\ Aluminum Silicon Carbide Particulate Metal Matrix Composite Development Via Stir Casting Processing
A. 0. Inegbenebor, C. A. Bolu, P. 0. Babalola, A. I. Inegbenebor & 0. S. I. Fayomi
Silicon
ISSN 1876-990X
Silicon DOI10.1007/s12633-016-9451 -7
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S11icon Aluminum Silicon Carbide Particulate Metal Matrix Composite Development Via Stir Casting Processing 1 1 1 2 A. 0. lnegbenebor ·C. A. Bolu • P. 0 . Babalola · A. I. l ncgbenebor • 0. S. I. Fayomi 1.3 Rece1ved. 25 December 20 15 I Accepted: I August 20 16 Abstract In this paper, conventional simple methods of Also; the electrical conductivity properties of the two grit producing MMC with attained properties through the dis sizes of the silicon carbides were less than the base metal persion of silicon carbide in the matrix are investigated. To for all the volume fractions of sil icon carbide. achieve these objectives a two-step mixing method of stir casting technique was employed. Aluminum (99.66 %C.P) Keywords Particul ate · Aluminum composite matrix · and SiC (320 and 1200 gri ts) were chosen as matri x Electrical properties · Silicon carbide and rein forcement materi als respectively. Experiments were conducted by varyi ng the weight fr action of SiC fo r 2.5 %, 5.0 %. 7.5 % and 10 %. The result indicated that the 1 Introduction stir casting method was quite successful to obtain uni form dispersion of reinforcement in the matrix. This was Metal matrix composites (MMC) are a range of advanced evident by the improvement of properties of composites materials that are combinations of metal and hard particles, over the base metal. Reinforced Aluminum Silicon Car which are usually ceramics [ 1). This product can be used for bide (ASC) showed an increase in Young's modulus (E) and a wide range of applicati ons. The MMC have superior prop hardness above the unreinforced case and marginal reduc erties to the base metal. These properties include improved tion of electrical conductivity was recorded for the com thermal conductivity, abrasion resistance, tribology, creep posites. The silicon carbide of 1200 gnts (3 J.l m) showed resistance, di mensional stabili ty, and exceptionally good increased Young's modulus (E) and hardness of 15 17.6 Mpa stiffness. Li ke all composites, aluminum matrix composites and 26. 1 Hv values at 7.5% volume fraction silicon carbide; are not a single materi al but a family of materials whose when compared with the silicon carbide 320 grit (29 J.lm). stiffness, strength, density, thermal and electrical properties can be tail ored [2]. According to Beffort [3], Aluminum Matri x Compos ites (AMC), are used for specific applications such as main cargo bay struts in the space shuttle. The mate ./ 0 S. I. Fayomi ojosu nda yfayomi3@ gmai l.com, rial used was 6061/B/50f. Also, A359/SiC/20p is used ojo. fayo m1@covenantuniversi ty.edu. ng for brake disks and drums; 2014/AI20 3!10-20p (Al-4.4Cu- 0.5Mg-Si··M n), 6061/ AI203/I 0-20p (AI-1.0Mg-0.6Si-Cu Cr) and 7005/Ah0 3/l Op (AI-4.6Zn- 1.4Mg-Mn-Cr-Zr-TI) Department of Mechanical Engineeri ng. Covenant University. are used in bicycle frames, drive shafts and cylinder P.M.B 1023. Ota. Ogun State. Nigeria liners. A357/SiCII0-20p (AI-7.0Si-0.5Mg), A359/SiC/I0- f . Department of Chemistry, Covenant Universi ty, P.M.B 1023, 20p (AI-9.0Si-0.5Mg), A339/SiC!I 0-20p (AI-12Si-1.0Mg- - Ota, Ogun State. Nigeria 1.0Ni-2.25Cu), A360/SiCII0-20p (AI-9.5Si-0.5Mg) and A380/SiCII 0-20p (AI-8.5Si-3.5Mg) are applicable in brake Department of Chemical, Metallurgical and Materials Engineering. Tshwane Univcrs1 ty of Technology, dru ms and brake discs; also while 606 l/Al20 31IOp is P.M.B. X680. Pretona. South Africa used in automobil e drive shaft s; 6092/SiC/17 .5p and Published online 26 October 20 16 ~Sp r inge r Author's personal copy Silicon 2009/SiC/15p-T4 are used in fan exit guide vanes of jet Table 1 The Compositions in Percentage of Aluminum Ingot engi nes and Al/Nextel61 0/45f is used for electrical conduc Obtained from Aluminium Rolling Mills, Ota. Ogun State tors. Fe Si Mn Cu Zn Ti Mg Pb Sn AI Also an aluminum matrix composite processing route entails the using of aluminum