Effects of particle loading and particle size on tribological properties of ...

Journal of Tribology. Received November 06, 2015; Accepted manuscript posted March 24, 2016. doi:10.1115/1.4033131 Copyright (c) 2016 by ASME ASME Journal of Tribology

Effects of particle loading and particle size on tribological properties of biochar particulate reinforced polymer composites Richard. S1

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J. Selwin Rajadurai

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Department of Mechanical Engineering, Dr. Sivanthi Aditanar College of Engineering, Tiruchendur 628215, Tamil Nadu, India e-mail: [email protected]

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Department of Mechanical Engineering, Government College of Engineering, Tirunelveli 627007, Tamil Nadu, India e-mail: [email protected]

V. Manikandan

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Department of Mechanical Engineering, Kalasalingam University, Krishnankoil – 626190, Tamil Nadu, India e-mail: [email protected] ABSTRACT

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In this research work, pulverized biochar obtained by the pyrolysis of rice husk is used as particulate reinforcement in unsaturated polyester matrix. The effects of the particle loading and particle size on tribological properties of the particulate composites were investigated. The

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average size of biochar particles obtained through pulverizing using ball-mill varied from 510nm

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to 45nm while milling for a duration ranging from 6h to 30h. The particle loading in the

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composite was varied from 0.5wt% to 2.5wt%. It was observed that the particle size and particle

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content played a vital role in the tribological properties of the composites. The specific wear rate of the specimen having particle loading of 2.5wt% with 45nm particle size exhibited a decrease of 56.36% upon comparing with the specific wear rate of cured pure resin. The coefficient of

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friction of the same sample decreased by 6.42% when compared to that of a cured pure resin. The biochar particles were subjected to XRD, FT-IR and AFM analysis for characterization. Morphological studies were performed on the worn surfaces by SEM and Optical Microscopy.

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1. INTRODUCTION During the recent years, numerous researchers have shown immense interest in

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composites since they own superior and unique properties [1-4]. Composite materials find their applications widely in, automobile industry [5], aerospace industry [6] and other engineering

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applications, due to their high strength to weight ratio which crafts them as a good replacement for metals [7]. Polymer composites are rapidly developing class of materials due to their

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combination of high specific strength and specific modulus. Since polyester matrix has highly

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cross linked aromatic structure, it holds high rigidity, good adhesive properties, excellent

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dimensional stability, and outstanding heat and fire resistance. The properties of the polymers

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are further improved by the inclusion of fibres or particulate fillers or both as reinforcements

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resulting in polymer composites reducing cure shrinkage and high brittleness [8]. Particulate composite are composite material in which the filler materials are approximately spherical particles and the mechanical properties of particulate filled polymer composites depend primarily

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on size, shape, particle loading, distribution of filler particles in the polymer matrix and the

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interfacial adhesion between filler and matrix [7].

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Using natural substances as reinforcing fillers in composites is not only inexpensive but

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also minimizes the environmental pollution caused by the characteristic biodegradability, enabling these composites to play a vital role in resolving future environmental problems [9]. The requirement for materials those are harmless to the human beings which also possess appropriate characteristics for specific purposes are ever increasing due to the increasing levels of environmental pollution. Thus, research is going on in developing composites using various TRIB-15-1397

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recycled wastes [10,11], especially in developing composites using environmentally friendly biowastes as reinforcing fillers in polymers as matrixes. Using nano sized particles as fillers in polymer matrix composites is currently attracting the attention of many materials scientists,

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industrialists and technologists [12-14]. Based on numerous researches carried out on nano particles filled polymer composites it is evident that they possess noteworthy traits in producing

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materials with good wear resistance [15-17]. Nano particulate polymer composites, being a new class of material, offer significant enhancement in properties at very low filler loading [18-22].

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Having extremely high surface area is the most attractive characteristics of nano particles because it creates a great amount of interphase in the composite and thereby, creating a strong

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interaction between the matrix and the fillers at a very low nano-filler loading [23]. Many

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researchers [24–28] have reported that the tribological properties of polymer was improved by

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the addition of nano Al2O3, ZnO, SiC, CuO, TiO2, ZrO2, Fe2O3etc.

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Rice husk is an abundantly available and well-known agricultural byproduct in riceproducing countries. Global rice production is almost seven hundred million tons annually, and

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waste from rice husks - the outer, protective covering of a rice kernel, which is nearly 20 wt% of the kernel, is approximately 120 million tons a year [29]. The disposal of rice husk has become a

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great threat to the environment because of dumping it to the land and the surrounding areas [30].

