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Zirconium-modified materials exhibit good adsorption performance, but their large-scale application is limited by the cost of carrier materials and the difficulty of solid–liquid separation of powder adsorbents. Therefore, in this study, we used low-cost gasification slag for zirconium oxide loading to avoid the aforementioned problems and successfully prepared a novel gasification slag–based zirconium-doped magnetic adsorbent material (GS-Z2M). GS-Z2M is a mesoporous adsorbent material with a large specific surface area (188 m2/g); it completely adsorbed phosphate with an initial concentration of 10 mg/L within 3 h. The rate-controlling step of phosphate removal using GS-Z2M was chemisorption. The Langmuir model proved more suitable for describing the adsorption of phosphate on GS-Z2M than the Freundlich and Temkin models, and the maximum phosphate adsorption capacity calculated using the Langmuir model was 26.02 mg/g. GS-Z2M showed good phosphate adsorption selectivity and reusability (can be recycled at least 5 times). GS-Z2M also showed good capacity for treating actual phosphate wastewater under dynamic flow conditions. The mechanism of phosphate adsorption on GS-Z2M mainly involved ligand exchange and inner-sphere complexation. The obtained results suggest that GS-Z2M is a promising adsorbent and vital for the development of phosphate adsorbents and recycling of gasification slag.

Superlubricity can be unstable in graphene systems, especially under high applied loads. Here the authors use microspheres uniformly coated by graphene to measure friction between 2D materials and show that superlow friction is preserved for long periods of time under high loads and various atmospheres.

Abstract There are few experimental results available on film thickness at speeds above 5 m/s and they are almost all based on the optical ball-on-disc test rig. In contrast to the contacts in a rolling bearing, in which the lubricant in the oil reservoir distributes symmetrically, ball-on-disc contact shows asymmetry of lubricant distribution due to centrifugal effects. In order to closely imitate the contact occurring between the ball and the outer ring of a ball bearing, this study proposes an experimental model based on ball-on-glass ring contact. An optical matrix method is used to analyze the optical system, which is composed of a steel ball-lubricant-chromium-coated glass ring. Based on the optical analysis, the measurement system is improved in order to obtain a high quality interference image, which makes it possible to measure the film thickness at high-speeds conditions.

Elastohydrodynamic lubrication (EHL) analysis in finite line contacts is usually modeled by a finite-length roller contacting with a half-space, which ignores effect of the two free boundaries existing in many applications such as gears or roller bearings. This paper presents a semi-analytical method, involving the overlapping method and matrix formation, for EHL analysis in the finite line contact problem to consider the effect of two free end surfaces. Three half-spaces with mirrored loads to be solved are overlapped to cancel out the stresses at expected surfaces, and three matrices can be obtained and reused for the same finite-length space. The isothermal Reynolds equation is solved to obtain the pressure distribution and the fast Fourier transform (FFT) is used to speed up the elastic deformation and stress related calculation. Different line contact situations, including straight rollers, tapered rollers, and Lundberg profile rollers, are discussed to explore the effect of free end surfaces. [ABSTRACT FROM AUTHOR]

Oil-air lubrication is widely used in the high-speed rotary machines; the oil is usually in the form of discrete droplets. The lubrication behavior of the oil droplet is rarely investigated. This paper investigates the effect of the oil droplet on lubrication performance based on the developed transient lubrication model with consideration of starvation conditions. The oil droplet is modeled as spherical segment with different heights, base radius, and positions, which will change the inlet oil supply conditions. The results show that the oil droplet with large size can generate thick oil film which is close to the one in fully flooded condition and can remain long time; the position of the oil droplet entering the contact region also has significant effect on the lubrication performance. [ABSTRACT FROM AUTHOR]

Finite-length line contact conditions, existing in applications such as gears or roller hearings, lead to subsurface stress distribution influenced by the free boundaries. This paper presents a semi-analytical method (SAM) for the finite-length line contact problem, based on the overlapping concept and matrix formation, to consider the effect of two free-end surfaces. In order to obtain two free surfaces, three half-spaces with mirrored loads to be solved are overlapped to cancel out the stresses at expected surfaces. The error introduced by this method is analyzed and proven to be negligible. The conjugate gradient method (CGM) is used to solve the pressure distribution, and the fast Fourier transform (FFT) is used to speed up the elastic deformation and stress-related calculation. The model is verified by finite element method (FEM) and shows a high conformity and efficiency. Besides, the line contact situations are discussed to explore the effect of free surfaces. [ABSTRACT FROM AUTHOR]