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Laser cladding is a powerful surface treatment technique that can significantly enhance the properties of metal alloys. This study delves into the liquid phase separation behavior of Cu-Fe-Cr alloys under the rapid solidification conditions inherent in laser cladding and evaluates the influence of 4% Mo and 2% B4C additions on the resulting alloy characteristics. The intensive undercooling characteristic of the laser cladding process facilitates the alloy's entry into the liquid-phase immiscibility gap, prompting pronounced phase separation. Our investigation reveals the emergence of Fe-rich regions, exhibiting a variety of shapes, set against a continuous Cu-rich matrix. The incorporation of Mo and B4C was found to modulate the mixing enthalpy and entropy, thereby refining the phase distribution: Mo was observed to prevent the agglomeration of Fe cores, resulting in a dispersion of isolated Fe cores throughout the Cu-rich matrix, while B4C promoted a more uniform compositional distribution. This study further enumerates the enhancements in microhardness, wear resistance, and magnetic properties of the alloys. Notably, the Cu-Fe-Cr-Mo-B4C alloy demonstrated a microhardness exceeding 600 HV, a low coefficient of friction around 0.15, high saturation magnetization, and reduced coercivity. These results underscore the efficacy of laser cladding in tailoring the microstructure and properties of Cu-Fe alloys, providing insights for the controlled manipulation of phase separation to optimize surface characteristics for engineering applications. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) with different aspect ratios were modified by a silane coupling agent. The modified CNTs were embedded into a silicone elastomer (SE) matrix to obtain the composites. The dielectric behaviors of the composites with different frequencies of outer electric field were investigated. The results showed that the CNTs were modified by a silane coupling agent to improve the interaction with the SE matrix. The dielectric loss and permittivity of the SE were enhanced by the addition of CNTs. The CNTs with larger aspect ratios had a more effective dielectric loss and permittivity-enhancing effect. There were three existent polarization mechanisms in the composites, and the response times of the three were different. When the field frequency increased, a polarization mechanism or two would not catch up with the increase, and the dielectric loss and permittivity would obviously be affected. The CNTs with larger aspect ratios had a more effective dielectric loss and permittivity-enhancing effect. According to the Debye equation, CNT/SE composites have a similar function as the parallel RLC circuit.

To improve the wear resistance of Fe-based cladding, NbC particles with different morphology are generated in situ by adding Nb, Cr 3 C 2 and C with different content. The composition of samples and the morphology of NbC particles generated in situ are revealed by XRD, SEM and EDS. The wear resistance is studied by a reciprocating friction and wear testing machine. The wear mode and the wear mechanism of each sample are investigated. The results show that although NbC particles are generated in situ in samples with different Nb, Cr 3 C 2 and C content, the morphology of NbC particles is varied. The wear resistance of samples containing cross-shaped NbC particles is more outstanding than that of samples containing only rectangular NbC particles. In addition, changing Nb, Cr 3 C 2 and C content does not result in a change in wear mode, but leads to the formation of continuous lattice structure of Cr 0.19 Fe 0.7 Ni 0.11 and Cr 23 C 6 compounds at grain boundaries and a change in the wear resistance. When the additions of Nb, Cr 3 C 2 and C are 11.2 wt%, 8.6 wt% and 0.2 wt% respectively, the coefficient of friction of the sample is the lowest, and the wear resistance is the most outstanding. [ABSTRACT FROM AUTHOR]

Performance recovery is the main emphasis in most remanufactured machine tools, rather than the effective combination of customer requirements (CRs) and redesign processes. Because of this, remanufactured machine tools do not reach their potential competitiveness, highly restricting the implementations to recover used machine tools. To help remedy this, fuzzy nonlinear regression is applied to the fuzzy relationships between CRs and redesign parameters, and the fuzzy correlations among redesign parameters are analysed by fully considering the uncertainties between CRs and redesign parameters. Improved planning equations based on fuzzy nonlinear regression are proposed by injecting fuzziness into the original planning equations. The redesign process of a machine tool is taken as an example to implement the proposed method. The results show that the improved planning equations can obtain higher customer satisfaction compared to the unimproved planning equations. This can provide new thinking to effectively combine CRs and redesign processes. [ABSTRACT FROM AUTHOR]