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Hence, recycling the waste and producing materials having high-value is not only beneficial to

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the environment but also a promising bio-resource technology.

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In this study, fine particles of biochar derived from waste rice husk is used as reinforcement and the effect of particle size on the mechanical behavior of nano composites at low levels of filler content [23] has been focused. Five different nano sized particulate biochar were considered. Wear tests were carried out and tribological properties were studied. The morphological studies were performed by using Scanning Electron Microscope (SEM)

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observations and optical microscopy on the surface of the tested specimens. This work contributes to the better understanding of tribological properties of the rice husk biochar nano particle filled polymer matrix composites.

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2. EXPERIMENTAL DETAILS 2.1. Materials

rice husk as particulate reinforcement in this research work.

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2.1.1. Unsaturated polyester resin

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Unsaturated polyester resin has been used as matrix and biochar particles derived from

The matrix used for this work was commercially available unsaturated polyester resin

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with a trade name Sree polymer. Methyl Ethyl Ketone Peroxide (MEKP) was used as a curing

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catalyst and Cobalt Naphthenate as accelerator. The unsaturated polyester resin, catalyst and

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accelerator were supplied by Srinithi Chemicals, Tirunelveli, Tamil Nadu, India. The cured resin

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was tested at Composites Technology Centre, Indian Institute of Technology-Madras, Chennai,

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Tamil Nadu, India. The testing was conducted at ambient temperature (24°C) and a relative humidity of about 65%. The test results of cured matrix resin are given in Table 1. The obtained results were closer to the results obtained by Sreenivasan et.al.[2]

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2.1.2. Bio Char

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Biochar is a fine-grained charcoal high in carbon and largely resistant to decomposition.

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It is produced from pyrolysis of plant and waste feed stocks. In this work, biochar derived from

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pyrolysis of rice husk is used. Rice husk is the foremost by-product of the rice milling process and a major waste product of the agricultural industry. Rice husks contain approximately 20 wt% of Silica, which is present in hydrated amorphous form. They have become an important source of raw biomass material for producing value-added silicon composite products like pure silicon, silicon carbide, magnesium silicide, silicon nitride, silicon tetrachloride and zeolite [31]. Rice TRIB-15-1397

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husk (Fig. 1a) was obtained from a rice mill in the nearby village of Keelapudukudi Kaspa in Tuticorin District of Tamil Nadu, India. The sample was rinsed with distilled water to remove any adherent dust and extracts and then dried at 110°C for 2–3 hrs.

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Pyrolysis is a process of producing biochar where the biomass is heated in anoxic conditions. Pyrolysis may also produce liquids and gases from biomass apart from biochar. The

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absence of oxygen prevents combustion. The relative yield of products from pyrolysis depends on the temperature. Temperatures of 400–500 °C (752–932 °F) produce more char, while

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temperatures above 700 °C (1,292 °F) yields liquid and gas fuel components. Cleaned and dried rice husk was placed inside a cylindrical porcelain crucible of diameter 80 mm and height 100

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mm in an electric muffle furnace and the crucible was closed with a lid having perforations of 1

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mm which provided a small opening for steam and gas to escape. A temperature of 450°C

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(842°F) was maintained for a duration of 60 mins and then the furnace was switched off and

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allowed to cool for about 30 min before transferring the samples into a desiccator for further cooling. This resulted in the biochar powder (Fig. 1b) having uneven particle size which was

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maintained inside a desiccator in order to avoid agglomeration. Biochar thus obtained was milled in planetary ball mill for various time periods ranging

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from 6 h to 30 h. Ball milling resulted in fine particles of biochar (Fig. 2). Variation of milling

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time resulted in varied particle size. The average particle size of biochar thus powdered was

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measured using particle analyzer and was found to be 510 nm for 6 h milled powder, 430 nm for

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12 h milled powder (Fig. 3), 230 nm for 18 h milled powder, 140 nm for 24 h milled power and 45 nm for 30 h milled powder. It is clearly seen that the average particle size of the biochar powder decreased upon increasing the milling duration and it is depicted from the graph shown in Fig. 4.

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2.2. Preparation of composite specimen The resin transfer moulding method was adopted for the fabrication of composites using a mould made of acrylic sheet with a mould cavity size of 300 x 125 x 3 mm. The mould cavity

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was coated with PVA (Poly Vinyl Alcohol), a mould release agent for easy ejection of the composite. A measured quantity of 510 nm biochar powder was mixed with pre defined volume

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of resin. This mixture was added with 0.5% Cobalt Naphthenate (accelerator) and 2% MEKP (catalyst/hardener) [32] and the slurry was mixed in a hand mixer to get a homogeneous mixture.

