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Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams
Materials Today: Proceedings xxx (xxxx) xxx
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams Ch. Sri Chaitanya ⇑, R. Narasimha Rao Department of Mechanical Engineering, National Institute of Technology Warangal, Warangal 506004, India
a r t i c l e
i n f o
Article history: Received 20 September 2019 Received in revised form 24 November 2019 Accepted 10 December 2019 Available online xxxx Keywords: Syntactic foams Tribological behaviour Cenospheres Polymer composites Wear rate
a b s t r a c t In the present study, the tribological behaviour of the syntactic foams manufactured using the fly ash cenospheres as the reinforcements and the epoxy as the matrix were studied for their tribological performance. The effect of the reinforcement concentration on the tribological properties like wear rate and the coefficient of friction were observed by using the pin on disc tribo tester. Four types of samples were prepared by varying the cenosphere volume fraction from 10% to 40% and tribological tests were conducted at constant sliding speed of 1 m/s and constant applied load of 50 N for a sliding distance of 2000 m. The increase in cenosphere volume fraction reduced wear rate and increased friction coefficient. The reduction in the wear rate may be due to the reduction in the effective contact area due to the pores created by crushed cenospheres. The increment in the coefficient of friction may be due to the increase in the cenosphere shells in the wear debris which act as obstacles. The worn surfaces of the foams were observed using the scanning electron microscope to determine the dominant wear mechanism. Ó 2019 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization.
1. Introduction Composite materials present unique combination of properties which usually include high strength to weight ratio. The composite materials are obtained by bonding a two or more types of materials. The obtained composites will have the mixture of the properties of their constituents. The composites with the hollow micro balloons as the reinforcements are called the syntactic foams. Most of the thermal power plants use coal as the fuel for generating electricity. Fly ash was obtained after burning the coal which was discarded. The moisture in the coal and the air in the atmosphere gets trapped in the particles of the coal when burned at a high temperature. These micro spheres will be in the fly ash and are used in numerous applications by leveraging the properties like low moisture absorption properties, low thermal conductivity and high compressive strength [1]. The cenospheres were separated from the fly ash by using the density variation between the hollow cenosphere particles and the fly ash particles. The majority of the cenosphere particles contain air which reduces the density of the cenospheres below the density of water. Hence the cenospheres
⇑ Corresponding author.
float on water while fly ash sinks into the water. The precipitate was then collected and dried to obtain the cenospheres [2]. The initial research on the syntactic foams was done with a goal to use them for the structural and the energy absorbing materials. In the recent past the syntactic foams were being considered to use for the applications in the transportation and machinery. These applications require the study of the tribological properties of the syntactic foams. Different types of micro balloons manufactured using fly ash, polymer, glass etc. were prepared to observe the effect of the type of hollow micro balloon on the properties of the syntactic foams. Birla et al. studied the compression deformation behaviour of the syntactic foams manufactured with aluminium alloy as the matrix. The effect of the quantity of cenospheres in the matrix and the relative density of the syntactic foams on the energy absorption behaviour of the syntactic foams were studied. The energy absorption of the cenosphere syntactic foams were quantified by integrating the stress strain relation obtained from the stress strain curve. The energy absorption of the syntactic foams increased with the increase in the amount of the cenosphere reinforcement due to the enhancement of the range of the densification strain region. The densification strain was invariant with the cenosphere volume fraction. The effect of the ratio cenosphere radius to the shell thick-
E-mail address: [email protected] (Ch. Sri Chaitanya). https://doi.org/10.1016/j.matpr.2019.12.070 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
2
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
