623
1 INTRODUCTION
The main difficulty in Electro spark alloying (ESA)
process,isselectionofmaterialofalloyingelectrods.
Until recently they were made of standard solid
brand like VC Tungsten‐cobalt alloys and TK
Titanium‐tungsten‐cobaltalloys.Buttheexpansionof
thesphereswhereapplicationofelectro‐sparkcoating
isinuse,anddifficult
yinfindingoftherawtungsten,
lead to search for a new electrode materials based on
refractorycompounds.
The above‐mentioned difficalty is including the
necessity to be taken into accoaunt of numerous
factorsthatinfluencetotheformationofalloyingcoat:
Erosionoforganizational solid phase, physicochemical
interactionoftheelectrodes’materials,thecreationof
a second structure on the anode’s working surface,
ma
in (from cathode to anode) mass transition,
conditionality collection of unusual erosion’s
electrodematerials[1]
In the ESA process not only the anode’s
material,butalsomakescathodeerosion.Itserosion,
as a rule not taken into account, which canleadtoerrors
in anode’s erosion and cathode’s increase
determination.Inaddition,theinversetra
nsitionof
materials is one of the reasons of formation of the
second structure on the electrode’s working surface
[2].
For the first time the material transition from
cathodetoanode, inthe spectral analysis of materials and
alloys, aswellasinmeasuringprocessparametersof
Electro‐sparkdischarge,andreverse process of the ESA
differingbycontactingparametersofelectrodepa
irs,
itsquantityanditsimpactonthecharacteristicsofthe
processhadbeenevaluatedinthework[3]
It was shown that during ESA process based on
transition materials the quantity of such a transition
fortheelectrodepairsisnotmorethan10%compared
tothealloyingmeta
l’serosion.
Group IVСhemically active metals (as a
consequence gripping of electrodes) low thermal
conductivity easy-melting metals (with effect of vapor
phaseofanodeincathode)easy‐removebalefromthe
The Anode Material Selection for Electrospark Alloying
(ESA) and its Mass Transition Phenomena
Z.Z.Sharifov&F.N.Gurbanov
A
zerbaijanStateMaritimeAcademy,Baku,Azerbaijan
ABSTRACT: The expression used in this article is to take into account the inverse transition of electrode’s
materialwhenitisselectedinelectro‐sparkprocessing;aformulaisderivedthatestimatestheratioofsolid‐
phaseandliquid‐vaporconstituentsoferosion.
Itisdeterminedtha
tastheselectioncriteriafortheanodeincrease,theamountoftransitionofitsmaterialto
the cathode in the liquid‐vapor phase increases as well. When choosing the electrode material, the most
importanttasktobetakenintoaccountisthesolid‐phaseconstituentsoferosion.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 4
December 2017
DOI:10.12716/1001.11.04.07
624
surfaceduetotheincreaseinthevolumeoftheliquid
phaseisexceptional.
Therefore,itisimportanttoofferanassessmentof
the choosing parameter of alloying electrode.This
assessment can be done by advantage provision
transitioningoftheelectrodetocathode.
Thisprovisionis controlled by the ratio heat-physical
constants ofmaterialsofthe
electrodes,whichistaken
accordingtothecriteriaofL.S.Palatnikin4
Asimilarcriterionfortheselectionofmaterial in
plasmasprinklingʺmeltingdifficultiesʺtheparameter
applied materials and its heat-physical rate confirms
the importance of their physical and chemical
interactions.
2 THEDISCUSSIONOFTHERESULTS
Summarizing
of results of the erosion legitimacy
researches 5, taking into account the inverse
transition of the material in multi-impulse processing
brings to the following erosionexpression:
aabbkkktR
tRR
(1)
R
t,RR–aretheratioswithconsiderationtothesecond
structure’smodeandformation;
M, b, bk‐contribution of erosion’s solid and
liquid‐vaporconstituents;
k‐transitionofcontact‐bridgeofsubstances;
ək‐theinversetransitionofsubstances.
Contact‐bridge transition of the models achieves
during moment of contact of electrodes, possible in
both directions anddetermined with the help of
Thompson,KollerandPelte[6]effects.
Inexpression(1)thecontribution
bk‐asaresult
ofbrittle failuresofthenumberofimpulsesbuildup
from the single discharge, the spherical erosion’s
volumeandcavitycorrelationcanbeassessed.
