Search

In the present research, the effects of volume fraction of SiC+Al2O3 particles and aging temperature on the machinability of stir-casted Al7075 metal matrix composites (MMC) have been investigated. The hybrid composites were fabricated using the liquid metallurgy route. Al7075 was reinforced with different wt. % of SiC (3%, 6%, and 9%) and Al2O3 (2%, 4%, and 6%) which were used to fabricate the hybrid metal matrix composites. The samples were aged at different temperatures (140 ºC, 160 ºC, and 180 ºC) for 4 h and cooled at furnace temperature (27 ºC). The machinability of hybrid metal matrix composites was studied by carrying out L27 orthogonal array experiments. Three process parameters were selected, such as 0.2 mm/min of the depth of cut, 0.1 mm/min of feed rate, and 1500 rpm of spindle speed. The obtained results indicate that the surface roughness and machining force of MMCs increase with an increase in weight percentage of Al2O3/SiC and decrease with the increase in aging temperature. Optimum machining force and surface roughness were obtained at 2% Al2O3 + 3 % SiC and 180°C of aging temperature.

This work reports the effect of varying red mud and fixed E-glass fiber content on the corrosion behavior of Al6061 hybrid composites. The red mud content was varied from 3% to 12% in the step of 3% and E-glass fiber content was fixed to 2%. Both unreinforced Al6061 alloy and its hybrid composites were produced using stir casting process under identical processing conditions. The corrosion behavior of Al6061 alloy and its hybrid composites compared with its matrix in 3.5% NaCl using electrochemical potentiodynamic polarization test in accordance with ASTM G3 standard. The obtained result indicates the corrosion resistance of the hybrid composites with red mud and E-Glass fiber was higher than that of the Al6061 alloy. Microscopy analysis of corroded surfaces showed formation of Al(OH)3 protective layer which covered surface of the hybrid composites and resulted in low corrosion rate.

With the rapid development of electronic technology, many new promising ideas and technologies were introduced into thermal management, one of which is pulsating heat pipe (PHP), which is different from traditional heat transfer strategy. Hence, an investigation on pulsating heat pipe with multi turns will be conducted in order to examine nanoparticles effect on heat transport ability. The pulsating heat pipe consists of copper tube having inside radius of 1 mm, thickness of 0.5 mm and total length of 1605 mm. The investigation is done with acetone with a filling proportion of 60% for different % mass concentration of 1%, 2%, 3%, 4% and 5% of Al2O3 nanoparticles for differed heat contribution from 20 W to 60 W . From the results of different % mass concentration, the most reduced value of thermal resistance is 0.28 K/W at 1% mass concentration. Hence the PHP operates better with 1% mass concentration of Al2O3 nanoparticles.

In the present work we report the development of Ni3Ti intermetallic compound by high energy ball milling of Ni and Ti powders. The ball milled powders were taken at various intervals (4, 6, 8, 10, and 11 h) to analyze the formation of Ni x Ti x intermetallic compounds. The ball milled powders were analyzed using scanning electron microscopy and X-ray diffraction. The layered shaped powder particles of Ni3Ti phase were formed after 11 h of ball milling, which was confirmed by X-ray peaks. Further High-Velocity Oxy-Fuel (HVOF) process was used to coat Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) on MDN 420 steel. Both the coated materials displayed excellent cohesion with minimal porosity less than 2%. The tensile adhesion strength test was carried out on these coatings to check the bond strength. Out of the two the Ni3Ti coating showed excellent bond strength of 41.04 MPa compared to that of Ni3Ti + (Cr3C2 + 20NiCr) coating.

This paper reports the development of Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings on AISI 420 stainless steel (MDN-420) and titanium alloy ASTM B265 (Ti-15) by HVOF technique. Microstructure, microhardness and high temperature oxidation behaviour of coatings were investigated. Microstructure of coatings was dense and displayed layers depicting lamellar structure. The microhardness of coatings was significantly higher than that of substrate owing to higher density and cohesive strength between individual splats of coating materials. Cyclic oxidation studies conducted on Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings showed oxide scale was composed of various oxides like NiO, NiCr2O4 and Cr2O3 phases. The formation of compact and protective NiO phase in case of Ni3Ti coatings; NiO and Cr2O3 phases in Ni3Ti+(Cr3C2+20NiCr) coatings stabilised the weight gain exhibited slow oxidation rate at higher temperatures.