ness of the cenosphere on the compression deformation behaviour of the syntactic foams were studied by Gupta et al. [3]. The quasi static, dynamic compression behaviour and the thermal properties were also studied [4,5]. The compression deformation behaviour of the cenosphere reinforcements with the epoxy matrix syntactic foams were also reported [6]. The tribological behaviour of the metal matrix syntactic foams with various reinforcements were studied and it was reported that the particle size, applied loading and the sliding speed affect the wear rate considerably [7–10]. Chaitanya et al. [11] observed the improvement of the wear resistance of the aluminium matrix syntactic foams at higher sliding speeds. Chauhan et al. [12] studied the tribological behaviour of the foams manufactured using vinyl ester as matrix and reported that the wear rate was higher at larger sliding distances. The abrasive wear behaviour of the LDPE matrix syntactic foams were also studied [13]. In the present study the tribological behaviour of the epoxy syntactic foams with fly ash cenospheres as the reinforcements were studied. The effect of the fly ash content in the syntactic foam on their tribological properties was studied by using 10%, 20%, 30% and 40% cenosphere volume fraction syntactic foams. The wear tests were conducted by keeping all the parameters like sliding speed, sliding distance and applied load as constant. 2. Materials and methods The syntactic foams that were used for the present study were manufactured using epoxy resin and hardener as the matrix materials. The cenospheres obtained from the fly ash were used as the reinforcement particles. Four different types syntactic foams were prepared using different volume fractions of the reinforcement particles. The cenospheres that were obtained from the thermal power plant have different sizes. The wide range of the sizes of the cenosphere will reduce the repeatability of the experiments. To eliminate the repeatability errors in determining the properties of the syntactic foams due to the variation of the size of the cenospheres, they were graded by the size by us mechanical sieving. For the current study the cenospheres of the size less than 75 lm were used. The finer particles will provide better tribological properties and hence these particles were utilized. The moisture from the cenosphere particles was removed by heating them. Based on the density of the cenospheres, epoxy and hardener, the weights of the each were measured for making the syntactic foams. Four types of the syntactic foams were prepared with the volume fraction of cenospheres as 10%, 20%, 30% and 40% were utilized. The cenospheres and the epoxy were taken into a container and mixed thoroughly with stirrer made up of wood. After the uniform mixture was achieved, the hardener was mixed to them and poured in the dies of size 10 mm diameter and the height of 35 mm. The syntactic foams were cured at room temperature for a couple of days and then the samples obtained were used for the study. The samples were then machined to get the samples with 27 mm length. The samples obtained should have regular distribution of the reinforcements to have isotropic properties and uniform properties. The distribution of the cenospheres were observed using the scanning electron microscope (SEM). The quality of the bonding between the matrix and the reinforcements can also be observed using the SEM. The samples were then tested for the tribological properties using pin on disc tribo tester. The EN31 steel material disc was used as the counter surface for the tests. The experiments were done at a sliding speed of 1 m/s, applied load of 50 N and the sliding distance of 2000 m and the tribological behaviour of the syntactic foams in terms of the wear rate and the friction coefficient were reported. The wear rate of the syntactic foams was calculated using the following Eq. (1).
Wear Rate ¼
Weight Loss of the sample during experiment density of the sample sliding distance
ð1Þ
The weights of the sample were measured before and after the experimentation. The density of the samples were obtained using Archimedes principle. The coefficient of friction of the polymer syntactic foams were obtained from the ratio of the frictional force from the pin on disc tribo tester and the applied load. The obtained worn surfaces as a result of the tribological tests were studied under the SEM to determine the wear mechanism in the syntactic foams.
3. Results and discussion The syntactic foam samples obtained were selected randomly and then cut into pieces and were observed using SEM. The distribution of the cenospheres in the syntactic foams and their bonding with the matrix was shown in the Fig. 1. To reduce the damage to the cenospheres wooden stirrer was utilized for mixing the cenospheres in the matrix. The cenosphere reinforcements in the epoxy matrix were fairly distributed and the damage to the cenospheres or the matrix was minimal. Fig. 1 shows that the manual mixing and sealing the dies was sufficient to obtain the fair distribution of the cenospheres in the syntactic foam. The samples that were obtained were used for the tribological tests. The wear rate of the syntactic foams as a function of the reinforcement volume fraction was shown in the Fig. 2. The coefficient of friction of the syntactic foams with the variation of the porosity in the sample was shown in Fig. 3. The density of the samples was
Fig. 1. Scanning Electron Micrographs of the syntactic foams showing the distribution and the bonding of the cenospheres with the matrix.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
3
Wear Rate (m3/m) 10
1 m/s 2000 m 50 N
8 6 4 2 0
10% Cenosphere 20% Cenosphere 30% Cenosphere 40% Cenosphere
Fig. 2. The wear rate of the syntactic foams as the function of the quantity of the reinforcements in the matrix.
