Search

• 1 HfC x N y -Cu composites were prepared with copper and HfC x N y powder. • 2 The microstructure and properties of HfC x N y -Cu composites were investigated. • 3 The composites samples were analyzed by XRD, SEM and EDS. In this work, novel HfC x N y -Cu composites with varying HfC x N y contents were fabricated via subsequent spark pulse sintering (SPS). The influence of HfC x N y addition on the mechanical properties, wear properties, and electrical conductivity of the HfC x N y -Cu composites was systematically studied. The 5HCu composites exhibit a hardness of 136.8 HV and an electrical conductivity of 50.2 % ICAS. Whereas, the hardness of the 10HCu composites increased to 148.3 HV. Moreover, 5HCu composites rather than 10HCu exhibited better lubrication performance and wear resistance, the average friction coefficient and wear rate were measured to be 0.41 and 0.026 mg/min, respectively. The potential applications of HfC x N y -Cu composites include high-temperature structures and electronic device heat dissipation. [ABSTRACT FROM AUTHOR]

Smart hydrogels that can adsorb both anionic and cationic dyes and have excellent mechanical properties have not been reported yet, despite bright prospect in dye adsorption. The emergence of polyampholyte made it possible for the preparation of novel hydrogels. PMAD (copolymer of AM, AA and DMC) is a novel thermo-responsive hydrogel based on polyampholyte, whereas poor mechanical properties limit its application. Herein, we designed a novel polysaccharide crosslinker, which integrates chemical-crosslinking network and physical-entanglements to fabricate PMAD hydrogels. Chemical-crosslinking network maintains the shape of hydrogel as backbone, whereas physical-entanglements enhance the energy-dissipation capacity by disentangle upon deformation. Synergistic effect of the above structure improves the fracture strength and elongation of PMAD by nearly 4700% and 900%, respectively. Moreover, the hydrogel can be used as controllable adsorption material towards both cationic and anionic dyes, which could greatly increase adsorption capacity after reaching the critical temperature due to its unique temperature-sensitive characteristics. [Display omitted] [ABSTRACT FROM AUTHOR]

Poor mechanical properties of PMAD (the copolymer of AM, AA and DMC) hydrogel derived from its high-density rigid crosslinking structure is main obstacle for its functional application. Herein, inspired by spring-like structure, nano-SiO 2 based crosslinker was used to fabricate mechanical robust thermo-responsive PMAD-matrix hydrogel. Nano-SiO 2 was modified with poly (ethylene imine) (PEI), which was further introduced in crosslinking network of PMAD hydrogel. Flexible PEI chains can elongate under stress, which endows crosslinking network deformability, like that of spring in tension. Meanwhile, nano-SiO 2 can improve the tensile strength of the hydrogel, and amino groups in PEI can improve its dispersity in water. When content of the crosslinker is 15‰, tensile strength and elongation at break can be improved by nearly 3540% and 503% respectively owing to synergistic effect of PEI and SiO 2. More interesting, mechanical properties of hydrogels can be designed flexibly by controlling the structure of the nano-SiO 2 based crosslinker, which realizes structure management of hydrogel. Moreover, hydrogel prepared by this method also shows thermo-responsivity, endowing it potential for functional application. [Display omitted] • Novel crosslinker SiO 2 -PEI-AGE inspired by spring-like structure was synthesized. • Synergistic effect of SiO 2 and PEI can improve both strength and fracture. • Tensile strength and elongation of PMAD can be increased by 3540% and 503%. • Structure management of PMAD can be realized by structure control of SiO 2 -PEI-AGE. • PMAD hydrogel prepared by this method also shows UCST thermo-responsivity. [ABSTRACT FROM AUTHOR]

• The welding current is the most important parameter for the features. • The regression model performs well and its maximum relative error is about 9%. • Five features were selected to express the shape of the dynamic resistance signal. In this paper, relevant twenty features were extracted from the dynamic resistance signal of the welding operation and subsequent mathematical models incorporating the qualifying features were developed to investigate the relationship among dynamic resistance, welding quality and welding parameters based on the stepwise regression method. The results of the analysis of variance indicated the peak point location t 1 , the initial resistance value r 0 , and the first slope k 1 had little correlation with welding process parameters. The welding current is the most significant factor affecting the dynamic resistance signal, followed by welding time and electrode pressure. The welding current has significant effects on all the extracted features, while the electrode pressure only affects seven features. The model utilizing the features of r mean , r e , r α , r β and r med was developed to predict the welding quality. r mean is the most significant factor in the model whose maximum relative error is less than 10%. [ABSTRACT FROM AUTHOR]