Molybdenum disulfide (MoS 2 ) is one of the most commonly used solid lubricants for Cu-Fe-based friction materials. Nevertheless, MoS 2 reacts with metal matrices to produce metal sulfides (e.g., FeS) and Mo during sintering, and the lubricity of the composite may be related to the generation of FeS. Herein, the use of FeS as an alternative to MoS 2 for producing Cu-Fe-based friction materials was investigated. According to the reaction principle of thermodynamics, two composites-one with MoS 2 (Fe-Cu-MoS 2 sample) and the other with FeS (FeS-Cu 2 S-Cu-Fe-Mo sample), were prepared and their friction behaviors and mechanical properties were compared. The results showed that MoS 2 reacted with the Cu-Fe matrix to produce FeS, metallic ternary sulfides, and Mo when sintered at 1050°C. The MoS 2 -Cu-Fe and FeS-Cu 2 S-Cu-Fe-Mo samples thereby exhibited similar characteristics with respect to phase composition, density, hardness, and tribological behaviors. Micrographs of the worn surfaces revealed that the stable friction regime for both composites stemmed from the iron sulfides friction layers rather than from the molybdenum sulfides layers.
A novel micro fused-casting for metal (MFCM) process for producing A356 aluminum alloy slurry was proposed. MFCM means that the refined metal slurry is pressed out from the outlet of bottom of crucible to the horizontal movable plate. With the aid of 3D manufacturing software, the melt is solidified and formed layer by layer. The stirring could keep the ingredients and the heat diffusion of metal slurry uniform in the crucible due to the shear force breaking down the dendrite arms. The solidus and liquidus temperatures of A356 alloy were 559.2 and 626.3 ℃, respectively, which were measured by differential scanning calorimetry (DSC). Effect of different stirring velocities of MFCM on the microstructure and mechanical properties of A356 slurry was investigated with the pouring temperature controlled at 620 ℃. The microstructure and mechanical performance were the best when the stirring velocity was 1 200 r/min in MFCM. The microstructures of the A356 aluminum alloy slurry were mainly composed of fine spherical or rose grains. The average roundness and average grain size reached 2.2 and 41 µm and the tensile strength of A356 alloy slurry reached 207.8 MPa, while the average vickers hardness was 81.1 HV.
Compared with traditional industries, the industries of the future are disruptive, high-growth industries with huge development scope and great potential of explosive growth. In the face of great change not seen in a century, the development of the industries of the future is a new focus of competition. The industries of the future are cutting-edge industries that are found during scientific and technological innovations to have the potential to revolutionize traditional industries, and the high growth potential of those industries will play a critical role in supporting and leading socioeconomic transformation in the future. Many efforts are intended to change the current situation that Zhejiang's research and development in the industries of the future mostly relies on a small number of leading enterprises and improve the basic innovation ability of a large number of small and medium-sized enterprises operating in a wide range of fields.
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