Heat Treatment to Optimize Friction and Wear Behavior of Aluminum Composites Using Taguchi Technique - Assignment Example

Parameters of Heat treatment to Optimize Friction and Wear Behavior of Aluminum Composites Using Taguchi Technique Name of student Name of tutor Name of the student Abstract The Aluminum hybrid metal matrix composites (HAMMCs) which are in advance extensively used in some areas due to its enhanced mechanical characteristics more especially when they are compared with the metal alloys specifically in the application where weight and strength are most crucial consequences. The specimens are then tested as per the procedure recommended, and the entire experiment is done as per the L9 standard orthogonal array. The measured results are analyzed using computer aided software MINITAB 16 which is specifically designed for the experiment application. 1.0 Introduction In the current development, the matrix metal composite do congregate to meet the increasing the demand overall for the light weight, eco-friendly, high performance, corrosion resistant material and wear (Skinner, 231). The Aluminum hybrid metal matrix composites (HAMMCs) which are in advance extensively used in some areas due to its enhanced mechanical characteristics more especially when they are compared with the metal alloys specifically in the application where weight and strength are most crucial consequences. The merits of particulate reinforced composites over others are their formability with the benefit of expenditure and its distinct strengthen mechanisms (Zhang et al., 3). The HAMMCs are very good in use in the appliance that obliges characteristics such as a combined strength, damping characteristics thermal conductivity and coefficient of thermal expansion along with lesser density. The unique features of HAMMCs enhance their usage in automotive and tribological applications such as in the piston, brake drum, brake disk and cylinder block. In the process of casting, the reinforcing elements such as metal borides, metal carbides, metal nitrides and metal oxide are discrete within molten alloy matrix under atmospheric pressure. In recent times, liquid processing method is developed to make MMCs with higher volume fraction of reinforcement under a much lower pressure (Zhang et al., 13). The recent research studies shows that the homogeneous mixing that can be obtained by selecting the most appropriate processing parameters like stirring speed, temperature and time of the metal which is molten by initially heating temperature of the mould and standardized nourish rate of the given particles. The desired kind, distribution, and quantity determine the selection process of engineering design of the reinforcement component, the matrix alloy, and its application. Among the various aluminum alloys, one of the most popular choice as a matrix material is 7075, to prepare metal matrix composite owing to its better formability properties and the option of the modification of the strength of the composite through heat treatment (Skinner, 131).. The reinforcement of the particles is done through SiC into the aluminum matrix that increases the wear confrontation as a result of the hardness of the particles. With a specific reinforcement, HAMMCs, reinforcement is added to the matrix of the bulk material to improve its fitness and strength. The addition of strong ceramics like Al2O3, B4C and SiC, this addition enhances wear resistance and strength to weight ratio than the conventional alloys. It entirely depends on the primary selection of the reinforcement and the methods of production and the chemical compatibility with the matrix to achieve the toughness. Material system in engineering, the heat treatment processes are incredibly essential for improving the composite material characteristics. The main aim of the heat treatment is to create the material system structurally and physically strong and fit for engineering application. The treatment of the heat to aluminum allows do the maximum concentration of hardening solute to dissolve into solution. This particular method is suspiciously conceded out by heat treatment of and allows to a temperature at which solitary, exists a solid phase. On one occasion the alloy is heated to the optional revolutionizing temperature, it is then