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The purpose of this paper is to study the dynamic modeling and controller design for the series element actuator (SEA) joints. The robot equipped with SEA joints is a strong coupling, nonlinear, highly flexible system, which can prevent itself from damaging by the accidental impact and the people to be injured by the robot.

Based on the torque source model, the authors built a dynamic model for the SEA joint. To improve the accuracy of this model, the authors designed an elastic element into the joint and implemented the vector control for the joint motor. A control method of combined PD controller and back-stepping was proposed. Moreover, the torque control could be transformed into position control by stiffness transformation.

The established model and the proposed method are verified by the position and torque control experiments. The experimental results show that the dynamic model of the SEA joint is accurate and the proposed control strategies for the SEA joint are reasonable and feasible.

The main contribution of the paper is as follows: designing an elastic element with high linearity to improve the model accuracy of the SEA joint. The control strategy-based back-stepping method for the SEA joint is proposed to increase the robustness of the controller.

The purpose of this paper is to investigate the morphology evolution and the composition transformation of Au-Sn intermetallic compounds (IMCs) of the new Au/Sn-5Sb-1Cu-0.1Ni-0.1Ag/(Au)Ni solder joint during the high temperature aging.

Sn-5Sb-1Cu-0.1Ni-0.1Ag solder balls (500 µm in diameter), heat sink with structure of 7.4 µm Au layer on 5 µm Ni-plated Cu alloy and Si chip with 5.16 µm plated Au were used to fabricate micro-solder joints. The joints were performed in a furnace at 150°C for 150, 250 and 350 h aging. The samples were polished and deep etched before analyzed by metallographic microscope and scanning electron microscopy, respectively. Energy dispersive x-ray spectroscopy was used to identify the composition of the IMCs.

ß-(Au,Ni,Cu)₁₀Sn phase is formed during the soldering process. The IMCs evolution has two periods during the aging. The first is the ξ-(Au,Ni,Cu)₅Sn, ξ-(Au,Cu)₅Sn and δ-AuSn were formed and grew to form a full-compound joint after about 150 h aging. The second is the conversion of the full-compound joint. The IMCs converted to ξ′ phase when the aging time extends to 250 h, and transformed to ε-(Au,Ni,Cu)Sn₂ and η-(Au,Ni,Cu)Sn₄ after 350 h aging. The thicker gold layer and thinner solder joint can promote the growth of the IMCs. ß-(Au,Ni,Cu)₁₀Sn emerged in Au/SnSb-CuNiAg/(Au)Ni in this research, which is not usually found.

The results in this study have a significant meaning for the application of the new Sn-5Sb-1Cu-0.1Ni-0.1Ag in harsh conditions.

This study aims to reveal the tribological mechanism of synergistic effect between MoDTC and P-containing additives in aluminum-based grease.

The authors prepared a molybdenum dialkyl dithiocarbamate (MoDTC) and revealed the tribological mechanism of synergistic effect between MoDTC and P-containing additives in aluminum-based grease by combining with ZDDP and P-containing and S-free additives.

The MoDTC the authors prepared has good friction-reducing and anti-wear properties in aluminum-based grease and has an obvious synergistic effect with ZDDP. MoDTC and ZDDP have a significant synergistic effect on the tribological properties in aluminum-based grease, mainly because of the formation of phosphates and metaphosphates as well as more MoS₂ in the friction film. P element plays a facilitating role in the chemical conversion of MoDTC to MoS₂.

The experiments of MoDTC with tributyl phosphate and trimethylphenyl phosphate confirm that the P element plays a facilitating role in the chemical conversion of MoDTC into MoS₂.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0410

The purpose of this paper is to investigate the tribological performance of graphene oxide (GO) sheets as water-based lubricant additive when ultra-high molecular weight polyethylene (UHMWPE) plates slid against 316L stainless steel ball using a reciprocating tribometre.

The factors influencing the tribological performance were considered, including the viscosity of the GO dispersion, normal load, sliding velocity and the roughness of UHMWPE. The surface microstructure and properties of UHMWPE were studied by means of scanning electron microscopy, laser confocal microscopy, Raman spectroscopy and contact angle measurements.

The results revealed that the GO dispersion reduced friction and sliding-wear. The surface images of the wear UHMWPE plates indicated that GO sheets were prone to adsorption on the surface and form a thin physical tribofilms at the substrate.

Based on the experimental findings for the evolution of the microstructure morphology and the development of subsurface cracks, less debris and cracking can be observed in the UHMWPE plates lubricated by GO dispersion.

The purpose of this paper is to investigate the tribological properties of novel phosphorous-nitrogen (P-N) type additives in water.

The tribological properties of the novel P-N additives in water are compared with a commercial lubricant additive of the P-N type using a four-ball machine. The tribological mechanism was investigated by X-ray absorption near-edge structure (XANES) spectroscopy.

The experimental results indicate that the phosphoramidate derivatives possess good anti-wear and friction-reducing properties. The XANES analysis shows that the prepared compounds can form a protective film containing phosphate and/or polyphosphate that affects the tribological behavior.

The purpose of this paper is to investigate the tribological properties of the novel P-N type additives in water.

The management issues of this article, and the author is attempting to address these issues, are as follows: What is the optimal decision of each entity in the closed-loop supply chain for the cascading utilization of power batteries under three government measures: no subsidies, subsidies and rewards and punishments? How do different measures affect the process of cascading the utilization of power batteries? Which measures will help incentivize cascading utilization and battery recycling efforts?

The paper uses game analysis methods to study the optimal decisions of various stakeholders in the supply chain under the conditions of subsidies, non-subsidies and reward and punishment policies. The impact of various parameters on the returns of game entities is tested through Matlab numerical simulation.

