pressure of ring to the cylinder face from forces of resiliency, MPа;
b – height of ring, m.
Knowing that Sm = 10-5 corresponds to the transient behavior of friction to set the change of types of lu-
brication at moving of piston. For a double piston movement the detail surfaces operate at the different modes of
friction: limiting mode, transitional and hydrodynamic.
Following the hydrodynamic theory of lubricating the thickness of tape, dividing a ring and cylinder, is
based on formula [10]:
mSh = , (2)
It is possible to assert that at the hydrodynamic lubricating of running- in surfaces an electrochemical
reaction flows cleanly: a current passes through details, part the layer of electrolyte. Investigation of it is an
etched surface during their anodal polarization with frequency of alternating current. The mode of limiting and
transitional friction, besides other, is activating surfaces that strengthen the effect of electrochemical reaction at a
liquid friction.
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
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From fig. 3 it is evident, that any process macro running-in of two surfaces is possible to take to run-
ning-in of surface, inclined with the corner of defect γ, in relation to other one. For the running-in of sliding
bearings, it is necessary to take into account frequency of rotation of shaft ω and presence of macro-geometrical
rejections δ (fig. 3).
According to the hydrodynamic theory of friction, the thickness of tape between a shaft and journal
bearing depends on frequency of rotation of crankshaft. Except for it, important parameters are properties of lu-
bricating environment and geometrical parameters of journal bearing. The laws of the hydrodynamic lubricating
allow describing the minimum thickness of oily tape of the freely rotated crankshaft based on the formula:
,
36,18
2
min kSc
nd
h
η
= (3)
where d – diameter of shaft, mm;
n – frequency of rotation of shaft, min-1;
η – dynamic viscidity of oil, Pa · s;
k – loading on a shaft, Pa;
S – gap, mm;
c - amendment of Glyumbel.
By formula (3) it is possible to define the minimum thickness of electrolyte layer at ECMR in the area
of direct contact of the running-in surfaces of shaft and bearing without the account of macro-geometrical rejec-
tions (fig. 3).
a b
Fig. 3 - Scheme of ECMR of details with with rotation (a) and reciprocal (b) motion:
δ – maximum size of a running-in allowance;
Vа – electrochemical etching rate of material from detail surface on a gap;
Vаd – electrochemical etching rate of material from detail surface at mechanical activation;
Vм – mechanical wear rate from detail surface;
h – radial electrode gap at fluid friction;
γ – angle of obliquity of running-in surfaces;
а – joint gap, dependent on γ
To conduct error analysis, select factors, influencing on the change of size the error of form of detail
dδ/dt and relation of speed of electrochemical output on an area with the depassivation of surface to speed of
output on an area without a depassivation Vad/Va. Assume that material of detail on the area of the mechanical
activating is taken off as micro-volumes of metal, then:
,maxmax aaдmelcm VVVVVdt
d
V −+=+=
δ
= (4)
where Vm – speed of mechanical output;
V
elc
– speed of electrochemical output;
V
ad
– speed of anodal dissolution of metal with mechanical depassivations;
V
a
– speed of anodal dissolution of metal without mechanical depassivations.
It is possible to express constituent V
ad
coming from laws Faraday and Ohm [11] taking into account
the periodic breaking of anodal dissolution in the examined point of surface of ring because of pickoff at the me-
chanical activating (in the areas of limiting friction mode). By analogy with expression speed, output of metal
will make on the area of anodal dissolution. After the calculation of the equation takes the form:
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
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),)()1()(/)(
)()1(/)(()1(5,0
1
22
min
1
2
min1max
tUkhU
tUkhUkVV
kaakaa
kaдaдkададm
⋅ϕ+ϕ−η⋅
ρ
χε
−+δ+ϕ+ϕ−⋅η−
−⋅ϕ+ϕ−η⋅
ρ
χε
−+ϕ+ϕ−⋅η⋅
ρ
χε
⋅−⋅+=
(5)
where 0,5 – coefficient, taking into account an alternating current;
k1 – coefficient, taking into account the limiting friction mode (Sm < 10
-5) in general time of cycle (one
turn of crankshaft);
U – working voltage, V;
ϕ
аd
– anodal potential at mechanical activation, V;
ϕk – cathode potential, V;
η
аd
– anodal current output at the mechanical activating, %;
χ – specific conductivity of electrolyte, Om-1·сm-1;
ρ – density of material, g/сm3;
с – electrochemical equivalent of material of anode, g/А·h;
h – a radial gap in the area of liquid friction, сm,
η
а
– anodal current output, %;
ϕ
а
– anodal potential, В;
δ – maximal size of running-in allowance, см,
t – time of ECMR process.
