Processing and dry sliding wear behavior of Al2O3 nanoparticles reinforced ZA-27 composites

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ScienceDirect Materials Today: Proceedings 4 (2017) 4006–4012

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5th International Conference of Materials Processing and Characterization (ICMPC 2016)

Processing and dry sliding wear behavior of Al2O3 nanoparticles reinforced ZA-27 composites Shivakumar.N1 *, Vasu. V1, Narasaiah N2 1

Department of Mechanical Engineering, National Institute of Technology Warangal, Telangana. 506004.

2

Department of Metallurgical and Materials Engineering, National Institute of Technology Warangal, Telangana. 506004.

Abstract ZA-27 nanocomposites is very promising material, which are suitable for a large number of applications. These nanocomposites consists of a metal matrix with nano-particles to improve the mechanical properties and wear resistance compare to the base material.ZA-27 alloy and composites reinforced with aluminium oxide (Al2O3) nanoparticles, ranging from 1, 2 and 3 weight percentage (wt %) are fabricated by using stir casting followed by ultrasonic assisted casting method. Microstructure analysis of alloy and nanocomposites were examined by using Optical Microscope (OM).Dry sliding wear is measured on Pinon-Disc testing apparatus, at various testing conditions for alloy and nanocomposite materials. Morphology study of the wear samples are also carried out by using Optical Microscope (OM). From the results, it’s observed that, as the wt% of the reinforced Al2O3 nanoparticles increases, the wear resistance increases. ©2017 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of 5th International Conference of Materials Processing and Characterization (ICMPC 2016). Keywords: ZA-27 nanocomposites, Aluminium Oxide, ultrasonic assisted Casting, Optical Microscope, Wear

* Corresponding author. Tel.: +91 9849185161; E-mail address:[email protected] 2214-7853©2017 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of 5th International Conference of Materials Processing and Characterization (ICMPC 2016).

