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As an emerging measurement technique with the merit of easy alignment and high sensitivity, laser self-mixing interferometry (SMI) has wide applications in the detection of physical quantities. Considering that the characteristics of lasers have a determining influence on sensors’ performance, the authors have established an open cavity solid-state laser (SSL) with more adjustment flexibility to act as a laser source.

The fundamental structure of a SSL has been presented with an Nd:YAG rod severing as an active material and a birefringent filter inserted in the resonator as a mode selecting element. The power stability has been tested by a power meter, while the mode pattern has been inspected with a scanning Fabry–Perot interferometer, and the linewidth has been observed through a wavelength meter. A loudspeaker driven by a function generator is located in the extracavity to introduce phase modulation for SMI signal observation.

The established Nd:YAG SSL operates in a single longitudinal mode with the power stability of 0.2 mW and the linewidth less than 10 MHz. The SMI phenomenon occurs in the SSL, and the SMI signal obtained shows a fine signal-to-noise ratio of about 30 dB.

To the authors knowledge, SMI sensors using SSLs, especially in open cavity type, have rarely been reported, and they can find significant applications in designing high performance SMI sensors and instruments.

This study aims to ameliorate the strength and uniformity of the magnetic field in the air-gap of quartz flexible accelerometers. Quartz flexible accelerometers (QFAs), a type of magneto-electric inertial sensors, have wide applications in inertial navigation systems, and their precision, linearity and stability performance are largely determined by the magnetic field in operation air-gap. To enhance the strength and uniformity of the magnetic field in the air-gap, a magnetic hat structure has been proposed to replace the traditional magnetic pole piece which tends to produce stratiform magnetic field distribution.

Three-dimensional analysis in ANSYS workbench helps to exhibit magnetic field distribution for the structures with a pole piece and a magnetic hat, and under the hypothesis of cylindrical symmetry, two-dimensional finite element optimization by ANSYS APDL gives an optimal set of dimensions of the magnetic hat.

Three structures of the QFA with a pole piece, a non-optimized magnetic hat and an optimized magnetic hat are compared by the simulation in ANSYS Maxwell and experiments measuring the electromagnetic rebalance force. The results show that the optimized hat can supply stronger and more uniform magnetic field, which is reflected by larger and more linear rebalance force.

To the authors ' knowledge, the magnetic hat and its dimension optimization have rarely been reported, and they can find significant applications in designing QFAs or other similar magnetic sensors.

The purpose of this paper was to present a simple and convenient technology to produce the electronic-grade CuO. The prepared electronic-grade CuO fully meets the demands of industrial production of high density interconnect (HDI).

A new method termed as open-circuit potential-time technology is proposed to measure the dissolution time of CuO in plating solution. X-ray diffraction (XRD) scanning electron microscopy (SEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) were used to characterize the prepared CuO. Solder shock and reflow tests were carried out to examine the Cu deposits.

All aspects of the prepared CuO meet the demands of printed circuit board (PCB) industry.

A simple and convenient technology was presented to produce the electronic-grade CuO. A new method was proposed to determine the dissolution time of CuO in plating solution.

The purpose of this study is to prepare copper oxide nanoparticles (CuO NPs) in an easy and efficient way using a natural and environmentally friendly substance like ascorbic acid. Various concentrations of these nanoparticles were then added to solvent-free coating formulations to produce highly hydrophobic, corrosion-resistant and antimicrobial hybrid coatings. These hybrid formulations were also used to coat the spent fuel casks for their integrity.

The hybrid coated films were then characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), water contact angle and Scanning electron microscope (SEM). In addition, different measurements, namely, mechanical, physical, chemical, thermal, corrosion tests, open circuit potential and antimicrobial activity of these hybrid films were performed.

The results showed that the copper oxide was prepared at nanometer scales with good homogeneity and diffusion in the epoxy acrylate matrix. It also showed that some hybrid coatings have high corrosion resistance, strong hardness, excellent water resistance, remarkable antimicrobial activity and high thermal stability compared to virgin epoxy acrylates.

The formula containing 0.5% CuO NPs was found to provide the highest corrosion protection and antimicrobial activity for mild steel in 3.5% sodium chloride (NaCl).