It is clear that speed of diminishing of running-in allowance depends, except for mechanical (V
m
), geo-
metrical (δ) and from electrochemical factors, such as specific conductivity χ, values of anodal potentials ϕ
аd
,
ϕ
а
and outputs on a current η
ад
, η
а
. The mechanical activating is reduced by anodal potential, and confirmation
that an anodal output on a current increases as a result of periodic mechanical influence, present in [12].
Thus, the choice of the modes of ECMR can be carried out on the basis of information about sizes ϕ
аd
and ϕ
а
, η
ад
and η
а
at the certain conditions of running-in. Diminishing coefficient k accelerates the running-in
details. The coefficient k depends on the criterion of Sommerfeld Sm.
Thickness of layer h is the function of piston speed V also and dynamic viscosity µ, however an in-
crease of h will result in the increase of transitional resistance of layer of electrolyte. It is concordantly Eq. (5)
necessary for the increase of speed of running-in details, that size h it was minimum, but the terms of the hy-
drodynamic lubricating would be provided here. Decline of bearing strength of electrolyte, with the purpose of
diminishing h, possibly due to gasification. At electrochemical-mechanical running-in electrolyte is filled gas
bubbles due to electrochemical processes, flowing on the surfaces of pair of friction. It is known that gasification
depends on current parameters. A gas stream with a liquid provides a high degree of compressibility that can be
used for diminishing h in the process of running-in with the use of ECMR. Several gas bubbles will be useful in
localization of process of anodal dissolution, which is widely used in many processes of electrochemical size
treatment of details of machines.
The evident picture of terms of transition of one mode of friction f in other gives diagram of Gersi, in
which the coefficient of friction is related to the parameter μV/P.This parameter is named description of the
bearing mode. On diagram line Sm = 10-5, passing through the point of a minimum of coefficient of friction, di-
vides the areas of friction at a liquid and other types of lubricating (fig. 4).
As obvious from Fig. 5, diminishing of macro-geometrical form defection dδ/dt due to a mechanical
wear Vм possibly only at the dry and limiting types of friction. Thus, than more surfaces is divided the layer of
lubricating, the less than influence of mechanical wear on the process of improvement of macro-geometry of de-
tails surface. The mechanical factor is absents at a liquid friction.
Influence of electrochemical factor increases with the division of the running-in surfaces the layer of
electrolyte (V
ad
increases at a limiting friction). However, it is necessary to provide a minimum gap; because re-
sistance of layer of electrolyte grows with its increase those results in deceleration of electrochemical reactions
(Vа goes down at a liquid friction with growth of thickness of electrolyte layer). Experimental confirmation of
improvement of tribotechnical descriptions of friction surfaces at ECMR is presented in [13 - 15]. The use of this
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
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high-efficiency method of forming of surfaces of details allows considerably increasing their resource. Research
of anodal output on a current η
аd
in the pair of friction with the rotatory mutual moving present in [16].
Fig. 4 – Speed of diminishing of macro-geometrical error
of form of detail at ECMR
Most intensively process of ECMR tribosystem shaft and journal bearing will be flows at outputs on a
current η
аd
near to 100 %. Such values were observed at the closeness’s of current less 1000А/m2. At the high-
current density efficiency of process is minimal, a wear takes a place due to a mechanical factor and an output on
a current does not exceed 10 %.
Examining factors, influencing on a friction resistance and intensity of output of material, it is possible
to see at EСMR, that on an intensity of wear influence: form of area of contact, type of friction, properties of the
surfaces and factors of external influence. Obviously, that flowing process of running-in of the surfaces depends
on initial geometry of surfaces. At ECMR tribotechnical characteristics of the running-in surfaces at the different
types of friction are improved. Thus the change of surfaces takes place on all of three stages of running-in that is
impossible at ordinary methods, being based on a mechanical wear or creation on the grinding surfaces of differ-
ent type of tapes. Surface forming at ECMR takes place due to electrochemical and mechanical influence. Influ-
ence of different factors allows forming top surface relief of roughness of surfaces. The mechanical strengthen-
ing is instrumental in the etching of tops of ledges, and the presence of superficial tapes and gasification is di-
minished by creation of cavities.
Conclusions
1. It is possible to control the processes of running-in due to the change of speed index are frequencies
of crankshaft rotation and current parameters I and U. The mode of ECMR must provide a high output on a cur-
rent η
аd
and minimum gap h. An alternating electric current on the friction surface coupling a piston-cylinder
accelerates the running-in of the contact surfaces at the misalignment of their axes. With increasing tilt axis of
piston and sleeve increases the friction torque.
2. Most of the wear rate of the samples at an alternating current leads to a decrease in the friction torque
at the investigated distortions 0,38 and 0,76 mm, which to some extent eliminates misalignment axes to macro-
geometry burnishing. Biases of the piston and the cylinder axis of 1,14 and 1,52 mm did not provide running-
surface even when applying current.