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The entrapped air in the mixer was removed by vacuum desiccators.

This homogeneous mixture was then slowly decanted into the mould held in an inclined

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position in order to avoid the formation of air bubbles until the cavity is filled. It was then left to

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cure at room temperature for about 24–26 h after which the cured composite (Fig. 5) was taken

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out of the mould. Similarly the samples are prepared with 430 nm, 230 nm, 140 nm and 45 nm

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by the same procedure by varying the bio char content with 0.5, 1, 1.5, 2 and 2.5 %. A specimen without biochar particulate reinforcement was also prepared. 26 samples of composites thus

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fabricated are designated in the table 2. 2.3. Mechanical Characterization

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In order to have a complete understanding of the influence of the particle size and particle

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loading on the mechanical and tribological properties of the particulate composite, the following

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complementary tests were carried out.

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2.3.1 Density and Void fraction In this research work, the theoretical and experimental densities of biochar filled polyester composites along with the corresponding volume fraction of voids were studied. The experimental densities of the composites were obtained by Archimedes principle. Theoretical

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density of composites can be calculated using rule-of-mixture as shown in the following expression (Eqn. 1) t =

1 Wm m

+

- Eqn. 1

Wp p

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Where m is the theoretical density of the composite, W and  represents the weight

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fraction and density respectively. The suffix m and p stands for the matrix and particulate filler. The density of the matrix (m) was found to be 1.22 g/cm3 and that of the biochar particle was 1.47 g/cm3. The actual density (e) of the composites can be determined experimentally by water

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immersion technique. The volume fraction of the voids (Vv) of composites is calculated using the

t − e t

- Eqn. 2

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Vv =

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following equation (Eqn. 2.):

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calculate the void fraction of the composites.

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The theoretical density of the composite was compared with experimental density so as to

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2.3.2 Wear Testing

The dry sliding wear characteristics of the composite were analyzed using a pin-on-disc test apparatus as per ASTM G99-95 standards. The tests were conducted on the sample of size

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10 x 10 x 3 mm. Prior to testing, the samples were rubbed over a 600 grade Silicon Carbide

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paper to ensure proper contact with the counter surface. The surface of both the disc and the

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samples were cleaned with a soft paper soaked in acetone before conducting the test. The test

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setup used for the experimentation is shown in the Fig. 6. The specimen is held stationary and the disc is rotated and a normal force is applied using a lever mechanism. The test was conducted for a sliding distance of 3000m under a normal loading of 30 N at a constant sliding velocity of 3 m/s [33]. The environmental condition in the laboratory was 27° C and 43% relative humidity. Weight loss method was followed for calculating the specific wear rate. TRIB-15-1397

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The specimens were weighed both before and after the tests in precision balance. The specific wear rate is then expressed on volume loss basis using the Eqn. 3:[28] ∆𝑀

𝐾𝑆 = 𝜌𝐿 𝐹

𝑛

𝑚𝑚 3

- Eqn. 3

𝑁𝑚

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Where M is the mass loss in test duration (gm),  is the density of composite (gm/cm3), L is the sliding distance (m) and Fn is the applied normal load (N). In order to take repeatability

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into account, the results for friction and wear tests have been obtained for six readings and the average value have been reported graphically.

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2.5. Atomic Force Microscopy

Atomic Force Microscope (XE 70, Park Systems - Korea) is used here to analyze the

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topography (3D view) of the biochar particle. Topography is three -dimensional arrangement of

2.6. Scanning electron microscopy (SEM)

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physical attributes (such as shape, height, and depth) of a surface in a place or region.

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Fractography of the failure surface of tested composite samples were examined using

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Scanning Electron Microscopes, TESCAN VEGA3 SBU and Carl Zeiss EVO 18. The fractured portions of the samples were cut and gold sputtered in order to make the surface conducting. Then the worn out surface of wear tested samples were examined at appropriate magnifications

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subjecting the specimen to a high voltage ranging from 10 to 15 kV and the SEM micrographs

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were taken.

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2.7. Optical Micrograph

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Top view optical microscopy images of the wear tracks were taken by using an Olympus BX60 optical microscope in reflection mode with 100 X magnification to observe the wear tracks on the surface of the composite specimen.

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2.8. X-ray diffraction (XRD) analysis XRD analysis were carried out on an X'Pert PRO X-ray diffractometer (PANalytical) with Cu Kα (λα1 = 0.15406 nm, λα2 = 0.15443 nm) radiation. Continuous scan mode was

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followed to collect 2θ data from 10° to 80°. The voltage and current were 40 kV and 30 mA, respectively.