Nanofluid exhibits higher density, higher viscosity, higher thermal conductivity and reduced specific heat capacity along with improved heat transfer characteristics. It is comparatively better than conventional fluids in terms of thermo-physical properties. This paper aims to investigate experimentally the overall performance of the shell and tube heat exchanger operated under two different configurations – without baffles (STHX_1) and with baffles (STHX_2) using 0.01 Vol.% and 0.02 Vol.% of CuO-W nanofluid.

Two different configurations, one without baffles (STHX_1) and other with single segmental baffles (STHX_2), are chosen with all other dimensional details of shell and tube remaining same. Water is used as base fluid. CuO nanoparticle is chosen, as its thermal conductivity is higher compared to other metal oxides. A comparative study on the thermal performance of these shell and tube heat exchangers are performed by considering different Vol.% concentrations of CuO-W nanofluid and the outcome are compared with the base fluid (i.e., water). The influence of varying the mass flow rate of the tube side fluid by keeping shell side fluid mass flow rate as constant and vice versa on the thermal performance of shell and tube heat exchanger are studied.

The modified shell and tube heat exchanger with baffles (STHX_2) give an improved performance. The heat transfer coefficient improved by about 11.28 and 7.54 per cent for 0.02 and 0.01 Vol.% of CuO-W nanofluid compared to water. Overall heat transfer coefficient for STHX_2 enhanced between 118.26% to 123.06% in comparison with base fluid for 0.02 Vol.% of CuO-W nanofluid whereas, it improved between 79.20% to 87.51% for 0.01 Vol.% of CuO-W nanofluid. Similarly, the actual heat transfer enhanced between 71.79% to 77.77% and between 48.71% to 55.55% for 0.02 and 0.01 Vol.% of CuO-W nanofluid, respectively. Moreover, mass flow rates of the working fluids significantly influence the performance of the shell and tube heat exchanger.

Two cases are considered here. first, by varying the shell side fluid mass flow rate and keeping the tube side fluid mass flow rate as constant. Later, tube side fluid mass flow rates are varied and shell side fluid mass flow rate is kept constant. It is found that in Case 2, for both 0.01 and 0.02 Vol.% of CuO-W nanofluid, highest performance is obtained for 150 kg/h of shell side and tube side fluid flows involving STHX_2. Finally, the modified shell and tube heat exchanger with baffle arrangement gives the best performance by using 0.02 Vol.% of CuO-W nanofluid.

The purpose of this paper is to investigate the anti-wear (AW) and extreme pressure (EP) performances of CuO and graphite nanoparticles as a palm oil additive.

In this study, the AW and EP performances of CuO and graphite nanoparticles as additives in palm oil were evaluated using four ball tribotester in accordance to ASTM D4172 and ASTM D2783, respectively. The wear worn surfaces of the steel balls were analysed using high resolution microscope.

The results obtained demonstrate that CuO and graphite nanoparticles improved the AW and EP performances of the palm oil up to 2.77 and 12 per cent, respectively. The graphite nanoparticles provide better AW and EP performance than that of CuO nanoparticles.

This demonstrates the potential of CuO and graphite nanoparticles for improving AW and EP performances of palm oil base lubricant. Different morphology of nanoparticles will affect the AW and EP performances of nanolubricants.

The purpose of this paper is to study the effect of doping, annealing temperature and visible optical excitation on CuO-ZnO nanocomposites’ acetone sensing properties and introduce an attractive candidate for acetone detection at about room temperature.

ZnO nanoparticles doped with CuO were prepared by sol-gel method, and the structure and morphology were characterized via X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and Brunauer-Emmett-Teller. The photoelectric responses of CuO-ZnO nanocomposites to cetone under the irradiation of visible light were investigated at about 30°C. The photoelectric response mechanism was also discussed with the model of double Schottky.

The doping of CuO enhanced performance of ZnO nanoparticles in terms of the photoelectric responses and the gas response and selectivity to acetone of ZnO nanoparticles, in addition, decreasing the operating temperature to about 30ºC. The optimum performance was obtained by 4.17% CuO-ZnO nanocomposites. Even at the operating temperature, about 30ºC, the response to 1,000 ppm acetone was significantly increased to 579.24 under the visible light irradiation.

