The influence of deep cryogenic treatment on wear resistance and life of nickel coated flywheel was studied. Nickel was deposited on to the flywheel workpiece by plating method. The nickel coated pieces were tested at various loads and speeds on a pin-on-disc apparatus, different loading conditions were used in order to compare the wear rate. The pin-on-disc gave ample results on the wear rate of the coating. Then the coated pieces were cryogenically treated at -196? at various time interval of 8,16 &amp; 24 hours with constant supply of liquid nitrogen. Later the cryogenic treated specimen was tested for wear rates to compare the wear rate results to ultimately find the wear before and after cryogenic treatment. The microstructures of cryogenic and conventionally treated samples were analyzed. Additionally, transformation of retained austenite to martensiteplayed an effective role, i.e. improved hardness values

Bheeman, Phawan

D, Gopikannan

G, Prabhu

R.S, Prakash

S, Prabhu

S, Priyavardhanan

International Research Journal of Automotive Technology (IRJAT)

        
 
 
 
 
 
 
 
INTERNATIONAL RESEARCH JOURNAL OF AUTOMOTIVE TECHNOLOGY (IRJAT) 
 
http://www.mapletreejournals.com/index.php/IRJAT                  
Received 22 March 2018                     ISSN 2581-5865   
Accepted 29 March 2018                        2019; 2(2); 6-13 
Published online 30 March 2018 
Effects of Deep Cryogenic Treatment on Wear Resistance & Life 
of Nickel Coated Flywheel 
R.S. Prakash1, G. Prabhu2, B. Phawan3*, D. Gopikannan3, S. Prabhu3, 
S.Priyavardhanan3 
1Assistant Professor, Department of Automobile Engineering, Hindusthan Institute of Technology, 
Otthakkalmandapam, Coimbatore, Tamil Nadu 641032. 
2Assistant Professor, Department of Mechanical Engineering, Adithya Institute of Technology, Sathy Rd, 
Kurumbapalayam, Coimbatore, Tamil Nadu 641107. 
3 Department of Automobile Engineering, Hindusthan Institute of Technology, Otthakkalmandapam, Coimbatore, 
Tamil Nadu 641032. 
*Corresponding author E-Mail ID: phawanbheeman@gmail.com, Mobile: 9994315415 
ABSTRACT 
The influence of deep cryogenic treatment on wear resistance and life of nickel coated flywheel 
was studied. Nickel was deposited on to the flywheel workpiece by plating method. The nickel 
coated pieces were tested at various loads and speeds on a pin-on-disc apparatus, different loading 
conditions were used in order to compare the wear rate. The pin-on-disc gave ample results on the 
wear rate of the coating. Then the coated pieces were cryogenically treated at -196℃ at various 
time interval of 8,16 & 24 hours with constant supply of liquid nitrogen. Later the cryogenic 
treated specimen was tested for wear rates to compare the wear rate results to ultimately find the 
wear before and after cryogenic treatment. The microstructures of cryogenic and conventionally 
treated samples were analyzed. Additionally, transformation of retained austenite to martensite 
played an effective role, i.e. improved hardness values. 
Keywords: Flywheel, Nickel coating, Deep cryogenic treatment, Wear resistance 
1. INTRODUCTION 
1.1. Deep cryogenic treatment 
Freezing of metals has been acknowledged for many decades as an effective method for 
increasing wear life and decreasing residual stress in tool steels. Low-temperature treatment is 
generally classified as either “Cold Treatment” at temperature down to approximately −80℃ (dry 
ice temperature), or “Deep Cryogenic Treatment” at −196℃ (liquid nitrogen temperature) [1]. It 
should be noticed that cooling and heating rates must be kept constant at about 0.5℃/min to avoid 
any thermal micro-cracking formation. Since the cryogenic treatment is normally done at very 
slow rates, it itself, relieves the brittleness and stress accumulation; however, low-temperature 
tempering at 150–200℃after cryogenic treatment is done to relieve any remained brittleness. [2] 
According to the previous literatures two metallurgical phenomena are reported as the main 
reasons for using cryogenic treatment. Firstly, the elimination on retained austenite and secondly 
the initiating of nucleation sites for subsequent precipitation of large number of very fine carbide 
particles. In many cases hardness increasing about 1–3 Rockwell points have been claimed; 
however, some authors reported little increasing in hardness values. There is a little evidence 
concerning toughness changes. One of the most prevalent claims is the improvement of wear 
resistance. Effect of deep cryogenic treatment on the matrix structure and abrasion resistance of 
cast iron subjected to destabilization heat treatment has been investigated. [3] They showed that 
during cryogenic treatment, the secondary carbides precipitate in the austenite matrix, promote the 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
transformation of the retained austenite to martensite and consequently enhance hardness and 
wear resistance of the alloy. Following the results of neutron diffraction that the transformation of 
retained austenite to martensite occurred which, along with possible carbide formation during 
tempering, is a key factor in improving hardness and fatigue resistance of the cryogenically treated 
specimens. 
1.2. Electro plating of NICKEL 
The theory presented has been able to account for the phenomena due to composition and 
concentration of the electrolyte, to current density, temperature, solvent, colloids, other metals and 
cathodes. It has not accounted for the effect of acids and alkalis, nor for the effect of oxidizing and 
reducing agents, but this seems to be due to our ignorance of the chemistry of these solutions 
rather than to a defect in the theory. No one seems to have been struck by the absurdity of the 
statement, to be found in most books on plating, that nickel cannot be plated on nickel because it 
will not adhere.’ If this were true it would not be possible to deposit more than an infinitesimally 
thin film of nickel electrolytically. While it requires a higher voltage to deposit nickel than copper, 
nickel does not precipitate. copper to any appreciable extent when immersed in a copper sulphate 
solution. The nickel becomes passive and is probably covered with a thin film of oxide. What 
people mean is that an “active” nickel containing hydrogen will not adhere to a “passive” nickel. 
There is nothing surprising or mysterious about this. By making a strip of nickel the cathode in an 
acid solution for a few minutes before putting it in the nickel bath, Mr. Snowdon has been able to 
plate nickel on nickel getting a beautifully adherent deposit. The objective of this paper is to study 
the effects of deep cryogenic treatment on wear resistance and life improvement of nickel coated 
flywheel. Fig. 1 shows the coated samples. 
 