squashed at a high rate such that the atoms of the solute don't have apple time to precipitate out of the solution. It should be noted that conventional materials have certain shortcomings in good combination of the strength, stiffness, toughness, and density. For these demerits to be removed and the demand of the modern technology to be met, composite are some of the most crucial materials that are HMMC possess high specific toughness, strength, and the strength impact and low sensitivity to temperature, change. This has resulted in the use of HMMCS in the aerospace and automobile components. Aluminum based MMCS are still the subjects of research studies due to the fact their low density makes more merits in many applications. Among the various useful aluminum alloys, aluminum alloy Al 6061 is typically characterized by properties such as fluidity, castability, corrosion resistance and the high strength- weight ratio. It is not applicable to many tribological due to its high wear loss nature. The main concentration of the selection of suitable process engineering depends on the desired quantity and distribution of the reinforcement component, the matrix alloy, and its application. A numerical analysis of pin on disc tests on Al – Li/SiC composite at different loads and temperature. The properties of tribological such as wear and friction co-efficient are considered to be one of the important factors that influence HMMC performance. The tribological characteristics of the reinforced aluminum matrix composite that is prepared by the vortex method for short steel fibers, the friction coefficient and wear rate is established by using pin on the disc type apparatus through varying the applied load from 10 to 40 N with a constant sliding velocity of about 1.8m/s and sliding distance of about 200m and it is concluded that the volumetric wear increases with increasing applied load and the transition from the mild wear to severe wear that depends on the strength of the pin material adjacent to the surface (Zhang et al., 18). The factors mentioned here has created a tremendous development in the field of research all over the world more especially in the manufacturing HAMMCs with an improved both the mechanical, physical and tribological characteristics. Experiment is intended to evaluate concurrently two or more issues that possess their aptitude to affect the ensuing average or unpredictability of particular creation or process individuality. The main focus of experiment design should prefer level of influencing factors. Based on the Taguchi, an orthogonal array is used to reduce the number of experiments for findings out best test parameters as recognized. Examination of the trial outcomes uses SN to hold up the strength of mind of the premium process design and has efficiently been used for the study of dry sliding wear performance of the composites materials. The parameters influence identified by the wear rate and friction coefficient is applied load, sliding velocity, sliding time and the reinforcement percentage. The optimization technique called Taguchi design of experiment has also been chosen due to the above mixture of work, to examine the effect of limit such as practical load, sliding velocity and sliding coldness on dry sliding wear performance of the Al 7075/SiC/B4C composites. Considering the above facts, an attempt is further made to employ the use of ANOVA to find the percentage of the influence of various factors and its interaction on the dry sliding wear of the composite. 2.0 The material Assortment The supposed substance composition of Al 7075 alloy is given in table 1. The matrix alloy is preferred as it as it provides outstanding mixture of strength to heaviness ratio and injured tolerance at elevated and cryogenic temperatures. In the experiment, it was very important to set all the density measurement according to the ASTM standards that are C1270-88. The worth of inflexibility and thickness for matrix materials are set at 160 VHN and 2.76g/cm3 within a tempered condition. Hardness of the specimens was measured using Vicker hardness tester by applying the load of about 10 kg, and the average value of the hardness from about 10 different data of the experiments was considered. The Table 1 below gives the chemical composition of the Al 