The sensor fabricated by 4.17% CuO-ZnO nanocomposites exhibited excellent acetone-sensing characteristics at about 30ºC. It is promising to be applied in low power and miniature acetone gas sensors.

In the present research, a new nanocomposite material of CuO-ZnO was prepared by Sol-gel method. The optimum gas sensing properties to acetone were obtained by 4.17% CuO-ZnO nanocomposites at about 30ºC operating temperature when it was irradiated by visible light with the wavelength more than 420 nm.

Studies on this topic have shown the remarkable lubricating properties, viz. friction-reducing and anti-wear, of certain nanoparticles. This makes them potential candidates for replacing the lubrication additives currently used in automobile lubricants, especially because the latter is known to be pollutants and less efficient in some specific conditions. This has not gone unnoticed to professionals in the sector, including those commercializing these additives, the oil companies and the car industry, all of whom are following this burgeoning research area with keen interest. All of them are faced with the problem of providing lubricants that meet the needs of the technological evolution of engines while respecting ever-stricter environmental norms.

The impact of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles on the tribological properties of the SAE-40 pure diesel oil is studied in this paper. The two nanoparticles are not oxide or deteriorate with the base oil. The average size of CuO and ZnO nanoparticles is 40 and 20 nm, respectively. Nanoparticle concentrations of 0.1 Wt.%, 0.2 Wt.%, 0.3 Wt.%, 0.4 Wt.% and 0.5 Wt.% are tested using a pin-on-disk tribometer to evaluate their impact on friction and wear. The test is carried out at different loads and rotating speeds of 58.86 N and 300 rpm, 39.24 N and 500 rpm and 78.48 N and 900 rpm at room temperature, respectively.

The obtained results of the nanolubricants are compared with those of pure diesel oil in terms of % improvement in tribological properties. However, it is observed that an increase in the nanoparticle concentrations does not guarantee to enhance the tribological properties. Similarly, increasing the applied load and the rotating speed does not lead to improving the anti-friction and anti-wear properties. The results obtained revealed that the optimal improvements in the anti-friction and anti-wear properties of the pure oil are 69% and 77% when CuO nanoparticle concentrations of 0.3 Wt.% and the ZnO nanoparticle concentrations of 0.1 Wt.% are used, where the applied load and rotating speed are 39.24 N and 500 rpm, respectively. It has also been noticed that the CuO nanolubricants have a significant impact on the anti-friction property compared with ZnO nanolubricants.

All these nanoparticles have been the subject of detailed investigation in this research and many key issues have been tackled, such as the conditions leading to these properties, the lubrication mechanisms coming into play, the influence of parameters such as size, structure and morphology of the nanoparticles on their tribological properties/lubrication mechanisms and the interactions between the particles and the lubricant co-additives. To answer such questions, state-of-the-art characterization techniques are required, often in situ, and sometimes an extremely complex set up. Some of these can even visualize the behavior of a nanoparticle in real time during a tribological test. The research on this topic has given a good understanding of the way these nanoparticles behave, and we can now identify the key parameters to be adjusted when optimizing their lubrication properties.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2022-0234/

Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues.

Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al₂O₃ in base fluid water, Al₂O₃ in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO₂ in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al₂O₃ in base fluid SAE 30 particularly for heavy machinery applications.

The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations.

It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values.

Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

The purpose of this paper is to propose a new method of synthesis of CuO · SiO₂ oxide composite based on the reaction of precipitation from water solutions of sodium silicate and copper nitrate.

Solutions of sodium silicate and copper nitrate were used as substrates. The effects of direction of substrate supply, concentration, excess of reagents and temperature of precipitation on the physicochemical properties of the products were analysed.

A new method of synthesis of CuO · SiO₂ oxide composite based on a precipitation reaction is proposed.

Only sodium silicate and copper nitrate solutions were used.

The CuO · SiO₂ oxide composite obtained can be used as blue pigment or polymer filler.

The paper determines optimum conditions of CuO · SiO₂ oxide composite precipitation to obtain products with desired physicochemical, dispersive and structural properties.