M2 high-speed steel samples were fabricated by laser additive manufacturing and tempered at different times at a temperature of 560°C. The microstructures of deposited samples were characterised by fine equiaxial grains, dendrites and inter-dendritic network-shape eutectic carbides and were composed of supersaturated martensite, retained austenite and M2C-type carbides. The content of retained austenite gradually decreased with increasing tempering times. Meanwhile, the micro-hardness of deposited samples was 688 ± 10 HV, while the first, second and third tempering times were 833 ± 13 Hv, 710 ± 6 Hv and 740 ± 7 Hv, respectively (standard deviations).Wear resistances of all samples showed an adhesive wear mechanism, and M2 HSS without tempering had a lower friction coefficient with an average of 0.52. M2 HSS after tempering twice at 560°C/2 h had a larger wear volume loss than others.

No abstract

Disperse reactive dyes with appropriate chemical structure are key for the coloration of natural fibers in the water‐free environmentally friendly medium of supercritical carbon dioxide with various advantages. The objective of this work is to design and synthesize a novel anthraquinonoid disperse reactive dye involving a versatile bridge group to improve the coloration properties of the dye in supercritical carbon dioxide. Cross‐coupling condensation based on an Ullmann reaction between N‐phenylethylenediamine and 1‐chloroanthraquinone in a ligand‐free system is investigated by optimizing the synthesis parameters. Notable influences are observed from the dosages of N,N‐dimethyl formamide and potassium hydroxide, as well as the system temperature and reaction duration, on the isolated yield of the dye precursor. An optimized process is also recommended for synthesizing the designed novel dye. Then, the chemical structure, color characteristics, and coloration properties of the obtained dye are further investigated and successfully characterized by utilizing Fourier‐transform infrared analysis, 1H and 13C nuclear magnetic resonance spectroscopy, UV–vis absorption spectroscopy, elemental analysis, and liquid chromatography‐mass spectrometry. Additionally, practical coloration experiments are performed with cotton, silk, and wool in a supercritical carbon dioxide medium.

No abstract

No abstract

Due to the excellent lubricity of V2O5 and soft metals, V and Cu have been added to Mo-N based coatings to further improve the tribological properties. In this study, the Mo-V-Cu-N coatings were deposited by high power impulse magnetron sputtering (HIPIMS). The effects of V and Cu on the microstructure and mechanical properties of Mo-N coatings were investigated. With increasing V/Cu content ratio, the deposition rate decreased from 15.4 to 6.5 nm/min, and the microstructure transformed from a featureless structure into a dense columnar structure. At low Cu contents, less than 6.5 at.%, the Mo-V-Cu-N coatings exhibited a single solid solution phase of c-Mo2(V)N. When the Cu content reached 29.7 at.%, the Mo45V1Cu30N24 coating showed the lowest surface roughness of 2.0 nm, and the coating changed into a double-phase of c-Mo2(V)N and c-Cu. The adhesion strength gradually increased from 32.2 to 87.8 N with an increasing V/Cu content ratio. Due to the microstructure densification, a maximum hardness of 27.3 GPa was achieved for the Mo46V15Cu1N38 coating, which was accompanied by a high compressive residual stress.

No abstract

No abstract