Assessment of surface texturing of sustainable HVOF sprayed Al2O3+C powder coating

The mechanical and tribological behavior of XNBR rubber modified epoxy under dry sliding condition was investigated using a pin-on-disc wear tester at different normal loads. The mechanical properties including tensile strength, tensile modulus, flexural strength and flexural modulus were investigated as per ASTM standards. When modifying epoxy resin with liquid rubber (XNBR), the tensile modulus of epoxy/XNBR blend decreased by 50% for 2.5% XNBR content, whereas the tensile strength increased by 10.09% at 2.5% loading of XNBR rubber particles. As regards the flexural properties of the epoxy/XNBR blend, both modulus and strength decreased by 27% and 15%, respectively for 2.5% XNBR content. The frictional coefficient and sliding wear rate of epoxy/XNBR rubber blend were measured against the silicone carbide abrasive paper (grit size-70 μm) with the sliding distance of 235.5 m for 60 sec. The results showed that XNBR rubber particles increase the wear rate and reduce the coefficient of friction of epoxy/ XNBR blend as compared to neat epoxy resin. The friction coefficient of epoxy/XNBR blends are lower than neat epoxy resin and 2.5% XNBR blend is most effective at 300 g normal load in all compositions. On the other hand, the wear mass loss is higher in epoxy/XNBR blend when compared to unfilled epoxy, hence the specific wear rate is also high in case of epoxy/XNBR blend at same load condition. The 2.5% XNBR modified blend showed the maximum wear mass loss and specific wear rate. The wear rate and mass loss and specific wear rate. The wear rate and mass loss increase with increasing load.

Wear behaviour of zinc-based alloys as influenced by alloy composition, nature of the slurry and traversal distance

Bolometric properties of oxygen atmosphere annealed Nb:TiO 2−x films for infrared detectors

Wear rates (μgm/s) versus rotor speed for carbon samples sliding against smooth and wavy copper rotors (250 μm thick copper sheets were attached to smooth and wavy steel and polycarbonate backings) were identical at some speeds, but at other speeds wear rates for the wavy rotors were almost half those of the smooth rotors. Slider vibrations (periodic, with period set by rotation) perpendicular to the sliding surface were measured and Fourier analyzed. Comparison of vibration spectral amplitudes to spectral amplitudes derived from surface profiles identified vibration modes dynamically enhanced by surface waviness on the wavy rotor. At speeds where wear rates on the wavy rotor were most reduced, amplitudes of certain modes in the vibration spectrum were most enhanced. For all these cases, the product of mode number times speed was nearly constant, suggesting resonance. Contact forces and contact voltage drop (due to a mA current flowing from slider to rotor) were measured and plotted versus time during all experiments. Friction coefficients rapidly varied between 0.1 and 0.4, but averaged 0.2. Traces of friction coefficient versus time for both wavy and smooth rotors were similar, even when wear rates plunged on the wavy rotor. There were no large jumps in the contact voltage drop data, suggesting that the slider never disconnected from any of the rotors. Photoelastic visualizations (Bryant and Lin, 1993) of slider-rotor interfaces revealed concentrated contact on the smooth rotors, but none on the wavy rotors. The absence (induced by vibration) of concentrated contact may have caused differences in wear rates. Appreciable reductions (up to 50 percent) in wear rate are possible by adding small surface waves to a rotor that induce micro-vibrations of the slider-spring-rotor contact system. The effect appears most pronounced at resonance.

