Search

In this paper, the strength development of a pure steel slag (SS) system with various concentrations of N,N,N′,N′-Tetrakis-(2-hydroxyethyl) ethylenediamine (THEED) was investigated. The hydration kinetics, pore structure and microstructure of SS pastes with and without THEED were characterized to underscore the working mechanism of THEED. Results show that THEED additions significantly increase the 3, 7 and 28 days compressive strength of hardened SS pastes. The enhancement effect increases with the dosage of THEED. At a concentration of 2000 ppm, THEED increased the compressive strength by 733%, 665%, and 545% at 3, 7 and 28 days, respectively. It is confirmed that THEED additions improve the hydration degree of SS by accelerating hydration of the aluminum phase (C3A, PDF-38-1429; C12A7, PDF-48-1882) and C2F,(PDF 38-0408) to generate Mc (PDF-41-0219) and Pa (PDF-30-0222) in the presence of CaCO3. Also, the hydration degree of silicates is increased by THEED. In this way, THEED additions refine the pore structure of hardened SS paste by increasing the pore volume with a diameter below 300 nm to achieve enhancement. The chelating effect of THEED results in promoting dissolution of SS, which provides the driving force for accelerating SS hydration. [ABSTRACT FROM AUTHOR]

In order to improve the abrasion performance of 316Lss, make full use of its advantages and broaden its application fields, the tribological behavior of the TiC particles reinforced 316Lss composites—which were manufactured by selective laser melting (SLM)—were investigated. In this study, GCr15 bearing steel was selected as the friction material and experiments on the sliding friction and wear under different loads of 15 N, 25 N and 35 N at the sliding speeds of 60, 80 and 100 mm/min were carried out, respectively. The results show that the wear performance of the TiC/316Lss composite is higher than that of the matrix during the friction and wear experiments under all conditions and the wear rate of the TiC/316Lss composite decreases with increasing the friction rate. Similar to the wear mechanism under different loads, it changes from abrasive wear to delamination wear and severe oxidative wear. At the same time, the mechanical mixed layer formed at a high speed has a protective effect on the matrix. The reason for this phenomenon is that the mechanical properties of the TiC/316Lss composites are significantly improved due to the addition of TiC particles, the refinement of cells near the TiC particles and the formation of a large number of dislocations. In addition, due to the presence of the TiC particles, the hardness and strength of the TiC/316Lss composites are greatly improved, thus the processing hardening ability of sub-surface has been improved. [ABSTRACT FROM AUTHOR]

TiC/316L stainless steel (316Lss) metal matrix composite parts have been formed using selective laser melting (SLM). In this study, we have investigated the influence of the TiC mass fraction on the microstructure evolution, microhardness, friction properties, wear properties, and corrosion resistance of the TiC/316Lss composites. The results show that the microhardness increased by the addition of the TiC mass fraction. In terms of friction and wear properties, the corrosion resistance initially increased, and then decreased. Compared with the pure 316Lss (298.3 HV0.2), the microhardness of the TiC/316Lss composites, which were formed with 2 wt% TiC, was raised to 335.2 HV0.2, which was a 12.4% increase, while the average friction coefficient was 0.123. The reason for this is that the addition of TiC can effectively refine the cell size, and as the TiC content increases, the refinement effect is more obvious. During the melting process, TiC particles act as nucleation centres, hindering the growth of crystal cells, promoting the formation of the austenite phase, and forming fine equiaxed structures, which increases the strength. However, excessive TiC particles aggravate the spheroidisation during the process of SLM, leading to increased defects, as well as a decrease in density and corrosion resistance. [ABSTRACT FROM AUTHOR]