7075 alloy. Elements Si Fe Cu Mn Ni Zn Ti Mg Cr Al % by Weight 0.06 0.18 1.63 0.074 0.05 5.62 0.049 2.52 0.22 Balance 3.0 The composite preparation and testing Figure 1 shown below indicates the stir cast technique used to prepare the composite specimens. Matrix Alloy (Al 7075) is first superheated in this process until it reaches its melting point, and the temperature is slowly below the liquid temperature to keep the matrix allow in the same semi-solid state. After the cooling of preheated temperature, the percentage weight of the materials varies with SiC 5%, 10%, and 15% and B4C having a constant weight of 3% in addition to 1% magnesium (Mg) particles that will be introduced into the slurry and mixed. It should be noted that it is very important to improve the slurry composite temperature to the liquid state fully, and automatic stirring is continued for about 10 minutes at an average stirring speed of 500 rpm. The liquid melt is further superheated until it goes above the superheated liquid temperature and lastly poured into the iron cast enduring mould as per necessary dimensions. In order to obtain cylindrical pins, the specimens are machined having a width of different values and height. The example faces are metallographically refined. After polishing, the cast composites are subjected to solutionizing at a temperature of about 5300C for an hour followed by quenching using water. The quenched sample are further subjected to artificial aging for distinct duration of 4, 6, 8 hours respectively at a temperature of 175oC. The stir cast used is shown below; Figure 1: The experimental set up used in the fabrication of HAMMCs (Al 7075/SiC/B4C) The specimen is age hardened and the Vickers hardness values for distinct condition as per ASTM standard of testing. The solutionizing temperature and the duration of about 530oC and an hour respectively is adopted and further quenched n water media. A temperature of about 1750C with different duration of time the samples are heated and naturally cooled. The significance of aging and quenching is that it alters the micro hardness of both the Al 7075 allow matrix and the reinforced composites used in the experiment. 4.0 Set up and experimental procedure for wear testing In order to investigate the dry sliding wear characteristics of the composite, a pin on disc wear test is done. The slider disc is composed of 0.95 to 1.2% carbon, hardened steel disc with hardness of about 62 HRC having a diameter of about 165 mm. A track 100 m in diameter is used in all experiments. The initial surface finishing (Ra) of the steel disc is also used. The treated heat Hybrid Aluminum Metal Matrix Composite (HAMMC) samples are prepared as pins of dimension of around 12mm in diameter and 32 mm in height. It is very crucial to ensure that the test samples ends surface are flat and are polished by using metallographic techniques before wear testing. The test is done by applying normal loads such as 10, 20 and 40N at utmost descending coldness of 4241m at dissimilar velocities like 1.5, 3.0 and 4.5 m/s. The wear rates of test samples are then measured in weight units by weighing specific specimen prior and after the test is done and converted into volumetric wear loss. The wear losses of specimens are measured using a high degree of accuracy using an electronic balance. The specimens are then tested as per the procedure recommended, and the entire experiment is done as per the L9 standard orthogonal array. The measured results are analyzed using computer aided software MINITAB 16 which is specifically designed for the experiment application. The selected wear parameters used in the experiment are downhill speed, applied load, sliding time and the reinforcement percentage. Each and every parameter is assigned three levels, which is shown in table 2 below. The recommended standard L9 orthogonal array is composed of nine tests. Table 2: Process Parameters and Levels Level Speed S (m/s) Load L (N) Time t (min) Reinforcement R (%) 1 1.5 10 5 5 2 3 20 10 10 3 4.5 40 15 15 Table 3: Orthogonal Array L8 of Taguchi Method Ex No Speed (m/s) S Load (N) L Time (min) t Reinforcement (%) R Wear Rate mm3/m Wr S/N Ratio for Wear (db) Co-efficient of friction (Cof) S/N Ratio for Co-efficient of Friction (db) 1 1.5 10 5 5 0.100070 19.993922 0.4211 7.5122 