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2.9 Fourier Transform Infra Red (FT-IR)

The Fourier Transform Infrared Spectrometry was done to characterize the biochar

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powder and was performed using the NICOLET IS10 spectrometer at room temperature. The infrared light was passed through the biochar powder sample. When the infrared frequency was

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equal to the vibrational frequency of the bond, the absorption is done. The FT-IR spectrometer

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registered the interferogram and performed Fourier Transform on this interferogram to obtain the

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spectrum. The absorption spectrum was obtained and based on the analysis of this absorption

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spectrum, the functional compounds of the biochar were assigned.

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3. RESULTS AND DISCUSSION

The results obtained from the above tests are presented and discussed in detail as mentioned below.

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3.1 Biochar Particle characterization

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Towards knowing the size, shape, distribution, crystal structure and content of the

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been used.

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biochar particles obtained by ball milling process, the following characterization methods have

3.1.1. Morphological study of Biochar particle The morphological study of biochar particle was carried out using Scanning Electron Microscope images in magnified form. Fig. 7 shows the SEM image of biochar particles after milling for 30 hours from which it is seen that the particles are of nanometer scale which TRIB-15-1397

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confirms the observation through particle analyzer. It is also seen that the particles are spherical in shape after milling. However, some agglomeration are also seen due to the fineness of biochar particles.

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3.1.2. Atomic Force Microscopy The three dimensional topography of the milled biochar particles obtained from Atomic

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Force Microscopy is shown in the Fig. 8. From the topography it is clearly is seen that the bio char particles are in nano meter size and are having particles with size between a range of nano

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meter sizes which were also earlier observed by the particle analyzer. 3.1.3. Fourier Transform Infra Red (FT-IR) Spectroscopy

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Fourier Transform Infra Red (FTIR) analysis was performed and the absorption spectrum

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is shown in the Fig. 9. From the spectrum it is observed that the peak at the frequency of 800

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shows the presence of C-C where as the peak at 1088 shows the presence of C-O (Lactone). The

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peak at 1392 and 1584 depicts the presence of C=C and C=O respectively. The peak obtained in the spectrum at 3255 confirms the presence of C-H and the peak at 3313 shows the presence of

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O-H inter molecular H bonding. These above absorptions are may be due to the presence of carbohydrate in the rice husk. Carbohydrates contain C-C, C-O, O-H groups. Carbohydrate may

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also be present in the lactone form.

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3.1.4. X-ray diffraction (XRD) studies

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X-ray diffraction analysis was performed to identify the crystal structure of the biochar

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particles and the Fig. 10 shows the XRD pattern of the biochar particle. The powder X-ray diffraction technique has been employed to identify the crystalline phases of the samples using mono chromatized Cu- K(λ =1.5056A0) on X-ray diffractometer. The data collection was performed in the 2-theta range of 3º-80º in steps of 0.1º /sec. The XRD pattern of biochar from rice husk exhibits obvious poly-aromatic, turbo-static structural features, despite the fact that

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some amorphous structures may coexist due to the large half-peak width and low intensity of the related reflection. 3.2 Density and Void fraction

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The theoretical density and the experimental density of the composite specimens fabricated were obtained and are tabulated in Table 3 and represented graphically in Fig.11. It is

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noticed from Table 2 that composite density calculated using Eq. (2) may not be in agreement with the experimentally determined values. The difference is a measure of voids and pores

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presented in the composites. From the Fig. 11, it is observed that increasing the biochar particle content from 0.5 wt% to 2.5 wt%, results in an increase in void fraction. It is also observed that

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the void fraction for 510 nm biochar particle filled polyester composite is higher than that of 45

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nm biochar particle filled polyester composite. This may be due to fact that composite E with

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filler size 45 nm may entrap the air during the preparation of composite specimens by resin

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transfer moulding.

The specimen P fabricated with pure resin too has void fraction which may have arose

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because of the fine air bubbles which may have been entrapped inside the resin. It is seen that the void fraction has shown a drastic increase when the biochar particle wt % has been increased

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to 2.5 wt% which when increased beyond 2.5% may further increase the void fraction which

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may affect the mechanical properties of the composite. And hence the particle loading has been

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restricted within 2.5 wt%.

