17 Armoured Fighting Vehicles (AFVs) usually require durable brake pads with lesser wear and 18 longevity. However, the currently deployed Copper MMC -based brake pads do not fully 19 complement the requirements for an AFV. With the need for innovation, this research provides 20 various recipes of brake pads with varying quantities of carbon or basalt reinforcement ranging 21 from 0.25 wt% to 1.25%. However, the currently available literature does not provide sufficient 22 evidence for using Basalt Fiber & Carbon fiber and the possible effects within an AFV’s 23 environment. So, the formulations were tested, and compressed into green compact pin samples 24 for experiments after sintering, like Vickers’ hardness test, Pin on Disc Wear Test, SEM 25 analysis, EDX, and XRD analysis for validation. Additionally, modeling and simulation for 26 brake pads and their assembly were done for 1.5 to 5 tonnes of load. This research provides a 27 comparative study between Carbon and Basalt Fibers based copper samples for brake pad 28 applications and high -performance applications like Armoured Fighting Vehicles. 29 Keywords: Copper Metal Matrix, Carbon Fiber, Basalt Fiber, Powder Metallurgy, Sintering, 30 SEM analysis, Reinforcements, Armoured Fighting Vehicles, Heavy -Duty Vehicles 31 1. Introduction 32 Brake pads convert a vehicle’s kinetic energy to heat energy through friction. The brake has 33 two pads, one on each side of the rotor, facing the rotor’s friction surfaces. The caliper clamps 34 or squeezes the two pads onto the spinning rotor when the brakes are applied hydraulically to 35 slow and stop the vehicle [1 -3]. When a brake pad warms up from contact with the rotor, minute 36 quantities of friction material are transferred to the disc, producing a dull grey covering. The 37 friction material on the brake pad and disc “stick” to each other, generating friction that stops 38 the vehicle [4 -6]. In disc brakes, each disc rotor typically has two brake pads. A caliper 39 2 mounted to the wheel hub or suspension upright holds these in position and activates them. 1 Racing calipers can use up to six pads with various frictional qualities when placed in a 2 staggered pattern for best performance [7]. 3 Dhanalakshmi S et al. (2007) investigated the sintered copper brake pads and found their 4 performance appropriate, even during wet friction. The composition used contained Sn (4 -6%), 5 Multite (5.5 -8.5%), Graphite (4.5 -7.5%), along with Copper [8]. Peng Zhang et al. (2019) 6 added Al 2O3, which significantly reduced wear loss of the brake pad; the relationship between 7 braking properties and tribo -film was assessed in the research [9]. Peng Zhang et al. (2020) 8 further investigated the incorporation of 0 -1.2% of the 0.4% Carbon fiber samples in the 9 experiments obtain the best wear performance. The samples incorporated Cementite with Fe 10 particles were utilized as the friction coefficient stabilizer [10]. Further investigating the copper 11 brake pads, it was found that they should have appropriate oxidation resistance in the 12 temperature range of 400 -800°C to perform for a prolonged period in a commercial and heavy 13 vehicle environment [11]. In [11], the investigation involved granular & flake Graphite, 14 Ferrochrome (FeCr), which acts as a friction coefficient stabilizer, Silicon Carbide, and Iron 15 [12, 13]. Figure 1 shows the basics of a brake pad and what are the expected properties and 16 performance expectations of a brake pad being developed 17 18 (a) (b) Figure 1. General Brake Pad (a) Layout, (b) Desired Properties [14] 19 20 This study provides vital insight regarding the investigations