3. ECMR of the basic conjugations of engines is the high-efficiency process of running-in of the run-
ning-in surfaces: except for mechanical influence, characterized Vм, the process of running-in is accelerated due
to electrochemical processes. Macro running-in can be accelerated with the proper selection of optimum compo-
sition of electrolyte. It must possess low conductivity, passive properties, and also to provide the hydrodynamic
mode of friction.
References
1. Milind Kulkarni, Dedy Ng, Melloy Baker and other., 2007: Electropotential– stimulated wear of cop-
per during chemical mechanical planarization. Wear 263. – pp.1470– 1476.
2. Samuel B. Emery, Jennifer L. Hubbley, Maria A. Darling and other., 2005; Chemical factors for
chemical– mechanical and electrochemical– mechanical planarization of silver examined using potentiodynamic
and impedance measurements. Materials Chemistry and Physics 89. – pp.345– 353..
Diminishing of macro-geometrical error of detail′s form and friction torque by electrochemical-mechanical running-in
Проблеми трибології (Problems of Tribology) 2014, № 1
115
3. Yung– Fu Wu, Tzu– Hsuan Tsai. , 2007: Effect of organic acids on copper chemical mechanical pol-
ishing. Microelectronic Engineering. – pp.1– 9.
4. Economikos L., Wang X., Sakamoto A., and other., 2004.: Integrated Electro– Chemical Mechanical
Planarization (Ecmp) for Future Generation Device Technology// IEEE, – p.233– 235.
5. Canhua Li, Ishwara B. Bhat, Rongjun Wang, Joseph Seiler. , 2004: Electro– Chemical Mechanical
Polishing of Silicon Carbide. Journal of Electronic Materials, Vol.33, №5 – pp.481– 486.
6. Yuan– Long Chen, Shu– Min Zhu, Shuo– Jen Lee and other., 2003: The technology combined elec-
trochemical mechanical polishing. Journal of Materials Processing Technology 140. – pp.203– 205.
7. Alan S. Brown, 2005: Flat, Cheap, and Under Control. IEEE Spectrum. – January. – pp.40– 45.
8. Alexeev V.P., 2011: Electrochemical - mechanical macro-running-in of details. Monograph.-
Lugansk: Elton-2 . – P.204.
9. Peter J. Blau., 2005: On the nature of running– in. Tribology International 38. – pp.1007– 1012.
10. Semenov V., 1991.: Mode of lubricating of pair of friction piston ring- cylinder of engine // Engine
construction.- №10-11,- p.19-23.
11. Lyubimov V., Kitaev U., 1983.: Influence of anionic composition of electrolyte on leveler proper-
ties of electrochemical treatment with a periodic abrasive depassivation // Electronic treatment of materials.-
№5.- p.13-17.
12. Kadaner L., Kotlyar A., Scherbak M. and other. ,1971.: Method of research of anodal kinetics of
dissolution of metals in the conditions of their abrasive destruction // Electronic treatment of materials.- №1.-
p.15-20.
13. Taras Zamota., 2010: Improvement of tribotechnical characteristics of piston ring surfase at running
in / Taras Zamota, Alexander Kravchenko // TEKA, Commission of Motorization and Power Industry in Agri-
culture.-Vol. XB.-Lublin,.-P. 323 – 330.
14. Taras Zamota., 2010: Electrochemical-mechanical running in of the main engine′s conjugations /
Taras Zamota, Alexander Kravchenko //TEKA, Commission of Motorization and Power Industry in Agricul-
ture.-Vol. XD.- Lublin, - P.58-65
15. Taras Zamota, Victor Aulin. , 2013. Improvement of Tribotechnical Characteristics of the Main En-
gine′s Pairings at Electrochemical-Mechanical running-in //TEKA, Commission of Motorization and Power In-
dustry in Agriculture.-Vol. 13, № 3 - Lublin.- P.244-251
16. Zamota T.N., 2011: Electrochemical bases of process of macro- running-in of flat surfaces of fric-
tion at ECMR, / T.N. Zamota // Problems of Tribology. International scientific journal. – Khmel'nickiy National
university, №4, pp.56 – 61.
Поступила в редакцію 14.02.2014
Замота Т, Аулин В. Уменьшение макрогеометрических погрешностей форм деталей и момента трения
электрохимико-механической приработкой.
ЭХМП осуществляется в среде электролита, который влияет на эффективность процесса, режим трения и
скорость электрохимических реакций. Сущность ЭХМП следующая: деталям механизма придается рабочее движе-
ние, между ними прокачивается электролит и пропускается переменный электрический ток. Благодаря совместному
электрохимико-механическому воздействию происходит быстрая приспосабливаемость одной поверхности к другой.
Наиболее эффективным фактором является электрохимический, благодаря которому происходит стравливание ме-
талла поверхности при гидродинамическом режиме трения.
Ключевые слова: электрохимико - механическая приработка, двигатели, момент трения.