Study of corrosion resistance of doped surface layer with CuSn—CrxCy composition after plasma hardening

In the process of plasma surface hardening, coatings based on a mixture of CuSn alloy and 10/20 % OK 84.78 additive with high hardness were obtained. The study of the microstructures of the coatings showed that the content of the austenite phase decreases with an increase in the content of chromium carbide in the composition. The influence of the acidity parameter on the corrosion resistance of the alloyed surface layer with the composition of the mixture of alloys CuSn and the coating of the welding electrode OK 84.78 was evaluated. Corrosion control in 3% NaCl solutions with different pH values showed that the plasma coating has high corrosion resistance at pH = 7 and decreases by 2 times at pH = 3. An increase in the chromium content leads to an increase in the corrosion potential, and the presence of cracks leads to an increase in the corrosion current density.

Study of wear resistance of plasma coatings from a mixture of CuSn/CrxCy alloys

There is studied the wear resistance of coatings obtained by plasma heating of the mixture based on tin-bronze and chromium carbide. Measurement of the microhardness of the cross-section of the coatings showed that the thickness of the coating layer strongly affects the formation of the alloyed surface layer, and the addition of chromium carbide strongly leads to stronger hardening. Wear tests have shown that alloying with bronze provides the ability to improve the surface of the steel, and the CuSn + CrxCy type coating has the highest wear resistance.

PdRuIr ternary alloy as an effective NO reduction catalyst: insights from first-principles calculation

The PdRuIr ternary alloy surface is a promising catalyst for NO dissociation and is expected to be stable against the formation of volatile Ru oxide. A criterion for determining alloyed surface’ activity for NO dissociation is also proposed.

Laser Surface Alloying of Aluminium Alloys with Cu/Fe Metallic Powders

In this paper, the influence of laser surface alloying on the structure and mechanical properties of aluminium alloy was analysed. As a parent material aluminium EN AC-51300 alloy was applied. The laser surface alloying was executed by direct introduction of metallic powder Fe/Cu into the remelted area (molten pool). As a heat flux, the Hight Power Fiber Laser (HPFL) has been used. Metallic powder before the treatment was mixed in a ball mill and dried on the hot plate (90°C temperature). The mechanical and tribological properties of alloyed surface were analysed including hardness (HRF), microhardness (HV0.1) and ball-on-plate wear test. The structure of the laser alloyed surface was evaluated by light and scanning electron microscopy.

Investigating lattice strain impact on the alloyed surface of small Au@PdPt core–shell nanoparticles

We investigated lattice strain on alloyed surfaces using ∼10 nm core–shell nanoparticles with controlled size, shape, and composition.

Laser Surface Treatment of Sintered Stainless Steels for Wear Resistance Enhancement

In the present study, sintered austenitic stainless steel type 316L was laser surface alloyed with Inconel 625 powder by the fibre optic laser. The Inconel 625 spheroidal powder of grain size 60-150 μm was introduced by the coaxial feeding head directly to the liquid metal, during laser surface alloying. The process parameters were selected to melt and fully dissolve alloying powder into the alloyed surface. As a result of laser alloying, the porosity of sintered stainless steel was eliminated, a uniform distribution of nickel and molybdenum in the entire alloyed zone was obtained. The alloyed surface shows fully austenitic microstructure of 17%Cr, 18%Ni, 3%Mo. The superficial hardness, microhardness and surface wear resistance were significantly improved in respect to an untreated substrate material. The presented technique of laser surface alloying can be easily applied for sintered austenitic stainless steel components where selected component surfaces require an improved surface performance.

Ab Initio-Based Stochastic Simulations of Kinetic Processes on Surfaces

We briefly present the theoretical framework of a hierarchical multi-scale approach, which is an ab initio-based stochastic method, and its applications to several chemical/physical kinetic processes on metallic surfaces. We first introduce necessary theoretical basis of ab initio and Monte Carlo (MC) methods, and then illustrate different Monte Carlo algorithms for important ensembles, including canonical and grand canonical ensembles. In the following section, we describe two important protocols which are essential to integrate ab initio data and MC models. Two examples are presented in order to elucidate the power of this multi-scale approach. The first example focuses on the combination of kinetic Monte Carlo and transition state theory. We discuss the detailed processes of performing kinetic Monte Carlo simulation on atomic diffusion on alloyed surface, including some technical aspects. In the second example, we presents a different way to account for the local environment-sensitive metal-catalyzed O2 dissociation reactions using combinatory techniques including cluster expansion and grand canonical Monte Carlo methods. This approach provides steady-state rates and rate derivatives that are comparable with experiments. Moreover, the connection between the feasible mechanisms and the observed kinetic behaviors can now be built.