conducted to date and the gaps 21 this research fulfills regarding possible alternative materials apart from traditionally brake pads 22 have been scarcely explored, consisting of a Copper matrix, a solid lubricant. Secondly, 23 3 Ferrochrome as a friction coefficient stabilizer in brake pads has not been studied extensively 1 in defense applications, alongside decreasing the Molybdenum content compared to the 2 commercially used brake pads. Although Carbon reinforcement could be found, a negligible 3 amount of literature is available on using Basalt Fiber reinforcement. Furthermore, currently 4 available literature on Defence oriented brake pads is inaccessible or very limited; hence is not 5 readily available. In heavy vehicles, investigations have been conducted for high -speed trains 6 or commercial automotive vehicles [14]. 7 “Barites, mica, Allium sativum, and cashew dust are a few of the most popular alternatives 8 being studied for use as filler material” Selvaraj et al. (2021) [14]. However, comparatively, 9 investigations have not been conducted for the brake pads, and this research mainly provides a 10 fibers -related comparative analysis of Carbon and Basalt Fiber based copper brake pads. 11 12 2. Materials 13 Metals Used 14 We have taken metal powders and mixed them in a fixed proportion constituting 62% Cu with 15 Carbon or Basalt fiber, Silicon Carbide (SiC), Boron Nitrate (BN), Molybdenum Disulphide 16 (MoS 2), and Ferrochrome (FeCr) (Shiny Iron Powder) (Figure 1). 17 18 (a) (b) (c) (d) (e) 4 (f) Figure 2. Powders Used for Brake Pad Recipe (a) SiC, (b) Fe+2, (c) MoS 2, (d) Cu, (e) FeCr, 1 (f) Hydroxyapetite. 2 3 From Figure 2, the Materials Selected are as follows: 4 (1) Fe: It is added to stabilize the friction coefficient and enhance wear properties [15]. 5 (2) SiC: Excessive SiC addition will also cause a composite’s failure, as it may compromise 6 the ductility. The addition of silicon carbide in a limited amount (up to 10wt%) also 7 reduces surface wear [16]. 8 (3) BN: Its tight hexagonal lattice of alternating boron and nitrogen atoms is highly 9 resistant to change, unlike graphene and other 2 -D materials that can be easily 10 modified —aka functionalized —with other elements [17]. 11 (4) MoS 2: It acts as a lubricating agent to fill the macropores of the material [18]. It has an 12 adjusting property to fill the porosity throughout the matrix and is added 1 -2% in the 13 usual case [18]. 14 (5) Cr–Fe: the size of a few hundred micrometers in powder metallurgy pads (PM Pads) 15 were found to be embedded in the iron matrix. It has been reported that the Cr –Fe 16 particles in PM brake materials usually play the role of increasing friction effect in place 17 of just adding pure chromium. The Fe included in the composite is easily mixed in the 18 FerroChrome Matrix, enhancing the overall friction coefficient [19]. 19 (6) Cu: Copper has long been used in many friction materials because it is a good conductor 20 of heat. It helps cool the brake pads, stabilizing the friction characteristics for more 21 consistent braking and reduced fade. It also helps reduce noise [20]. 22 23 Fibers Used 24 The fibers used in this experiment were Carbon and Basalt Fibers (Figure 3). The fibers were 25 taken in fixed quantities in the Cu MMC. These fibers were reinforced in the Cu MMC for 26 further sample making, and testing. 27 28 5 (a) (b) Figure 3. The Fibers. (a) Carbon Fiber, (b) Basalt Fiber. 1 2 3. Experimentations 3 Mixing of Fibers & Powders 4 5 6 1 Figure 4. Mixing of Powders & Fibers for the Brake pad recipe. 