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  • Author: Janette Brezinová x
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Abstract

The present contribution deals with the influence of tribological conditions on coating quality. Two types of coatings were selected for analysis WC-WB-CO and WC-FeCrAl, to advise that a new type of coating - carbide green. These coatings were applied to the base material AISI 316L of technology HVOF – High velocity oxygen fuel. The aim of the experimental study was to determine the quality coatings and its resistance to abrasive wear, depending on the number of thermal cycles. It was evaluated hardness, thickness, the resistance to abrasive wear in free abrasives and firmly bonded abrasives. Results of experiments showed a higher resistance of the coating WC-Co-WB.

Abstract

the paper proposes the fourth restoration of a roller in continuous casting production lines which can enhance production efficiency and lowers costs. The roller was forged from the material 24CrMoV55 - DIN 17240. The roller has been restored three times and is chosen for further restoration. The roller was restored by submerged arc welding (SAW) where the first layer was made from UP-5-200-CZ wire and the covering layers made from UP-5-45-CZ wire. Quality of the weld deposits were evaluated by measuring the hardness, mixing the weld with basic material and by setting the basic mechanical properties in the critical under-weld deposit area. Structures of the weld deposits were evaluated by light microscopy and their chemical composition was determined by EDX analysis. Based on experiments it can be concluded that rollers can be restored for the fourth time, but the limiting factor is the extent of damage.

Abstract

The paper presents results of research aimed at determining the corrosive properties of steel with cathode metal coating in selected corrosive environments. The corrosion properties of the tin coated steel were evaluated using electrochemical impedance spectroscopy and potentiodynamic tests. For realised measurements, distilled water, 0.5 mol dm−3 NaCl solution, 0.1 mol dm−3 NaCl solution and SARS, which simulates acid rain were used as corrosive solutions. Both corrosion methods are suitable for diagnosing corrosion properties of steel with metal coatings.

Abstract

This paper presents the results of research aimed to measuring the corrosion properties of EDDQ steel sheet. The strain amount influence to the corrosion properties of the steel sheet for drawn parts has been proven by the modern methods of corrosion monitoring such as Electrochemical Impedance Spectroscopy. Corrosion rate was assessed using electrochemical methods in 0.1 M solution of NaCl. Experimental studies have pointed out if strain amount increases the corrosion rate of the steel sheet increases too.

Abstract

The paper presents results of the research focused on the characterization of two types of coatings – WC–FeCrAl and WC–WB–Co. The properties of the WC–FeCrAl coating (Co and Ni free) were compared against the WC–WB–Co coating to see if it could be used as an environmentally more suitable substitute for conventional Co and Ni containing powders. The coatings were applied by HVOF technology. The influence of thermal cyclic stress on the hardness, adhesion of coatings and their corrosion resistance was determined. A change in the phase composition of coatings after thermal cyclic loading was also determined.

Abstract

In this article, the attention is paid to the HVOF (High Velocity Oxygen Fuel) thermal spraying method by which the progressive coatings are applied on basic material C15E (STN 412020). These coatings are based on C-17CO, WC-CO-Cr and Cr3C2-25NiCr. There was made determination of the chemical composition of the coatings and assessment of coatings quality - adhesion, microhardness, porosity and wear resistance at room temperature (21°C) and also at operational elevated temperature (900°C). Results of adhesive wear showed high quality of all evaluated coatings and their suitability to extreme tribological conditions.

Abstract

The paper presents results of research of the essential characteristics of two kinds of advanced coatings applied by HVOF technology. One studied coating: WB-WC-Co (60-30-10%) contains two types of hard particles (WC and WB), the second coating is eco-friendly alternative to the previously used WC-based coatings, called “green carbides” with the composition WC-FeCrAl (85-15%). In green carbides coating the heavy metals (Co, Ni, NiCr) forming the binding matrix in conventional wear-resistant coatings are replaced by more environmentally friendly matrix based on FeCrAl alloy. On the coatings was carried out: metallographic analysis, measurement of thickness, micro-hardness, adhesion, resistance to thermal cyclic loading and adhesive wear resistance (pin-on-disk test). One thermal cycle consisted of heating the coatings to 600°C, dwell for 10 minutes, and subsequently cooling on the still air. The number of thermal cycles: 10. The base material was stainless steel AISI 316L, pretreatment prior to application of the coating: blasting with white corundum, application device JP-5000.