as the metal matrix with 0.232 0.078 0.000 0.0006 0.0016 0.006 0.0027 0.0012 0.007 99.66 mixing particles to form composites. It has already found commercial use on account of the fact that conventional pro cessing techniques such as powder metallurgy, vacuum hot between the two main substances, porosity in the cast metal pressing, co-spray deposition process, squeeze casting, and matrix composites, and chemical reactions between the rein stir casting methods can be readily adopted for the process forcement material and the matrix alloy [8]. In order to ing of such materials [ 4]. However, the stir casting method is achieve the optimum properties of the metal matrix com preferred to other methods because it is simple and process posite, the following steps should be taken. The distribution ing parameters can be readily varied and monitored [5-7]. of the reinforcement materials in the matrix alloy must be The designed stir casting system for this work is shown in uniform, and the wettability or bonding between these sub Fig. I . stances should be optimized [6]. In order to overcome the In the production of liquid metal matrix composites, stir diffi culty of achieving a uniform distribution of dispersion casting is generally accepted as a particularly promising of silicon carbide particles in the aluminum matrix, the help route, currently practiced commercially [8]. By using this of a two-step mixing method of the stir casting technique approach, there are many advantages such as simplicity, was employed. For the wettability, the pre-treatment of the Oexibility and ability to produce large quantity of prod si licon carbide helps in this direction and the tenacity of the uct. It is also attractive because in princtple it allows a bond between particles and matrix. conventional metal processing route to be used, and hence The focus of this study is to develop aluminum silicon minimizes the final cost of the product [2]. The stir casting carbide matrix composites, usi ng the stir casting system. technique is the most economical of all the available routes A lso, the effect of silicon grit sizes of the mechanical and for metal matrix composite production [9], it allows very electrical properties of the material is assessed. large sized components to be fabricated . The cost of prepar ing composites material using a stir casting method is about 1.1 Materials and Methods one-third to half that of competitive methods, and for high volu me production it is projected that the cost will fall to In this work, the stir casting method was used to prepare one- tenth [ 10]. samples of AMCs usi ng 1170AI reinforced with silicon car In prepanng metal matrix composites by the stir cast bide (SiC) particulates of 3 J.lm and 29 J.lm sizes respectively. ing method, there are several factors that need considerable The chemical composi tion of aluminum and sil icon carbide attention. These include the difficulty of achieving a uni are presented in Tables I and 2 respectively. form distribution of the reinforcement material, wet ability The liquid metallurgy route (stir casting technique) was adopted to prepare the cast composites as described above. A batch of 5.0 Kg of 11 70AI was melted at 750 oc in a graphite cruc ible using an oil-fired tilting furnace for 25 ; ===... ': ...... ~.....- --- minutes. The temperature of the melt was measured using a K-type thermocouple. The molten metal was then poured Swrcr into a mold preheated at 450° f for 3 hours and the melt r Iulll { - tnwa" Fig. 3 Comparative chart of Hardness of the two grit sizes of silicon Fig. 5 Comparative chart of Electrical Conductivity properties of the carb1de two grit sizes of silicon carbide The hardness of the composite was found to be consid tensile test might have activated the d islocation to by-pass erably higher than that of the matrix alloy and increased them leaving a "dislocation loop" around each particle. with increasing particle content. The higher hardness of the This will make the passage of a second dislocation much composite samples relative to that of the matrix aluminum more difficult. particularly since dislocations have greater could be attributed to