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1. Introduction Metal matrix nanocomposites are being investigated worldwide in recent years for their promising properties suitable for a large number of applications which are range from automobile to aerospace industries. Zinc –aluminium (ZA) based cast alloys have initiate significant industrial usage due to their good castability, mechanical properties and excellent wear resistance.ZA-alloys are important bearing materials, especially suitable for high-load and low speed applications. The prominent types available in ZA-casting alloys are ZA-8, ZA-12 and ZA-27.Among these types ZA-27 is classified as high strength alloy with tensile strength substantially higher than that of ordinary cast aluminium alloy. The cost reduction from 25–50% is observed when ZA alloys are used in place of aluminum and 40–75% when replacing brass alloys respectively [1-3]. ZA-27 alloy can be effectively utilized for bearings and bushing applications, as a replacement for bronze bearings because of its low cost and equivalent or superior bearing performance. Hence, this material shows poor mechanical properties in high temperature environment conditions. In order to improve their physical and mechanical properties at high temperature ceramic or metal particulates can be reinforced. Many researchers has worked on the ZA-27 alloy reinforced with hard and soft ceramics particles and reported that these composites materials will give superior mechanical and wear resistance properties [4-6].The study of microstructure and strength of ZA-27 based composites reinforced with Al2O3 particles and composites with different particle size of 12 µm and 250 µm of Al2O3 powder were produced by a compocasting process. From the results it was observed that the composites exhibit higher strength than the cast alloy, the particle size of 12 µm have shown more strength compare to the large particles of Al2O3 powder[7-8]. In this article work is concentrated on the preparation of ZA-27 alloy reinforced with Al2O3 nanoparticles with the weight percentage (wt %) of 1, 2 and 3 wt % by using liquid metallurgy route followed by ultrasonic assisted casting technique. Unlubricated sliding wear behavior of ZA-27/ Al2O3 nanocomposites were investigated by using taguchi design of experiment. Analysis of variance (ANOVA) will give the influence of various factors on the unlubricated sliding wear behavior of the ZA27/ Al2O3 nanocomposites. Optical microscope (OM) is used for characterize the microstructures of the ZA-27 alloy and nanocomposites wear samples. 2. Materials and methods ZA-27 alloy has been taken as matrix material for preparation of nanocomposites. The chemical composition of the base alloy (weight percentage of 25-27 Al, 1-1.5 Cu, 0.001-0.002 Mg & Bal- Zn). Alumina (Al2O3) nano particles of average particle size (APS) of 50nm have been selected as reinforcement material for the fabrication of ZA-27/ Al2O3 nanocomposites. ZA-27 alloy was placed in the graphite crucible which is melted at a temperature of 800oc in the electric resistance furnace. When the ZA-27 alloy melted completely, slag appeared on the top of molten metal was removed. Reinforcement of pre-heated Al2O3 nano particles with the different wt % of 1, 2 and 3 in the melt and stirring was done for 10 minutes with the help of mechanical stirrer. After stirring ultrasonification of the nanocomposites with ultrasonic probe for about 5 minutes was done and the nanocomposite melt was poured and solidified into a mild steel die in the form of cylindrical rods. Nanocomposites have been prepared for different wt. % of alumina nano particles through ultrasonic assisted stir casting. Optical microscope was used for the microstructures analysis of the ZA-27/ Al2O3 nanocomposites. Micro-hardness tester is used to test the Vickers hardness and Archimedes principle was used to measure the density of the nanocomposites. 2.1. Experimental design Pin on Disc machine is used to perform the dry sliding wear behavior of ZA-27/ Al2O3 nanocomposites in which the desire output was the wear volume loss. To study the wear volume loss of the ZA-27/ Al2O3 nanocomposites which depend on the many input parameters i.e. speed, load, distance and filler content. L16 orthogonal array was used for design of experiments to study the influence of these four input parameters with their four different levels on the wear volume loss of the ZA27 nanocomposites. The control parameters with their selected levels are shown in table 1.The wear volume loss results were further transform into the S/N (signal to noise) ratios and the response to be studied was smaller is better. S/N ratio was calculated for the minimum wear volume loss by the expression is given in equation (1) S/N = -10 log (Ʃy2/n) Where n – number of observations and y- experimental data

(1)

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Control Factors

Table 1 Control factors and their selected levels. Levels 1

2

3

4

Speed (m/s) Distance(m)

1 750

1.5 1500

2 2250

2.5 3000

Load (N)

15

30

45

60

Reinforcement (wt %)

0

1

2

3

3. Results and discussion 3.1. Micro-hardness and density of ZA27 Nanocomposites Micro-hardness and Density of the ZA-27/ Al2O3 nanocomposites specimens were shown in Table.2. It was observed that the micro-hardness of the ZA-27/ Al2O3 based nanocomposites increases with the increase in the filler content where as density decreases with the increase in the filler content. Table 2 Micro-hardness and Density of ZA-27/ Al2O3 nanocomposites Samples

Composition

Density(g/cm3)

Micro-hardness(HV)

1

ZA-27 alloy

4.81

118.9

2

ZA-27+1% Al2O3

4.69

120.8

3

ZA-27+2% Al2O3

4.58

124.7

4

ZA-27+3% Al2O3

4.46

130.1

3.2. Microstructure analysis Microgrophs of the ZA-27/ Al2O3 nanocomposites with varying weight percentage of Al2O3 nanoparticles reinforcement is shown in figure 1.

Fig 1. Microstructures of ZA-27/Al2O3 nanocomposites, (a) ZA-27 alloy,(b) ZA-27 with 1% Al2O3, (c) ZA-27 with 2% Al2O3,(d) ZA-27 with 3% Al2O3.

