Influence of modulation periods on the tribological behavior of Si/a-C: H multilayer film

Abstract

A series of Si/a-C: H multilayer films with different modulation periods were fabricated on stainless steel and silicon substrates by radio-frequency magnetron sputtering. The influence of the modulation period on the structure, morphology, mechanical properties and tribological behaviors in different environments (air, simulated acid rain, and NaCl solution) was investigated. The results show that the content of the sp 2 hybrid carbon, surface roughness and hardness of the multilayer film increased firstly and then decreased with the decreased modulation period. Furthermore, the combination of the sublayer agrees well with the formation of the SiC crystal at the interface. Interestingly, the films show quite substantially different tribological properties in various test environments. The lowest friction coefficient is 0.2 for the S1 film in air. However, the lowest friction coefficient can reach 0.13 in solution. Importantly, the tribological behavior of the multilayer film is mainly determined by its hardness, as well as surface roughness in air while it is closely related with modulation period and interface structure in solution.

Hydrogenation of 3-hydroxypropanal into 1,3-propanediol over bimetallic Ru–Ni catalyst

“…This result indicates that a lower LHSV is favorable for the conversion of 3-HPA and the selectivity to 1,3-PDO, and a higher LHSV, which corresponds to a shorter residence time, leading to an insufficient contact between the reactants and catalyst, inhibiting the hydrogenation of 3-HPA to 1,3-PDO. 58 From the above results, it can be established that the optimized conditions for the hydrogenation of 3-HPA to 1,3-PDO over the Ru-40Ni/SiO 2 catalyst are temperature ¼ 80 C, H 2 pressure ¼ 2.0 MPa and LHSV ¼ 0.4 h À1 , considering the production capacity, requirements for facilities, and energy consumption. Fig.…”

“…This indicates that the increase in the H 2 pressure has a positive effect on the conversion of 3-HPA and the selectivity to 1,3-PDO. 58 This is due to the fact that, as is well known, the gas-liquid-solid mass transfer resistance of hydrogen constitutes a very important limiting factor for many hydrogenation reaction, and therefore, an increase in the H 2 pressure promotes the accessibility of H 2 at the active sites of the catalyst, favoring the hydrogenation conversion of 3-HPA to 1,3-PDO. 59 In particular, it should be noted that a relatively high conversion of 3-HPA (ca.…”

Amorphous polymerization of nitrogen in compressed cupric azide

“…[14,[20][21][22] However, the experimental evidence for these high-pressure polymeric phases remains less available. [23][24][25] An important reason is that the present theoretical predictions are mostly based on structure searching algorithm with thermodynamic criteria, and the dynamics aspects are not involved. It is possible that amorphization occurs before the high-pressure phase transitions, as reported in the experiment of NaN 3.…”

Versatile Mechanical and Thermoresponsive Properties of Macroporous Copolymer Gels

“…It undergoes volume phase transition at around 33 °C, which is known as its LCST. [10] It also undergoes volume phase transition due to the variation of the composition of water in water-miscible organic solvents like methanol, [11][12][13] ethanol, [14] tetrahydrofuran, [15,16] dimethylsulphoxide, [16,17] and N,N-dimethylformamide [17,18] -which are good solvents for PNIPAM. This is mainly due to the co-nonsolvency phenomenon, [19][20][21] where mixtures of two good solvents behave as a poor solvent for a polymer or its cross-linked gel.…”