the existing hard particles (SiC) acting diJ'Iiculty in passing between particles which are near to as obstacles to the motion of dislocation. The presence of each other resulting in a higher strength of the small particle small separate particles in the microstructure can impede more than the bigger one. The mechanical force by mixing the movement of dislocations provided that these particles mechanically and pre-treatment of si Iicon carbide before the are stronger than the matrix in which they are embedded automatic mixing was applied to overcome surface tension [II, 12). The degree of strengthening producedalsodependson to improve wettability. the size of particles, their distance apart and the tenacity of the The electrical conductivity of composite materials was bond between particles and matrix. Also the small grit siLe observed to be invariably lower than that of the monolithic of silicon carbide influences the mechanical properties [ 13 ]. aluminum-base metal. The electrical conductivity of com The two-step mixing, helps to disperse the particles, po~ile materials decreased with increase in particle sizes which results in the strengthening produced by the small and the volume percent of the reinforcement phase during size particles. When compared with the bigger particles, stir casting. However, the low material density of AISiC 3 by pre-heating, the si licon carbide at 1200 oc for ti\O (3 g/cm ) made it ideal for weight sensitive applications hours before the mixing probably helped the tenacity of the such as portable devices over traditional thermal manage bond between the particles and the matrix, which added ment materials like copper molybdenum, CuMo, (10 g/cm3) to the strengthening effect. The particles of silicon C ~Springer Author's persc, if copy Silicon 3. There was marginal reduction of electrical conductiv 5. kumar B. Murugan N (2012) Metallurgical and Mechanical Char ity for composites when compared with the base metal au~ rization of Stir Cast AA6061 -t6-AINp Composite. Mater Des <10:52-5 8 aluminum. 6. Richard AMA, Fennessy K. Hay RA (1998) Aluminum Sili 4. The stir casting method seemed to disperse small grit L'Oll Carbide (AIStC) for Advanced Microelectronic Packages, of silicon carbide in the matrix better than the bigger Ceramic Process Systems. Corp. Chartley, MA 027 I 2 grit, which resulted in the improvement of the strength 7. BalasivanandhaPrabu. S., Karunamoorthy L, Kathiresan S, Mohan B (2006) Influence of ;tirring speed and stirring time on distribu and mechanical properties of the composite alloy. The '"'" of parltcles in cast metal matrix composite. J Mater Process small grit size of silicon carbide influences the strength Tc·<: hnol 17 I :268- 273 of mechanical properties of the composites. ~. II. him J, Looney L, Hashmi MSJ (1999) Metal matrix com l'"'·tcs, production by the stir casting method. J Mater Process Tccilnol92/93:1-7 9 :,tu •ppa. M. K., Surappa ( I 997) J Mater Process Techno) 63:325-333 References 10. ~~d>o DM. Schuster DM. Jolla L (1988) Process for prepara l.u.> of composite materials containing nonmetallic particles in a tllctallic matrix. and composite materials made by U.S patent. I. Babalola PO. Bolu CA. lnegbenebor AO. Odunfa KM (2014) :--;, -1786467 Development of aluminum matrix composites- A review, Online I I. 1."" E. Pang SD. Quek ST (201 1) Discrete dislocation analysis Intemauonal Journal of Engineering and Technology Research, ot he mechanical reponse of silicon carbide reinforced aluminum 20 14.2. 1- 1I. ISSN 2346452 •·· ·composite. Compo,ues, part B 42:92-98 2. Smgla M, Dwtvedi DD. Singh L. Chawla V (2009) De,cl 12. ~ •• ll man RE, Bishop RJ (1999) Modern physical metallurgy opment of Aluminum based Silicon Carbide Particulate ;• '' materials engineering- science, process, applications (61h ed.) Metal Matrix Composite. J Miner Mater Charact Eng 8(6): I .:rworth Heinemann, Jordan Hill, Oxford 455-467 13. I ,:bcnebor AO, Bolu CA. Babalola PO. Inegbenebor AI. 3. Olivier B (2001) Metal Matrix Composites (MMCs) from Space I omi OS (20 I 5) Inlluence of the Grit size of Silicon Car to Earth.EtggenossischeMaterialprufungs-und Forschungsanst.llt, I - ~ Spring~r