Theradiusofthecavity(R
ç)approximate internal
thermal tensions
(E) subject to the distance R from
thedottyimpulseheatsource,asperformulaofB.N.
Zolotıxın7canbefoundiftheR
çiscompatiblewith
thedegreeofresilienceofthematerial.
Suchadependancycalculatedfortheironisgiven
onFigure1.
For the iron
d 48MPa 8 as a term (during
ESAproccesathightempreturestakingintoaccount
theheatingoftheanode)wegetr
ç=12mkm.
R
çquantitycomparisonedwithexperimentalwill
be reduced, because real erosion cavity is formed
undereffectofappearedtensionsandinconsequence
of brittle failures, contribution given to this process and to
erosin’s liquid-vapor constituents.
Figure1. Dependancy up to point impulse heat source of
internal thermal tensions for iron. A pulsed energy 5C,
endurance10
‐4
s
Taking into account the contribution of chemical
communication of homopolar components, heat‐
physicalandmechanicalcharacteristicsofMaterialof
the electrode, the ratio of solid‐phase and liquid‐
vaporconstituentsOftheErosioncanbeassessed:
2
bk
2
b
()
()
()
c
bd
b
TT
E
TT
m
m
, (2)
‐ the movement of dislocations in the crystal
latticeparametertocharacterizetheresistance9;
(E)‐The maximum internal tensions;
T
m, Tb, Tc – melting, boiling and breaking cold
temperatures.
Taking into account the criteria of L.S.Palatnikin
4 in proportion to the quantity of cathode erosion
thevalueof
omcanbewrittenasfollows:
om1/Ckkk(Tə
k
‐Ts
k
)
2
, (3)
C
k,S k,k–heatcapacity,dencityandheatconductivity
ofcathode’smaterial.
Itshouldbenotedthattheestablishedpatternsof
erosionaswellasmetalcathodesformetalanodesare
kept, specifically: their erosion in the air is higher
than in argon, also by increasing tendency of the
melting and boiling temperatures of
them, its
exposure to a decrease in the number of transition
metalsfromgroupIVtogroupVI.
The main condition of effectiveness of the ESAisthe
prevailing transition of material from anode to
cathode, and controlled by
a of anode and
k of
cathodematerialserosionratio:
a
k, (4)
k=
k
bk
+
k
er
(
k
bk
and
k
er
‐ erosion of cathode in
solidandliquid‐vaporphase)
Takingintoaccountpreviouslyproposedformula
forrelative sustainabilityoferosion10theformula
(4)canbewrittenasfollows:
625
2
2
()
1
()
л k
kkkRs
a
kk a
bk er a a a R s
CTT
CTT
(5)
This expression proves adopted experimental
conditions of anode material to cathode prevailing
transition5:
a (5‐6)kvə Tə
a
(3‐4)Tə
k
(6)
Taking into account the interatomic covalent
interactions of materials of the Anode (
a
*
) and
cathode (
k
*
) and its communication, then (2.5)
alloying electrode’s material selection criteria is
determined‐D
m:
2
2
()
1
()
Kk
kkkR s
k
m
kk
ak
aaa R s a k
CTT
r
D
rr
CTT
(7)
The more significant quantity of D
m, the more
quantity ofAnode’s material is transfering to
cathodeatliquid‐vaporphase;Theeffectofthelast
is taken into accountby 1/
ka
coefficient. If
theelectrodesaremetalthisratioaswellastheanode
(r
a)ofthemetals,andcathode’s(rk)metalsmeasured
atom radius ratio interact plays a key role.
Homogeneous metals in ESA r
k=ra and Dm
, it
meets the maximum efficiency of ESA. 5.
Refractory compounds are characterized by Low
mutual solubility of metals. in determining prevailing
erosionoftheirsolidphase covalent communication
theinteratomiccovalentinteractionsplaysakeyrole.
Therefore, the expression (7) for such compounds
takesthefollowingform:
2
2
()
1
()
Kk
kkkR s
m
kk
aaa R s a k
CTT
D
CTT
(8)
Using the information 9,11 regarding heat‐
physical characteristics of the materials, the D
m
parameter for the most widely used metals and ESA
condition of iron with carbides are calculated (the table
below) accordingtoformulas(7),(8)
It appears from the information provided, the
biggest D
m parameter of iron with unlimited solid
solution of chromium, while the smallest D
m
parameterisfortitanium,characterizedbymaximum
covalentofinteratomicinteractionsinit.