2 1.5 20 10 10 0.100150 19.986980 0.3979 8.0045 3 1.5 40 15 15 0.097830 20.190558 0.3489 9.14598 4 3 10 10 15 0.011100 39.093540 0.3489 10.4546 5 3 20 15 5 0.076510 22.32563 0.3001 8.69958 6 3 40 5 10 0.079963 21.942218 0.3389 9.3985 7 4.5 10 15 10 0.023410 32.611971 0.3101 10.1699 8 4.5 20 5 15 0.002032 53.841525 0.3117 10.123 9 4.5 40 10 5 0.019622 34.145134 0.3779 8.45246 5.0 Result and discussion The controlled parameters like sliding speed, sliding time, applied load and reinforcement percentage that influence analyzed And the ranking involved factors like wear rate and co-efficient of friction that supports signal supports to Noise response (SN). The results are shown in the table below; TABLE 4: Response Table for SN Ratio- Smaller is better (Wear Rate) Level 1 Speed (m/s) Load L (N) Time t (min) Reinforcement (%) R 1 20.06 26.57 31.93 25.49 2 27.79 32.05 31.08 24.85 3 4-.20 37.43 25.04 34.71 Delta 20.14 10.86 6.88 9.22 Rank 1 2 3 4 TABLE 5: Response Table for SN Ratio- Smaller is better (Friction Co-efficient) Level 1 Speed (m/s) Load L (N) Time t (min) Reinforcement (%) R 1 8.221 9.379 9.012 8.221 2 9.518 8.943 8.971 9.191 3 9.583 8.999 9.339 9.909 Delta 1.362 0.436 0.368 1.687 Rank 2 3 4 1 6.0 Analysis of variance (ANOVA) for wear rate The ANOVA is specifically used to analyze the rate of wear and for Sic and B4C particulates reinforced Al 7075 alloy matrix composite. The analysis is carried out at confidence level of 95%. From the result in table 6 below, it can be seen that the sliding speed factor is greater and has an influence on wear rate of 46.8231%. For this reason, the sliding speed is important control process parameters to be taken into account in wear process. Applied load is given to be 32.6391% while the reinforcement is at 17.6178%.The table 6 below gives the MINITAB ANOVA results Table 6: Analysis of Variance Source DF Seq SS Adj SS Adj MSS F- test P -value Pr % S (m/sec) 2 0.004422 0.004422 0.00533 8.27 0.038 46.8231 L (N) 2 0.0038 0.0038 0.00034 0.54 0.621 32.6391 T (Min) 2 0.000057 0.000057 0.00088 0.31 0.749 2.9285 R (%) 2 0.0097 0.00097 0.00408 0.14 0.871 17.6178 Error 0 0.01405 0.01405 0 Total 8 0 For friction coefficient, it gives 40.86% compared to other factors. Hence, we can conclude that added percentage of reinforcement is the most crucial parameter. It is followed by sliding speed at 31%, applied load at 27.08% and sliding time at 0.69183%. Table 7 below shows the Analysis of variance for friction co-efficient Table 7: Analysis of Variance for friction co-efficient Source DF Seq SS Adj SS Adj MSS F- test P -value Pr % S (m/sec) 2 0.004422 0.004422 0.00303 1.59 0.310 31.50 L (N) 2 0.0038 0.0038 0.0001882 0.10 0.908 27.0864 T (Min) 2 9.711 9.711 0.002522 0.16 0.860 0.69183 R (%) 2 0.0057 0.0057 0.00355 2.21 0.226 40.866 Error 0 0.01405 0.01405 0 Total 8 0 7.0 Multiple regression models from the MINITAB result The regression equation is mostly used to develop an equation between dependent and independent variable. It is developed and a response variable by fitting a liner equation to the measured data. The regression wear rate and the friction co-efficient of the model are found to be 0.896 and 0.871 respectively. The equations are; Wr = 0.149 – 0.0281S + 0.000643L + 0.00052t – 0.00284R ……………… Esq. (1) Cof = 0.485- 0.0187S + 0.000301L – 0.00151t – 0.00685R …………………Esq. (2) 8.0 Conclusion In using the Taguchi technique to find out the optimum parameters for wear rate and friction co-efficient of the composite, it can be concludes that first, the stir cast experimental set up cold be successfully adopted in the preparation of Al7075/SiC/B4C. The DoE by Taguchi technique and regression equation is successfully used to study the dry sliding wear rate and friction co-efficient of the composite and lastly, the wear rate and friction co-efficient are dominated by different parameters in the order of applied load, sliding speed, percentage of reinforcement and sliding time. Reference Skinner, Burrhus Frederic. Contingencies of reinforcement: A theoretical analysis. Vol. 3. BF Skinner Foundation, 2014. Zhang, L. W., et al. "Large deflection geometrically nonlinear analysis of carbon nanotube-reinforced functionally graded cylindrical panels." Computer Methods in Applied Mechanics and Engineering 273 (2014): 1-18. Read More