2 3 Figure 4 explains the whole process of mixing the powders and fibers. The procedure involves 4 de-fiberizing Carbon and Basalt Fiber separately in a mixture machine (Figure 5). We had 5 increased the speed to 160 -180 rpm for 10 mins. When mixed Cu, Fe, and FeCr, we reduced 6 the mixer’s speed to 80 rpm. 7 8 7 1 Figure 5. Mixture Machine with Speed Adjuster. 2 3 We added SiC and 7 -8% of BN, and after these additions, we added MoS 2 for Flowability and 4 Texture. The whole recipe is shown in Table 2 for Carbon Fiber and Table 3 for Basalt Fiber 5 with a detailed list of elements mixed in fixed proportions. We have checked the process every 6 30 mins if the powder was not stuck and was mixed appropriately to maintain the homogeneity 7 of the mixture and avoid its sticking to the surface of the powder mixing machine. For 6 cycles, 8 comprising 3 hours for the whole process, each powder sample underwent the process, and we 9 have prepared 6 such powders with fixed percentages of Carbon and Basalt as applicable. 10 Figure 5(a), (b), and (c) show a visual representation of the selected compositions in Table 1, 11 2. 12 13 Table 2. Brake Pad Recipe Using Carbon Fiber. 14 Formation 1: Carbon fibre 0.25 wt% S.no . Material wt% wt for 350gms 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 2.75 9.625 6 C-Fiber 0.25 0.875 total 100 350 Formation 2: Carbon fibre 0.75 wt% 8 S.no . Material wt% wt for 350gms 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 2.25 7.875 6 C-Fiber 0.75 2.625 total 100 350 Formation 3: Carbon fibre 1.25 wt% S.no . Material wt% wt for 350gms 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 1.75 6.125 6 C-Fiber 1.25 4.375 total 100 350 1 2 Table 3. Brake Pad Recipe Using Basalt Fiber. 3 Formation 1: Basalt fibre 0.25 wt% S.no . Material wt % wt for 350gms 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 2.75 9.625 6 B-Fiber 0.25 0.875 total 100 350 Formation 2: Basalt fibre 0.75 wt% S.no . Material wt % wt for 350gms 9 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 2.25 7.875 6 B-Fiber 0.75 2.625 total 100 350 Formation 3: Basalt fibre 1.25 wt% S.no . Material wt % wt for 350gms 1 Cu 62 217 2 Fe2+ 8 28 3 CrFe 10 35 3 SiC 7 24.5 4 BN 10 35 5 MoS 2 1.75 6.125 6 B-Fiber 1.25 4.375 total 100 350 1 Manufacturing of Pin Samples 2 3 10 1 Figure 6. Manufacturing of Pins. 2 3 The powder is taken in approximately 7 -8 g amounts for the desired sample inside a die. The 4 plunger is marked using a marker for 35 mm and 40 mm measurements and keeping track of 5 compaction under the hydraulic press only for reference since a bottom punch of 10 mm is 6 added. The desired height for green compact samples was required to be 25 mm. A 10 mm 7 11 bottom punch is kept below inside the die for appropriate compression into a green compact 1 to ensure the powder does not come out of the die (Figure 6). Approximately 60 green compact 2 samples were made after the compaction in the hydraulic press for further testing. The samples 3 and their heights, indicator value of the hydraulic press, initial & final weights of the obtained 4 pin samples, density (Initial & Final), and porosity for Cabon & Basalt Fiber samples in 5 0.25wt%, 0.75wt%, and 1.25wt% have been provided in Table 4, 5. 