Coefficient of Friction 0.7 0.6 0.5
1 m/s 2000 m 50 N
0.4 0.3 0.2 0.1 0
10% Cenosphere 20% Cenosphere 30% Cenosphere 40% Cenosphere
Fig. 4. The Scanning Electron Microscopy study of the worn surfaces (a) 20% cenosphere syntactic foam, (b) 40% cenosphere syntactic foam.
Fig. 3. The variation of the coefficient of friction with the variation of the reinforcement volume fraction in the foam.
4. Conclusions required to the calculate the wear rate from the weight loss during the tribological tests. The density of the syntactic foams was measured using Archimedes principle. The density of the syntactic foams reduced with the increase in the porosity caused due the cenospheres reinforcement. The wear rate of the cenosphere reinforced polymer syntactic foams was reduced with an increase in the cenosphere volume fraction. The wear rate of the 40% cenosphere reinforced syntactic foam was nearly 50% lower than the wear rate of the 10% cenosphere syntactic foam. The high reinforcement content increases the porosity of the foam. The effective area of contact reduces with the increase in the porosity which reduces the wear rate. The wear debris formed from the broken shells of the cenosphere gets accumulated at the pores created by them. At the low speeds the wear debris from the shells of the cenosphere particles remain on the sliding path of the pin sample over the disc. These debris particles increase the force required to push the sample over the disc, which increases the coefficient of friction. The increase in the coefficient of friction was evident from the Fig. 3. The worn surfaces of the syntactic foams were observed using scanning electron microscope to study the wear mechanisms. The worn surface of the 20% cenosphere syntactic foam and the 40% cenosphere syntactic foams were shown in Fig. 4. The accumulation of the cenospheres and the hard crushed cenosphere shells were also showed in the Fig. 4. The flow of the material and the absence of the deep wear grooves on the worn surface indicate adhesive wear of the syntactic foams.
The conclusions of the current study can be listed as follows The porosity in the matrix can be achieved by introducing the cenospheres. The damage to the cenospheres was negligible during mixing of cenospheres in the matrix. The mechanical mixing of cenospheres in matrix and sealing of the dies during curing give a reasonable distribution of cenospheres which are used as reinforcement in the syntactic foams. The wear rate of the syntactic foams reduces with the increase in the porosity due to the addition of the cenospheres at constant sliding distance of 2000 m, applied load of 50 N and the sliding speed of 1 m/s. The coefficient of friction of the syntactic foams increases with the increase in the amount of the cenosphere reinforcement in the foam at the above conditions due to the wear debris accumulation between the syntactic foam and the counter surface at lower speeds. This trend may vary at higher speeds as the wear debris will be removed by the centrifugal force.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
4
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
References [1] N. Ranjbar, C. Kuenzel, Fuel 207 (2017) 1–12. [2] P.K. Kolay, S. Bhusal, Fuel 117 (2014) 118–124. [3] N. Gupta, E. Woldesenbet, P. Mensah, Compos. Part A Appl. Sci. Manuf. 35 (2004) 103–111. [4] Q. Zhang, Y. Lin, H. Chi, J. Chang, G. Wu, Compos. Struct. 183 (2017) 499–509. [5] M. Labella, S.E. Zeltmann, V.C. Shunmugasamy, N. Gupta, P.K. Rohatgi, Fuel 121 (2014) 240–249.
