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Different amounts of PTFE were doped in the process of Cr3+ electroplating to form Cr3+ composite coating. The effects of PTFE particles with different concentrations on the micro-structure and mechanical properties of Cr3+ composite coating were studied in this paper. The micro-structure and mechanical properties of Cr3+ coating were characterized and tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), nano-indenter and friction wear testing machine, respectively. The results show that different concentrations of PTFE had significant effects on the micro-structures and mechanical properties of Cr3+ composite coatings. When the concentration of PTFE in the plating solution was 12.5 mL/L, the current density was 35 A/dm², the pH was about 2.0, the temperature was 45 °C, and the deposition time was 20 min, the obtained Cr3+ composite coating had the best comprehensive performance, with the hardness of 6.8 GPa and the lowest friction coefficient value of 0.28. [ABSTRACT FROM AUTHOR]

Coral concrete with coral crumbs as coarse aggregate and coral sand as fine aggregates plays a huge role in solving the shortage of materials in the construction of distant island reefs. This paper began with a scientific measurement analysis of mainstream journals, keywords, scholars and institutions active in coral aggregate concrete research. Then the problems of preparation, mechanical properties, durability and microstructure of coral concrete were summarized, and the shortcomings of coral concrete research were proposed. [ABSTRACT FROM AUTHOR]

In this paper, Ag-15Cu-10Au-2Ni alloy has been fabricated by vacuum induction melting, and the plastic deformation and microstructure, mechanical and electrical properties after heat treatment were investigated. The results show that the Ag-15Cu-10Au-2Ni alloy was mainly composed of silver-rich phase and copper-rich phase, as well as Ni mostly existed in copper-rich phase. The significant strengthening effect could be observed obviously, while the hardness was 201 Hv (90 Hv as cast condition) and the tensile strength was 744 MPa for the 95% deformed alloy. For the specimen annealed at 650 °C for 1 h, the elongation reached 31.8% and the hardness was close to that of the cast condition. The resistivity of the alloy decreased at first and then increased with the increase of annealing temperature. The alloy annealed at 350 °C for 1 h had minimum resistivity (3.98 Ωµ ⋅ cm) due to the emerge of order phase transition after annealing at low temperature region. [ABSTRACT FROM AUTHOR]

The effects of Cu addition on the microstructure, corrosion resistance and mechanical properties of Ni-P-PTFE composite coatings were studied in this paper. The microstructure, corrosion resistance and mechanical properties of the coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical workstation, nano-indenter, and friction wear testing machine, respectively. The results show that Cu addition has great influence on the composition, microstructure, corrosion resistance and mechanical properties of Ni-P-PTFE composite coating. With the increase of Cu2+ concentration in the plating solution, Cu content in the coating first increased and then decreased, while the content of Ni, P, and PTFE first decreased and then increased. With the increase of Cu content in the coating, the corrosion resistance and hardness of Ni-Cu-P-PTFE composite coatings improved, while the friction performance decreased. [ABSTRACT FROM AUTHOR]