6 7 The calculations performed in Tables 4, 5 are using the below equations: 8 9 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =𝑊𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑃𝑖𝑛 𝜋∗𝑟𝑎𝑑𝑖𝑖2∗𝐻𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓𝑝𝑖𝑛 (1) 10 11 ∆𝑝𝑜𝑟𝑜𝑠𝑖𝑡𝑦 =1− 𝐴𝑓𝑡𝑒𝑟 𝑠𝑖𝑛𝑡𝑒𝑟𝑖𝑛𝑔 𝑤𝑒𝑖𝑔 ℎ𝑡 𝐵𝑒𝑓𝑜𝑟𝑒 𝑠𝑖𝑛𝑡𝑒𝑟𝑖𝑛𝑔 𝑤𝑒𝑖𝑔 ℎ𝑡 (2) 12 13 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑎𝑝𝑝𝑙𝑖𝑒𝑑 (𝑀𝑝𝑎 )= 𝐹𝑜𝑟𝑐𝑒 (𝑘𝑔)∗9.8 𝜋∗𝑟𝑎𝑑𝑖𝑖2 (3) 14 15 Table 4. Evaluation of Carbon Fiber Pin Samples. (Attached Separately) 16 Carbon fiber 0.25wt% S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin sinteri ng Density porosity re- sizi ng Micro hardne ss forc e (ton e) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sintering befo re afte r 1 7.8 15.2 7.9 23.68 4.25 0 1.17 145.9676 63 2 7.8 9 7.8 24.78 4.01 0 0.69 86.42822 15 3 7.8 8.5 7.8 25.04 3.96 8 0.65 81.62665 36 4 7.7 8 7.6 25.04 3.86 6 0.62 76.82508 57 5 7.8 8.3 7.8 6.95 25.22 25.84 * 3.94 0 3.42 6 0.130353 457 Y 0.64 79.70602 65 6 7.8 10.5 7.8 23.78 4.17 8 0.81 100.8329 25 7 7.8 8 7.8 6.91 25.44 25.9 * 3.90 6 3.39 9 0.129836 65 0.62 76.82508 57 8 7.8 8.5 7.8 25.1 3.95 9 0.65 81.62665 36 9 7.8 9.1 7.7 25.88 3.79 0 0.70 87.38853 5 10 7.7 8.7 7.7 7.11 25.76 26.56 * 3.80 8 3.41 0 0.104435 926 Y 0.67 83.54728 07 12 Carbon fiber 0.75wt% S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin sinteri ng Density porosity re- sizi ng Micro hardne ss forc e (ton e) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sintering befo re afte r 1 7.6 16.2 7.6 22.84 4.23 9 1.25 155.5707 99 2 7.7 10.8 7.7 25.08 3.91 1 0.83 103.7138 66 3 7.8 9.7 7.8 7.01 25.18 25.64 * 3.94 6 3.48 3 0.117405 696 y 0.75 93.15041 65 4 7.8 11.1 7.7 24.88 3.94 2 0.85 106.5948 06 5 7.8 9.1 7.8 7.12 25.68 25.8 * 3.86 9 3.51 6 0.091425 164 y 0.70 87.38853 5 6 7.8 10 7.8 7.01 25.78 25.58 * 3.85 4 3.49 1 0.094255 328 0.77 96.03135 72 7 7.9 9.9 7.9 25.5 3.94 7 0.76 95.07104 36 8 7.8 10.3 7.8 25.5 3.89 7 0.79 98.91229 79 9 7.8 9.8 7.8 25 3.97 5 0.75 94.11073 10 7.8 22.2 7.8 22.85 4.34 8 1.71 213.1896 13 Carbon fiber 1.25wt% 14/03/20 22 S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin Density porosity re- sizi ng Micro hardne ss forc e (ton e) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sintering befo re afte r 1 7.8 10.2 7.9 25.56 3.93 7 0.78 97.95198 43 2 8 11.4 8 25.88 3.93 8 0.88 109.4757 47 3 7.7 10.9 7.6 7.06 23.56 24.88 * 4.10 9 3.61 5 0.120337 621 y 0.84 104.6741 79 4 7.8 10.1 7.7 25.02 3.92 0 0.78 96.99167 07 5 7.8 9.7 7.8 6.95 25.64 26.98 * 3.87 5 3.28 2 0.153228 412 y 0.75 93.15041 65 6 7.8 13.5 7.8 24.38 4.07 6 1.04 129.6423 32 7 7.8 9 7.9 26.22 3.83 8 0.69 86.42822 15 13 8 7.9 10.2 7.8 25.88 3.83 9 0.78 97.95198 43 9 7.8 9.4 7.8 6.88 25.56 26.82 * 3.88 7 3.26 8 0.159387 369 0.72 90.26947 57 10 7.8 9 7.8 26.18 3.79 5 0.69 86.42822 15 1 Legends: 2 y- The sample was used for sintering 3 *-Sintered Samples 4 5 Table 5. Evaluation of Basalt Fiber Pin Samples. (Attached Separately) 6 Basalt fiber 0.25wt% S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin sinteri ng Density porosity re- sizi ng Micro hardne ss force (tonne s) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sinteri ng befo re afte r 1 7.8 8.9 7.5 25.06 3.81 3 0.68 85.46790 79 2 7.8 10.7 7.7 25.1 3.90 8 0.82 102.7535 52 3 7.9 11 7.7 24.46 4.01 0 0.85 105.6344 93 4 7.8 9.6 7.7 6.94 25.64 24.12 * 3.82 6 3.66 5 0.041903 039 0.74 92.19010 29 5 7.8 9.4 7.8 6.98 25.74 24.08 * 3.86 0 3.69 3 0.043438 538 y 0.72 90.26947 57 6 7.8 12.7 7.7 24.74 3.96 5 0.98 121.9598 24 7 7.8 9 7.8 25.82 3.84 8 0.69 86.42822 15 8 7.8 10.2 7.7 25.62 3.82 9 0.78 97.95198 43 9 7.8 10.2 7.8 7.06 25.64 24.14 * 3.87 5 3.72 6 0.038629 363 Y 0.78 97.95198 43 10 7.8 11.5 7.8 25.08 3.96 2 0.88 110.4360 61 Basalt fiber 0.75wt% S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin sinteri ng Density porosity re- sizi ng Micro hardne ss force (tonne s) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sinteri ng befo re afte r 1 7.9 10.8 7.8 24.56 4.04 6 0.83 103.7138 66 14 1 Legends: 2 Y- The sample was used for Microhardness test 3 y- The sample was used for sintering & resizing after sintering 4 *-Sintered Samples 5 6 2 7.8 24 7.8 22.22 4.47 2 1.85 230.4752 57 3 7.86 11.2 7.83 26.02 3.83 3 0.86 107.5551 2 4 7.86 14 7.85 7.36 25.36 25.34 * 3.94 3 3.70 0 0.061680 382 1.08 134.4439 5 7.84 10.8 7.79 26.04 3.81 1 0.83 103.7138 66 6 7.82 13.7 7.52 24.54 3.90 4 1.05 131.5629 59 7 7.82 10.4 7.82 26.08 3.82 0 0.80 99.87261 15 8 7.88 17.1 7.84 24.6 4.06 0 1.32 164.2136 21 9 7.96 16.1 7.94 7.5 25.26 25.88 * 4.00 4 3.69 2 0.078044 764 y 1.24 154.6104 85 10 7.87 11.9 7.84 7.37 25.78 26.14 * 3.87 4 3.59 2 0.072895 359 Y 0.92 114.2773 15 Basalt fiber 1.25wt% S.n o. wt. of powd er Indicat or value Weight of Pin Height of Pin sinteri ng Density porosity re- sizi ng Micro hardne ss force (tonne s) pressure (Mpa) before sinteri ng after sinteri ng before sinteri ng after sinteri ng befo re afte r 1 7.87 15.9 7.8 7.33 25.94 26.12 * 3.83 0 3.57 5 0.066732 438 Y 1.22 152.6898 58 2 7.85 20.8 7.83 25.02 3.98 7 1.60 199.7452 23 3 7.85 15.1 7.8 7.33 26.2 26.18 * 3.79 2 3.56 7 0.059538 501 y 1.16 145.0073 49 4 7.86 17.3 7.78 7.31 25.46 25.66 * 3.89 3 3.62 9 0.067734 684 1.33 166.1342 48 5 8.53 18.9 8.5 27.78 3.89 8 1.45 181.4992 65 6 8.58 18.7 8.53 27.86 3.90 0 1.44 179.5786 38 7 8.55 20.5 8.4 26.06 4.10 6 1.58 196.8642 82 15 1 (a) (b) 2 Figure 7. (a) Hydraulic Press and (b) its indicator value calculation sheet. 3 4 This system (powder, bottom punch, die, and plunger) is then taken to a hydraulic press for 5 compression. In the hydraulic press, we set an indicator value of 26, equivalent to 2 Tonnes, 6 as provided in the manual for the press (Figure 7 (a), (b)). The samples we pressed were under 7 1-1.5 Tonnes of 250 Mpa. This pressure is appropriate based on the literature, and pressure 8 value may influence the outcomes visibly. 9 After compression, the material will be kept for some time to settle down. After 2 -3 minutes, 10 we use the ejection system (a hollow metal tool with a circular shape, which is similar to the 11 die’s dimensions) to remove the bottom punch and press the system under the hydraulic press 12 in 2 iterations, the second iteration being for removal of the ‘green compact’ sample (Figure 13 8). 14 15 16 Figure 8. The Green Compact Samples. 17 18 16 We convert the indicator value (as shown in Figure 7(b)) provided in the manual for the 1 hydraulic into tonnes, which are then converted into Newtons, and divide the area of the pin 2 sample (10 mm diameter) to obtain the pressure. The obtained value is 78.5, divided by the 3 factor obtained using the indicator value from the manual for the indicated amount of pressure. 4 5 Sintering Process 6 7 8 Figure 9. Tubular Furnace. 9 10 We set our green compact samples (samples undergone compaction only 1 time before 11 sintering) and heated the sample at 925°C for sintering in a tubular furnace (Figure 9). The 12 total time for the process was 7.5 hours, where 3 hours were consumed in the heating process 13 in the Tubular Furnace. The crucibles contained all the green compact samples kept inside the 14 tubular furnace. 2.5 hours were consumed for heating the furnace to 925°C (Figure 10). 15 16 17 1 Figure 10. Sintered Samples in the crucible. 2 3 The rising of the temperature was controlled to 5°C/min. 1.5 hours for temperature 4 stabilization during the sintering process, where slag, moisture, and porosity are maximally 5 removed. There was a reported black deposition, mainly due to the high temperature inside the 6 Tubular Furnace (Figure 9). 7 8 18 1 Figure 11. Sintering Process & Re -compaction after Sintering of Samples. 2 3 After sintering, the green compact samples are hardened, but the porosity is retained due to 4 the water molecules or slag present in the sample. This porosity is removed by re -compaction 5 of the samples under a hydraulic press (Figure 11). 