[6] S.C. Ch, R.N. Rao, Mater. Res. Express 6 (2019), 125303. [7] A. Vishwakarma, D.P. Mondal, S. Birla, S. Das, P. Prasanth, Tribol. Int. 110 (2017) 8–22. [8] D.P. Mondal, S. Das, N. Jha, Mater. Des. 30 (2009) 2563–2568. [9] K. Májlinger, B. Bozoki, G. Kalacska, Phys. Rev. 57 (1940) 246. [10] N. Jha, A. Badkul, D.P. Mondal, S. Das, M. Singh, Tribol. Int. 44 (2011) 220–231. [11] C.S. Chaitanya, R.N. Rao, Mater. Today Proc. 15 (2019) 63–67. [12] S.R. Chauhan, S. Thakur, Mater. Des. 51 (2013) 398–408. [13] N. Chand, P. Sharma, M. Fahim, Compos. Interfaces 18 (2011) 575–586.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams Ch. Sri Chaitanya ⇑, R. Narasimha Rao Department of Mechanical Engineering, National Institute of Technology Warangal, Warangal 506004, India
a r t i c l e
i n f o
Article history: Received 20 September 2019 Received in revised form 24 November 2019 Accepted 10 December 2019 Available online xxxx Keywords: Syntactic foams Tribological behaviour Cenospheres Polymer composites Wear rate
a b s t r a c t In the present study, the tribological behaviour of the syntactic foams manufactured using the fly ash cenospheres as the reinforcements and the epoxy as the matrix were studied for their tribological performance. The effect of the reinforcement concentration on the tribological properties like wear rate and the coefficient of friction were observed by using the pin on disc tribo tester. Four types of samples were prepared by varying the cenosphere volume fraction from 10% to 40% and tribological tests were conducted at constant sliding speed of 1 m/s and constant applied load of 50 N for a sliding distance of 2000 m. The increase in cenosphere volume fraction reduced wear rate and increased friction coefficient. The reduction in the wear rate may be due to the reduction in the effective contact area due to the pores created by crushed cenospheres. The increment in the coefficient of friction may be due to the increase in the cenosphere shells in the wear debris which act as obstacles. The worn surfaces of the foams were observed using the scanning electron microscope to determine the dominant wear mechanism. Ó 2019 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization.
1. Introduction Composite materials present unique combination of properties which usually include high strength to weight ratio. The composite materials are obtained by bonding a two or more types of materials. The obtained composites will have the mixture of the properties of their constituents. The composites with the hollow micro balloons as the reinforcements are called the syntactic foams. Most of the thermal power plants use coal as the fuel for generating electricity. Fly ash was obtained after burning the coal which was discarded. The moisture in the coal and the air in the atmosphere gets trapped in the particles of the coal when burned at a high temperature. These micro spheres will be in the fly ash and are used in numerous applications by leveraging the properties like low moisture absorption properties, low thermal conductivity and high compressive strength [1]. The cenospheres were separated from the fly ash by using the density variation between the hollow cenosphere particles and the fly ash particles. The majority of the cenosphere particles contain air which reduces the density of the cenospheres below the density of water. Hence the cenospheres
⇑ Corresponding author.
float on water while fly ash sinks into the water. The precipitate was then collected and dried to obtain the cenospheres [2]. The initial research on the syntactic foams was done with a goal to use them for the structural and the energy absorbing materials. In the recent past the syntactic foams were being considered to use for the applications in the transportation and machinery. These applications require the study of the tribological properties of the syntactic foams. Different types of micro balloons manufactured using fly ash, polymer, glass etc. were prepared to observe the effect of the type of hollow micro balloon on the properties of the syntactic foams. Birla et al. studied the compression deformation behaviour of the syntactic foams manufactured with aluminium alloy as the matrix. The effect of the quantity of cenospheres in the matrix and the relative density of the syntactic foams on the energy absorption behaviour of the syntactic foams were studied. The energy absorption of the cenosphere syntactic foams were quantified by integrating the stress strain relation obtained from the stress strain curve. The energy absorption of the syntactic foams increased with the increase in the amount of the cenosphere reinforcement due to the enhancement of the range of the densification strain region. The densification strain was invariant with the cenosphere volume fraction. The effect of the ratio cenosphere radius to the shell thick-
E-mail address: [email protected] (Ch. Sri Chaitanya). https://doi.org/10.1016/j.matpr.2019.12.070 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and of the scientific committee of the 10th International Conference of Materials Processing and Characterization.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
2
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