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The microstructure of ZA-27 matrix alloy appears very similar to dendritic structure with uniform distribution of the alumina nanoparticles due to the ultrasonic assisted stir casting technique. The typical optical microscope micrographs of ZA-27/ Al2O3 nanocomposites reinforced with 1, 2 and 3 wt % are shown in figure 1.The alumina nanoparticles were located at the interdentritic regions of the nanocomposites, in which alumina nanoparticles were observed white in color with fine cored dentrites of aluminium and zinc. 3.3. Wear test Al2O3 reinforced ZA-27 nanocomposites of various combinations of factors for unlubricated sliding wear performance was shown in table 3.The wear volume loss of the specimen was taken from the average of three replicates of each sample and this output was transforms into (S/N) signal to noise ratios. Popular software MINITAB 16 was used for the experimental analysis. Table 3 Experimental design (Taguchi L16 OA) with output and S/N ratios

Test run

Speed (m/s)

Load (N)

Distance (m)

Filler content (wt %)

Wear volume loss(mm3)

Signal to noise (S/N) ratios

1

1

15

750

0

0.644

3.8223

2

1

30

1500

1

1.599

-4.077

3

1

45

2250

2

2.729

-8.7201

4

1

60

3000

3

3.923

-11.8724

5

1.5

15

1500

2

2.314

-7.2873

6

1.5

30

750

3

0.627

4.0546

7

1.5

45

3000

0

6.528

-16.2956

8

1.5

60

2250

1

3.987

-12.0129

9

2

15

2250

3

2.354

-7.4361

10

2

30

3000

2

4.388

-12.8453

11

2

45

750

1

1.535

-3.7222

12

2

60

1500

0

3.991

-12.0216

13

2.5

15

3000

1

5.01

-13.9968

14

2.5

30

2250

0

3.801

-11.598

15

2.5

45

1500

3

1.053

-0.4486

16

2.5

60

750

2

1.462

-3.2989

The analysis of variance (ANOVA) was used to study which parameters was significantly influence the wear characteristic. The results of ANOVA for Al2O3 reinforced ZA-27 nanocomposites were shown in Table 4.Percentage of contribution (p) of each control factors which affect the ZA27 nanocomposite materials are shown in column 7 from the Table 4.

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Table 4. Analysis of variance for ZA-27/Al2O3 composites

Source

DF

Seq SS

Adj MS

F-ratio

P-value

Speed Load Distance Filler Residual Error

3 3 3 3 3

2.8078 1.5385 32.5883 6.3295 0.7436

0.9359 0.5128 10.8628 2.1098 0.2479

3.78 2.07 43.82 8.51

0.152 0.283 0.006 0.056

Total R-Sq = 98.3%

15 R-Sq (adj) = 91.6%

44.0078

Percentage(%) of contribution 6.4 3.5 74.0 14.4 1.7 100

The response for signal to noise ratio was given in Table 5, from which it can be concluded that among all the control factors, the sliding distance was the most significant parameter which was followed by filler content, sliding speed and load has the negligible significance on the wear volume loss of the Al2O3 reinforced ZA-27 nanocomposites. Table 5. Response for signal to noise ratios for wear test Level

Speed

Load

Distance

Filler

1

-5.2118

-6.2245

-0.214

-9.0232

2

-7.8853

-6.1164

-5.9586

-8.4522

3

-9.0063

-7.2966

-9.9418

-8.0379

4

-7.3356

-9.8015

-13.7525

-3.9256

Delta

3.7945

3.6851

13.9665

5.0976

Rank

3

4

1

2

Fig 2. Effects of individual control parameters for S/N ratios

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From the figure. 2 it was observed that the individual influence of control parameters for signal to noise ratio and it concludes the parameter combination of filler (4th level),speed (1st level),load( 2nd level) and distance (1st level) will gives the minimum wear volume loss. 3.4. Worn surfaces by using OM Wear surfaces of the specimens were examined by using OM. The micrographs of the worn samples are shown in figure 2. From the microstructure of wear surfaces it can be seen that the unreinforced ZA27 sample has deep and coarse grooves on the worn surface. The addition of Al2O3 particles into the alloy increased the hardness of the ZA27 matrix. Also, the Al2O3 nanoparticles hinder the ploughing during wear. The grooves became shallower as the content of Al2O3 nanoparticles were increased in the ZA27 nanocomposites.

