Manowar Hussain

Development of cBN reinforced Ti6Al4V MMCs through laser sintering and process optimization

ABSTRACT In this work, a systematic study and optimization on direct metal laser sintering (DMLS) of a cBN reinforced Ti6Al4V metal matrix composite (MMC) has been carried out using the response surface methodology (RSM). Variable process parameters such as volume % of cBN (5–15%), laser power (50–60 W), scanning speed (3500–4500 mm/min), and constant parameters such as laser spot diameter (0.2 mm), hatching gap (0.2 mm), and layer thickness (0.4) were considered for the experiments. The RSM was employed to establish a regression equation to predict different output parameters of the sintered samples such as the wear rate, relative density, and microhardness. Based on the developed model, the influence of process parameters on the wear rate, density, and microhardness were accomplished with optimized results. Hence, the result, thus, obtained showed the maximum hardness and density of 519 HV0.2 and 4.23 g/cm3, respectively, and the minimum wear of 26.49 µm in a testing time duration of 10 minutes. X-Ray Diffraction (XRD) analysis of the fabricated MMC confirms the presence of different phases such as cBN, AlN, TiN, TiB2, and TiO2 as a consequence of a series of chemical reactions among cBN and different elements of Ti6Al4V in an argon atmosphere.

Pulse current co-deposition of Ni-WS2 nano-composite film for solid lubrication

ABSTRACT This study was undertaken to observe the effect of nano-composite coating on steel surface for enhancing its tribological properties. In the investigation, EN31 steel surfaces were coated with nano-composite (Ni-WS2) by pulse current co-deposition process in order to improve the tribological properties of the surface. The coatings were prepared according to different parameter settings. The effect of variations on coating thickness, microstructure, surface morphology, microhardness and tribological properties was observed. The maximum coating thickness of 117 µm with 8% by weight of WS2 particle concentration could be attained with the following parameter settings: applied voltage: 5 V; pulse frequency: 20 Hz; WS2 concentration: 20 g/l; duty factor: 0.6 and bath temperature: 50°C. The average friction coefficient of the deposited surface was 0.11, which is significantly less than that of the EN31 steel surface (average coefficient of friction > 0.5).

Synthesis and characterization of CuO nanoparticles using strong base electrolyte through electrochemical discharge process

In the present study, cupric oxide (CuO) nanoparticles were synthesized by electrochemical discharge process using strong base electrolytes. The experiments were carried out separately using NaOH and KOH electrolytes. The mass output rate and the crystal size were obtained with variation of the rotation speed of magnetic stirrer for both types of electrolytes. The mass output rate of CuO nanoparticles increased with the increase in the speed of rotation, and, after an optimum speed, it started decreasing. However, the size of the particles reduced with the increase of the rotation speed. The crystal plane of the obtained CuO nanoparticles was similar for both the electrolytes whereas the yield of nanoparticles was higher in KOH as compared with NaOH under the same experiment conditions. In this set of experiments, the maximum output rates obtained were 21.66 mg h−1 for NaOH and 24.66 mg h−1 for KOH at 200 rpm for a single discharge arrangement. The average crystal size of CuO particles obtained was in the range of 13–18 nm for KOH electrolyte and 15–20 nm for NaOH electrolyte. Scanning electron microscopy images revealed that flower-like and caddice clew-shaped CuO nanocrystalline particles were synthesized by the electrochemical discharge process. Fourier transform infrared spectrum showed that the CuO nanoparticles have a pure and monolithic phase. UV–vis–NIR spectroscopy was used to monitor oxidation course of Cu → CuO and the band gap energy was measured as 2 and 2.6 eV for CuO nanoparticle synthesized in NaOH and KOH solutions, respectively.

A novel application of micro-EDM process for the generation of nickel nanoparticles with different shapes

ABSTRACT This article explains production of nickel nanoparticles through a micro-electrical discharge machining (EDM) process with a combination of different process parameters. The production of nickel nanoparticles was carried out in a dielectric medium (deionized water) with developed micro-EDM while polyvinyl alcohol worked as the stabilizing agent. The characterization of nickel nanoparticle was done by scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV–Vis spectroscopy, and Fourier transform infrared (FTIR) analysis. From this investigation, the mean crystal size of the nickel nanoparticles was found to be in the range of 15–20 mm for a pulse-on time variation of 2–0.3 µs and the crystal size was found to decrease with the decrease of pulse-on time. It was also observed that with this decrease, the shape and size of nickel nanoparticles change from spherical to needle-like. The dispersion stability of nickel nanofluid was determined by viscosity measurements and the dynamic viscosity was noted to decrease by decreasing the pulse duration. From the FTIR spectrum results, it was confirmed that the synthesized nickel nanoparticles in deionized water were pure and monolithic. UV–Vis–NIR spectroscopy depicted that the band gap energy increases with a reduction in the pulse-on time and obtains a higher band gap (5.31 eV) for 0.3 µs pulse-on time.

Micro-electrical discharge machining of difficult-to-machine materials: A review:

Electrical discharge machining has emerged as one of the most accepted non-traditional machining methods that have the capability of attaining complex shapes and better feature size in difficult-to-machine materials. In this article, an advanced review of conventional electrical discharge machining and micro–electrical discharge machining of difficult-to-machine materials, such as nickel and its alloys, titanium alloys, stainless steel (SUS 304) and advanced ceramics, has been presented. The review begins with an introduction to the conventional electrical discharge machining and micro–electrical discharge machining processes, followed by classifications and a brief discussion on different aspects of micro-manufacturing methods. The current research trends and developments, research gaps and challenges of the conventional electrical discharge machining and micro–electrical discharge machining of nickel and its alloys, titanium alloys (Ti6Al4V), stainless steel and advanced ceramics are also discussed in depth. A brief note on future research trends, based on the available literature, has been included in the last section.