Development of ball surface acoustic wave gas chromatograph for environmental monitoring in spacecraft and its application on the ground

For on-site analysis of surface materials on the moon, planets, and small bodies and for the monitoring of air quality in crewed spacecraft, we have developed a portable gas chromatograph (GC) equipped with a ball surface acoustic wave (SAW) sensor. In this study, we fabricated a 10 cm cube GC that implements the forward flush method using two metal micro-electro-mechanical-system (MEMS) columns coated with different stationary phases in microchannels fabricated by wet etching and diffusion bonding of stainless-steel plates. Using this GC, we succeeded in analyzing 10 kinds of gas within 10 min. In addition, for the application of the ball SAW GC on the ground, we also developed a palm-sized GC with a single metal capillary column and used it in the analysis of the headspace gas of sake. We showed that the ratio of peak areas differed among odorants depending on the brand and brewing process of sake.

Tribological investigations of trimethylolpropane trioleate bio-based lubricants

Purpose The screening of lube oil performance prior to field trials is the most significant for the formulation of novel lubricants. This paper aims to investigate the efficacy of trimethylolpropane trioleate oil (TMPTO) based lubricants with different additives. Design/methodology/approach In this endeavor, initially five lubricating blends along-with TMPTO based oil with variable additives were evaluated for their tribological performances using ASTM standards. Out of these, the top three best-performing oils were further investigated for possible physical or chemical synergies among lube oils, additives and ball surface using SEM. The molecule structures of TMPTO based lube oils were confirmed using Fourier transform infrared spectroscopy (FTIR). Findings The wear preventive and extreme pressure characteristics of different TMPTO based samples were evaluated and compared for compatibility and synergy of additives. Morphological analysis of SEM images was used to understand the wear behavior of the worn surfaces. Practical implications Further investigation of TMPTO oil on its oxidation stability at high temperature and pressure to make it technologically competitive and commercially viable metal-working lubricant is suggested. Originality/value This paper highlights the tribo-effects of TMPTO to be rendered as a suitable lubricant for metal-cutting operations. The surface morphology of the worn-out surface significantly demonstrates the effect of loading conditions.

Si3N4 Ceramic Ball Surface Defects’ Detection Based on SWT and Nonlinear Enhancement

In order to improve the detection accuracy and efficiency of silicon nitride ceramic ball surface defects, a defect detection algorithm based on SWT and nonlinear enhancement is proposed. In view of the small surface defect area and low contrast of the silicon nitride ceramic ball, a machine vision-based nondestructive inspection system for surface images is constructed. Sobel operation is used to eliminate the nonuniform background, and the silicon nitride ceramic ball surface image is decomposed by SWT. And frequency-domain index low-pass filtering is used to modify the decomposition coefficients, and an adaptive nonlinear model is proposed to enhance defects; finally, the image is reconstructed and segmented by the stationary wavelet inverse transform and the dynamic threshold method, respectively. The enhanced algorithm can effectively identify surface defects and is superior to traditional defect detection algorithms.

Influence of the ultrasonic vibration on system dynamic responses in the multi-ball surface burnishing process

With the urgent demand of high-end equipment for high quality surfaces, the technique of ultrasonic vibration-assisted burnishing is introduced to strengthen the surface properties. To explore the influence of the ultrasonic vibration on the dynamic response of a burnishing system, the burnishing friction force generated from a multi-ball surface burnishing system was characterized by chaos theory. The system had four assisted forms: no ultrasonic vibration, one-dimensional (1D) ultrasonic in x-axis, 1D ultrasonic in z-axis, and 2D ultrasonic in xz-axis. The results showed that any burnishing system had chaotic nature. Under the 2D ultrasonic vibration-assisted burnishing, the burnishing friction force was reconstructed to be a chaotic attractor with high convergence degree. Moreover, the burnishing system has notable complexity and stability. The burnished Al7075 alloy sample has an excellent surface with a higher smoothness and hardness. The burnishing with 2D ultrasonic vibration in xz-axis is a technique to enhance surface properties.

The Crack Propagation Trend Analysis in Ceramic Rolling Element Bearing considering Initial Crack Angle and Contact Load Effect

Silicon nitride ceramic bearings are widely used for their excellent performance. However, due to their special manufacturing method, cracks will occur on ceramic ball surface, and this initial surface crack will propagate under the action of cyclic stress, which will lead to material spalling. This will greatly limit its service life in practical applications, especially under heavy load at high speed. Therefore, it is necessary to study the surface crack propagation of silicon nitride ceramic bearings. In this paper, the effect of initial crack angle and contact load on crack growth is analysed by the finite element method (FEM). A three-dimensional finite element model of a silicon nitride bearing ball containing an initial crack is created by the FEM. The cracks are initially classified based on the angle between the crack and the bearing ball surface, and the location of the most dangerous load for each type of crack is known by theoretical analysis. The stress intensity factors (SIFs) are calculated for the crack front to investigate the effect of load position on crack growth. Subsequently, the SIFs are calculated for each type of crack angle subdivided again to investigate the effect of crack angle on crack propagation.

A New Benzotriazole Phosphite Ammonium Salt Derivative (PN) Extreme Pressure Additive to Improve Gear Oil Tribological Properties

In this paper, a new benzotriazole phosphite ammonium salt derivative extreme pressure additive called PN was synthesized. Four-ball experiments and SRV experiments were used to test the high temperature and extreme pressure performance of PN additive, and comparisons were made with the commonly used additives including ZDDP and T304. The results show that the COF and wear amount of the PN additive in the four-ball experiment were much smaller than that of the ZDDP and T304 additives. The COF of the PN additive in the RSV experiment changed slightly with temperature, and it had better high temperature extreme pressure performance in friction reduction than the traditional ZDDP and T304 additives. When the temperature was 120oC, the COF of PN was about 30% lower than that of traditional additives. Thermogravimetric analysis showed that the failure temperature of PN additives was within 180-200oC, and the thermal stability was better than that of ZDDP and T304. After the four-ball test, SEM was used to observe the morphology of wear spots on the ball surface. It was found that the wear spots containing PN additive had slight adhesive wear, while those containing ZDDP and T304 showed serious adhesion and ploughing wear, and the surface appeared peeling and tearing. XPS was used to detect the chemical composition of friction surface containing PN additive, and thus the formation process of film on frictional surface was analyzed.

Investigation of Influence of Input Energy during Ball Milling of Aluminum Powder

Influence of the rate at which energy is applied to aluminum powder during its ball milling is investigated. Rolling granulation is a main process due to which treated particles achieve their unique morphology and microstructure. Drastic temperature rise at rapid ball milling leads to increase in plasticity and local melting of treated powder particles that result in their adherence to the surfaces of milling balls and mill cylinder walls. Mass of aluminum powder adhered to the ball surface is proportional to the total surface area of all balls loaded in mill.