Fig 2.OM micrographs of wear surfaces: (a) ZA-27 alloy, (b) ZA-27 with 1% Al2O3 (c) ZA-27 with 2% Al2O3 (d) ZA-27 with 3% Al2O3

4. Conclusions ZA-27 nanocomposites reinforced with nano-sized Alumina (Al2O3) particles in different weight percentage ranging from 1-3 wt% in a step of 1% each were prepared by the Stir casting process followed by ultrasonic assisted casting technique. Due to this method the nanoparticles dispersion in the matrix material was uniform is shown in the microstructures of the ZA-27/ Al2O3 nanocomposites by using optical microscope. Taguchi experimental design (Taguchi L16 OA) was used for analyzing the unlubricated sliding wear behavior of the ZA-27/ Al2O3 nanocomposites. The minimum wear volume loss was obtained from the combination of filler content (3 wt %), sliding speed (1m/s), load (30N) and sliding distance (750m). The most significant factor for the wear volume loss was sliding distance is followed by filler content, sliding speed and load has the least significance. It is observed that wear volume loss decreased substantially with the increase of Al2O3 particle content in the composites. 5. References [1] Riccardo Casati, Maurizio Vedani. Metal Matrix Composites Reinforced by Nano-Particles—A Review, Metals, ( 2014) 4, 65-83. [2] Shivakumar.N , Vasu.V, Narasaiah.N Subodh kumarSynthesis and Characterization of nano-sized Al2O3 particle reinforced ZA-27 metal matrix composites, Procedia Materials Science,( , 2015 ) 10, 159-167. [3] Srimant Kumar Mishra Sandhyarani Biswas, Alok Satapathy. A study on processing, characterization and erosion wear behavior of silicon carbide particle filled ZA-27 metal matrix composites, Materials and Design,( 2014) 55, 958-965. [4] B.K. Prasad. Wear response of a zinc-based alloy containing silicon as influenced by material microstructure and test conditions, Materials Science and Engineering A (2004) 367, 63–73.

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[5] B.M. Girish K.R. Prakash, B.M. Satish, P.K. Jain, Kameshwary Devi,. Need for optimization of graphite particle reinforcement in ZA-27 alloy composites for tribological applications, Materials and Engineering A (2011) 532, 382-388. [6] G.Ranganath, S.C.Sharma, M.Krishna.,. Dry sliding wear of garnet reinforced zinc/aluminium metal matrix composites, Wear (2001) 251, 1408-1413. [7] I. Bobic M.T. Jovanovic, N. Ilic. Microstructure and strength of ZA-27-based composites reinforced with Al2O3 particles, Materials Letters (2003) 57, 1683– 1688. [8] LI Run-xia, LI Rong-de. BAI Yan-hau. Effects of specific pressure on the microstructure and mechanical properties of squeeze casting ZA-27 alloy, Trans.Nonferrous Met.Soc. China (2010) 20, 59-63. [9] S. Basavarajappa G. Chandramohan, J. Paulo Davim. Application of Taguchi techniques to study dry sliding wear behaviour of metal matrix composites, Materials and Design (2007) 28, 1393-1398. [10] S. Rajesh, A. Gopala Krishna, P. Rama Murty Raju, M. Duraiselvam. Statistical Analysis of Dry Sliding Wear Behavior of Graphite Reinforced Aluminum MMCs, Procedia Materials Science (2014) 6, 1110-1120 [11] T.S. Kiran M. Prasanna Kumar, S. Basavarajappa, B.M. Viswanatha. Dry sliding wear behavior of heat treated hybrid metal matrix composite using Taguchi techniques, Materials and Design (2014) 63, 294-304. [12] Shouvik Ghosh, Prasanta Sahoo, Goutam Sutradhar, Wear Characteristics Optimization of Al-7.5%Sic Metal Matrix Composite Using Taguchi Method, Advanced Materials Manufacturing & Characterization (2014) 4 issue 2.