[en] The thermodynamic properties, including activity coefficients, osmotic coefficients and excess Gibbs free energy for RbCl and Rb₂SO₄ aqueous mixtures at T=298.15 K and in 0.01 mol · kg^-1 to 5 mol · kg^-1 ionic strength, were determined by emf measurements. The Rb-ISE and Ag-AgCl electrodes used in this work were prepared in our laboratory and had a reasonably good Nernst response. The experimental data were fitted by using the Harned rule and Pitzer model. The Harned coefficients and the Pitzer binary and ternary interaction parameters for the system have been evaluated. The experimental results obey the Harned rule. The Pitzer model can be used to describe this aqueous system satisfactorily

[en] A synchronous rolling method was proposed to assist laser multilayer cladding, and the effects of this method on microstructure, microhardness, and wear resistance were studied. Results show that the microstructure and mechanical properties of the traditional cladding layer exhibit periodic inhomogeneity. Synchronous rolling breaks the columnar dendrite crystals to improve the uniformity of the organization, and the residual plastic energy promotes the precipitation of strengthening phases, as CrB, M₇C₃, etc. The hardness and wear resistance of the extruded cladding layer increase significantly because of the grain refinement, formation of dislocations, and dispersion strengthening. These positive significances of synchronous rolling provide a new direction for laser cladding technology.

[en] Aerodynamic journal bearings are commonly used in high speed machines, which have weaknesses of low steady-state performance specifications. It is of great significance to study the effects of herringbone grooves on the characteristics of aerodynamic journal bearings. This paper investigates effects of herringbone grooves on functions of aerodynamic journal bearings by numerically solving the Reynolds equation based on improved finite element method. The obtained results show that the herringbone grooved aerodynamic journal bearings have a critical speed and they should run at a speed of greater than the critical speed. Ultra-high speeds and low eccentricity ratios are the suitable working conditions of the herringbone grooved aerodynamic journal bearings. The performance of aerodynamic journal bearings is enhanced with advancing groove numbers, and an optimal groove depth is existed with respect to the herringbone grooved aerodynamic journal bearing. (paper)

[en] It is essential to thoroughly investigate influences of orifice layouts on properties of aerostatic journal bearings employed in ultra-high speed spindles. In this paper, four orifice layouts of aerostatic journal bearings which have a large length-diameter ratio are designed and investigated, particularly in light of the nonlinear compressible Reynolds equation and the associated computational analysis and algorithms using the FEM-based Galerkin weighted residual method. A series of pressure distributions as well as the load capacity, attitude angle, volume flow rate and air film stiffness of the aerostatic journal bearings for the cases of four orifice layouts are analysed with respect to different rotational speeds and eccentricity ratios. It can be concluded that increasing orifice sets is not beneficial to enhance the performance of the aerostatic journal bearing. The aerostatic journal bearing divided into two identical independent aerostatic journal bearings has relative optimal performance at rotational speeds from 0 r/min to 160,000 r/min, such as the highest load capacity, the lowest attitude angle and modest air film stiffness, however, with consumption of the largest quantities of pressurized gas. The designers can use the analysis results to optimize the orifice layout for improving the performance of the aerostatic journal bearing. (paper)