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Nano-magnetite (Fe3O4) particles have a potential to lead to the formation of lubrication tribofilm that reduces the friction and wear in hot steel strip rolling. In this paper, an attempt to fabricate the oxide film with magnetite precipitates from thermally-grown wustite (Fe1-xO) layer during isothermal cooling of low carbon microallyed steel, was obtained. The precipitation behaviors were investgated on Gleeble 3500 thermomechanical simulator under the humid air with water vaour content of 19.5 per vol percent. Several types of magnetite precipitates were examined using scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. The tribological properties of magnetite precipitates were investigated in pin-on-disc configuration. It was found that the dispersed magnetite particles originate from either the pro-eutectoid precipitation above 570 degrees celcius or the partical decomposition of wustite below 570 degrees celcius. The oxide film on the presence of free particles durin g eutectoid precipitation could be a lubricant and consequently resist wear, particularly for the oxide scale with a typical thickness in the range of 8 to 11 um in dry ai and moisture atmosphere. Furthermore, characterisation and precipitation process of the oxide scale are discussed, with respect to a probable mechanism to explain the lubricated properties has been proposed. thermo-mechanical simulator under the humid air with water vapour content of 19.5 vol.%. Several types of magnetite precipitates were examined using scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. The tribological properties of magnetite precipitates were investigated in pin-on-disc configuration. It found that the disperse magnetite particles originate from either the pro-eutectoid precipitation above 570C or the partial decomposition of wustite below 570C. The oxide film on the presence of free particles during eutectoid precipitation could be a lubricant and consequently resist wear, particularly for the oxide scale with a typical thickness in the range of 8 to 11μm in dry air and moisture atmosphere. Furthermore, characterisation and precipitation process of the oxide scale are discussed, with respect to a probable mechanism to explain the lubricated properties has been proposed.

Purpose The application of smart contract can greatly reduce transaction costs and improve transaction efficiency. The existing smart contract are expensive, single application scenario and inefficient. This paper aims to propose a new smart contract model to solve these problems. Design/methodology/approach By investigating the research history, models and platforms, this paper summarizes the shortcomings of existing smart contracts. Based on the content and architecture of traditional contract, a smart contract model with wider application scope is designed. Findings In this paper, several models are used to describe the operation mechanism of smart contracts. To facilitate computer execution, a decomposition method is proposed, which divides smart contracts into several sub-contracts. Then, the advantages and deployment methods of smart contract are discussed. On this basis, a specific example is given to illustrate how the application of smart contract will change our life. Originality/value Smart contract is gradually applied to more fields. In this paper, the structure and operation mechanism of smart contract system in reality are given, which will be beneficial to the application of smart contract to more complex systems.

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The characters of grain boundaries in oxide layers formed on substrates influence adhesion and friction behaviour, surface fracture and wear during high temperature steel processing. In this work, an electron backscattered diffraction (EBSD) analysis was conducted to investigate the role of surface grain boundary and orientation in magnetite (Fe 3 O 4 )/haematite (α-Fe 2 O 3 ) scale during hot rolling, and further evaluate their effects on tribological properties of water-based nanoparticles lubrication. The results demonstrate that Fe 3 O 4 (100) plane is strongly sensitive to the surface characteristics as the minimisation of surface energy. Coincident site lattice (CSL) boundaries in microstructure is in presence of Σ3 in the Fe 3 O 4 and Σ13b in the Fe 2 O 3 of the substrates subjected to a thickness reduction of 28% and cooling rate of 28 ° C/s. This is due in great part to the changes in crystal slip systems. These low-Σ CSL boundaries in oxide scale offer obstacles to the propagation of cracks, where some of nanoparticles collected would be trapped at the interface and thereby may cause high wear rates. A lubrication mechanism is proposed to explain the grain boundary effect on nanoparticles lubrication, and further to determine the dependence of frictional behaviour on surface energy, crystallographic preferred orientation (microtexture) and crystal structure. These results provide an intriguing new insight into the application of water-based lubricant with graphite nanoparticles. AbstractThe characters of grain boundaries in oxide layers formed on substrates influence adhesion and friction behaviour, surface fracture and wear during high temperature steel processing. In this work, a thickness reduction of 28% and cooling rate of 28 °C/s. This is due in great part to the changes in crystal slip systems. These low-Σ CSL boundaries in oxide scale offer obstacles to the propagation of cracks, where some of nanoparticles collected would be trapped at the interface and thereby may cause high wear rates. A lubrication mechanism is proposed to explain the grain boundary effect on nanoparticles lubrication, and further to determine the dependence of frictional behaviour on surface energy, crystallographic preferred orientation (microtexture) and crystal structure. These results provide an intriguing new insight into the application of water-based lubricant with graphite nanoparticles.

Q. (2014). Effect of a grain-refined microalloyed steel substrate on the formation mechanism of a tight oxide scale. Corrosion Science, Effect of a grain-refined microalloyed steel substrate on the formation mechanism of a tight oxide scale AbstractThe formation mechanism of tight oxide scale on the microalloyed steel was investigated at temperatures of 550-850 °C in dry air. Microstructural characterisations reveal that the spallation of oxide scale dominates at the centre of coarse grains on the oxidation initiation. The fine-grained steel improves the adhesive properties of oxide scale by enhanced grain-boundary diffusion. The lower activation energy and higher oxidation rate accelerate cation/anion migration along grain boundaries, leading to high magnetite content in the oxide scale. The approach by grain refinement at initial oxidation has been proposed to generate the pickle-free tight oxide scale. Q. (2014). Effect of a grain-refined microalloyed steel substrate on the formation mechanism of a tight oxide scale. Corrosion Science, 85 115-125. AbstractThe formation mechanism of tight oxide scale on the microalloyed steel was investigated at temperatures of 550 to 850 C in dry air. Microstructural characterisations reveal that the spallation of oxide scale dominates at the centre of coarse grains on the oxidation initiation. The fine-grained steel improves the adhesive properties of oxide scale by enhanced grain-boundary diffusion. The lower activation energy and higher oxidation rate accelerate cation/anion migration along grain boundaries, leading to high magnetite content in the oxide scale. The approach by grain refinement at initial oxidation has been proposed to generate the pickle-free tight oxide scale.