6 Nitrogen flows at a very high rate within the furnace to maintain a Nitrogen atmosphere for 7 the sintering process to occur, which is done to avert any surface roughness. According to 8 various research, Argon and other similar gases may encourage surface roughness when their 9 flow rate is high due to their heaviness compared to Nitorgen’s usage. Cu has an FCC structure, 10 and in an N 2 environment, a cubic phase is favoured. However, taking the Argon environment 11 will promote the Hexagonal phase, which is unsuitable for sintering Cu [21, 22]. 12 13 19 4. Results and Discussions: Testing of Samples & Outcomes 1 4.1. Material Characterization 2 4.1.1. SEM & EDX Analysis 3 (a) (b) (c) (d) Figure 12. SEM Analysis of the Extreme Samples (a) Carbon Formation: 0.25wt%, (b) Basalt 4 Formulation: 0.25wt%, (c) Carbon Formation: 1.25wt%, (d) Basalt Formulation: 1.25wt%. 5 The SEM analysis for the samples was conducted using Carl Zeiss EVO/18, with a 6 magnification of 4000 -12000X, at 10000V. Figure 12 shows the microstructures of the sintered 7 green compact samples, after one iteration, before re -compaction. There were 4 samples taken 8 for the SEM analysis, which were the extremes of both Carbon & Basalt Fiber samples, 9 0.25wt% and 1.25wt% samples. The microstructure obtained is evident in the fibers and 10 dendritic growth on the surfaces. 11 12 20 (a) (b) (c) 21 (d) Figure 13. Energy Dispersive X -ray (EDX) Analysis of the Fiber Reinforced Samples. (a) 1 Carbon 1.25%wt, (b) Basalt 0.25wt%, (c) Carbon 0.25wt%, (d) Basalt 1.25wt% 2 3 Figure 13 shows the Energy Dispersive X -Ray (EDX) Analysis of the Carbon and Basalt 4 Fibers. A preliminary XRF test was conducted to investigate the elemental composition of the 5 powder samples used for further preparation of the green compact samples before SEM & EDX 6 analyses. Tables 6 to 8 list the elemental composition for each sample obtained in the EDX 7 analysis. 8 9 Table 6. EDX elemental composition for Basalt 0.25wt% (Figure 13 (b)) 10 Element Weight% Atomic% C K 36.67 66.52 O K 11.26 15.33 Si K 1.15 0.89 Ca K 1.71 0.93 Fe L 10.28 4.01 Cu L 30.06 10.31 Mo L 8.88 2.02 Total 100 11 Table 7. EDX elemental composition for Carbon 0.25wt% (Figure 13 (c)) 12 Element Weight% Atomic% C 43.12 68.52 22 O 14.41 17.19 Si 2.36 1.60 S 2.16 1.29 Cu L 37.94 11.39 Total 100 1 Table 8. EDX elemental composition for Basalt 0.25wt% (Figure 13 (d)) 2 Element Weight% Atomic% C 36.75 62.79 O 15.52 19.90 Si 2.91 2.12 Ca 3.72 1.90 Cu L 41.11 13.28 Total 100 3 4.1.2. XRD Analysis 4 The X -Ray Diffractometer analysis was conducted using Bruker D8 Advance, Germany, with 5 source being 2.2KW Cu anode, Ceramic X -Ray Tube. Theere were 6 samples tested, 3 for 6 carbon fiber samples (0.25wt%, 0.75wt%, 1.25wt%), and Basalt Fiber (0.25wt%, 0.75wt%, 7 1.25wt%) in powder form. The values obtained for 2Ɵ were then processed using OriginLab 8 software to obtain the graphs. The peaks obtained are verified, as shown in Figure 14 (a, b). 9 An X -ray tube is generating monochromatic intensity of Cu Kα radiation in the 10° to 80° 10 range at a scan speed of 5°/min. The generator is working at 40 kV and 30 mA. FWHM and 11 peak analysis helps in determining the crystallite size using Scherer’s formula which is given 12 in Equation (4), and crystalline index of the cellulose region was determined using multiple 13 peak fit analysis and Segal empirical equation which is given in Equation (5) where Scherrer’s 14 constant is given by K = 0.89 and λ is the wavelength of the radiation and β is the peak’s full 15 width at half -maximum [23]. 