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3.3. Wear Test

3.3.1. Wear rate and coefficient of friction The effect of particle size on the specific wear rate and coefficient of friction of biochar filled polyester composites at 3000 m sliding distance and an applied normal load of 30 N at a constant velocity of 3 m/sec were studied for all the samples and the results were graphically

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represented in Fig. 12 and 13. The specific wear rate of cured pure resin was found to be 22 x 10-6 mm3/Nm and its coefficient of friction as 0.56. Upon introducing a nano sized biochar particle into the cured pure resin matrix, the specific wear rate and the coefficient of friction

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exhibits a decreasing trend. For the sample fabricated with 510 nm sized biochar powder, the specific wear rate was

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lowered by 41.66% from 20.4 x 10-6 mm3/Nm to 11.9 x 10-6 mm3/Nm for an increase of particle loading from 0.5 wt% to 2.5 wt%. Similarly, the coefficient of friction reduced by 20.75% from

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0.53 to 0.42 while increasing the particle loading from 0.5 wt% to 2.5 wt%. A similar trend of decrease in specific wear rate and coefficient of friction was observed for the above said range of

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particle loading when the reinforcement was made with biochar particles of size ranging from

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430nm to 45nm. The specific wear rate of the specimen having particle loading of 2.5 wt% with

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45 nm particle size exhibited 56.36 % decrease when compared to that of cured pure resin.

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For the least particle loading of 0.5 wt%, the specific wear rate was found to decrease by 10.78% from 20.4 x 10-6 mm3/Nm to 18.2 x 10-6 mm3/Nm where as the coefficient of friction

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decreased by 16.98% from 0.53 to 0.44 when the particle size was reduced from 510nm to 45nm. For the maximum particle loading of 2.5 wt%, 19.32% decrease was observed in specific wear

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rate from 11.9 x 10-6 mm3/Nm to 9.6 x 10-6 mm3/Nm and 28.57% decrease was noted in the

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coefficient of friction from 0.42 to 0.3 when the particle size was decreased from 510nm to

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45nm. The coefficient of friction of the specimen having particle loading of 2.5 wt % with 45 nm

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particle size exhibited 46.42% decrease when compared to that of cured pure resin. The experimental results showed that with decrease in particle size of biochar and increase in particle loading, the wear rate and coefficient of friction gradually decreases which may be due to the presence of Carbon which is highly known for its superior dry lubricating property.

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3.3.2. SEM observation of wear surface morphology Worn surfaces of pure polyester resin and biochar reinforced particulate composites were studied with Scanning Electron Microscope and are presented in Fig. 14 to Fig. 19. The Fig. 14

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shows the wear mechanism of cured pure resin specimen. It is clearly observed that severe wear and plastic deformation has occurred on the surface due to the absence of particulate Fig. 15(a) and Fig. 15(b) presents the SEM images of worn surfaces of

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reinforcement.

composites fabricated with average particle size of 510 nm with particle loading of 0.5 wt% and

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2.5 wt% respectively. It is clearly visible that the surfaces possesses more number of deep grooves and bigger wear debris and broken particles. This may be because of the bigger particle

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size which cases poor bonding between reinforcement and matrix. However, in Fig 15(b) when

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compared to Fig 15(a) the deep grooves and plastic deformation are comparatively lesser which

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may be due to higher particle loading and the self lubricating property of carbon present in

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biochar particles.

Fig. 16(a) and Fig. 16(b) presents the images of worn surface of the composites having

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particle size of 430nm and particulate loading of 0.5 wt% and 2.5 wt% respectively.

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reduction in particle size increases the contact area of particulates in the surface. The carbon When friction

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which is present in the biochar particulate reduces the dry sliding friction.

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reduces, the surface temperature also reduces during wear. Due to lower sliding temperature the

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possibility of plastic deformation and debonding is reduced. The impact of reduction in particle

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size in reducing the plastic deformation and debonding is clearly evident from Fig 16 to Fig. 19. The decreasing trend in the depth of deep grooves is predominantly visible in the above mentioned Fig. The size of wear debris and voids has considerable reduced because of the reduction of biochar particle size. The SEM images of worn surfaces of composites having higher particle loading (2.5 wt %) of biochar shown in Fig. 15(b), 16(b), 17(b), 18(b) and 19(b)

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depicts lesser plastic deformation, deep grooves, smaller wear debris and voids when compared to surfaces of samples with lesser particle loading (0.5 wt%) shown in Fig. 15(a), 16(a), 17(a), 18(a) and 19(a). The Fig. 19(b) having higher particle loading and lesser particle size shows

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smooth surface having less deep grooves, less plastic deformation, few voids and very fine wear debris.

