Evaluation of electrochemical properties of steel sheets for automotive applications

Galvanizing as a process of zinc coating of base material is still the most widely used technology applied in surface treatment of materials which are supposed to meet the requirement of high corrosion resistance in various environments. This article presents the results of research aimed at determining the corrosive properties of galvanized sheets in selected environments – distilled water, NaCl and SARS solution, using electrochemical potentiodynamic test

Mogućnosti rabljenja visoko brzinskih kisikovih (VBK) prevlaka u uvjetima toplinskog cikličkog opterećenja

The item deals with the possibilities of utilization HVOF coatings in thermal cyclic loading conditions. There were evaluated three types of coatings based on WC-Co, WC-Co-Cr and Cr3C2-25NiCr. The quality of coatings was evaluated in terms of their adhesion as sprayed and also during the cyclic thermal loading, EDX analysis and evaluation of microhardness. Construction and structure of coatings were studied using optical and electron microscopy. There was also evaluated resistance of the coatings against erosive wear.Članak objašnjava mogućnosti rabljenja VBK-a prevlake u uvjetima toplinsko cikličnog opterećenja. Vrijednosti su za tri prevlake na temelju WC-Co, WC-Co-Cr i Cr3C2-25 NiCr. Kakvoća analize je provedena na temelju prijanjanja u početnom stanju i tijekom cikličkog toplinskog opterećenja sa EDX elektronskim mikroskopom. Vrijednovane su također otpornost prevlake na erozivno trošenje

Mogućnosti rabljenja visoko brzinskih kisikovih (VBK) prevlaka u uvjetima toplinskog cikličkog opterećenja

The item deals with the possibilities of utilization HVOF coatings in thermal cyclic loading conditions. There were evaluated three types of coatings based on WC-Co, WC-Co-Cr and Cr3C2-25NiCr. The quality of coatings was evaluated in terms of their adhesion as sprayed and also during the cyclic thermal loading, EDX analysis and evaluation of microhardness. Construction and structure of coatings were studied using optical and electron microscopy. There was also evaluated resistance of the coatings against erosive wear.Članak objašnjava mogućnosti rabljenja VBK-a prevlake u uvjetima toplinsko cikličnog opterećenja. Vrijednosti su za tri prevlake na temelju WC-Co, WC-Co-Cr i Cr3C2-25 NiCr. Kakvoća analize je provedena na temelju prijanjanja u početnom stanju i tijekom cikličkog toplinskog opterećenja sa EDX elektronskim mikroskopom. Vrijednovane su također otpornost prevlake na erozivno trošenje

Diagnostics of degradation of surfaces treated by thermal spraying

The paper deals with possibilities of utilization HVOF coatings in thermal cyclic loading and wear conditions. There were evaluated three types of coatings based on WC-Co, WC-Co-Cr and Cr3C2-25NiCr. The quality of coatings was evaluated in terms of their adhesion during the cyclic thermal loading (pull-off test), microhardness and wear resistance (pin-on-disc test). Structure of coatings was studied using optical and electron microscopy. The coating Cr3C2-25NiCr showed the highest resistance to thermal cycles and wear resistance at 900°C and can be recommended for renovation components stressed by high and cyclic temperatures and wear

Assessment of properties thermal sprayed coatings realised using cermet blend powder

The article deals with the assessment of selected properties of plasma sprayed coatings based on ZrSiO₄ doped with different volume fractions of metal dopant (Ni). Mixed powders are cermet blends. Aim of the work consists of verificating the possibility to replace the application of Ni interlayer by adding Ni directly to the ceramic powder and apply them together in a single technological operation. The coatings were studied from point of view of their structure, porosity, adhesion of the coatings in relation to the volume of dopant added and wear resistance. The best properties reached composite coating doped with 12 % Ni

Resistance of surface layers to selected tribodegradation factors

Contribution presents the results of research focused on resistance of surface layers to selected tribodegradation factors. Research is focused on the renovation of dies for hot work. Newly created renovation layers made with new types of filler materials are compared with conventionally used renovation materials. X37CrMoV5-1 was chosen as the die base material, which was hardened and tempered to a working hardness of 500 ± 15HV. The experiments are carried out practical measurements of mechanical properties of cladding. The quality of cladding was evaluated in tribological conditions of adhesion wear (ČSN EN 1071-13) and abrasive wear (STN 01 5084)

Orbital Josephson effect and interactions in driven atom condensates on a ring

In a system of ac-driven condensed bosons we study a new type of Josephson effect occurring between states sharing the same region of space and the same internal atom structure. We first develop a technique to calculate the long time dynamics of a driven interacting many-body system. For resonant frequencies, this dynamics can be shown to derive from an effective time-independent Hamiltonian which is expressed in terms of standard creation and annihilation operators. Within the subspace of resonant states, and if the undriven states are plane waves, a locally repulsive interaction between bosons translates into an effective attraction. We apply the method to study the effect of interactions on the coherent ratchet current of an asymmetrically driven boson system. We find a wealth of dynamical regimes which includes Rabi oscillations, self-trapping, and chaotic behavior. In the latter case, a full many-body calculation deviates from the mean-field results by predicting large quantum fluctuations of the relative particle number.Comment: Published versio

The change in the morphology of the blasted surface after phosphating and cataphoretic coating

The paper focuses on the quality of coatings applied by cataphoretic deposition and cataphoretic deposition technology with a phosphate layer. The quality of the coatings was evaluated by determining the roughness of the coatings, the morphology of the coatings, spectral analyses were performed detecting the presence of individual elements in the coatings. There was analysed also defect – uncoated spot