ness of the cenosphere on the compression deformation behaviour of the syntactic foams were studied by Gupta et al. [3]. The quasi static, dynamic compression behaviour and the thermal properties were also studied [4,5]. The compression deformation behaviour of the cenosphere reinforcements with the epoxy matrix syntactic foams were also reported [6]. The tribological behaviour of the metal matrix syntactic foams with various reinforcements were studied and it was reported that the particle size, applied loading and the sliding speed affect the wear rate considerably [7–10]. Chaitanya et al. [11] observed the improvement of the wear resistance of the aluminium matrix syntactic foams at higher sliding speeds. Chauhan et al. [12] studied the tribological behaviour of the foams manufactured using vinyl ester as matrix and reported that the wear rate was higher at larger sliding distances. The abrasive wear behaviour of the LDPE matrix syntactic foams were also studied [13]. In the present study the tribological behaviour of the epoxy syntactic foams with fly ash cenospheres as the reinforcements were studied. The effect of the fly ash content in the syntactic foam on their tribological properties was studied by using 10%, 20%, 30% and 40% cenosphere volume fraction syntactic foams. The wear tests were conducted by keeping all the parameters like sliding speed, sliding distance and applied load as constant. 2. Materials and methods The syntactic foams that were used for the present study were manufactured using epoxy resin and hardener as the matrix materials. The cenospheres obtained from the fly ash were used as the reinforcement particles. Four different types syntactic foams were prepared using different volume fractions of the reinforcement particles. The cenospheres that were obtained from the thermal power plant have different sizes. The wide range of the sizes of the cenosphere will reduce the repeatability of the experiments. To eliminate the repeatability errors in determining the properties of the syntactic foams due to the variation of the size of the cenospheres, they were graded by the size by us mechanical sieving. For the current study the cenospheres of the size less than 75 lm were used. The finer particles will provide better tribological properties and hence these particles were utilized. The moisture from the cenosphere particles was removed by heating them. Based on the density of the cenospheres, epoxy and hardener, the weights of the each were measured for making the syntactic foams. Four types of the syntactic foams were prepared with the volume fraction of cenospheres as 10%, 20%, 30% and 40% were utilized. The cenospheres and the epoxy were taken into a container and mixed thoroughly with stirrer made up of wood. After the uniform mixture was achieved, the hardener was mixed to them and poured in the dies of size 10 mm diameter and the height of 35 mm. The syntactic foams were cured at room temperature for a couple of days and then the samples obtained were used for the study. The samples were then machined to get the samples with 27 mm length. The samples obtained should have regular distribution of the reinforcements to have isotropic properties and uniform properties. The distribution of the cenospheres were observed using the scanning electron microscope (SEM). The quality of the bonding between the matrix and the reinforcements can also be observed using the SEM. The samples were then tested for the tribological properties using pin on disc tribo tester. The EN31 steel material disc was used as the counter surface for the tests. The experiments were done at a sliding speed of 1 m/s, applied load of 50 N and the sliding distance of 2000 m and the tribological behaviour of the syntactic foams in terms of the wear rate and the friction coefficient were reported. The wear rate of the syntactic foams was calculated using the following Eq. (1).
Wear Rate ¼
Weight Loss of the sample during experiment density of the sample sliding distance
ð1Þ
The weights of the sample were measured before and after the experimentation. The density of the samples were obtained using Archimedes principle. The coefficient of friction of the polymer syntactic foams were obtained from the ratio of the frictional force from the pin on disc tribo tester and the applied load. The obtained worn surfaces as a result of the tribological tests were studied under the SEM to determine the wear mechanism in the syntactic foams.
3. Results and discussion The syntactic foam samples obtained were selected randomly and then cut into pieces and were observed using SEM. The distribution of the cenospheres in the syntactic foams and their bonding with the matrix was shown in the Fig. 1. To reduce the damage to the cenospheres wooden stirrer was utilized for mixing the cenospheres in the matrix. The cenosphere reinforcements in the epoxy matrix were fairly distributed and the damage to the cenospheres or the matrix was minimal. Fig. 1 shows that the manual mixing and sealing the dies was sufficient to obtain the fair distribution of the cenospheres in the syntactic foam. The samples that were obtained were used for the tribological tests. The wear rate of the syntactic foams as a function of the reinforcement volume fraction was shown in the Fig. 2. The coefficient of friction of the syntactic foams with the variation of the porosity in the sample was shown in Fig. 3. The density of the samples was
Fig. 1. Scanning Electron Micrographs of the syntactic foams showing the distribution and the bonding of the cenospheres with the matrix.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
3
Wear Rate (m3/m) 10
1 m/s 2000 m 50 N
8 6 4 2 0
10% Cenosphere 20% Cenosphere 30% Cenosphere 40% Cenosphere
Fig. 2. The wear rate of the syntactic foams as the function of the quantity of the reinforcements in the matrix.
Coefficient of Friction 0.7 0.6 0.5
1 m/s 2000 m 50 N
0.4 0.3 0.2 0.1 0
10% Cenosphere 20% Cenosphere 30% Cenosphere 40% Cenosphere
Fig. 4. The Scanning Electron Microscopy study of the worn surfaces (a) 20% cenosphere syntactic foam, (b) 40% cenosphere syntactic foam.