During the last few decade, magnetite/hydroxyapatite nanoparticles have attracted much attention for its potential applications in the field of medicine and controlled drug delivery. In the present work, we have intended and synthesized, magnetite/hydroxyapatite nanoparticles by wet-chemical precipitation route. The thermal decomposition of the prepared sample was carried out by Thermogravimetric and Differential Scanning Calorimetry (TG/DSC) analysis upto 1000 °C, it showed that the sample was stable up to 919.2 °C. The phase formation, functional groups, morphology and magnetic property of as-prepared and annealed samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), micro Raman, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM) and vibrating-sample magnetometer (VSM). By adopting Scherer method detailed structural analysis like the crystallite size, strain, dislocation density, lattice parameter, unit cell volume, surface area and fraction of crystallinity were calculated for as-prepared and annealed HAP samples. The average crystallite size of the as-prepared, annealed at 700 °C, 800 °C and 900 °C are 39, 46, 51 and 65 nm, respectively. The dislocation density, strain and surface area were decreased. FT-IR and Raman spectra showed both as-prepared and annealed samples possessed the characteristic bands of HAP. FE-SEM and TEM images depicted and confirmed the morphological characteristics of HAP. The VSM analysis confirmed that both as-prepared and annealed samples of HAP are in diamagnetic nature. The dielectric constant of as-prepared and annealed samples decreased with increase in annealing temperature whereas the conductivity increases with increase in frequency. The antibacterial property of apatite samples depending on the types of bacterial strains and also activity changed with the crystallite size.

Tribological properties of copper-graphene (CuG) composite fabricated by accumulative roll bonding

This work emphasized the preparation, mechanical characterization, and evaluation of dry sliding wear behaviour of Aluminium Alloy (AA) 6082 metal matrix composites reinforced with metakaolin particles. The reinforcement particles were incorporated in the aluminium matrix at an amount of 0% to 15% in terms of weight, in a step of 2.5%. Ultra-sonic cavitation assisted stir casting process was employed for the preparation of the composites and the prepared composites were subjected to T6 heat treatment. Optical micrographs were utilized to examine the dispersion of reinforcement particles in the matrix. The tensile properties were enhanced with an increase in the amount of the reinforcement particles up to 7.5 weight % and then started to degrade. The micro-hardness and wear behaviour also expressed a similar trend. The fractured surfaces were examined using a Scanning Electron Microscope (SEM). The pin-on-disc wear test was employed to characterize the wear behaviour of the composites. Wear rate and average coefficient friction of the prepared composites were analyzed by varying the significant parameters such as load, sliding velocity, and sliding distance. Field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) data were utilized to examine the worn-out surfaces. The T6 heat-treated specimens expressed remarkable enhancement in mechanical and wear properties compared to as-cast samples.

An investigation into the effect of film thickness on nanowear with amorphous carbon-based coatings

Sandwich structures of magnesium phthalocyanine (MgPc) thin films using aluminium (Al) and gold (Au) electrodes were prepared by thermal evaporation. Device characteristics of Al/MgPc/Au were found to show rectification properties. The electrical conductivity had been measured for the oxygen-doped, as-deposited and annealed samples. Current density–voltage characteristics under forward bias (aluminium electrode negative) were found to be due to the ohmic conduction at lower voltage regions with a hole concentration p0 = 3.92 × 1018 m−3 and mobility μp = 1.81 × 10−6 m2 V−1 s−1 for the as-deposited films. At higher voltage regions space charge limited conductivity (SCLC) controlled by a discrete trapping level of 4.51 × 1021 m−3 was obtained at about 0.73 eV above the valance band edge. The electrical parameters of oxygen-doped, as-deposited and annealed samples in the ohmic and SCLC regions were determined. The reverse bias curves were interpreted in terms of a transition from the electrode-limited Schottky emission to the bulk-limited Poole–Frenkel effect. The Schottky barrier parameters of oxygen-doped and annealed structures along with the as-deposited samples were determined from the C2–V characteristics. The space charge density N = 2.54 × 1022 m−3, built-in potential Vbi = 0.80 eV, depletion width W = 135 nm and barrier height φ = 1.09 eV were obtained for the as-deposited films.

