Papers by Keyword: Metal Matrix Composite (MMC)

Abstract: History is often marked by the materials and technology that reflect human capability and understanding. Many a times scales begins with the stone age, which led to the bronze, iron, steel, aluminium and alloy ages as improvements in refining, smelting took place. Science made all these possible to move towards finding more advanced materials.Therefore in the present research work, an investigation has been carried out to fabricate and evaluate the microstructure, strength, micro hardness of chilled composites consisting of nickel matrix and fused SiO₂ particles as the reinforcement (size 40-150 μm) in the matrix. The reinforcement being added ranges from 3 to 9 wt. % in steps of 3%. The resulting composites cast in moulds containing metallic chill blocks (MS, SiC & Cu) were tested for their microstructure and mechanical properties. The main objective of the present research is to obtain fine grain Ni/SiO₂ chilled sound composite having very good mechanical properties. A detail of melting and composite preparation is described elsewhere by number of researchers. After melting the matrix material in an induction furnace at around 1600 °C in an inert atmosphere, coated fused SiO₂ particles preheated to 500 °C were introduced evenly into the molten metal alloy by means of special feeding attachments. The moulds for the plate type of castings 150*20*20 mm (American Foundrymen Society standard) were prepared using silica sand with 5% bentonite as binder and 5% moisture and finally they were dried in an air furnace at a temperature of 1580 °C, which was cooled from one end by a chill block set in the mould. After solidification the specimens of chill end were tested for various mechanical and microstructural studies. Keywords: Metal matrix composite, Mechanical properties, Nickel alloy, Fused silica, Chills.

Abstract: The aim of the work was to investigate the wear properties of basalt short fiber reinforced aluminum Metal Matrix Composites (MMCs) using pin-on-disc wear test rig. The Al/basalt MMCs contains basalt short fiber from 2.5 to 10 % in steps of 2.5 wt. % and fabricated using compocasting technique. The influences of the content of basalt short fiber, wear load, sliding distance, sliding velocity and mode of worn-out surface were discussed. The results indicated that Al/basalt short fiber composite had better wear resistance than that of the matrix alloy and it decreases with wt. % of basalt short fiber content. In other direction wear rate of both unreinforced alloy and reinforced composites increased with increasing in wear load and the sliding speed. Surfaces before and after wear tests were characterized using scanning electron microscopy (SEM). Keywords: Metal matrix composite (MMCs), Basalt fibers, sliding wear, wear rate

Abstract: A hybrid Al7075 metal matrix composites have been fabricated through liquid metallurgy route (Stir Casting method) using Al₂O₃ and B₄C as reinforcement materials. The effect of weight percentage of reinforcement materials on mechanical properties of the composites have been studied by varying the weight percentage of Al₂O₃ as 3, 6, 9, 12 and 15% while keeping constant weight percentage of B₄C (3%). The as-cast microstructure, tensile strength, micro and macro hardness of the fabricated hybrid composites have been studied. The mechanical properties of the prepared composites were increased with increasing the weight percentage of the reinforcement in the composite. The maximum tensile strength, micro-hardness and macro-hardness of 309 MPa, 140 VHN, and 112 BHN, respectively, were obtained for a hybrid Al7075 matrix composite containing 15% Al₂O₃ and 3% B₄C.

Abstract: Micro sized particles such as SiC, Al₂O₃ and diamond particles reinforced with metal matrix composites are most commonly used in high performance applications like military, automotive and aerospace industries. Nowadays nano sized particles are replacing the micro sized particles because of their improved physical and mechanical properties. This paper reviews the stir processing method, mechanical properties, effect of particle size on properties of composites and structure of the metal matrix composites reinforced with nanoparticles. Among the variety of liquid metallurgy techniques processes available for preparing metal matrix composites, stir casting technique is generally accepted route and currently practised commercially because of its simplicity flexibility and Uniform distribution.

Abstract: This present paper is an investigation made to study the un-lubricated sliding wear behavior of Al6061 alloy composites reinforced with graphite particulates of size 100-125 μm. The content of graphite in the alloy was varied from 6-9% in steps of 3 wt. %. The liquid metallurgy technique was used to fabricate the composites. A pin-on-disc wear testing machine was used to evaluate the volumetric wear loss, in which a hardened EN32 steel disc was used as the counter face. The results indicated that the volumetric wear loss of the composites was lesser than that of the Al6061 matrix alloy and it further decreased with the increase in graphite content up-to 6 wt.%. For composites containing 9 wt. % of graphite particulates, the volumetric wear loss was more than that of 6wt. % composites, but lesser than base matrix alloy. However, the material loss in terms of wear volume increased with the increase in load and sliding speed, both in case of composites and the alloy.