16 Crystallite Size (L) = K/βcosθ (4) 17 Crystallinity Index = ((I 200 - Iamorphous )/ I200) x 100 (5) 18 19 23 1 (a) 2 3 (b) 4 Figure 14. XRD Analysis Graph (Intensity vs. 2Ɵ), (a) Carbon Fiber Samples, (b) Basalt 5 Fiber Samples. 6 7 24 4.2. Vicker’s Hardness Test 1 (a) (b) Figure 15. (a) Vickers hardness tester, (b) Test Screen. 2 3 The Vickers hardness test was conducted for all the 6 samples for Carbon & Basalt fibers, using 4 a Matsuzawa Vickers Hardness Tester (Figure 15). Equation (6) was used for further 5 calculations which are shown in Tables 9 to 14. 6 𝑉𝑖𝑐𝑘𝑒𝑟 𝑠′𝐻𝑎𝑟𝑑𝑛𝑒𝑠𝑠 (𝐺𝑝𝑎 )=0.1891 ∗𝐹𝑜𝑟𝑐𝑒 (2∗𝑟𝑎𝑑𝑖𝑖 )2 (6) 7 8 Table 9. Vickers Hardness Test for Carbon 0.25wt% Sample. 9 Statistics Data Point Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 193.5 128.8 64.7 164.7 23.2 900 200 5.03 -0.51 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardness Conv. Conv. No X Y Distance Load D1 D2 HV Scale Hardness Judge 1 3.186 1.004 3.34 200 53.3 54.01 128.8 HRC 0 OK 2 3.593 1.004 3.731 200 38.94 56 164.5 HRC 1.5 OK 3 3.891 1.187 4.068 200 39.23 48.32 193.5 HRC 9.3 OK 4 4.062 1.231 4.244 200 45.34 49.03 166.5 HRC 2.1 OK 5 3.859 1.626 4.188 200 44.34 49.03 170.1 HRC 3.1 OK 10 Table 10. Vickers Hardness Test for Carbon 0.75wt% Sample. 11 Statistics Data Poin t Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 139.7 93.5 46.2 105.3 19.5 900 200 6 -1.62 25 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardnes s Conv. Conv. No X Y Distanc e Load D1 D2 HV Scale Hardnes s Judge 1 - 1.656 -7.797 7.971 200 62.11 58.84 101.4 HRC 0 OK 2 - 1.399 -7.797 7.922 200 62.68 62.54 94.6 HRC 0 OK 3 - 0.265 -7.518 7.523 200 58.84 67.08 93.5 HRC 0 OK 4 - 0.019 -7.443 7.443 200 58.27 65.09 97.4 HRC 0 OK 5 0.27 -7.371 7.376 200 49.46 53.58 139.7 HRC 0 OK 1 Table 11. Vickers Hardness Test for Carbon 1.25wt% Sample. 2 Statistics Data Point Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 126.1 102.8 23.3 116.7 9.7 900 200 11.97 -2.85 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardnes s Conv. Conv. No X Y Distanc e Load D1 D2 HV Scale Hardnes s Judge 1 3.889 0.269 3.898 200 49.46 66.37 110.5 HRC 0 OK 2 3.219 0.206 3.226 200 57.42 62.68 102.8 HRC 0 OK 3 3.31 0.378 3.332 200 48.75 59.69 126.1 HRC 0 OK 4 3.31 0.604 3.365 200 54.43 55.14 123.5 HRC 0 OK 5 3.354 1.004 3.501 200 51.88 59.12 120.4 HRC 0 OK 3 Table 12. Vickers Hardness Test for Basalt 0.25wt% Sample 4 Statistics Data Point Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 243.6 194.2 49.4 219.9 20.3 900 200 5.75 0.33 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardnes s Conv. Conv. No X Y Distanc e Load D1 D2 HV Scale Hardnes s Judge 1 0.025 -0.04 0.047 200 37.95 42.07 231.6 HRC 18.4 OK 2 0.153 -0.115 0.191 200 35.96 42.07 243.6 HRC 21.1 OK 3 0.723 -0.115 0.732 200 40.08 45.19 204 HRC 12 OK 4 0.864 -0.147 0.876 200 39.65 41.36 226 HRC 17 OK 5 0.997 -0.22 1.021 200 40.93 46.47 194.2 HRC 9.5 OK 5 Table 13. Vickers Hardness Test for Basalt 0.75wt% 6 26 Statistics Data Point Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 278 76.4 201.6 189.4 76.1 900 200 1.53 -0.05 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardnes s Conv. Conv. No X Y Distanc e Load D1 D2 HV Scale Hardnes s Judge 1 2.082 0.309 2.105 200 36.1 40.08 255.6 HRC 23.2 OK 2 2.395 0.195 2.403 200 31.98 41.07 278 HRC 26.8 OK 3 2.796 0.195 2.803 200 36.52 45.62 219.8 HRC 15.5 OK 4 3.112 0.195 3.118 200 47.18 46.9 167.6 HRC 2.4 OK 5 3.823 0.195 3.828 200 48.18 55.14 138.9 HRC 0 OK 6 4.086 0.225 4.092 100 48.32 50.17 76.4 HRC 0 OK 1 Table 14. Vickers Hardness Test for Basalt 1.25wt% Sample. 