Design of cycle structure on microstructure,mechanical properties and tribology behavior of AlCrN/AlCrSiN coatings

AlCrN/AlCrSiN coatings with cycle structure, composed of fcc-CrN, hcp-AlN and amorphous Si₃N₄ phases, were fabricated to protect high speed steel (HSS) tools by high energy ion source enhanced multi-arc ion plating technology with Al₇₀Cr₃₀ and Al₆₀Cr₃₀Si₁₀ alloying targets. With the increasing cycle structure, the crystal grains of AlCrN layers was refined from 60–110 nm to 8–15 nm, and the growth behavior transformed from (200)fcc to the coexistence of both (200)fcc and (111)fcc preferred orientation as demonstrated by GIXRD spectrum, calculated texture coefficient and HRTEM results. The HRTEM results investigated that the inter-planar spacing of CrN(111) was basically equal to that of AlN(0002) with parallel orientation relationship and the interface-1 between the substrate and adhesion layer with a semi-coherent appearance presented a specific orientation relationship. The coating with two cycle structure (Cycle 2) possessed better adhesion strength (HF1 grade, 62.7±1.3 N of Lc2), higher hardness (30.2±1.7 GPa), better fracture toughness (0.099 of H/E, 0.29 GPa of H³/E² and 9.8±0.3 MPa m^1/2 of K_IC under 20 kgf loading), lower friction coefficient (0.54), less wear rate (4.2 × 10^?16 m³/N·m) and longer service life (7.4 m).     

Numerical Investigation of Third‐Body Behavior in Dry and Wet Environments under Plane Shearing

A coupled discrete element method and computational fluid dynamics (DEM‐CFD) approach to model and assess third‐body behavior in dry and wet environments under plane shearing is presented. DEM is used to model the granular media, while the fluid side of the system is simulated with CFD, which is based on the finite volume method. The applied model is extended to consider buoyancy as well as lubrication effects. The third body is confined and compressed between two walls, which are sheared in opposite direction with a constant velocity. The influence of different shear velocities, fluid viscosities, and gravity orientations on particle and fluid rheology is investigated. Obtained results of both dry and lubricated systems are compared regarding velocity and porosity distribution across the gap, sliding friction, and particle interaction.     

柴油机主要摩擦副磨损型式的识别

本文首先提出了柴油机磨损型式识别的重要性,进而阐述了磨损型式模糊模式识别的过程,即：模糊模式识别原理,建立磨损型式的标准样板库,隶属函数的确定等等,最后给出了结论。