Fig. 1- Nickel coated samples 
2. EXPERIMENTAL METHOD  
Chemical composition and relevant properties of the used flywheel (FG150) is presented in 
Table: 1 
Table1: Chemical composition of flywheel 
Fe 93.31 
C 3.656 
Si 1.792 
Mn 0.732 
P 0.057 
S 0.050 
Cr 0.107 
Mo 0.052 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
Ni 0.015 
Al 0.011 
Cu 0.047 
Sn 0.010 
Ti 0.039 
V 0.007 
Mg 0.005 
W 0.15 
Pb 0.050 
Nb 0.020 
Zn 0.023 
2.1. Physical vapour deposition 
Physical vapour deposition (PVD) describes a variety of vacuum deposition methods which 
can be used to produce thin films and coatings. The most common PVD processes are sputtering 
and evaporation. PVD is used in the manufacture of items which require thin films for 
mechanical, optical, chemical or electronic functions. Fig. 2 shows process flow diagram of 
physical vapour deposition. 
 
Fig: 2- Schematic diagram of a PVD process 
2.2. Deep cryogenic test 
Cryogenic treatment was performed by placing the workpieces in an isolated alumina chamber 
immerged gradually in a liquid nitrogen reservoir by means of an electric motor. The isolated 
chamber was designed according to heat transfer equations to estimate the thermal gradient of the 
chamber. Fig. 3 shows cryogenic treatment instrument schematically. Deep cryogenic treatment 
consisted of slowly cooling the workpieces to approximately −196◦C and holding at this low-
temperature for 24h and gradually bringing the specimens back to room temperature. In order to 
avoid thermal shocks from rapid cooling and heating, the specimens were cooled down and heated 
up slowly, to and from the cryogenic temperature (−196◦C), over an 8h period with the 
temperature being monitored by a thermocouple attached to the specimen. This gives an average 
heating/cooling rate of 0.5◦C/min. Two types of flywheel pieces were tested, reference flywheel 
pieces with no extra treatment, cryogenic-treated flywheel pieces (CT) and cryogenic with a 1h 
temper at 200◦C treated flywheel pieces (CTT). Fig: 3 shows the heat treatment cycle of each 
flywheel category. The microstructure of coated flywheel(CT) was studied by a Philips XL 40 
scanning electron microscope (SEM). 
 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
 
Fig: 3 – Schematic configuration of cryogenic treatment system. 
2.3. Hardness test  
Hardness test was performed on a Brinell hardness instrument, shown in fig. 4. The Brinell 
hardness was measured on faces of coated flywheel (CT) using a Wilson4JR hardness tester. Most 
commonly it is used to test materials that have a structure that is too coarse or that have a surface 
that is too rough to be tested using another test method, e.g., castings and forgings. Brinell testing 
often use a very high test load (3000 kgf) and a 10mm diameter indenter so that the resulting 
indentation averages out most surface and sub-surface inconsistencies. The coated flywheel (CT) 
is placed on a hard surface of the instrument and a predetermined test load (F) is applied on the 
workpiece of fixed diameter (D) which is held for a predetermined time period and then removed. 
 
