Papers by Keyword: SiC_P

Abstract: The composite materials with 2, 4 and 6 % Cu were developed using a noble stir casting method. Tensile test was conducted using universal tensile test machine according to ASTM-2002 (E8M-01) standard and the fracture surface was analysed using scanning electron microscope (SEM). The result showed that the ultimate tensile strength (UTS) was increased due to the percentage increment of Cu in the Al-Cu matrix. A significant change in UTS was observed from 2 to 4 % Cu whereas slight improvement was seen from 4 to 6 % Cu addition. The SEM micrograph of the fracture surface reveals that the cracks were propagated in the fibrous zone resulting from the initiation of micro voids between the matrix and particle interfaces. The number and size of dimples for 2% Cu were considerably lower and the facet features were noticeably higher than higher Cu content composition, whereas, the dimple and facet size and number for the 4% Cu are very close to the 6% Cu content composite which may play important role in the improvement of tensile strength. These findings tinted for the potential application of SiC_p reinforced Cu influenced Al-Cu-SiCp composite for automotive engine components and other similar applications as well.

Abstract: Amongst the Metal Matrix Composites (MMCs), Al-Si-Mg alloy/ SiCp MMCs are very attractive for their properties. But, the formation of brittle interfacial reaction product, Aluminium carbide has been one of the major concerns when these materials are processed by liquid phase methods. The extent of Aluminium carbide formation depends on various processing parameters such as temperature, wt% of SiCp, particle size of SiCp and chemical composition of the matrix alloy especially Silicon (Si) content. According to recent studies, various difficulties in finding the process parameters to get desirable properties of Al alloy/ SiCp MMCs as desired by the industries. Thus, in the present study thermodynamic & structural estimates in Al alloy/ SiCp MMCs under various process conditions, composition, microstructures were performed. The relatively low cost liquid stir casting technique is used in the production of Al alloy/ SiCp MMCs with varying Silicon content (0–7%) in the alloy matrix using process temperature 710°C. Aluminium carbide layer formation on SiCp surface, Critical Si content for Aluminium carbide separation from SiCp surface, eutectic Si formation, existence of near-dislocation segregation regions after formation of Aluminium carbide on SiCp surface and the equilibrium amount of Si to suppress Aluminium carbide formation were investigated using Transmission electron microscopy (TEM). The separation of Aluminium carbide from SiCp surface was observed after 3% Si. The equilibrium Si content of 7% was found to suppress the formation of Aluminium carbide with thermodynamic model and its significance has been assessed.

Abstract: The main aim of this paper is to investigate the crystallinity and hardness properties of Al-Cu/SiCp matrix composite (AMC) materials. The materials were prepared using a noble stir casting technique by varying the percentage of Cu in the Al-Cu matrix. Qualitative X-ray analysis has been carried out to characterize the crystallinity of the Al-Cu/SiCp as-cast composite materials. Sample was cut and shaped into 25 mm×15 mm×4 mm in dimension then polished with diamond paste. X-ray diffraction diagrams were recorded using a transmission technique with a SHIMADZU Lab X (XRD-6000) X-ray generator operating at Cu Kα1 radiation. Hardness test was conducted using Vickers hardness tester (Mitutuyo, MVK-H2). The results indicated that a significant crystal growth was occurred in the composite materials due to increase of Cu from 2 to 4 % whereas a slight improvement of crystallinity was observed when the Cu percentage was increased from 4 to 6 % in the matrix. It was also revealed from the result that a similar trend was grasped in hardness increment with the crystallinity of Al-Cu/SiCp AMCs.

Abstract: Aluminum composites containing 10wt. % of Al₂O₃ with 3 µm size of particles have been produced using powder metallurgy (PM) method and wear behavior of the composites were tested under dry condition. A comparison is also made with SiCp reinforced Al composite produced at the same conditions. The wear rate of both types’ composites increased with all applied loads, but wear rate of the composites was a strong function of normal load rather than that of type of particles used for the manufacturing MMCs. Furthermore, the wear rate of Al-Al₂O₃ composite was smaller than that of Al-SiCp reinforced composite, but not indicating significant differences on it. Moreover, SEM examination showed that plastic deformation was the dominant type of wear for the Al₂O₃ particle reinforced MMCs, but the fragmented-deformed layer of particles was more effective for the SiCp reinforced MMCs due to more fracturing of particles.

