This paper presents the comparative study of the mechanical properties of Al6061-Tungsten carbide composites containing Tungsten carbide (WC) particulate, and Al6061-graphite particulate composites containing graphite particles. The reinforcing particulates in the MMCs vary from 0% to 4% by weight. The 'vortex method' of production was employed to fabricate the composites, in which the reinforcements were poured into the vortex created by stirring the molten metal by means of a mechanical agitator. The composites so produced were subjected to a series of tests. The results of this study revealed that as the Tungsten carbide particle content was increased, there were significant increases in the ultimate tensile strength, hardness and Young's modulus, accompanied by a reduction in its ductility. There was, however, only a very marginal increase in the compressive strength, where as in graphite reinforced composites as the graphite content was increased, there were significant reduction in hardness and monotonic increases in the ductility, ultimate tensile strength (UTS), compressive strength and Young's modulus of the composite, An attempt is made in the paper to provide explanations for these phenomena.

Aluminum (Al) alloys started replacing cast iron and bronze alloys in the manufacture of wear-resistant parts and are materials of interest owing to their low density, higher strength to weight ratio, which is an additional advantage in aerospace, marine and automotive applications. Al-metal matrix composite (MMC) materials are very much popular due to the reason that these composites possess good mechanical properties and higher wear resistance. This article is aimed to present the experimental results of microstructure, hardness, tensile, yield and compression strength, percentagage elongation, volumetric wear loss, and wear rate of Al6061-Tungsten Carbide (WC)-Graphite (Gr) reinforced hybrid MMCs. The composites were prepared using the liquid metallurgy technique, in which 0 to 4 wt% of WC particulates were dispersed into the matrix alloy in steps of 1 wt% by maintaining the Gr to 4 wt% constant. The experimental results indicate that the density of the hybrid-MMCs increases with increased WC content and further, agree to the values obtained through the rule of mixtures. The physical, mechanical and the tribological properties of the Al6061-WC-Gr hybrid MMCs were found to increase with increased WC content in the matrix at the cost of reduced ductility. The WC and Gr reinforcements contributed significantly in improving the wear resistance of Al6061-WC-Gr hybrid MMCs.

No abstract

The present research examines the performance of a resistance heating furnace using two different heating elements, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi2) to raise working chamber temperature to 1600ᴼC. SiC rods are used first, starting from the beginning (ambience) temperature 35ᴼC up to 1300ᴼC, followed by MoSi2 heating elements to raise chamber temperature from 1300ᴼC to set temperature at 1600ᴼC. Transition from SiC to MoSi2, heating system is uninterrupted, and swift in heating element effected by inter-locking system (an electronic device or an electro-magnetic system) without any drop in effect. The system under analysis consists of Programmable (Proportional-Integral-Derivative) PID, (Silicon Controlled Rectifier) Thyristor power pack, recrystallised alumina tubes, sensing elements: thermo-couple, Pt-Pt/13%.Rh, semiconductor based circuit that controls power and current to the system requirement (step down) and thereby control voltage automatically with transformer (depending on size of working area, and 53 amp (I), 220 V for single phase, reduced to 60V by a step down transformer) and auto current limiting facilities. Present analysis is designed for programmable and also for non-programmable type of cycles of operations set before starting the furnace within maximum working temperature of 1600ᴼC to achieve objectives, like saving of amperage (current consumption 53 amp) and power at reduced voltage (40V), long life of the heating elements (2 years and more) and optimization of thermal efficiency (60%) for high working temperature 1600ᴼC for long hours of operation in a Compound Heating Resistance (CHR) furnace.

The Aluminum (Al) and its alloys are finding extensive applications in industries like automobile, aerospace and marine fields. Aluminum-based Metal Matrix Composites (MMC?s) reinforced with hard particulates offer superior operating performance and resistance to wear. Al based MMC materials provide higher abrasive resistance and provide a longer service life compared to other materials. The popularity of composites may be the reason that these composites possess good mechanical properties, good corrosion resistance, wear resistance in addition they are light-in-weight. In this paper it is aimed to present the experimental results of the studies conducted related to hardness, tensile strength, and compression strength of Al6061-Tungstan Carbide (WC) composites. The composites were prepared using the liquid metallurgy technique (stir casting technique), in which 0-4 wt. % of reinforcing tungsten carbide particulates were dispersed into the base matrix alloy in steps of 1%. The obtained cast composites of Al6061-WC and unreinforced base alloy was subjected mechanical tests and composites were subjected to microstructural examination. The test results reveal that the hardness and strength of the alloy has increased monotonically. The wear resistance obtained using computerized pin on disc wear tester with counter surface as EN31 steel disc (HRC60) and the composite pin as specimens, demonstrated the superior wear resistance property of the composites.