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3.3.3. Optical Micrograph study of worn surface

Worn surfaces of pure polyester resin and biochar reinforced particulate composites were

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studied with Optical Microscope and are presented in Fig. 20 and 21. From the Fig. 20, which shows the optical micrograph of the worn out surface of cured pure resin, it is clearly seen that

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the plastic deformation and depth of wear track are high along the shown direction of wear. The

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coefficient of friction for the cured pure resin is high (0.56) which offers more resistance to the

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sliding surface which in-turn results in elevated temperature on the wear surface. The generated

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heat creates plastic deformation along the surface. Fig. 21 (a) shows the worn surface of A5 specimen which contains 2.5 wt% of biochar particles having average particle size of 510nm.

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The inclusion of biochar particles containing carbon reduces the coefficient of friction which inturn reduces the sliding resistance resulting in less wear and less plastic deformation along the

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direction of wear which is evident from the Fig. 21(a) to 21(e). From the Fig. 21(a) to 21(e) in

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which the particle loading remains 2.5wt%, and the biochar particle size is decreased from 510

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nm to 45 nm, it is obvious that, the reduction in particle size has played a significant role in

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reducing the friction and thereby reducing the wear and plastic deformation. It can be concluded that incorporation of small size biochar particles at a higher particle loading into pure polyester reduces the rate of wear and enhances the tribological properties of particulate composites. The carbon content in the nano sized biochar particles in the composite act as a solid lubricant and it reduces the wear upon increasing its concentration.

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Also the rate of wear is reduced

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considerably upon reducing the particle size which is due to the nano sized biochar particles present in the surface subjected to wear which decreases the area of contact between the two surfaces and hence, smaller the particle size, lesser the contact area and lesser the rate of wear.

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4. CONCLUSION In this research work biochar obtained by pyrolysis of rice husk was pulverized to five

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different nano sized particles using ball mill. Biochar particles were characterized using Particle analyzer, FT-IR, XRD and SEM spectroscopy. Five different nano sized biochar particles were

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reinforced with polymer matrix with five different particle loading resulting in 25 combinations of particulate composites and a pure cured resin specimen was also fabricated.

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Tribological properties of the biochar particulate filled polyester composites have been

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investigated. The effects of particle size and particle loading on the tribological properties were

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investigated. The worn surface morphology was studied using Scanning Electron microscope and

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Optical microscope.



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The research findings are abridged as follows:

Specific wear rate and the coefficient of friction of the biochar particulate composite decreased while increasing the particle loading and reducing the particle size when

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compared to that of cured pure resin. The specific wear rate of the specimen having

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maximum particle loading of 2.5 wt % with minimum particle size of 45 nm decreased

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56.36 % comparing to that of cured pure resin and the coefficient of friction decreased by

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46.42 % when compared to that of cured pure resin. Hence the composites having higher particle loading and lower particle size of biochar may find its application where good wear resistance is essential.

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ACKNOWLEDGMENT The authors gratefully acknowledge the management of Dr. Sivanthi Aditanar College of Engineering, Tiruchendur, Kalasalingam University, Krishnankoil and Government College of

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Engineering, Tirunelveli, Tamil Nadu, India for providing research facilities.

REFERENCES

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[25] Tao Sun, Hongyu Fan, Zhi Wang, Xin Liu and Zhanjun Wu, 2015, “Modified nano Fe2O3-epoxy composite with enhanced mechanical properties”, Materials & Design, 87, pp. 10–16. doi: 10.1016/j.matdes.2015.07.177 [26] Bahadur S and Sunkara C, 2005, “Effect of transfer film structure, composition and bonding on the tribological behavior of polyphenylene sulfide filled with nano particles of TiO2, ZnO, CuO and SiC”, Wear, 258, pp. 1411–21. DOI:10.1016/j.wear.2004.08.009 [27] Chang Li, Zhang Zhong, Ye Lin and Friedrich Klaus, 2007, “Tribological properties of high temperature resistant polymer composites with fine particles”, Tribology International, 40, pp. 1170–1178. DOI:10.1016/j.triboint.2006.12.002 [28] Kurahatti RV, Surendranathan AO, Srivastava S, Singh N, Ramesh Kumar AV and Suresha B., 2011, “Role of zirconia filler on friction and dry sliding wear behaviour of bismaleimide Nanocomposites”, Materials and Design, 32, pp. 2644–2649. DOI:10.1016/j.matdes.2011.01.030 [29] C. Tuck, E. Perez, I. Horvath, R. Sheldon and M. Poliakoff, 2012, “Valorization of biomass: deriving more value from waste”, Science, 337(6095) pp. 695–699. DOI: 10.1126/science.1218930 [30] Johar, N., Ahmad, I. and Dufresne, A., 2012, “Extraction, preparation and characterizationof cellulose fibres and nanocrystals from rice husk”, Industrial Crops and Products, 37, pp. 93–99. DOI: 10.1016/j.indcrop.2011.12.016 [31] Turmanova, S., Genieva, S. and Vlaev. L., 2012, “Obtaining Some Polymer Composites Filled with Rice Husks Ash-A Review”, International Journal of Chemistry, 44, pp. 62. DOI: 10.5539/ijc.v4n4p62 [32] R. Satheesh Raja, K. Manisekar and V. Manikandan, 2014, “Study on mechanical properties of fly ash impregnated glass fiber reinforced polymer composites using mixture design analysis”, Materials and Design, 55, pp. 499–508. DOI:10.1016/j.matdes.2013.10.026 [33] V. Arumuga Prabu, V. Manikandan, and M. Uthayakumar, 2012, “Friction and dry sliding wear behavior of red mud filled banana fibre reinforced unsaturated polyester composites using Taguchi approach”, Materials Physics and Mechanics, 1, pp. 34–45.