Abstract: The paper presents constitutive model of the aluminium metal matrix composite reinforced by a silicon carbide. Developed equation includes an empirically estimated term which takes into account softening effects of the composite due to reinforcement damages at a large strain. Experimental investigation of the aluminium based MMCs reinforced by silicon carbide of volume fraction equal to 0%, 10%, 20% and 30% were carried out. Tests were conducted at wide range of strain rates and large magnitudes of strains. Comparison between experimental and predicted data shows that the elaborated model may be applied for composite materials in computer simulations of large deformations.

Abstract: A SiC_p/Cu composite with excellent performance is prepared by using the advanced powder injection molding technology. The microhardness and tensile strength of the composite are detected, and the surface microstructure and the tensile fractures are observed. The results show that SiC particles are uniformly distributed in Cu matrix and excellently bonded with the Cu matrix. With the increase of the SiC content, the microhardness of the composite is increased while the tensile strength is increased first and then decreased. A crackle source of the composite for tensile fracture mainly includes two kinds: cracking of the Cu matrix in vicinity of the SiC particles and debonding of an interface of the SiC particles and the Cu matrix.

Abstract: SiC_p/Gr/ZL101 aluminum-based composites is prepared by semi-solid stirring and gravity pouring method. The effects of SiC_p/Gr with different volume fractions on the microstructure and property of aluminum-based composites are studied by means of microstructure observation, tensile test, fracture scanning and analysis and damping capacity test and analysis. The results show that the primary phase α-Al of ZL101 alloy prepared by semi-solid stirring and gravity pouring method is fragmented dentrite，along with the rising SiC_p volume fractions, the tensile strength of the composites first increases and then decreases while its elongation gradually decreases, the maximum tensile strength of the material can reach to 168MPa, up to 16% than that of ZL101 alloy, the fracture morphology is obvious brittle fracture. They also show that the addition of SiC_p and Gr improves the damping capacity of ZL101alloy, the internal dissipation Q^-1 of the composites is obviously higher than that of matrix alloy and gradually increases along with the rising SiC_p volume fractions. The damping mechanism of the composites is mainly the combined effects of both dislocation damping and interfacial damping.

Abstract: Roll casting of Al-SiCp composite alloy strip was tried using a vertical type high speed twin roll caster equipped with mild steel rolls. The Al-20vol% SiCp and Al-30vol%SiCp alloy could be roll-cast to the strip. The casting speed was 30m/min. The thickness of as-cast strip was thinner than 2.5mm. The SiCp powder was dispersed uniformly at the thickness direction. The as-cast strip could be thin down to 1mm by the hot rolling and the cold rolling without broken.

Abstract: SiCp/Al composite was fabricated by the method of pressureless-infiltration. In atmospheric environment, the atmospheric corrosion behavior of SiCp/Al composites (ZL101+49%SiC+5%Mg) was studied by mass loss, optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR), respectivelhy.The results show that the corrosion rate of the SiCp/Al composites increases with increasing of time in atmospheric environment. Pitting corrosion is the main characteristic of SiCp/Al composite, and corrosion area gradually extends around with time increasing. At last, sheet like corrosion substrates distribute in the surface of n the SiCp/Al composites. Amorphous Al2O3 and amorphous AlxSO4yOHz are the main corrosion products.

Abstract: Al alloy reinforced with SiCp (size: 70-220μm) was fabricated by pressureless-infiltration. Its wear resistant property was investigated under different heat-treatment conditions, and morphology of worn surface was examined. The results showed that the composite was integrated, uniform and compact, and its wear resistant property was better than that of the unreinforced matrix alloy. It was indicated that some rigid SiCp in the abraded surface of the composite could support part of loads and replace matrix to wear-tear, which improved the wear resistant property. Compared to annealing, solution aging strengthens Al alloy matrix and cohesion with SiCp, and the wear resistant property of composites was better. Combining interface is also an important factor which influences on wear resistant property. During the wear test, the smaller SiCp size, the more interfaces, there are more SiCp falling off because of loosening combining interface, which results in more wear-tearing value. The wear rate of composite increases with decreasing SiCp size, thus, the composite with larger SiCp has better wear-resistant property than that with smaller SiCp. At last, the wear mechanism of the composite was also studied, and it showed that abrasive wear dominated in the abrasion process.