Fig: 4- Schematic representation of hardness test instrument 
Test Method Illustration  
D = Ball diameter  
d = impression diameter  
F = load  
HB = Brinell result  
Hardness Report 
Sample ID: Casting cut sample 
Hardness value: 229BHN 
Indenter: 2.5mm ball 
Lod applied: 187.5kgfs 
2.4. Pin-on-Disc test 
The experimentation is carried out on pin on disc wear testing machine this is a study versatile 
machine, shown in fig. 5 which facilitates study of friction and wear characteristics in sliding 
contacts under desired conditions. The coated workpiece is placed as the sitting mass right above 
the hard surface where the piece is pulled by the hanging mass and pulled on the other direction 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
by the frictional force and the surface keeps spinning at the given rpms. Normal load, rotational 
speed and wear track diameter can be varying to suit the test conditions. Frictional force and wear 
are monitored through electronic sensors. 
 
 
Fig: 5- Schematic representation pin-on-disc test rig 
2.5. Microstructure study 
The microstructures of cryogenic and conventionally treated samples were analysed by 
Optical Microscopy (OM). Samples were polished using Sic emery papers grades as follows 600, 
800 and 1000 and then super finished using diamond paste on the velvet cloth disc with kerosene 
as the suspension medium. Etching of these samples was carried out. Micro structures of samples 
were revealed at a magnification of 500X. Then the micrographs of conventional and cryogenic 
treated samples were analysed. 
3. Results and discussion  
The changes due to the cryogenic treatment can be easily differentiated from the comparison 
results in the below content. 
3.1. Microstructural analysis 
The microstructural analysis can strongly influence physical properties such as strength, 
toughness, ductility, hardness, corrosion resistance, high/low temperature behaviour or wear 
resistance. Micrograph and analysed micrograph of conventionally heat treated sample are shown 
in the following fig: 6 and 7. Micrograph and analysed micrograph of deep cryogenic treated 
sample are shown in the following. This microstructure shows larger amount of austenite at 
tempered condition with finely dispersed precipitated carbide particles. From the  
 
Fig: 6- Micrograph of original sample 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
 
Fig: 7- Micrograph of cryogenic treated sample 
3.2. Hardness test results  
Table 2: Parameter 
S. No. Material Sliding 
Velocity 
(M/S) 
Wear In 
(MICRON) 
COF 
(AVERAGE) 
Frictional 
Force(N) 
1. FG (NC) 0.8378 0.0076 0.2089 3.524 
The hardness values for the conventional, shallow and deep cryogenic treated samples are 
presented in Table 3. From the results it is clear that the cryogenic treatment improves the 
hardness.  
Table 3: Hardness test result comparison 
S.No. Materials Hardness values 
1. Fly wheel (CI) 156BHN 
2. Fly wheel (CI) coated with nickel 200BHN 
3.3. Wear test result 
From the pin on disc test performed to investigate the wear resistance properties of the 
material it can be confirmed that there are expected improvement in the wear properties in the 
cryogenic treated flywheel. Table 4 shows the wear results in different conditions. 
Table: 4 Represents for different loading conditions 
S. No. Material Sliding 
Velocity 
(M/S) 
Wear In 
(MICRON) 
COF 
(AVERAGE) 
Frictional 
Force(N) 
1. FG (NC) 0.8378 0.0076 0.2089 3.524 
 
 
B.Phawan et al. / International Research Journal of Automotive Technology 2019; 2(2): 6-13 
 
2. FG(C) 1.6755 0.0041 0.0487 3.305 
3. FG(CT) 0.8378 0.0036 0.4214 3.213 
4. FG(CCT) 1.6755 0.0006 0.6831 3.145 
4. CONCLUSION 
The micro structure result shows that change of austenite structure improve in wear 
resistance. And the hardness values of Cryogenic treated with Nickel Coated fly wheel material 
have a significant change in value. The wear rate of the fly wheel is average in 20N load at 200 
rpm is 10 micron with average friction force of 3.145N. Hence the coated flywheel shows 
significantly better wear resistance and life when compared to conventional flywheel. 
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Effects of Deep Cryogenic Treatment on Wear Resistance & Life of Nickel Coated Flywheel

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Effects of Deep Cryogenic Treatment on Wear Resistance & Life of Nickel Coated Flywheel

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