2 Statistics Data Poin t Max. Min. R Ave. Stdev Limit(U ) Limit(L) Cp Cpk 10 225.2 120.1 105.1 155 43.5 900 200 2.68 -0.34 Test Data Measurement Position （ｍｍ） Diagonal(μm) Hardnes s Conv. Conv. No X Y Distanc e Load D1 D2 HV Scale Hardnes s Judge 1 - 0.062 0.064 0.089 200 43.2 37.95 225.2 HRC 16.8 OK 2 0.223 0.071 0.234 200 46.19 48.32 166 HRC 2 OK 3 0.653 8.125 8.151 200 49.46 52.3 143.2 HRC 0 OK 4 0.902 0.41 0.991 200 55.71 55.43 120.1 HRC 0 OK 5 0.878 0.652 1.094 200 53.58 57.28 120.7 HRC 0 OK 3 4 27 1 Figure 16. Vickers Hardness Test Results 2 3 Figure 16 shows a graphical representation of the Vickers hardness test results for all the 6 4 samples as shown in Tables 8 to 13. The Basalt Fiber 0.25wt% and Basalt 0.75 have shown a 5 consistent performance in the hardness test. Carbon has shown a rather inconsistent trends in 6 hardness. 7 4.3. Pin on Disc Wear Test 8 This test was conducted using a DUCOM TR -201LE Pin on Disc Friction & Wear Testing 9 Machine, for the 6 samples of Carbon & Basalt Fiber Reinforced Compact Sintered Samples. 10 Each sample was tested on 450 rpm speed, and loads of 4 Kg. Before the test the disc was 11 grinded, and cleaned with acetone to ensure appropriate reading, after each sample was tested 12 for wear. The wear measurements were taken in microns. Figure 17 (a) to (f) shows all the 13 graphs obtained in Pin on Disc wear tests for the samples, and Figure 17 (g) shows the setup. 14 15 28 (a) (b) (c) (d) (e) (f) 29 (g) Figure 17. Pin on Disc Wear Test (a) C0.25wt%, (b) B0.25wt%, (c) C0.75wt%, (d) 1 B0.75wt%, (e) C1.25wt%, (f) B1.25wt%, (g) Pin -on Disc Test Setup Illustration [14]. 2 In the pin on disc wear test Basalt 0.25wt%, Basalt 0.75wt%, and Carbon 1.25wt% have shown 3 the best result and a stable graph, visible in Figure 17 (b, d, e). 4 5 5. Conclusions 6 Basalt 0.25 wt% sample has shown a consistent performance in various tests, and the best 7 performing sample reported. Basalt 0.75 wt% sample had the best results in some tests. Due to 8 the inconsistent results of Basalt 0.75wt% samples in multiple iterations, but comparatively 9 better performance than the samples with Carbon Fibers reinforced in the Copper Matrix. 10 Vicker’s hardness test and Pin on Disc wear tests show that the most consistent reading 11 obtained is for the Basalt 0.25wt% has been much more consistent than for Basalt 0.75wt% 12 and Carbon 1.25wt% samples. 13 Now, based on the XRD analysis and Pin on Disc Wear Test, Figure 18 shows two graphs for 14 Carbon and Basalt Fiber based Copper samples’ performance. Basalt samples have a divergent 15 graphs, whereas carbon samples show consistency in wear. The graph is intended to display 16 the longevity of the samples during wear based on the tests conducted. 17 18 19 30 1 (a) 2 3 (b) 4 Figure 18. Time vs Wear Graph (a) Basalt Fiber (b) Carbon Fiber. 5 There was noise reported during the pin -on-disc wear test, which must be controlled. Copper 6 is known for noise reduction while braking, but the Cu content being around 60 -65%, there is 7 a possibility of adding a small amount of additives to this recipe to control it because increasing 8 copper will decrease the attained strength after reinforcing the fibers. 9 31 There is a possibility for experimentations of various other fibers compatible for increasing the 1 strength of the Cu or any other matrix for braking, which can be vegetable or plant -based 2 natural fibers as conducted by V. Vineeth Kumar et al. (2020) [23]. 3 4 Declaration of Interests 5 The authors declare no conflict of interests. 6 7 Data Availability 8 Data is available upon reasonable request to the authors. 9 10 Funding 11 This research received no funding. 12 13