This result is matching the results of high
efficiencyof ironandsteels alloyingwithchrome in
ESA process, and low results of alloying by titanium
carbide. 5.
Thus,theproblemofthecreationandselectionof
electrodematerials
fortheESA,reflectsexperimental
studyofthemostimportantmoment,likesolid‐phase
constituents of erosion, taking into account the
materials’ mutual solution, and its transition from
cathodetoanode.
3 RESULTS
1 The selection of electrode material for ESA and
masstransitionkineticsofthis processhave been
investigated.
Considering thepossibilityof inverse
transition of material In Multi‐pulse ESA, the
mathematicalexpression of the occurring erosion
had been obtained. The proportional formula for
erosionofCathodewasderived.
Analytic expression which determines the rate of
the erosions occurring in cathode and anode
havebeenidentified.
2 The
criterion formula for selection of alloying
electrode’s material with taking into account the
typeofinteratomiccommunicationofmaterialsof
theanode andcathodeand their mutual solution
was obtained. It was determined that as the
selectioncriteria grows, the amount of transfered
anode’smaterialtocathodeinliquid‐vapor‐phase
increasesaswell.
3 It was determined that, the solid‐phase
constituents of erosion is not considered as the
most important issue in the problem of making
andselectionofelectrode’smaterialforESA,and
reflectsexperimentalstudyofmaterials’transition
fromcathodetoanodeandtheirmutualsolution.
Table1.ThecalculationofrationalcriteriafortheselectionofelectrodematerialforironESA
___________________________________________________________________________________________
Electrode Ckol/, R,kal/Tə,K TS,K
*
68
k
ka
r
rr
Dm
material (mol‐degree) q/sm
3
(smsdegree)
___________________________________________________________________________________________
‐Fe6,017,87 0,3561812 273 1
Cr5,577,19 0,7372176
700 1,05 127 75,1
W5,9319,26 0,1163650
900 19,13,64
Ti5,984,50,2091938
273 17,113,4
Ta5,8316,6 0,5353270 831,06 6,74,41
TiC8,044,92 0,01623530 1173 8,4‐0,59
WC8,5315,77 0,073058‐5,49‐2,49
___________________________________________________________________________________________
626
REFERENCES
[1]A.D.Verkhoturov, I.M.MukhaElectrospark alloying
technology.Kiev:Technique,2002,182p.
[2]A.D.Verkhoturov, M.S.Kovalchenko, M.M.May and
others. Influence of the structure of titanium
dichloride
on the conditions for the formation of coatings during
electric spark alloying of steels / Powder Metallurgy,
2013,No.7/8,p.35‐39.
[3]E.P.Ignatenko, A.D.Verkhoturov, M.Z.Markman
Formation of the surface layer during electro‐alloy
dopingwithlow‐meltingmetals.‐Electronprocessingof
materials,2009,№3,p.18‐20.
[4]Polatnik
L.S. Phase transformations in electro spark
metal processing and experience in establishing the
criterion of observed interactions ‐ Rep. Academy of
SciencesoftheUSSR,1983,89, No.3,p.455‐458.
[5]VerhoturovA.D.Investigationofelectrodematerialsfor
electro spark alloying and the principles of their
creation.PreprintNo.5.‐Kiev
.:IPMNASU,2010,63p.
[6]Buravlev Yu.M., Rudnevsky NK, Grikit IA Spectral
analysis of metals and alloys. Kiev: Technique,1996.‐
192p.
[7]Zolotykh B.N. The main issues of the theory of the
electrical environment.‐Authorʹs abstract. Diss. Doct.
Tech.M.‐M.:MIEM,1998,p.52
[8]Physicaland
chemicalpropertiesofelements:Handbook
/Ed.G.Samsonova.‐Kiev:NaukDumka,1995.‐807p.
[9]Trefilov VI, Milman SE., Firstov SA. Physical basis of
strengthofrefractorymetals.‐Kiev:Nauk.Dumka,1995,
p.315
[10]Verhoturov A.D. Erosion resistance of refractory
metals. In: The electronic structure and physico‐
chemical properties of refractory
metals and
compounds.Kiev.:Sciences.Dumka,2000,p.455‐458.
[11]Samsonov GV, Vinitsky IM Refractory compounds:
Handbook.‐M.:Metallurgy,p.1996.‐556