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List of Figures - (a) Rice Husk, (b) Biochar

Fig. 2.

- Biochar particle after ball milling

Fig. 3.

- Particle size distribution of biochar milled for 12 h.

Fig. 4.

- Variation of mean particle size with varying milling hours

Fig. 5.

- One of the fabricated samples of Biochar reinforced composite

Fig. 6.

- Pin-on-disc setup

Fig. 7.

- SEM image of Biochar particles after milling

Fig. 8.

- Topography of the Biochar particulate

Fig. 9.

- FT-IR Spectroscopy of Biochar particles

Fig. 10.

- XRD Pattern of Biochar particles

Fig. 11.

- Void fraction of different composite specimen

Fig. 12.

- Variation of Specific Wear rate with biochar Wt % in composite specimen

Fig. 13.

- Variation of Coefficient of Friction with biochar Wt % in composite specimen

Fig. 14.

- SEM image of worn surface of clear polyester resin

Fig. 15.

- SEM pictures of the worn surfaces of biochar particulate (510nm) reinforced composites

tN

ot

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py ed

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Fig. 1.

- SEM pictures of the worn surfaces of biochar particulate (430nm) reinforced composites

sc r

Fig. 16.

ip

with Particle loading of 0.5 wt % (a) and 2.5 wt % (b)

with Particle loading of 0.5 wt % (a) and 2.5 wt % (b) - SEM pictures of the worn surfaces of biochar particulate (230nm) reinforced composites

Ma nu

Fig. 17.

with Particle loading of 0.5 wt % (a) and 2.5 wt % (b) Fig. 18.

- SEM pictures of the worn surfaces of biochar particulate (140nm) reinforced composites with Particle loading of 0.5 wt % (a) and 2.5 wt % (b) - SEM pictures of the worn surfaces of biochar particulate (45nm) reinforced composites with

ed

Fig. 19.

Particle loading of 0.5 wt % (a) and 2.5 wt % (b) - Optical Micrographs of the worn surface of pure polyester resin

Fig. 21.

- Optical Micrographs of the worn surfaces of biochar particulate reinforced composite

ce

pt

Fig. 20.

Ac

specimen A5 (a), B5 (b), C5 (c), D5 (d) and E5 (e)

List of Tables Table 1

- Typical properties of the unsaturated polyester resin

Table 2

- Nomenclature for the composite samples prepared

Table 3

- Density and Void fraction of the composite samples

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ot

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FIGURES

Fig. 1(b). Biochar

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Fig. 1(a). Rice Husk

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Fig. 2. Biochar particle after ball milling

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Fig. 3. Particle size distribution of biochar milled for 12 h.

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Journal of Tribology. Received November 06, 2015; Accepted manuscript posted March 24, 2016. doi:10.1115/1.4033131 Copyright (c) 2016 by ASME ASME Journal of Tribology 600

510 430

400 300

230

200

140

100

45

0 6

12

18

24

30

py ed

Milling Hours

ite d

Particle size in nm

500

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Fig. 4. Variation of mean particle size with varying milling hours

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Fig. 5. One of the fabricated samples of Biochar reinforced composite

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Fig. 6. Pin-on-disc setup

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Fig. 7. SEM image of Biochar particles after milling

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Co

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Fig. 8. Topography of the Biochar particulate

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100

95

85

ite d

Absorbance

90

1584

py ed

1392 800

80

3300

Co

75

70

ot

1088 65 1000

1500

2000

2500

3000

3500

4000

4500

tN

500

-1

Frequency(cm )

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Fig. 9. FT-IR Spectroscopy of Biochar particles