The analysis discovered that each party in the supply chain will see an increase in earnings if the government boosts trade-in subsidies, which means that the degree of recycling efforts of each entity will also increase; under the condition with subsidies, the recycling efforts and echelon utilization rates of each stakeholder are higher than those under the incentive and punishment measure. In terms of the power battery echelon’s closed-loop supply chain incentive, the subsidy policy exceeds the reward and punishment policy.

The article takes the perspective of differential games and considers the dynamic process of exchanging old for new, providing important value for the practice of using old for new behavior in the closed-loop supply chain of power battery cascading utilization.

Nanoparticles are not well dispersed in non‐polar organic solvents due to their hydrophilic property which limits their applications in lubricant oils. To improve the oil‐solubility of nanoparticles, a novel technology was used to prepare a kind of lubricant containing calcium borate nanoparticles.

The microstructures of the prepared nanoparticles were characterized by transmission electron microscope (TEM) and infrared spectra (IR). Tribological properties of calcium borate nanoparticles used as additive in base oil were evaluated using four‐ball tribotester and SRV tribotester, and the worn surface of the steel ball was investigated by Polarized microscope (PM) and X‐ray photoelectron spectroscopy (XPS). In addition, the dispersing stability and antioxidation property of lubricant containing nanoparticles were also studied.

The results indicate that the average size of the prepared nanoparticles is in the range of 50‐100 nm, and the surface of the nanoparticles was altered from hydrophilicity to hydrophobicity. At the same time, the nanoparticles can be well dispersed in the base oil totally under novel process which has no significantly negative effect on the antioxidation property. The results of tribological tests show that calcium borate nanoparticles under the novel process (CBNN) show better antiwear property and friction‐reducing property in base oil compared to calcium borate nanoparticles under tradition process (CBNT). Based on the results of PM and XPS, it can be deduced that a continuous resistance film containing depositions and the tribochemical reaction products such as B₂O₃, FeB, Fe₂O₃ and CaO formed during the sliding process.

The main innovative thought of this work lies in dealing with the oil‐solubility problem through the combination effect of surface modification and special blend process of lubricating oil, and this method was first used to prepare lubricant containing calcium borate nanoparticles. It should be helpful for the borate nanoparticles used as additives in engine oil, gear oil and other industrial lubricants.

As multifunctional additives, ZDDP, which provides excellent oxidation resistance and superior antiwear properties, has been used widely in lubricants, however, it shows oppositional effect with friction modifiers when used together. In this paper, an attempt is made to find a novel kind of borate ester which can be used as potential substitute for ZDDP.

A novel borate ester containing dialkylthiophosphate group was prepared and characterized. Its tribological properties as an additive in synthetic ester were evaluated using a four‐ball tribometer and antioxidative ability tested by pressurized differential scanning calorimetry (PDSC). Thermal degradation tests were conducted to identify its thermal stabilities using thermogravimetric analyzer (TGA). The worn surface of the steel ball was investigated by X‐ray photoelectron spectroscopy (XPS) and the antiwear mechanism of the additive was preliminarily discussed.

Results show the additive possesses outstanding loading‐carrying and friction‐reducing properties, compared with ZDDP, and can improve antiwear properties of the base oil dramatically. Moreover, it also has excellent antioxidation performance and thermal stability.

This paper provides a multifunctional ashless additive which possesses excellent tribological properties, and gives another selection for industrial applications in which ZDDP is needed.

The aim of this paper is to study the tribological performance and self-repairing performance of surface-modified nanoscale serpentine powders as lubricant additives in the mineral base oil (5-CST).

Fourier transform infrared spectroscopy spectra and thermo-gravimetric analysis of both modified and unmodified serpentine were performed to analyse their grafting ratio and suspension after modified using a long-chain naphthene aliphatic acid. The tribological properties of surface-modified serpentine as lubricant additives in 5-CST were evaluated and the worn surfaces were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES).

The results show that the serpentine particles have high grafting ratio, improving the dispersity in 5-CST. When the serpentine concentration of 1.00 weight per cent is used as additives in 5-CST, friction coefficient reduces by 14.80 per cent under 294 N and wear scar diameter (WSD) decreases by 11.82 per cent. The results of X-ray absorption near edge structure and XANES show that the adsorption and tribochemical reactions occur to form self-repairing lubrication films.

The paper illustrates a tribofilm form on the rubbed surface, which is responsible for the decrease in friction and wear, mainly containing iron oxides, silicon oxides, magnesium oxides and organic compounds. The results are useful for further applications in advanced environmental friendly lubricating oils and additives.

The purpose of the research was to test whether the novel synthesized additive TEAT can be a substitution for the traditional additive ZDDP partly or entirely in mineral oil.

The extreme pressure, antiwear (AW) and friction reducing property of TEAT was examined, the tribological property of the combination of TEAT and ZDDP was also examined. The worn surfaces of the steel balls were observed using a polarizing optical microscope and x‐ray absorption near edge structure spectroscopy.

The results show that: TEAT can enhance the P_B value of the base oil obviously; TEAT shows better AW performance than ZDDP in high load and a wide range of concentration, it shows better friction‐reducing performance than ZDDP in high load and all the concentration tested; TEAT alone can provide a better AW and friction reducing property than ZDDP and the combination of TEAT and ZDDP; and the tribochemical reaction occurs between novel compound and metallic surface, generating sulfur containing layer mainly exists in the form of FeS.

These findings indicate that TEAT presents better tribological properties than ZDDP in a wide range of practical conditions. TEAT may be a substitute for ZDDP in the future.