Synthesis and characterization of Ni-based infiltration brazed coating reinforced with Co-P shell-coated WC

In the present study, various compositions of TiB2-Co coating were deposited on AISI 1020 mild steel by tungsten inert gas cladding method. In this work, various heat energy of TIG with a fixed travelling speed of 1.5 mm s−1 was used to deposit the coating layer. The aim of this study was to investigate the optimal heat input of TIG to develop a thick layer in terms of coating microstructure and bonding quality. The influence of cobalt addition and current variation on microhardness and wear properties of the cladded layer was also investigated. The metallographic examination and microstructural analysis were investigated by x-ray diffraction, scanning electron microscope (SEM) and energy dispersive spectroscopy. The microhardness and wear rate have been analyzed by Vickers microhardness and dry sliding wear test, respectively. The investigations reveal that the influence of heat input on the wear resistance and hardness of the coated layer was significant. The microhardness value increases with increase in wt.% of TiB2 coating powder when TIG parameter is constant. The microhardness value also increases with decrease in heat input of the TIG when composition of the coating is kept constant. The maximum microhardness value was achieved up to 2563 HV0.1 which was 15 times higher than the substrate hardness value of 170 HV0.1. From the wear test result, it was noticed that the minimum wear rate found was 8.24 × 10–8 g Nm−1 for the coating composed by lower heat input (720 J mm−1) and higher wt.% of TiB2 (90 wt.%).

The present study focused on the experimental investigation of the metallurgical, tribological, and mechanical behavior of the developed Al-Zn-Mg-Cu-Sr-WC (Al7075-Sr-WC) metal matrix composite. The effect of the reinforcements such as strontium and tungsten carbide (WC) along with a 2 wt% magnesium as the wetting agent during the stir casting of the synthesized aluminum metal matrix composite (MMC) was investigated by varying the weight percentages. The microstructure examination was characterized using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) techniques. Wear analysis and mechanical testing were conducted to study the effect of WC particles in the matrix phase by examining their wear rate, tensile strength, proof strength, and hardness values. From the mechanical and tribological tests, it was observed that there was an increase of 55% in hardness and 43% in tensile strength, along with a 31% reduction in wear rate. The secondary phases revealed from XRD analysis lead to more hardness along the refined grain boundaries. The tensile strength of the composite initially increased with a 3 wt% of WC and 5 wt% strontium due to hindrance to the dislocation movement but decreased with more reinforcement particles caused by brittleness. The hard WC particles presence has reduced the wear rate significantly due to its resistance towards abrasive wear and lubricating effect. The unique combination of a grain refiner and a binder helped develop a novel composite with superior characteristics that could replace many aerospace components made up of Al7075 alloy.

Tribological performance and phase transition of MAX-phase/YSZ abradable seal coating produced by air plasma spraying

This article investigates the radiation effects on as-deposited and annealed AlN films on 4H-SiC substrates under gamma-rays. The AlN films are prepared using plasma-enhanced-atomic-layer-deposition on an n-type 4H-SiC substrate. The AlN/4H-SiC MIS structure is subjected to gamma-ray irradiation with total doses of 0, 300, and 600 krad(Si). Physical, chemical, and electrical methods were employed to study the variations in surface morphology, charge transport, and interfacial trapping characteristics induced by irradiation. After 300 krad(Si) irradiation, the as-deposited and annealed samples exhibit their highest root mean square values of 0.917 nm and 1.190 nm, respectively, which is attributed to N vacancy defects induced by irradiation. Under irradiation, the flatband voltage (V fb) of the as-deposited sample shifts from 2.24 to 0.78 V, while the annealed sample shifts from 1.18 to 2.16 V. X-ray photoelectron spectrum analysis reveals the decomposition of O-related defects in the as-deposited AlN and the formation of Al(NO x ) y compounds in the annealed sample. Furthermore, the space-charge-limits-conduction (SCLC) in the as-deposited sample is enhanced after radiation, while the barrier height of the annealed sample decreases from 1.12 to 0.84 eV, accompanied by the occurrence of the SCLC. The physical mechanism of the degradation of electrical performance in irradiated devices is the introduction of defects like N vacancies and O-related defects like Al(NO x ) y . These findings provide valuable insights for SiC power devices in space applications.

Mechanical, tribological, and morphological properties of SiC and Gr reinforced Al-0.7Fe-0.6Si-0.375Cr-0.25Zn based stir-casted hybrid metal matrix composites for automotive applications: Fabrication and characterizations