Abstract: Aluminum based Titanium carbide particulate reinforced metal matrix composite (Al-TiC PMMC) draws attention by many researchers & industries over alloy materials because of its excellent thermo-physical and mechanical characteristics. Despite of its superior properties of Al-TiC MMC, its complexity in manufacturing process and poor machinability has been the main deterrents to its application level. Controlling agglomeration of TiC particles is a challenging task to retain improved microstructure. The hard abrasive nature of carbide particles cause poor machinability and high machining cost. Therefore, in this paper an attempt has been made to study the various manufacturing techniques to achieve uniform distribution of TiC reinforcements in Al matrix.Further, the review follows the secondary manufacturing process of Al-TiC PMMC, which addressee’sthree topics: machining, forming & welding.

Abstract: Generally in the drilling of new engineering materials such as metal matrix composites, problems frequently occur in terms of poor finished surface, tool stress, tool wear, high drilling forces as well as low process reliability. A useful and promising method to overcome these problems is the use of ultrasonic vibration as an assistance, where high-frequency and low amplitude vibration are added to the conventional movement of cutting tools or workpieces. This research presents the new design of an ultrasonic assisted system and the experimental investigation of ultrasonically assisted drilling of Al/SiC metal matrix composites under different cutting conditions. The effect of cutting conditions and ultrasonic amplitude on the circularity, cylindericity, and hole oversize of the ultrasonically and conventionally drilled workpieces were investigated. The obtained results show that the ultrasonic vibration can improve the hole quality.

Abstract: A novel graphite/copper alloy-based self-lubricating composite materials were prepared using the powder metallurgy method by composing 663 bronze, Ni, W, nanoAl₂O₃, MoS₂, Ag, CaF₂, Sm₂O₃ as the basic alloy powder and adding 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.% graphite and nickel coated graphite powder respectively to the composite powder. The microstructure, mechanical properties and friction properties of the samples were studied. The results show that the samples with nickel coated graphite powder have their wettability and the composite structure between graphite and copper alloy matrix is improved. When the content of graphite is 3wt.%, the properties of samples prepared by Ni-coated graphite are improved compared with those prepared by uncoated graphite. The hardness is increased from 34HV to 38HV, the crushing strength is from 116MPa to 151MPa, the friction coefficient is reduced from 0.28 to 0.21, wear loss is reduced from 20mg to 12mg. The samples prepared by Ni-coated graphite have good self-lubricating performance.

Abstract: This paper presents two new 3D finite element Multi Fiber Models (MFM) that account for the effects of neighboring fibers on the stress distribution over fiber-matrix interface. One model assumes a hexagonal packing pattern of the neighboring fibers whereas the other assumes that the neighboring fibers are packed in a square pattern. Two scenarios regarding the contact surface between the fiber and the matrix are considered: the first one assumes no bond over the interface while in the other one the interface is perfectly bonded. The cooling process of the composite was simulated and then a transverse loading is applied to the composite. The results indicate that packing system and the characteristics of the fiber-matrix interface greatly influence the magnitude of the residual stresses developed in the matrix.

Abstract: An investigation has been made into the machining feasibility when wire electro-discharge machining with an extremely high travelling speed of wire electrode (WEDM-HS) has been employed to process particle-reinforced 6061 Al matrix composites with 20-vol% Al₂O₃ (20ALO). And in this study, for the water based emulsion is used as working liquid, there exists an electrochemical effect. And thus, the EDM spark can operate under a relatively large spark gap size condition, and this would be helpful for the removal of the loosen particles and the machined debris. In this study, the material removal rate (MRR) has been examined. Since there are many factors that can influence the MRR during the wire electro-discharge machining process, in order to determine which factor has the most significant effect on the MRR and to obtain the optimal machining parameters, the relative importance of the various machining parameters on material removal rate was analysed by employing an orthogonal design. The results of the orthogonal analysis show that to obtain a high MRR for WEDM-HS machining of 20ALO materials, the duty cycle has the most significant effect on the MRR among current, pulse duration and duty cycle. And the impact of significance for the different factors follows the sequence of duty cycle > current > pulse duration. And under the experiment condition of this study, a duty cycle of 1:4, a current of 5A and a pulse duration of 32μs is the best arrangement for the MRR.