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ot

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Fig. 10. XRD Pattern of Biochar particles

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0.65 510 nm

430 nm

230 nm

140 nm

45 nm

0.6

0.45

ite d py ed

0.5

Void Fraction (%)

0.55

Co

0.4

ot

0.35

tN

0.3

ip

0.5 % biochar + 1 % biochar + 1.5 % biochar + 2 % biochar + 2.5 % biochar + Polyester Polyester Polyester Polyester Polyester

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Fig. 11. Void fraction of different composite specimen

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510 nm

430 nm

230 nm

140 nm

45 nm

21 19

ite d

17 15 13 11 9 0.5 1 1.5 2 Weight % of Biochar in specimen

2.5

3

Co

0

py ed

Specific Wear rate x 10-6 mm3/Nm

23

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Fig. 12. Variation of Specific Wear rate with biochar Wt % in composite specimen

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0.6 510 nm

430 nm

230 nm

140 nm

45 nm

0.5 0.45

ite d

0.4 0.35 0.3 0.25 0.2 0

0.5

1

1.5

2

py ed

Coefficient of Friction

0.55

2.5

3

Co

Weight % of Biochar in specimen

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Fig. 13. Variation of Coefficient of Friction with biochar Wt % in composite specimen

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py ed

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Fig. 14. SEM image of worn surface of clear polyester resin

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py ed

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Fig. 15. SEM pictures of the worn surfaces of biochar particulate (510nm) reinforced composites with Particle loading of 0.5 wt % (a) and 2.5 wt % (b)

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py ed

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py ed

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Fig. 20. Optical Micrographs of the worn surface of pure polyester resin

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Ma nu

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Fig. 21. Optical Micrographs of the worn surfaces of biochar particulate reinforced composite specimen A5 (a), B5 (b), C5 (c), D5 (d) and E5 (e)

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TABLES

1.23

Tensile strength (MPa)

35 ± 1.5

Tensile modulus (GPa)

1 ± 0.3

Elongation at break (%)

1.5 ± 0.14

Impact strength (J/cm2)

0.23 ± 0.05

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Density (g/cm3)

ite d

Table 1: Typical properties of the unsaturated polyester resin

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Table 2: Nomenclature for the composite samples prepared

D

230 nm

140 nm

45 nm

ite d

0% biochar + Polyester 0.5 % biochar + Polyester 1 % biochar + Polyester 1.5 % biochar + Polyester 2 % biochar + Polyester 2.5 % biochar + Polyester 0.5 % biochar + Polyester 1 % biochar + Polyester 1.5 % biochar + Polyester 2 % biochar + Polyester 2.5 % biochar + Polyester 0.5 % biochar + Polyester 1 % biochar + Polyester 1.5 % biochar + Polyester 2 % biochar + Polyester 2.5 % biochar + Polyester 0.5 % biochar + Polyester 1 % biochar + Polyester 1.5 % biochar + Polyester 2 % biochar + Polyester 2.5 % biochar + Polyester 0.5 % biochar + Polyester 1 % biochar + Polyester 1.5 % biochar + Polyester 2 % biochar + Polyester 2.5 % biochar + Polyester

py ed

430 nm

Ac

ce

pt

ed

Ma nu

sc r

E

510 nm

Co

C

Composite specification

ot

B

Mean Biochar particle size (nm) -

tN

A

Specific Designation of composite specimens P A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 C5 D1 D2 D3 D4 D5 E1 E2 E3 E4 E5

ip

Broad Designation of composite specimens P

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Table 3: Density and Void fraction of the composite samples Theoretical density of the composite (t) in g/cm3

Experimental density of the composite (e) in g/cm3

Void fraction (%)

P A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 C5 D1 D2 D3 D4 D5 E1 E2 E3 E4 E5

1.231 1.221 1.113 1.059 1.005 0.952 1.221 1.113 1.059 1.005 0.952 1.221 1.113 1.059 1.005 0.952 1.221 1.113 1.059 1.005 0.952 1.221 1.113 1.059 1.005 0.952

1.230 1.217 1.108 1.055 1.001 0.946 1.217 1.108 1.054 1.000 0.946 1.217 1.108 1.054 1.000 0.946 1.217 1.108 1.054 1.000 0.946 1.217 1.108 1.054 1.000 0.946

0.130 0.315 0.393 0.429 0.472 0.585 0.324 0.417 0.450 0.493 0.605 0.324 0.417 0.450 0.493 0.605 0.338 0.421 0.460 0.502 0.610 0.348 0.422 0.467 0.507 0.620

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Specific Designation of composite specimens

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