Fig. 3. The variation of the coefficient of friction with the variation of the reinforcement volume fraction in the foam.
4. Conclusions required to the calculate the wear rate from the weight loss during the tribological tests. The density of the syntactic foams was measured using Archimedes principle. The density of the syntactic foams reduced with the increase in the porosity caused due the cenospheres reinforcement. The wear rate of the cenosphere reinforced polymer syntactic foams was reduced with an increase in the cenosphere volume fraction. The wear rate of the 40% cenosphere reinforced syntactic foam was nearly 50% lower than the wear rate of the 10% cenosphere syntactic foam. The high reinforcement content increases the porosity of the foam. The effective area of contact reduces with the increase in the porosity which reduces the wear rate. The wear debris formed from the broken shells of the cenosphere gets accumulated at the pores created by them. At the low speeds the wear debris from the shells of the cenosphere particles remain on the sliding path of the pin sample over the disc. These debris particles increase the force required to push the sample over the disc, which increases the coefficient of friction. The increase in the coefficient of friction was evident from the Fig. 3. The worn surfaces of the syntactic foams were observed using scanning electron microscope to study the wear mechanisms. The worn surface of the 20% cenosphere syntactic foam and the 40% cenosphere syntactic foams were shown in Fig. 4. The accumulation of the cenospheres and the hard crushed cenosphere shells were also showed in the Fig. 4. The flow of the material and the absence of the deep wear grooves on the worn surface indicate adhesive wear of the syntactic foams.
The conclusions of the current study can be listed as follows The porosity in the matrix can be achieved by introducing the cenospheres. The damage to the cenospheres was negligible during mixing of cenospheres in the matrix. The mechanical mixing of cenospheres in matrix and sealing of the dies during curing give a reasonable distribution of cenospheres which are used as reinforcement in the syntactic foams. The wear rate of the syntactic foams reduces with the increase in the porosity due to the addition of the cenospheres at constant sliding distance of 2000 m, applied load of 50 N and the sliding speed of 1 m/s. The coefficient of friction of the syntactic foams increases with the increase in the amount of the cenosphere reinforcement in the foam at the above conditions due to the wear debris accumulation between the syntactic foam and the counter surface at lower speeds. This trend may vary at higher speeds as the wear debris will be removed by the centrifugal force.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070
4
Ch. Sri Chaitanya, R. Narasimha Rao / Materials Today: Proceedings xxx (xxxx) xxx
References [1] N. Ranjbar, C. Kuenzel, Fuel 207 (2017) 1–12. [2] P.K. Kolay, S. Bhusal, Fuel 117 (2014) 118–124. [3] N. Gupta, E. Woldesenbet, P. Mensah, Compos. Part A Appl. Sci. Manuf. 35 (2004) 103–111. [4] Q. Zhang, Y. Lin, H. Chi, J. Chang, G. Wu, Compos. Struct. 183 (2017) 499–509. [5] M. Labella, S.E. Zeltmann, V.C. Shunmugasamy, N. Gupta, P.K. Rohatgi, Fuel 121 (2014) 240–249.
[6] S.C. Ch, R.N. Rao, Mater. Res. Express 6 (2019), 125303. [7] A. Vishwakarma, D.P. Mondal, S. Birla, S. Das, P. Prasanth, Tribol. Int. 110 (2017) 8–22. [8] D.P. Mondal, S. Das, N. Jha, Mater. Des. 30 (2009) 2563–2568. [9] K. Májlinger, B. Bozoki, G. Kalacska, Phys. Rev. 57 (1940) 246. [10] N. Jha, A. Badkul, D.P. Mondal, S. Das, M. Singh, Tribol. Int. 44 (2011) 220–231. [11] C.S. Chaitanya, R.N. Rao, Mater. Today Proc. 15 (2019) 63–67. [12] S.R. Chauhan, S. Thakur, Mater. Des. 51 (2013) 398–408. [13] N. Chand, P. Sharma, M. Fahim, Compos. Interfaces 18 (2011) 575–586.
Please cite this article as: C. Sri Chaitanya and R. Narasimha Rao, Effect of addition of reinforcements on the tribological behaviour of the polymer based syntactic foams, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.070